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• My stitched frames colors looks very different from my original video, causing my video to not be able to stitch it back properly [closed]

  27 mai 2024, par Wer Wer

  I am trying to extract some frames off my video to do some form of steganography. I accidentally used a 120fps video, causing the files to be too big when i extract every single frame. To fix this, I decided to calculate how many frames is needed to hide the bits (LSB replacement for every 8 bit) and then extract only certain amount of frames. This means

  


  

  1. if i only need 1 frame, ill extract frame0.png

  


  2. ill remove frame0 from the original video

  


  3. encode my data into frame0.png

  


  4. stitch frame0 back into ffv1 video

  


  5. concatenate frame0 video to the rest of the video, frame0 video in front.

  


  


  I can do extraction and remove frame0 from the video. However, when looking at frame0.mkv and the original.mkv, i realised the colors seemed to be different.
Frame0.mkv
original.mkv

  


  This causes a glitch during the stitching of videos together, where the end of the video has some corrupted pixels. Not only that, it stops the video at where frame0 ends. I think those corrupted pixels were supposed to be original.mkv pixels, but they did not concatenate properly.
results.mkv

  


  I use an ffmpeg sub command to extract frames and stitch them

  


      def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)



  


  This code splits the video into the required number of frames. It checks if the total amount of frame bits is enough to encode the hidden text

  


  def remove_frames_from_video(self, input_video, frames_to_remove):
    if not input_video.endswith(".mkv"):
        input_video += ".mkv"

    input_video_path = os.path.join(self.here, input_video)

    # Create a filter string to exclude specific frames
    filter_str = (
        "select='not("
        + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
        + ")',setpts=N/FRAME_RATE/TB"
    )

    # Temporary output video path
    output_video_path = os.path.join(self.here, "temp_output.mkv")

    command = [
        "ffmpeg",
        "-y",
        "-i",
        input_video_path,
        "-vf",
        filter_str,
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        "-an",  # Remove audio
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Frames removed. Temporary video created at {output_video_path}")

        # Replace the original video with the new video
        os.replace(output_video_path, input_video_path)
        print(f"Original video replaced with updated video at {input_video_path}")

        # Re-add the trimmed audio to the new video
        self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")
        if os.path.exists(output_video_path):
            os.remove(output_video_path)

def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
    # Calculate the new duration based on the remaining frames
    fps = 60  # Assuming the framerate is 60 fps
    total_frames_removed = len(frames_to_remove)
    original_duration = self.get_video_duration(video_path)
    new_duration = original_duration - (total_frames_removed / fps)

    # Extract and trim the audio
    audio_path = os.path.join(self.here, "trimmed_audio.aac")
    command_extract_trim = [
        "ffmpeg",
        "-y",
        "-i",
        video_path,
        "-t",
        str(new_duration),
        "-q:a",
        "0",
        "-map",
        "a",
        audio_path,
    ]
    try:
        subprocess.run(command_extract_trim, check=True)
        print(f"Audio successfully trimmed and extracted to {audio_path}")

        # Add the trimmed audio back to the video
        final_video_path = video_path.replace(".mkv", "_final.mkv")
        command_add_audio = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-i",
            audio_path,
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_video_path,
        ]
        subprocess.run(command_add_audio, check=True)
        print(f"Final video with trimmed audio created at {final_video_path}")

        # Replace the original video with the final video
        os.replace(final_video_path, video_path)
        print(f"Original video replaced with final video at {video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")

def get_video_duration(self, video_path):
    command = [
        "ffprobe",
        "-v",
        "error",
        "-show_entries",
        "format=duration",
        "-of",
        "default=noprint_wrappers=1:nokey=1",
        video_path,
    ]
    try:
        result = subprocess.run(
            command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
        )
        duration = float(result.stdout.decode().strip())
        return duration
    except subprocess.CalledProcessError as e:
        print(f"An error occurred while getting video duration: {e}")
        return 0.0


  


  here ill remove all the frames that has been extracted from the video

  


  def stitch_frames_to_video(self, ffv1_video, framerate=60):
    # this command is another ffmpeg subcommand.
    # it takes every single frame from data1 directory and stitch it back into a ffv1 video
    if not ffv1_video.endswith(".mkv"):
        ffv1_video += ".mkv"

    output_video_path = os.path.join(self.here, ffv1_video)

    command = [
        "ffmpeg",
        "-y",
        "-framerate",
        str(framerate),
        "-i",
        os.path.join(self.frames_directory, "frame%d.png"),
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Video successfully created at {output_video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  after encoding the frames, ill try to stitch the frames back into ffv1 video

  


  def concatenate_videos(self, video1_path, video2_path, output_path):
    if not video1_path.endswith(".mkv"):
        video1_path += ".mkv"
    if not video2_path.endswith(".mkv"):
        video2_path += ".mkv"
    if not output_path.endswith(".mkv"):
        output_path += ".mkv"

    video1_path = os.path.join(self.here, video1_path)
    video2_path = os.path.join(self.here, video2_path)
    output_video_path = os.path.join(self.here, output_path)

    # Create a text file with the paths of the videos to concatenate
    concat_list_path = os.path.join(self.here, "concat_list.txt")
    with open(concat_list_path, "w") as f:
        f.write(f"file '{video1_path}'\n")
        f.write(f"file '{video2_path}'\n")

    command = [
        "ffmpeg",
        "-y",
        "-f",
        "concat",
        "-safe",
        "0",
        "-i",
        concat_list_path,
        "-c",
        "copy",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Videos successfully concatenated into {output_video_path}")
        os.remove(concat_list_path)  # Clean up the temporary file
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  now i try to concatenate the frames video with the original video, but it is corrupting as the colors are different.

