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• libavutil : add an FFT & MDCT implementation

  2 mai 2019, par Lynne

  libavutil : add an FFT & MDCT implementation
  This commit adds a new API to libavutil to allow for arbitrary transformations
  
  on various types of data.
  
  This is a partly new implementation, with the power of two transforms taken
  
  from libavcodec/fft_template, the 5 and 15-point FFT taken from mdct15, while
  
  the 3-point FFT was written from scratch.
  
  The (i)mdct folding code is taken from mdct15 as well, as the mdct_template
  
  code was somewhat old, messy and not easy to separate.
  A notable feature of this implementation is that it allows for 3xM and 5xM
  
  based transforms, where M is a power of two, e.g. 384, 640, 768, 1280, etc.
  
  AC-4 uses 3xM transforms while Siren uses 5xM transforms, so the code will
  
  allow for decoding of such streams.
  
  A non-exaustive list of supported sizes :
  
  4, 8, 12, 16, 20, 24, 32, 40, 48, 60, 64, 80, 96, 120, 128, 160, 192, 240,
  
  256, 320, 384, 480, 512, 640, 768, 960, 1024, 1280, 1536, 1920, 2048, 2560...
  The API was designed such that it allows for not only 1D transforms but also
  
  2D transforms of certain block sizes. This was partly on accident as the stride
  
  argument is required for Opus MDCTs, but can be used in the context of a 2D
  
  transform as well.
  
  Also, various data types would be implemented eventually as well, such as
  
  "double" and "int32_t".
  Some performance comparisons with libfftw3f (SIMD disabled for both) :
  
  120 :
  
    22353 decicycles in     fftwf_execute,     1024 runs,      0 skips
  
    21836 decicycles in compound_fft_15x8,     1024 runs,      0 skips
  128 :
  
    22003 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
    23132 decicycles in monolithic_fft_ptwo,   1024 runs,      0 skips
  384 :
  
    75939 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
    73973 decicycles in compound_fft_3x128,    1024 runs,      0 skips
  640 :
  
   104354 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
   149518 decicycles in compound_fft_5x128,    1024 runs,      0 skips
  768 :
  
   109323 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
   164096 decicycles in compound_fft_3x256,    1024 runs,      0 skips
  960 :
  
   186210 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
   215256 decicycles in compound_fft_15x64,    1024 runs,      0 skips
  1024 :
  
   163464 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
   199686 decicycles in monolithic_fft_ptwo,   1024 runs,      0 skips
  With SIMD we should be faster than fftw for 15xM transforms as our fft15 SIMD
  
  is around 2x faster than theirs, even if our ptwo SIMD is slightly slower.
  The goal is to remove the libavcodec/mdct15 code and deprecate the
  
  libavcodec/avfft interface once aarch64 and x86 SIMD code has been ported.
  
  New code throughout the project should use this API.
  The implementation passes fate when used in Opus, AAC and Vorbis, and the output
  
  is identical with ATRAC9 as well.
  

  • [DH] libavutil/Makefile
  • [DH] libavutil/tx.c
  • [DH] libavutil/tx.h

• checkasm : add function to check and diff memory

  20 juin 2019, par Martin Storsjö

  checkasm : add function to check and diff memory
  This was ported from dav1d (c950e7101bdf5f7117bfca816984a21e550509f0).
  Signed-off-by : Josh de Kock <josh@itanimul.li>
  

  • [DH] tests/checkasm/checkasm.c
  • [DH] tests/checkasm/checkasm.h

• How to make mpv more compatible with ffmpeg filters like minterpolate ?

  1er octobre 2020, par F usedEmacs -con fused

  ffmpeg filter minterpolate (motion interpolation) does not work in MPV.

  



  (Nevertheless the file then is played normally without the minterpolate).

  



  (I researched using search engines and throughout documentation and troubleshooted to make a use of opengl and generally tried everything apart from asking for help and learning to understand more in the source code and I'm not a programmer)…

  



  --gpu-context=angle --gpu-api=opengl also does not make opengl work. (I'm guessing opengl could help from seeing its use in the documentations).

  



  


  Note

  
 


  To get a full list of available video filters, see —vf=help and
 http://ffmpeg.org/ffmpeg-filters.html .

  
 


  Also, keep in mind that most actual filters are available via the
 lavfi wrapper, which gives you access to most of libavfilter's
 filters. This includes all filters that have been ported from MPlayer
 to libavfilter.

  
 


  Most builtin filters are deprecated in some ways, unless they're only
 available in mpv (such as filters which deal with mpv specifics, or
 which are implemented in mpv only).

  
 


  If a filter is not builtin, the lavfi-bridge will be automatically
 tried. This bridge does not support help output, and does not verify
 parameters before the filter is actually used. Although the mpv syntax
 is rather similar to libavfilter's, it's not the same. (Which means
 not everything accepted by vf_lavfi's graph option will be accepted by
 —vf.)

  
 


  You can also prefix the filter name with lavfi- to force the wrapper.
 This is helpful if the filter name collides with a deprecated mpv
 builtin filter. For example —vf=lavfi-scale=args would use
 libavfilter's scale filter over mpv's deprecated builtin one.

  


  



  I expect MPV to play with minterpolate (one of several filters that MPV can use, listed in http://ffmpeg.org/ffmpeg-filters.html) enabled. But this is what happens :

  



  Input : "--vf=lavfi=[minterpolate=fps=60000/1001:mi_mode=mci]"

  



  Output :

  



     cplayer:  (+) Video --vid=1 (*) (h264 1280x720 29.970fps)
   cplayer:  (+) Audio --aid=1 (*) (aac 2ch 44100Hz)
        vd: Using hardware decoding (d3d11va).
    ffmpeg: Impossible to convert between the formats supported by the filter 'mpv_src_in0' and the filter 'auto_scaler_0'
     lavfi: failed to configure the filter graph
        vf: Disabling filter lavfi.00 because it has failed.


  



  (Interesting is also that --gpu-api=opengl does not work (despite that according to specification my—not to brag—HD Graphics 400 Braswell supports its 4.2 version)… And that aresample seems to have no effect too, and with the few audio filters selected playback often doesn't start nor output errors.)