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• tests/movenc : Validate that normal muxer usage doesn't print warnings

  3 avril 2024, par Martin Storsjö

  tests/movenc : Validate that normal muxer usage doesn't print warnings
  We have test to make sure that certain configurations do print
  
  warnings. However, the normal operation of the muxer within this
  
  test always printed a warning, so those tests to check for
  
  extra warnings didn't essentially guard anything.
  The warning that always was printed, "track 1 : codec frame size is
  
  not set" was not present in the libav fork where this testcase
  
  originated, it was removed in f234e8a32e6c69d7b63f8627f278be7c2c987f43.
  Set the frame size for the audio stream to silence the warning,
  
  and use this frame size in a couple later calculations, and check
  
  that one test configuration doesn't print warnings.
  Setting the frame size apparently changes the rounding of a timestamp
  
  in the ismv muxing testcase.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/tests/movenc.c
  • [DH] tests/ref/fate/movenc

• lavc/vvc : Remove left shifts of negative values

  20 janvier 2024, par Frank Plowman

  lavc/vvc : Remove left shifts of negative values
  VVC specifies << as arithmetic left shift, i.e. x << y is equivalent to
  
  x * pow2(y).  C's << on the other hand has UB if x is negative.  This
  
  patch removes all UB resulting from this, mostly by replacing x << y
  
  with x * (1 << y), but there are also a couple places where the OOP was
  
  changed instead.
  Signed-off-by : Frank Plowman <post@frankplowman.com>
  
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/vvc/vvc_ctu.c
  • [DH] libavcodec/vvc/vvc_filter.c
  • [DH] libavcodec/vvc/vvc_inter.c
  • [DH] libavcodec/vvc/vvc_inter_template.c
  • [DH] libavcodec/vvc/vvc_mvs.c

• HLS implementation with FFmpeg

  10 août 2015, par Joseph K

  I am trying to implement HLS using FFmpeg for transcoding + segmenting but have been facing a couple of issues that have been bugging me for the past week.

  Issue

  Webserver currently receives live MP4 fragments being recorded on-the-go and needs to take care of transcoding and segmentation.

  As mp4 fragments are being received, they need to be encoded. Then segmented. If i run a segmenter (be it ffmpeg or apple mediastreamsegmenter), every mp4 fragment is being treated as a VOD by itself and I’m not being able to integrate them as part of a larger live event implementation.

  I thought of a solution where every time I receive an mp4 fragment, I first use fmpeg to concatenate it with previous ones to form the larger mp4 that I then pass to be segmented for HLS. That did not work either because the entire stream has to be re-segmented each and every time and existing TS fragments replaced by new ones that are similar yet shifted in time.

  Implementation 1

  ffmpeg -re -i fragmentX.mp4 -b:v 118k -b:a 32k -vcodec copy -preset:v veryfast -acodec aac -strict -2 -ac 2 -f mpegts -y fragmentX.ts

  I manage the m3u8 manifest on my own, deleting old fragments and appending new ones.

  When validating the stream, I find it stacked with EXT-X-DISCONTINUITY tags making the stream unwatchable.

  Implementation 2

  First combine latest fragment with overall.mp4

  ffmpeg -i "concat:newfragment.mp4|existing.mp4" -c copy overall.mp4

  Then pass the combination to ffmpeg for HLS segmentation

  ffmpeg -re -i overall.mp4 -ac 2 -r 20 -vcodec libx264 -b:v 318k -preset:v veryfast -acodec aac -strict -2 -b:a 32k -hls_time 2 -hls_list_size 3 -hls_allow_cache 0 -hls_base_url /Users/JosephKalash/Desktop/test/350/ -hls_segment_filename ’350/fragment%03d.ts’ -hls_flags delete_segments 350/index.m3u8

  Concatenation is not perfect and there are noticeable glitches where the fragments are supposed to be stitched. Segmentation replaces older fragments and the manifest is rewritten as if it’s a new HLS stream every time ffmpeg is called.

  I cannot figure out how to get this to work properly.

  Any ideas ?