  


  this code does the other processing by removing all the extracted frames from the video, as well as trimming the audio (but i think ill be removing the audio trimming as i realised it is not needed at all)

  


  I think its because .png frames will lose colors when they get extracted out. The only work around I know is to extract every single frame. But this causes the program to run too long as for a 12 second video, I will extract 700++ frames. Is there a way to fix this ?

  


  my full code

  


  import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


class FFV1Steganography:
    def __init__(self):
        self.here = os.path.dirname(os.path.abspath(__file__))

        # Create a folder to save the frames
        self.frames_directory = os.path.join(self.here, "data")
        try:
            if not os.path.exists(self.frames_directory):
                os.makedirs(self.frames_directory)
        except OSError:
            print("Error: Creating directory of data")

    def read_hidden_text(self, filename):
        file_path_txt = os.path.join(self.here, filename)
        # Read the content of the file in binary mode
        with open(file_path_txt, "rb") as f:
            hidden_text_content = f.read()
        return hidden_text_content

    def calculate_length_of_hidden_text(self, filename):
        hidden_text_content = self.read_hidden_text(filename)
        # Convert each byte to its binary representation and join them
        return len("".join(format(byte, "08b") for byte in hidden_text_content))

    def find_raw_video_file(self, filename):
        file_extensions = [".mp4", ".mkv", ".avi"]
        for ext in file_extensions:
            file_path = os.path.join(self.here, filename + ext)
            if os.path.isfile(file_path):
                return file_path
        return None

    def convert_video(self, input_file, ffv1_video):
        # this function is the same as running this command line
        # ffmpeg -i video.mp4 -t 12 -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 -slices 4 -slicecrc 1 -c:a copy output.mkv

        # in order to run any ffmpeg subprocess, you have to have ffmpeg installed into the computer.
        # https://ffmpeg.org/download.html

        # WARNING:
        # the ffmpeg you should download is not the same as the ffmpeg library for python.
        # you need to download the exe from the link above, then add ffmpeg bin directory to system variables
        output_file = os.path.join(self.here, ffv1_video)

        if not output_file.endswith(".mkv"):
            output_file += ".mkv"

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_file,
            "-t",
            "12",
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-c:a",
            "copy",
            output_file,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Conversion successful: {output_file}")
            return output_file
        except subprocess.CalledProcessError as e:
            print(f"Error during conversion: {e}")

    def extract_audio(self, ffv1_video, audio_path):
        # Ensure the audio output file has the correct extension
        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        # Full path to the extracted audio file
        extracted_audio = os.path.join(self.here, audio_path)

        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        command = [
            "ffmpeg",
            "-i",
            ffv1_video,
            "-q:a",
            "0",
            "-map",
            "a",
            extracted_audio,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            print(f"Audio successfully extracted to {extracted_audio}")
            print(result.stdout.decode())
            print(result.stderr.decode())
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            print(e.stdout.decode())
            print(e.stderr.decode())

    def read_frame_binary(self, frame_path):
        # Open the image and convert to binary
        with open(frame_path, "rb") as f:
            binary_content = f.read()
            binary_string = "".join(format(byte, "08b") for byte in binary_content)
        return binary_string

    def remove_frames_from_video(self, input_video, frames_to_remove):
        if not input_video.endswith(".mkv"):
            input_video += ".mkv"

        input_video_path = os.path.join(self.here, input_video)

        # Create a filter string to exclude specific frames
        filter_str = (
            "select='not("
            + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
            + ")',setpts=N/FRAME_RATE/TB"
        )

        # Temporary output video path
        output_video_path = os.path.join(self.here, "temp_output.mkv")

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_video_path,
            "-vf",
            filter_str,
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-an",  # Remove audio
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Frames removed. Temporary video created at {output_video_path}")

            # Replace the original video with the new video
            os.replace(output_video_path, input_video_path)
            print(f"Original video replaced with updated video at {input_video_path}")

            # Re-add the trimmed audio to the new video
            self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            if os.path.exists(output_video_path):
                os.remove(output_video_path)

    def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
        # Calculate the new duration based on the remaining frames
        fps = 60  # Assuming the framerate is 60 fps
        total_frames_removed = len(frames_to_remove)
        original_duration = self.get_video_duration(video_path)
        new_duration = original_duration - (total_frames_removed / fps)

        # Extract and trim the audio
        audio_path = os.path.join(self.here, "trimmed_audio.aac")
        command_extract_trim = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-t",
            str(new_duration),
            "-q:a",
            "0",
            "-map",
            "a",
            audio_path,
        ]
        try:
            subprocess.run(command_extract_trim, check=True)
            print(f"Audio successfully trimmed and extracted to {audio_path}")

