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• Segmenting only specific parts of a video file

  30 mai 2013, par Christian P.

  I have some video files that I wish to serve up "dynamically", given the following workflow :

  1. Convert video from MP4 container to segmented .ts files with accompanying .m3u8 playlist
  2. Delete .ts files
  3. On request, generate .ts files (but only those requested, not for the entire video)

  I can generate .ts files for the entire video using ffmpeg using this command

  ffmpeg -y -i video.mp4 -c:a copy -bsf:a aac_adtstoasc -c:v copy -bsf:v h264_mp4toannexb -flags -global_header -map 0 -f segment -segment_time 10 -segment_list playlist.m3u8 -segment_format mpegts chunk_%03d.ts

  This is what I do in step 1 and it works just fine, video is playing fine. Due to disk constraints, I do not want to have two copies of every video (the original MP4 and the segmented .ts fies), so what I am trying to achieve is to find a command that will allow me to produce only the segments I need, on a per-request basis.

  Given the command above we may produce a sample playlist like this :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-ALLOW-CACHE:YES
  
  #EXT-X-TARGETDURATION:12
  
  #EXTINF:11.261267,
  
  chunk_000.ts
  
  #EXTINF:11.261256,
  
  chunk_001.ts
  
  #EXTINF:7.507511,
  
  chunk_002.ts
  
  #EXTINF:11.261256,
  
  chunk_003.ts
  
  #EXTINF:11.261267,
  
  chunk_004.ts
  
  #EXTINF:7.507511,
  
  chunk_005.ts

  I have tried, using the -ss and -t flags available in ffmpeg, to create only a specific segments. For instance I might skip the first to segments by adding -ss 22.522523 (the total length of the two first segments), but this produces chunks that are not byte-for-byte identical to the original chunks and as such unusable (the video playback just stops). Is there a way to have ffmpeg (or another program) reproduce the same exact chunks, without producing all of them ?

  Short version : If I produce a playlist with chunks of an entire video (and accompanying .ts files), can I later reproduce a specific interval of those chunks that are byte-for-byte identical to the original chunks ?

• avcodec/h264 : Move COPY_PICTURE() to h264.h so it can be used from other parts of...

  8 février 2015, par Michael Niedermayer

  avcodec/h264 : Move COPY_PICTURE() to h264.h so it can be used from other parts of the h264 decoder
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/h264.h
  • [DH] libavcodec/h264_refs.c

• Split into equal parts and convert many mp4 videos using ffmpeg

  9 septembre 2015, par bobafetta

  I have a ton of videos I need to convert from mp4 to wmv using ffmpeg and break up each file into 10 minute segments, but I am a total cmd scripting newb (in fact, I am a scripting newb :)

  After spending six hours trying to find an answer, I thought I would bring it to you guys.

  The code I have is working a little bit, but I need to be able to read data coming from the command line and send it back into the script for evaluation. I am not sure what code ffmpeg will spit out when it is done processing a video file (when the timestamp reaches an end), but this FOR loop just keeps on trying to create new file segments even though the video is over. This is what I saw when it tried to create a new file, so I think it might work to search for this :

  frame= 0 fps=0.0 q=0.0 Lsize= 1kB time=00:00:00.00 bitrate=N/A

  This is the code I have come up with so far (Don’t laugh :)

  @echo off
  
  setlocal ENABLEEXTENSIONS
  
  setlocal ENABLEDELAYEDEXPANSION
  
  
  
  for %%a in ("*.mp4") do (
  
  set hour=00
  
  
  
  for /L %%i IN (1,1,10) do (
  
  :Beginning
  
      set /a start=%%i-1
  
          set end=%%i
  
          if !start! lss 10 set start=!start!0
  
          if !end! lss 10 set end=!end!0
  
          ffmpeg -ss !hour!:!start!:00 -i "%%a" -b:v 1500k -vcodec msmpeg4 -acodec wmav2 -t !hour!:!end!:00 "Converted\%%~na-!hour!-!start!-!end!.wmv"
  
          if end==60 CALL :Increment
  
      )   
  
  )
  
  
  
  :Increment
  
      set /a !hour!+1
  
      set %%i=1
  
      GOTO :Beginning
  
  pause

  Based on reading this thread was thinking something like this might go in the code, but not sure what to do with it :

  set "dosstring=%*"
  
  
  
  echo.!dosstring!|findstr /C:"frame=    0 fps=0.0 q=0.0 Lsize=       1kB time=00:00:00.00 bitrate=N/A" >nul 2>&1

  Thanks so much for you help !