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• avcodec/mips/aaccoder_mips : Remove MIPS-specific aaccoder

  15 mars 2024, par Andreas Rheinhardt

  avcodec/mips/aaccoder_mips : Remove MIPS-specific aaccoder
  ff_aac_coder_init_mips() modifies a static const structure of
  
  function pointers. This will crash if the binary uses relro
  
  and is a data race in any case.
  Furthermore it points to a maintainability issue : The
  
  AACCoefficientsEncoder structures have been constified
  
  in commit fd9212f2edfe9b107c3c08ba2df5fd2cba5ab9e3,
  
  a Libav commit merged in 318778de9ebec276cb9dfc65509231ca56590d13.
  
  Libav did not have the MIPS-specific AAC code and so this was
  
  fine for them ; yet FFmpeg had them, but this was not recognized.
  Commit 75a099fc734a4ee2b1347d0a3d8c53d883b95174 points to another
  
  maintainability issue : Contrary to ordinary DSP code, this code
  
  here is way more complex and needs to be constantly kept in sync
  
  with the ordinary code which it mimicks and replaces. Said commit
  
  is the only commit actually changing aaccoder.c in the last few
  
  years and the same change has not been performed for the MIPS
  
  clone ; before that, it even happened several times that the mips
  
  code was broken due to changes of the generic code (see commits
  
  97437bd17a8c5d4135b2f3b1b299bd7bb72ce02c and
  
  de262d018d7d7d9c967af1dfd1b861c4b9eb2a60 or
  
  860dbe0275e57cbf4228f3f653f872ff66ca596b or
  
  933309a6ca0f18bf1d40e917fff455221f57fb4b or
  
  b65ffa316e377213c29736929beba584d0d80d7c). This might even lead
  
  to scenarios where someone changing non-dsp aacenc code would
  
  have to modify mips inline asm in order to keep them in sync.
  
  This is obviously a significant burden (if the AAC encoder were
  
  actively developed).
  Finally, the code does not even compile here due to errors like
  
  "Error : float register should be even, was 1".
  Reviewed-by : Lynne <dev@lynne.ee>
  
  Reviewed-by : Jean-Baptiste Kempf <jb@videolan.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/aacenc.c
  • [DH] libavcodec/aacenc.h
  • [DH] libavcodec/mips/Makefile
  • [DH] libavcodec/mips/aaccoder_mips.c

• Ffmpeg cpp libav randomly uses high cpu and less gpu or uses high gpu and less cpu with hw accel

  29 avril 2024, par cngkyt

  I am using ffmpeg as library with cpp
the integration of library is perfectly done i am using AVFilterGraph as audio resampler and video pixfmt converter.

  


  I cannot share code because it is a complete library and contains too many files but i can assure there is no problem about code but maybe approach.

  


  My whole class is based on the transcode example of ffmpeg
text

  


  The problem is when i run my program that encodes approx 90 streams

  


  it starts with 25% cpu usage 80% gpu encode usage %85 gpu decode usage with 100% sm utilization

  


  or

  


  it starts with 80% cpu usage 45% gpu encode usage 50% gpu decode usage with 60% sm utilization

  


  when it start like second type of utilization videos are perfect
but when it starts like the first type of utilization videos are freezing

  


  my program uses pure gpu for encoding for all streams but using gpu decoding for every 3 cpu deoding
that means i use hwaccel for 1/3 of streams
because my cards are 4070 ti super and they have 2 NVENC 1 NVDEC chips

  


  my program takes udp streams and encode it and outputs udp mpegts

  


  bitrate and quality settings are persistent across streams depending on resolution

  


  i always test on same streams

  


  the problem happens randomly
but if it starts with high cpu and low gpu utilization it goes on like this
when i restart program problem occurs randomly again

  


  what can couse this

  


  just as an info i have experience on c++ more than 25 years

  


  if there is someone who can teach me something i will be happy

  


  thanks for your further helps

  


  i have tried to reproduce it with compiled ffmpeg instead of my libav library usage
same thing happens but not often

  


  i have tried using hevc_cuvid instead of hwacceleration with avcodec_find_decoder_by_name function

  


• avcodec/bsf/mp3_header_decompress : Remove BSF

  28 février 2024, par Andreas Rheinhardt

  avcodec/bsf/mp3_header_decompress : Remove BSF
  This BSF is supposed to be used in conjunction with mp3_header_compress,
  
  which has been removed more than ten years ago in commit
  
  c6080d89009056530119ab794ad02e4d515c7754. It mangled the headers
  
  by removing the CRC field as well as fields that are supposed
  
  to stay constant for the entirety of a stream (which are put into
  
  extradata). This made these files unplayable ; they need to be
  
  decompressed with the BSF first (which does not happen automatically).
  
  Even in this case the CRC does not get restored.
  I am not aware that such compressed files exist at all ; therefore
  
  this commit removes the BSF completely.
  Reviewed-by : Anton Khirnov <anton@khirnov.net>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] doc/bitstream_filters.texi
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/bitstream_filters.c
  • [DH] libavcodec/bsf/Makefile
  • [DH] libavcodec/bsf/mp3_header_decompress.c
  • [DH] libavcodec/version.h