            # Add the trimmed audio back to the video
            final_video_path = video_path.replace(".mkv", "_final.mkv")
            command_add_audio = [
                "ffmpeg",
                "-y",
                "-i",
                video_path,
                "-i",
                audio_path,
                "-c:v",
                "copy",
                "-c:a",
                "aac",
                "-strict",
                "experimental",
                final_video_path,
            ]
            subprocess.run(command_add_audio, check=True)
            print(f"Final video with trimmed audio created at {final_video_path}")

            # Replace the original video with the final video
            os.replace(final_video_path, video_path)
            print(f"Original video replaced with final video at {video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def get_video_duration(self, video_path):
        command = [
            "ffprobe",
            "-v",
            "error",
            "-show_entries",
            "format=duration",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            video_path,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            duration = float(result.stdout.decode().strip())
            return duration
        except subprocess.CalledProcessError as e:
            print(f"An error occurred while getting video duration: {e}")
            return 0.0

    def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)

    def stitch_frames_to_video(self, ffv1_video, framerate=60):
        # this command is another ffmpeg subcommand.
        # it takes every single frame from data1 directory and stitch it back into a ffv1 video
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        output_video_path = os.path.join(self.here, ffv1_video)

        command = [
            "ffmpeg",
            "-y",
            "-framerate",
            str(framerate),
            "-i",
            os.path.join(self.frames_directory, "frame%d.png"),
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Video successfully created at {output_video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def add_audio_to_video(self, encoded_video, audio_path, final_video):
        # the audio will be lost during splitting and restitching.
        # that is why previously we separated the audio from video and saved it as aac.
        # now, we can put the audio back into the video, again using ffmpeg subcommand.

        if not encoded_video.endswith(".mkv"):
            encoded_video += ".mkv"

        if not final_video.endswith(".mkv"):
            final_video += ".mkv"

        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        final_output_path = os.path.join(self.here, final_video)

        command = [
            "ffmpeg",
            "-y",
            "-i",
            os.path.join(self.here, encoded_video),
            "-i",
            os.path.join(self.here, audio_path),
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_output_path,
        ]
        try:
            subprocess.run(command, check=True)
            print(f"Final video with audio created at {final_output_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def concatenate_videos(self, video1_path, video2_path, output_path):
        if not video1_path.endswith(".mkv"):
            video1_path += ".mkv"
        if not video2_path.endswith(".mkv"):
            video2_path += ".mkv"
        if not output_path.endswith(".mkv"):
            output_path += ".mkv"

        video1_path = os.path.join(self.here, video1_path)
        video2_path = os.path.join(self.here, video2_path)
        output_video_path = os.path.join(self.here, output_path)

        # Create a text file with the paths of the videos to concatenate
        concat_list_path = os.path.join(self.here, "concat_list.txt")
        with open(concat_list_path, "w") as f:
            f.write(f"file '{video1_path}'\n")
            f.write(f"file '{video2_path}'\n")

        command = [
            "ffmpeg",
            "-y",
            "-f",
            "concat",
            "-safe",
            "0",
            "-i",
            concat_list_path,
            "-c",
            "copy",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Videos successfully concatenated into {output_video_path}")
            os.remove(concat_list_path)  # Clean up the temporary file
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def cleanup(self, files_to_delete):
        # Delete specified files
        for file in files_to_delete:
            file_path = os.path.join(self.here, file)
            if os.path.exists(file_path):
                os.remove(file_path)
                print(f"Deleted file: {file_path}")
            else:
                print(f"File not found: {file_path}")

        # Delete the frames directory and its contents
        if os.path.exists(self.frames_directory):
            shutil.rmtree(self.frames_directory)
            print(f"Deleted directory and its contents: {self.frames_directory}")
        else:
            print(f"Directory not found: {self.frames_directory}")


if __name__ == "__main__":
    stego = FFV1Steganography()

    # original video (mp4,mkv,avi)
    original_video = "video"
    # converted ffv1 video
    ffv1_video = "output"
    # extracted audio
    extracted_audio = "audio"
    # encoded video without sound
    encoded_video = "encoded"
    # final result video, encoded, with sound
    final_video = "result"

    # region --hidden text processing --
    hidden_text = stego.read_hidden_text("hiddentext.txt")
    hidden_text_length = stego.calculate_length_of_hidden_text("hiddentext.txt")
    # endregion

    # region -- raw video locating --
    raw_video_file = stego.find_raw_video_file(original_video)
    if raw_video_file:
        print(f"Found video file: {raw_video_file}")
    else:
        print("video.mp4 not found.")
    # endregion

    # region -- video processing INPUT--
    # converted_video_file = stego.convert_video(raw_video_file, ffv1_video)
    # if converted_video_file and os.path.exists(converted_video_file):
    #     stego.extract_audio(converted_video_file, extracted_audio)
    # else:
    #     print(f"Conversion failed: {converted_video_file} not found.")

