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• lavc : Use av_gettime_relative()

  6 mai 2014, par Olivier Langlois

  lavc : Use av_gettime_relative()
  Whenever av_gettime() is used to measure relative period of time,
  
  av_gettime_relative() is prefered as it guarantee monotonic time
  
  on supported platforms.
  Signed-off-by : Olivier Langlois <olivier@trillion01.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/dct-test.c
  • [DH] libavcodec/fft-test.c
  • [DH] libavcodec/motion-test.c

• FFMPEG Audio/video out of sync after cutting and concatonating

  31 janvier 2020, par Ham789

  I am attempting to take cuts from a set of videos and concatonate them together with the concat demuxer.

  However, each video’s audio is out of sync in the output. At the beggening of each clip there is a short period of silence before the audio begins.

  For each video, I decode it, trim a clip from it and then encode it to 4k resolution at 25 fps with its audio :

  ffmpeg -ss 0.5 -t 0.5 -i input_video1.mp4 -r 25 -vf scale=3840:2160 output_video1.mp4

  I then take each of these videos and concatonate them together with the concat demuxer :

  ffmpeg -f concat -safe 0 -i cut_videos.txt -c copy -y output.mp4

  I am taking short cuts of each video (approximately 0.5s)

  I am using Python’s subprocess to automate the cutting and concatonating of the videos.

  It seems the audio becomes out of sync after the trimming step (not the concatonation) as when I play back the intermediate cut video files (output_video1.mp4 in the above code), there seems to be the same silence before the audio comes in at the start of the video.

  When I concatonate the videos, I get a lot of these warnings :

  [mp4 @ 0000021a252ce080] Non-monotonous DTS in output stream 0:1; previous: 51792, current: 50009; changing to 51793. This may result in incorrect timestamps in the output file.

  From this post, it seems to be a problem with cutting the videos and their timestamps. The solution proposed in the post is to decode, cut and then encode the video however I am already doing that.

  How can I ensure the audio and video are in sync ?

• lavfi/vf_libplacebo : allow operation without avhwdevice

  11 mai 2023, par Niklas Haas

  lavfi/vf_libplacebo : allow operation without avhwdevice
  Recent versions of libplacebo have required Vulkan versions incompatible
  
  with lavu Vulkan hwcontexts. While this is expected to change
  
  eventually, breaking vf_libplacebo every time there is such a transition
  
  period is obviously undesired behavior, as the following sea of bug
  
  reports shows.
  This commit adds a fallback path for init_vulkan failures which simply
  
  creates an internal device if there was no user-supplied Vulkan hwaccel.
  
  Useful when no interop with lavu vulkan hwframes is needed or desired,
  
  and makes using this filter easier inside certain applications.
  Fixes : https://github.com/haasn/libplacebo/issues/170
  
  Fixes : https://github.com/mpv-player/mpv/issues/9589#issuecomment-1535432185
  
  Fixes : https://github.com/mpv-player/mpv/issues/11363
  
  Fixes : https://github.com/mpv-player/mpv/issues/11685#issuecomment-1546627082
  
  Closes : https://code.videolan.org/videolan/libplacebo/-/issues/270
  

  • [DH] libavfilter/vf_libplacebo.c