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• ffmpeg specify image start/end time by seconds in slideshow

  31 décembre 2022, par Martin

  I have an ffmpeg command that when ran on command prompt in win10, will combine 2 mp3 files and 1 image file into a low resolution .mkv video file.

  


  06:23 = 383 = song1.mp3 length
05:40 = 340 = song2.mp3 length
12:03 = 723 = estimated total video length
12:04 = 724 = actual video length


  


  Command that generates video file :

  


  ffmpeg -loop 1 -framerate 2 -i images/img1.png  -i "audio files/song1.mp3"  -i "audio files/song2.mp3"  -c:a pcm_s32le  -filter_complex concat=n=2:v=0:a=1  -vcodec libx264  -bufsize 3M  -filter:v "scale=w=640:h=638,pad=ceil(iw/2)*2:ceil(ih/2)*2"  -crf 18  -pix_fmt yuv420p  -shortest  -tune stillimage  -t 724 audioAndImageIntoVideo.mkv 


  


  The current command just uses -i images/img1.png as a static image for the entire video. But I want to have one image for the duration of the first song, and a second image for the duration of the second song. With a timeline like so :

  


  song1.mp3 and img1.png start at 00:00 and end at 06:23 ( 383 seconds )
song2.mp3 and img2.png start at 06:23 ( 383 seconds ) and end at 12:03 ( 723 seconds )


  


  is there any flag to specify the timeline of two images ? Right now I am just trying to get them in order in a video, and then I can change the individual img resolution / size / stretching details for how it fills the frame

  


• Processing video frame by frame in AWS Lambda with Node.js and FFmpeg [closed]

  29 décembre 2023, par Aviato

  I am working on a project where I need to process video frames one at a time in an AWS Lambda function using Node.js. My goal is to avoid storing all frames in memory or the filesystem due to resource constraints. I plan to use the fluent-ffmpeg library or ffmpeg from child processes for video processing.

  


  In the past, I used OpenCV to process videos and frames without writing the frames on the disk or storing all the frames at once on the memory itself. But now as I am using node js, its a little hard to set up the code using ffmpeg, etc.

  


  Here is a small snippet from what I did with opencv :-

  


  import cv2

cap = cv2.VideoCapture(video_file)

out = cv2.VideoWriter('output.mp4', fourcc, fps, (width, height))

def generate_frame():
        while cap.isOpened():
            code, frame = cap.read()
            if code:
                yield frame
            else:
                print("completed")
                break

for i, frame in enumerate(generate_frame()):
          # Now we can process the video frames directly and write them on the output opencv
          out.write(editing_frames)


  


  Additionally, I intend to leverage image processing libraries like Sharp and the Canvas API to edit individual frames before assembling the final video. I am looking for help in handling video frames efficiently within the constraints of AWS Lambda.

  


  Any insights, code snippets, or recommendations would be greatly appreciated. Thank you !

  


• Is there a faster way to generate video from pixel arrays using python and ffmpeg ?

  8 mai 2019, par devneal17

  I’ve found a few sources which use python and ffmpeg to generate video from pixel arrays by passing the -f rawvideo flag 1 2. However, this is very slow for high-definition video since each individual pixel must be piped into ffmpeg.

  In fact this is provably wasteful, as I’ve found that 2.5Gb of pixel arrays generates about 80Kb of video. I’ve also chanced upon some examples where javascript can render high quality animations in near-real time 1, which makes me even more suspicious that I’m doing something wrong.

  Is there a way to do this more efficiently, perhaps by piping the differences between pixel arrays into ffmpeg rather than the pixels themselves ?

  (edit) This is the line I’m using. Most executions take the else path that follows.