    # stego.split_into_frames(ffv1_video, hidden_text_length * 50000)
    # endregion

    # region -- video processing RESULT --
    # stego.stitch_frames_to_video(encoded_video)
    stego.concatenate_videos(encoded_video, ffv1_video, final_video)
    # stego.add_audio_to_video(final_video, extracted_audio, final_video)
    # endregion

    # region -- cleanup --
    files_to_delete = [
        extracted_audio + ".aac",
        encoded_video + ".mkv",
        ffv1_video + ".mkv",
    ]

 stego.cleanup(files_to_delete)
    # endregion







  


  Edit for results expectations :
I dont know if there is a way to match the exact color encoding between the stitched png frames and the rest of the ffv1 video. Is there a way I can extract the frames such that the color, encoding or anything I may not know about ffv1 match the original ffv1 video ?

  


• FFMPEG My stitched frames colors looks very different from my original video, causing my video to not be able to stitch it back properly

  26 mai 2024, par Wer Wer

  I am trying to extract some frames off my video to do some form of steganography. I accidentally used a 120fps video, causing the files to be too big when i extract every single frame. To fix this, I decided to calculate how many frames is needed to hide the bits (LSB replacement for every 8 bit) and then extract only certain amount of frames. This means

  


  

  1. if i only need 1 frame, ill extract frame0.png

  


  2. ill remove frame0 from the original video

  


  3. encode my data into frame0.png

  


  4. stitch frame0 back into ffv1 video

  


  5. concatenate frame0 video to the rest of the video, frame0 video in front.

  


  


  I can do extraction and remove frame0 from the video. However, when looking at frame0.mkv and the original.mkv, i realised the colors seemed to be different.
Frame0.mkv
original.mkv

  


  This causes a glitch during the stitching of videos together, where the end of the video has some corrupted pixels. Not only that, it stops the video at where frame0 ends. I think those corrupted pixels were supposed to be original.mkv pixels, but they did not concatenate properly.
results.mkv

  


  I use an ffmpeg sub command to extract frames and stitch them

  


      def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)



  


  This code splits the video into the required number of frames. It checks if the total amount of frame bits is enough to encode the hidden text

  


  def remove_frames_from_video(self, input_video, frames_to_remove):
    if not input_video.endswith(".mkv"):
        input_video += ".mkv"

    input_video_path = os.path.join(self.here, input_video)

    # Create a filter string to exclude specific frames
    filter_str = (
        "select='not("
        + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
        + ")',setpts=N/FRAME_RATE/TB"
    )

    # Temporary output video path
    output_video_path = os.path.join(self.here, "temp_output.mkv")

    command = [
        "ffmpeg",
        "-y",
        "-i",
        input_video_path,
        "-vf",
        filter_str,
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        "-an",  # Remove audio
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Frames removed. Temporary video created at {output_video_path}")

        # Replace the original video with the new video
        os.replace(output_video_path, input_video_path)
        print(f"Original video replaced with updated video at {input_video_path}")

        # Re-add the trimmed audio to the new video
        self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")
        if os.path.exists(output_video_path):
            os.remove(output_video_path)

def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
    # Calculate the new duration based on the remaining frames
    fps = 60  # Assuming the framerate is 60 fps
    total_frames_removed = len(frames_to_remove)
    original_duration = self.get_video_duration(video_path)
    new_duration = original_duration - (total_frames_removed / fps)

    # Extract and trim the audio
    audio_path = os.path.join(self.here, "trimmed_audio.aac")
    command_extract_trim = [
        "ffmpeg",
        "-y",
        "-i",
        video_path,
        "-t",
        str(new_duration),
        "-q:a",
        "0",
        "-map",
        "a",
        audio_path,
    ]
    try:
        subprocess.run(command_extract_trim, check=True)
        print(f"Audio successfully trimmed and extracted to {audio_path}")

        # Add the trimmed audio back to the video
        final_video_path = video_path.replace(".mkv", "_final.mkv")
        command_add_audio = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-i",
            audio_path,
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_video_path,
        ]
        subprocess.run(command_add_audio, check=True)
        print(f"Final video with trimmed audio created at {final_video_path}")

        # Replace the original video with the final video
        os.replace(final_video_path, video_path)
        print(f"Original video replaced with final video at {video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")

def get_video_duration(self, video_path):
    command = [
        "ffprobe",
        "-v",
        "error",
        "-show_entries",
        "format=duration",
        "-of",
        "default=noprint_wrappers=1:nokey=1",
        video_path,
    ]
    try:
        result = subprocess.run(
            command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
        )
        duration = float(result.stdout.decode().strip())
        return duration
    except subprocess.CalledProcessError as e:
        print(f"An error occurred while getting video duration: {e}")
        return 0.0


  


  here ill remove all the frames that has been extracted from the video

  


  def stitch_frames_to_video(self, ffv1_video, framerate=60):
    # this command is another ffmpeg subcommand.
    # it takes every single frame from data1 directory and stitch it back into a ffv1 video
    if not ffv1_video.endswith(".mkv"):
        ffv1_video += ".mkv"

    output_video_path = os.path.join(self.here, ffv1_video)

    command = [
        "ffmpeg",
        "-y",
        "-framerate",
        str(framerate),
        "-i",
        os.path.join(self.frames_directory, "frame%d.png"),
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Video successfully created at {output_video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  after encoding the frames, ill try to stitch the frames back into ffv1 video

