Recherche avancée

Sur d’autres sites (10576)

• how to extract multi frame with ffmpeg exact and fast

  24 février 2018, par Questioner

  i want extract frame from video with ffmpeg

  for example

  ffmpeg.exe -an -r 21 -ss 00:17:50 -i "K :\test.mkv" -t 00:00:30 -s 560x314 -q:v 1 "T :\GIF\test_%05d.png"

  the command what i intend is

  extract frame from K :\test.mkv(O)
  start at 00:00:30 (O)
  extracted image size is 560x314 (o)
  output path and file name format T :\GIF\test_%05d.png (O)

  extract 30seconds from start point -t 00:00:30 (X)
  with frame rate 21(so if video’s original fps is 24fps, then it reduced to fps22)(maybe ? X)

  anyway this is not collect

  i got 660 images, image number is collect but this is not 30seconds video data
  only 15seconds data
  too large error, so i can’t ignore it

  i think i can fix it by -ss move to after -i
  but this need really a lot of time..

  how can i solve this problem
  1 5second error is ok but error is too large

• avcodec/h264 : fix stride calculation in slice_table for multi-slice field video deblo...

  24 décembre 2024, par Lingyi Kong

  avcodec/h264 : fix stride calculation in slice_table for multi-slice field video deblocking
  fix for https://trac.ffmpeg.org/ticket/11360
  
  A new fate test case is added to validate the fix, the smaple file is located at https://trac.ffmpeg.org/attachment/ticket/11360/slice2_field_aurora4.264.
  Signed-off-by : Lingyi Kong <konglingyi@visionular.com>
  

  • [DH] libavcodec/h264_mb.c
  • [DH] tests/fate/h264.mak
  • [DH] tests/ref/fate/h264-conformance-slice2_field_aurora4

• how to multi thread with ffmpeg ?

  10 juillet 2018, par priojeet priyom

  I am trying to split, convert and merge an audio. I used writingMinds FFmpeg build for Android. But it is taking to much time for long duration audios.

  To speed it up I tried using the "thread -4" command on a phone having 8 cores but it didn’t improve the performance.

  So then I split the audio into 4 parts (to use 4 threads) and then called FFmpeg.execute() inside separate threads for multithreading. But FFmpeg library processes the files sequentially. Is it possible for ffmpeg to parallelly process these 4 parts in 4 threads ? If so how ?

  UPDATE
  see alex cohn’s answer.
  In this case, it was also because of the calling method of FFmpegExecuteAsyncTask as execute method of Asynctask class only allows one instance to run at a time in modern APIs.
  a workaround was using this checks.

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { // Android 3.0 to
  
                      // Android 4.3
  
                      // Parallel AsyncTasks are not possible unless using executeOnExecutor
  
                      ffmpegExecuteAsyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
  
                  } else { // Below Android 3.0
  
                      // Parallel AsyncTasks are possible, with fixed thread-pool size
  
                      ffmpegExecuteAsyncTask.execute();
  
                  }