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• Graph-based video processing for .NET

  23 octobre 2016, par Borv

  Does anyone know a good object-oriented library (preferably high-level, like C# or Java) for working with video and audio streams ?

  I wrote an app which fiddles with video and audio streams, feeds and such. The original task was simple :

  • grab an RTSP feed
  • display original feed(s) on the display
  • convert it to a series of h264 ts files
  • extract audio into separate MP3 files
  • upload videos and audio to the web site (preferably in real time, few minute delay is acceptable)

  As you may have already guessed it is about recording events (e.g. lectures) and publishing them on the web.

  To pull this out I needed some graph-based non-linear editing for media. Two weeks in, I tried ffmpeg, vlc and WMF. The only library I got to work is ffmpeg, and that comes with lots of "however". WMF required a lot of coding (and I abandoned this path), vlc looked great on paper, but I stumbled across some bugs with input splitting I could not get around (e.g. transcode:es combination flat out refused to work).

  So, the question. What are good non-linear editing libraries besides ffmpeg, vlc and wmf/directshow that allow for building video processing graphs with sources, sinks and filters ? Or perhaps good bindings over ffmpeg and vlc allowing to build such graphs ?

• avcodec/ffv1dec_template : Optimize common case in run mode

  23 mai 2019, par Michael Niedermayer

  avcodec/ffv1dec_template : Optimize common case in run mode
  Fixes : Timeout (14sec -> 9sec)
  
  Fixes : 13398/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-5664106709778432
  decode_line() becomes 1% faster for fate/vsynth2-ffv1.avi
  
  for another fate sample there is a 0.5% speedup
  
  the effect should be bigger for files with "flat" colored areas
  
  the new faster branch is used in 97-100% of the cases in fate samples
  
  compared to the older more complex (which i tested)
  vsynth3-ffv1-v3-bgr0.avi had the lowest percentual useage of about 97%
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/ffv1dec_template.c

• Revision 3606b78108 : Modified test for auto key frame detection. The existing test was triggering a

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  Modified test for auto key frame detection.

  The existing test was triggering a lot of false positives on some types
  of animated material with very plain backgrounds. These were triggering
  code designed to catch key frames in letter box format clips.

  This patch tightens up the criteria and imposes a minimum requirement
  on the % blocks coded intra in the first pass and the ratio between the
  % coded intra and the modified inter % after discounting neutral (flat)
  blocks that are coded equally well either way.

  On a particular problem animation clip this change eliminated a large
  number of false positives including some cases where the old code
  selected kf several times in a row. Marginal false negatives are less
  damaging typically to compression and in the problem clip there are now
  a couple of cases where "visual" scene cuts are ignored because of well
  correlated content across the scene cut.

  Replaced some magic numbers related to this with #defines and added
  explanatory comments.

  Change-Id : Ia3d304ac60eb7e4323e3817eaf83b4752cd63ecf