  


  def concatenate_videos(self, video1_path, video2_path, output_path):
    if not video1_path.endswith(".mkv"):
        video1_path += ".mkv"
    if not video2_path.endswith(".mkv"):
        video2_path += ".mkv"
    if not output_path.endswith(".mkv"):
        output_path += ".mkv"

    video1_path = os.path.join(self.here, video1_path)
    video2_path = os.path.join(self.here, video2_path)
    output_video_path = os.path.join(self.here, output_path)

    # Create a text file with the paths of the videos to concatenate
    concat_list_path = os.path.join(self.here, "concat_list.txt")
    with open(concat_list_path, "w") as f:
        f.write(f"file '{video1_path}'\n")
        f.write(f"file '{video2_path}'\n")

    command = [
        "ffmpeg",
        "-y",
        "-f",
        "concat",
        "-safe",
        "0",
        "-i",
        concat_list_path,
        "-c",
        "copy",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Videos successfully concatenated into {output_video_path}")
        os.remove(concat_list_path)  # Clean up the temporary file
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  now i try to concatenate the frames video with the original video, but it is corrupting as the colors are different.

  


  this code does the other processing by removing all the extracted frames from the video, as well as trimming the audio (but i think ill be removing the audio trimming as i realised it is not needed at all)

  


  I think its because .png frames will lose colors when they get extracted out. The only work around I know is to extract every single frame. But this causes the program to run too long as for a 12 second video, I will extract 700++ frames. Is there a way to fix this ?

  


  my full code

  


  import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


class FFV1Steganography:
    def __init__(self):
        self.here = os.path.dirname(os.path.abspath(__file__))

        # Create a folder to save the frames
        self.frames_directory = os.path.join(self.here, "data")
        try:
            if not os.path.exists(self.frames_directory):
                os.makedirs(self.frames_directory)
        except OSError:
            print("Error: Creating directory of data")

    def read_hidden_text(self, filename):
        file_path_txt = os.path.join(self.here, filename)
        # Read the content of the file in binary mode
        with open(file_path_txt, "rb") as f:
            hidden_text_content = f.read()
        return hidden_text_content

    def calculate_length_of_hidden_text(self, filename):
        hidden_text_content = self.read_hidden_text(filename)
        # Convert each byte to its binary representation and join them
        return len("".join(format(byte, "08b") for byte in hidden_text_content))

    def find_raw_video_file(self, filename):
        file_extensions = [".mp4", ".mkv", ".avi"]
        for ext in file_extensions:
            file_path = os.path.join(self.here, filename + ext)
            if os.path.isfile(file_path):
                return file_path
        return None

    def convert_video(self, input_file, ffv1_video):
        # this function is the same as running this command line
        # ffmpeg -i video.mp4 -t 12 -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 -slices 4 -slicecrc 1 -c:a copy output.mkv

        # in order to run any ffmpeg subprocess, you have to have ffmpeg installed into the computer.
        # https://ffmpeg.org/download.html

        # WARNING:
        # the ffmpeg you should download is not the same as the ffmpeg library for python.
        # you need to download the exe from the link above, then add ffmpeg bin directory to system variables
        output_file = os.path.join(self.here, ffv1_video)

        if not output_file.endswith(".mkv"):
            output_file += ".mkv"

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_file,
            "-t",
            "12",
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-c:a",
            "copy",
            output_file,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Conversion successful: {output_file}")
            return output_file
        except subprocess.CalledProcessError as e:
            print(f"Error during conversion: {e}")

    def extract_audio(self, ffv1_video, audio_path):
        # Ensure the audio output file has the correct extension
        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        # Full path to the extracted audio file
        extracted_audio = os.path.join(self.here, audio_path)

        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        command = [
            "ffmpeg",
            "-i",
            ffv1_video,
            "-q:a",
            "0",
            "-map",
            "a",
            extracted_audio,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            print(f"Audio successfully extracted to {extracted_audio}")
            print(result.stdout.decode())
            print(result.stderr.decode())
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            print(e.stdout.decode())
            print(e.stderr.decode())

    def read_frame_binary(self, frame_path):
        # Open the image and convert to binary
        with open(frame_path, "rb") as f:
            binary_content = f.read()
            binary_string = "".join(format(byte, "08b") for byte in binary_content)
        return binary_string

    def remove_frames_from_video(self, input_video, frames_to_remove):
        if not input_video.endswith(".mkv"):
            input_video += ".mkv"

        input_video_path = os.path.join(self.here, input_video)

        # Create a filter string to exclude specific frames
        filter_str = (
            "select='not("
            + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
            + ")',setpts=N/FRAME_RATE/TB"
        )

        # Temporary output video path
        output_video_path = os.path.join(self.here, "temp_output.mkv")

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_video_path,
            "-vf",
            filter_str,
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-an",  # Remove audio
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Frames removed. Temporary video created at {output_video_path}")

