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• FFMPEG low bitrate at starting frames

  21 janvier 2018, par Y. T

  So I noticed that the first 1-4s of the videos that I’m converting start with a low bitrate and gradually increase untill its around the specified bitrate (-crf 17 -minrate 2000k -maxrate 3000k -bufsize 2000k).

  ...
  
  frame= 37 fps= 0.0 q=24.0 size = 113kB time=00:00:02.08 bitrate= 443.5kbits/s
  
  frame= 66 fps= 64 q=30.0 size = 619kB time=00:00:03.20 bitrate= 1581.6kbits/s
  
  frame= 99 fps= 64 q=28.0 size = 1106kB time=00:00:04.52 bitrate= 2002.2kbits/s
  
  frame= 131 fps= 63 q=23.0 size = 1599kB time=00:00:05.82 bitrate= 2247.8kbits/s
  
  ...

  I already tried changing several settings like -crf, -b:v, -minrate, -maxrate and -bufsize. From my trial-and-error experience, the lower the -crf / higher -b:v, the faster it reaches an appropriate bitrate, but it still has this "lagg" in the beginning of the conversion.

  Is it possible to immediately start with, for example 2000kbits/s, at the start of the conversion ?

  EDIT

  Around the first 1-30s (roughly), the clips are more pixelated than the rest of the clip. See this image for a comparison (zoomed in on area of an 1080p clip). The rest of the clip doesn’t have any visible loss like this (1850kbps encoded vs 2000kbps original), so I still assume it has something to do with the start of the encoding.

• FFmpeg producing a flickering video from images

  21 juin 2018, par jjohnn91

  So I’m trying to make a video of a fractal rotating through some values, much like seen here.

  I generate the frames (1000 of them) using a different program written in Java that works just fine, so for the purposes of this scenario assume that all the images are in the target folder and also in numerical order as they need to appear in the video.

  I found the following code on the web to stitch images into a video, and I haven’t the faintest idea how it works, and when I run it, all of the images are indeed stitched into a video and placed on the desktop, but the video appears to have one specific frame just jump in at random positions. I’m not totally sure which one, but its one of the earlier frames, somewhere between 1 and 200 of the 1000.

  I’ve also tested making two half videos, one using the first 500 frames, and the other using the second 500 frames. The first video (1 -> 500) has flickering, and the second video (501 -> 1000) appears not to have flickering to my observations.

  I am seeking help in fixing the flickering behavior, and I will upload the video file to google drive later if asked. The Images are all 1920x1080, and in proper numerical order.

  Thanks in advance !

  import static org.bytedeco.javacpp.opencv_imgcodecs.*;
  
  import java.io.File; 
  
  import org.bytedeco.javacpp.avcodec;
  
  import org.bytedeco.javacv.FFmpegFrameRecorder;
  
  import org.bytedeco.javacv.OpenCVFrameConverter;
  
  public class ImageToMovie{
  
      public static void main(String []args){
  
          String imgPath="C:\\Users\\John\\Images";
  
          String vidPath="C:\\Users\\John\\Desktop\\video.mp4";
  
          String[] links=new String[new File(imgPath).listFiles().length];
  
          File f=new File(imgPath);
  
          File[] f2=f.listFiles();
  
          for(int i=0;icode>

• Replace Special Characters In Batch-File Variable Feeding FFMPEG Programme

  6 janvier 2019, par whereswaller

  I am attempting to write a batch-file that leverages the FFMPEG programme to convert all files in a folder structure to mp3 format (specifically 128kbps).

  My batch-file is presently unable to process filenames (constructed by concatenating the %_SOURCE% and %% F variables) containing certain special characters, for example :

  ’
   
  "
  ö

  How can I modify my script so that the %% F variable escapes these characters correctly ?

  Example current filename input : "C :\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don’t Love Me.mp3"

  Example desired filename input : "C :\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don"^’"t Love Me.mp3"

  Script (see line beginning "C :\ffmpeg\bin\ffmpeg.exe") :

  @echo off
  
  setlocal EnableExtensions DisableDelayedExpansion
  
  
  
  rem // Define constants here:
  
  set "_SOURCE=C:\Users\Test\Documents\Input" & rem // (absolute source path)
  
  set "_TARGET=C:\Users\Test\Documents\Output"  & rem // (absolute target path)
  
  set "_PATTERN=*.*" & rem // (pure file pattern for input files)
  
  set "_FILEEXT=.mp3"   & rem // (pure file extension of output files)
  
  
  
  pushd "%_TARGET%" || exit /B 1
  
  for /F "delims=" %%F in ('
  
      cd /D "%_SOURCE%" ^&^& ^(rem/ list but do not copy: ^
  
          ^& xcopy /L /S /Y /I ".\%_PATTERN%" "%_TARGET%" ^
  
          ^| find ".\" ^& rem/ remove summary line;
  
      ^)
  
  ') do (
  
      2> nul mkdir "%%~dpF.
  
  
  
      rem // Set up the correct `ffmpeg` command line here:
  
      set "FFREPORT=file=C\:\\Users\\Test\\Documents\\Output\\ffreport-%%~F.log:level=32"
  
      "C:\ffmpeg\bin\ffmpeg.exe" -report -n -i "%_SOURCE%\%%~F" -vn -c:a libmp3lame -b:a 128k "%%~dpnF%_FILEEXT%"
  
      if not errorlevel 1  if exist "%%~dpnF%_FILEEXT%" del /f /q "%_SOURCE%\%%~F"
  
  
  
  )
  
  popd
  
  
  
  endlocal
  
  pause