            # Replace the original video with the new video
            os.replace(output_video_path, input_video_path)
            print(f"Original video replaced with updated video at {input_video_path}")

            # Re-add the trimmed audio to the new video
            self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            if os.path.exists(output_video_path):
                os.remove(output_video_path)

    def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
        # Calculate the new duration based on the remaining frames
        fps = 60  # Assuming the framerate is 60 fps
        total_frames_removed = len(frames_to_remove)
        original_duration = self.get_video_duration(video_path)
        new_duration = original_duration - (total_frames_removed / fps)

        # Extract and trim the audio
        audio_path = os.path.join(self.here, "trimmed_audio.aac")
        command_extract_trim = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-t",
            str(new_duration),
            "-q:a",
            "0",
            "-map",
            "a",
            audio_path,
        ]
        try:
            subprocess.run(command_extract_trim, check=True)
            print(f"Audio successfully trimmed and extracted to {audio_path}")

            # Add the trimmed audio back to the video
            final_video_path = video_path.replace(".mkv", "_final.mkv")
            command_add_audio = [
                "ffmpeg",
                "-y",
                "-i",
                video_path,
                "-i",
                audio_path,
                "-c:v",
                "copy",
                "-c:a",
                "aac",
                "-strict",
                "experimental",
                final_video_path,
            ]
            subprocess.run(command_add_audio, check=True)
            print(f"Final video with trimmed audio created at {final_video_path}")

            # Replace the original video with the final video
            os.replace(final_video_path, video_path)
            print(f"Original video replaced with final video at {video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def get_video_duration(self, video_path):
        command = [
            "ffprobe",
            "-v",
            "error",
            "-show_entries",
            "format=duration",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            video_path,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            duration = float(result.stdout.decode().strip())
            return duration
        except subprocess.CalledProcessError as e:
            print(f"An error occurred while getting video duration: {e}")
            return 0.0

    def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)

    def stitch_frames_to_video(self, ffv1_video, framerate=60):
        # this command is another ffmpeg subcommand.
        # it takes every single frame from data1 directory and stitch it back into a ffv1 video
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        output_video_path = os.path.join(self.here, ffv1_video)

        command = [
            "ffmpeg",
            "-y",
            "-framerate",
            str(framerate),
            "-i",
            os.path.join(self.frames_directory, "frame%d.png"),
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Video successfully created at {output_video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def add_audio_to_video(self, encoded_video, audio_path, final_video):
        # the audio will be lost during splitting and restitching.
        # that is why previously we separated the audio from video and saved it as aac.
        # now, we can put the audio back into the video, again using ffmpeg subcommand.

        if not encoded_video.endswith(".mkv"):
            encoded_video += ".mkv"

        if not final_video.endswith(".mkv"):
            final_video += ".mkv"

        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        final_output_path = os.path.join(self.here, final_video)

        command = [
            "ffmpeg",
            "-y",
            "-i",
            os.path.join(self.here, encoded_video),
            "-i",
            os.path.join(self.here, audio_path),
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_output_path,
        ]
        try:
            subprocess.run(command, check=True)
            print(f"Final video with audio created at {final_output_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def concatenate_videos(self, video1_path, video2_path, output_path):
        if not video1_path.endswith(".mkv"):
            video1_path += ".mkv"
        if not video2_path.endswith(".mkv"):
            video2_path += ".mkv"
        if not output_path.endswith(".mkv"):
            output_path += ".mkv"

        video1_path = os.path.join(self.here, video1_path)
        video2_path = os.path.join(self.here, video2_path)
        output_video_path = os.path.join(self.here, output_path)

        # Create a text file with the paths of the videos to concatenate
        concat_list_path = os.path.join(self.here, "concat_list.txt")
        with open(concat_list_path, "w") as f:
            f.write(f"file '{video1_path}'\n")
            f.write(f"file '{video2_path}'\n")

        command = [
            "ffmpeg",
            "-y",
            "-f",
            "concat",
            "-safe",
            "0",
            "-i",
            concat_list_path,
            "-c",
            "copy",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Videos successfully concatenated into {output_video_path}")
            os.remove(concat_list_path)  # Clean up the temporary file
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def cleanup(self, files_to_delete):
        # Delete specified files
        for file in files_to_delete:
            file_path = os.path.join(self.here, file)
            if os.path.exists(file_path):
                os.remove(file_path)
                print(f"Deleted file: {file_path}")
            else:
                print(f"File not found: {file_path}")

        # Delete the frames directory and its contents
        if os.path.exists(self.frames_directory):
            shutil.rmtree(self.frames_directory)
            print(f"Deleted directory and its contents: {self.frames_directory}")
        else:
            print(f"Directory not found: {self.frames_directory}")


if __name__ == "__main__":
    stego = FFV1Steganography()

    # original video (mp4,mkv,avi)
    original_video = "video"
    # converted ffv1 video
    ffv1_video = "output"
    # extracted audio
    extracted_audio = "audio"
    # encoded video without sound
    encoded_video = "encoded"
    # final result video, encoded, with sound
    final_video = "result"

    # region --hidden text processing --
    hidden_text = stego.read_hidden_text("hiddentext.txt")
    hidden_text_length = stego.calculate_length_of_hidden_text("hiddentext.txt")
    # endregion

    # region -- raw video locating --
    raw_video_file = stego.find_raw_video_file(original_video)
    if raw_video_file:
        print(f"Found video file: {raw_video_file}")
    else:
        print("video.mp4 not found.")
    # endregion

    # region -- video processing INPUT--
    # converted_video_file = stego.convert_video(raw_video_file, ffv1_video)
    # if converted_video_file and os.path.exists(converted_video_file):
    #     stego.extract_audio(converted_video_file, extracted_audio)
    # else:
    #     print(f"Conversion failed: {converted_video_file} not found.")

    # stego.split_into_frames(ffv1_video, hidden_text_length * 50000)
    # endregion

    # region -- video processing RESULT --
    # stego.stitch_frames_to_video(encoded_video)
    stego.concatenate_videos(encoded_video, ffv1_video, final_video)
    # stego.add_audio_to_video(final_video, extracted_audio, final_video)
    # endregion

    # region -- cleanup --
    files_to_delete = [
        extracted_audio + ".aac",
        encoded_video + ".mkv",
        ffv1_video + ".mkv",
    ]

 stego.cleanup(files_to_delete)
    # endregion







  


• When I use ffmpeg to go from a video to frames, and then back to video, the duration is different between the videos

  24 février 2024, par bluepanda

  I am trying to use ffmpeg to convert from a .mp4 (or .mov) video into individual frames, do some processing on those frames, and then convert back to .mp4. The problem is that the resulting video I create is a different duration than the input - I can see this visually when I play the two videos side by side. The difference is not large (i.e. 00:00:00.50 for the input video and 00:00:00.52 for the output video), but when the videos are looped next to each other they get out of sync.

  


  Here is information about the input video retrieved using fluent-ffmpeg's ffmpeg.ffprobe(videoPath) :

  


  metadata {
  streams: [
    {
      index: 0,
      codec_name: 'h264',
      codec_long_name: 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
      profile: 'High',
      codec_type: 'video',
      codec_tag_string: 'avc1',
      codec_tag: '0x31637661',
      width: 1080,
      height: 1920,
      coded_width: 1080,
      coded_height: 1920,
      closed_captions: 0,
      has_b_frames: 2,
      sample_aspect_ratio: 'N/A',
      display_aspect_ratio: 'N/A',
      pix_fmt: 'yuv420p',
      level: 40,
      color_range: 'tv',
      color_space: 'bt709',
      color_transfer: 'bt709',
      color_primaries: 'bt709',
      chroma_location: 'left',
      field_order: 'unknown',
      refs: 1,
      is_avc: 'true',
      nal_length_size: 4,
      id: 'N/A',
      r_frame_rate: '30000/1001',
      avg_frame_rate: '27000/1001',
      time_base: '1/30000',
      start_pts: 0,
      start_time: 0,
      duration_ts: 15100,
      duration: 0.503333,
      bit_rate: 5660223,
      max_bit_rate: 'N/A',
      bits_per_raw_sample: 8,
      nb_frames: 36,
      nb_read_frames: 'N/A',
      nb_read_packets: 'N/A',
      tags: [Object],
      disposition: [Object]
    },
    {
      index: 1,
      codec_name: 'aac',
      codec_long_name: 'AAC (Advanced Audio Coding)',
      profile: 'LC',
      codec_type: 'audio',
      codec_tag_string: 'mp4a',
      codec_tag: '0x6134706d',
      sample_fmt: 'fltp',
      sample_rate: 48000,
      channels: 2,
      channel_layout: 'stereo',
      bits_per_sample: 0,
      id: 'N/A',
      r_frame_rate: '0/0',
      avg_frame_rate: '0/0',
      time_base: '1/48000',
      start_pts: 0,
      start_time: 0,
      duration_ts: 24160,
      duration: 0.503333,
      bit_rate: 248416,
      max_bit_rate: 'N/A',
      bits_per_raw_sample: 'N/A',
      nb_frames: 27,
      nb_read_frames: 'N/A',
      nb_read_packets: 'N/A',
      tags: [Object],
      disposition: [Object]
    }
  ],
  format: {
    filename: '/Users/name/images/input.mp4',
    nb_streams: 2,
    nb_programs: 0,
    format_name: 'mov,mp4,m4a,3gp,3g2,mj2',
    format_long_name: 'QuickTime / MOV',
    start_time: 0,
    duration: 0.503333,
    size: 963879,
    bit_rate: 15319941,
    probe_score: 100,
    tags: {
      major_brand: 'mp42',
      minor_version: '1',
      compatible_brands: 'isommp41mp42',
      creation_time: '2024-02-14T01:21:12.000000Z'
    }
  },
  chapters: []
}


  


  and here is from running ffprobe directly :

  


  ffprobe '/Users/name/images/input.mp4'
ffprobe version 6.1.1 Copyright (c) 2007-2023 the FFmpeg developers
  built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58. 29.100 / 58. 29.100
  libavcodec     60. 31.102 / 60. 31.102
  libavformat    60. 16.100 / 60. 16.100
  libavdevice    60.  3.100 / 60.  3.100
  libavfilter     9. 12.100 /  9. 12.100
  libswscale      7.  5.100 /  7.  5.100
  libswresample   4. 12.100 /  4. 12.100
  libpostproc    57.  3.100 / 57.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/name/images/input.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: isommp41mp42
    creation_time   : 2024-02-14T01:21:12.000000Z
  Duration: 00:00:00.50, start: 0.000000, bitrate: 15319 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1080x1920, 5660 kb/s, 26.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2024-02-14T01:21:12.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 248 kb/s (default)
    Metadata:
      creation_time   : 2024-02-14T01:21:12.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]


  


  And this is my command to go from video to frames :

  


  ffmpeg -i /Users/name/images/input.mp4 -y -f image2 /Users/name/images/frames/%d.png


  


  After which I convert the frames back to video with this - note that I get by seeing avg_frame_rate is 27000/1001 = 26.97302697 :

  


  ffmpeg -r 26.973026973026972 -i /Users/name/images/frames/%d.png -y -r 26.973026973026972 -b:v 5660223k -f mp4 -pix_fmt yuv420p -t 0.503333 /Users/name/images/output.mp4


  


  And if I then run fluent-ffmpeg's ffmpeg.ffprobe(videoPath) I get :

  


  metadata {
  streams: [
    {
      index: 0,
      codec_name: 'h264',
      codec_long_name: 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
      profile: 'High',
      codec_type: 'video',
      codec_tag_string: 'avc1',
      codec_tag: '0x31637661',
      width: 1080,
      height: 1920,
      coded_width: 1080,
      coded_height: 1920,
      closed_captions: 0,
      has_b_frames: 2,
      sample_aspect_ratio: '1:1',
      display_aspect_ratio: '9:16',
      pix_fmt: 'yuv420p',
      level: 62,
      color_range: 'unknown',
      color_space: 'unknown',
      color_transfer: 'unknown',
      color_primaries: 'unknown',
      chroma_location: 'left',
      field_order: 'unknown',
      refs: 1,
      is_avc: 'true',
      nal_length_size: 4,
      id: 'N/A',
      r_frame_rate: '27000/1001',
      avg_frame_rate: '27000/1001',
      time_base: '1/27000',
      start_pts: 0,
      start_time: 0,
      duration_ts: 14014,
      duration: 0.519037,
      bit_rate: 52138429,
      max_bit_rate: 'N/A',
      bits_per_raw_sample: 8,
      nb_frames: 14,
      nb_read_frames: 'N/A',
      nb_read_packets: 'N/A',
      tags: [Object],
      disposition: [Object]
    }
  ],
  format: {
    filename: '/Users/name/images/output.mp4',
    nb_streams: 1,
    nb_programs: 0,
    format_name: 'mov,mp4,m4a,3gp,3g2,mj2',
    format_long_name: 'QuickTime / MOV',
    start_time: 0,
    duration: 0.52,
    size: 3383708,
    bit_rate: 52057046,
    probe_score: 100,
    tags: {
      major_brand: 'isom',
      minor_version: '512',
      compatible_brands: 'isomiso2avc1mp41',
      encoder: 'Lavf60.3.100'
    }
  },
  chapters: []
}


  


  and here is from running ffprobe directly :

  


  ffprobe '/Users/name/images/output.mp4'
ffprobe version 6.1.1 Copyright (c) 2007-2023 the FFmpeg developers
  built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      58. 29.100 / 58. 29.100
  libavcodec     60. 31.102 / 60. 31.102
  libavformat    60. 16.100 / 60. 16.100
  libavdevice    60.  3.100 / 60.  3.100
  libavfilter     9. 12.100 /  9. 12.100
  libswscale      7.  5.100 /  7.  5.100
  libswresample   4. 12.100 /  4. 12.100
  libpostproc    57.  3.100 / 57.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/name/images/output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.3.100
  Duration: 00:00:00.52, start: 0.000000, bitrate: 52153 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1080x1920 [SAR 1:1 DAR 9:16], 52138 kb/s, 26.97 fps, 26.97 tbr, 27k tbn (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.3.100 libx264


  


  This seems like it should be a fairly common scenario, but I have not been able to find examples of this, and the other questions about incorrect durations on Stack Overflow are about bigger differences (i.e. 3 seconds instead of 10 seconds : Wrong video duration when recording with ffmpeg).

  


  Some other details :

  


  

  • I am running this through a Node.js script with fluent-ffmpeg, but I have also tried running the commands directly in the terminal and the result is the same.

  


  • I am fine with the output frames being .png / .jpg / other formats.

  


  • I am fine with setting this to a different frame rate than the original as long as the two output videos end up with the same duration.

  


  • One suspicious thing is that I set -t 0.503333 when creating the video, but it doesn't seem to work as the result video shows duration: 0.519037 / 00:00:00.52.

  


  


  Thank you for any help !