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• swresample/resample : speed up Blackman Nuttall filter

  9 novembre 2015, par Ganesh Ajjanagadde

  swresample/resample : speed up Blackman Nuttall filter
  This may be a slightly surprising optimization, but is actually based on
  
  an understanding of how math libraries compute trigonometric functions.
  
  Explanation is given here so that future development uses libm more effectively
  
  across the codebase.
  All libm’s essentially compute transcendental functions via some kind of
  
  polynomial approximation, be it Taylor-Maclaurin or Chebyshev.
  
  Correction terms are added via polynomial correction factors when needed
  
  to squeeze out the last bits of accuracy. Lookup tables are also
  
  inserted strategically.
  In the case of trigonometric functions, periodicity is exploited via
  
  first doing a range reduction to an interval around zero, and then using
  
  some polynomial approximation.
  This range reduction is the most natural way of doing things - else one
  
  would need polynomials for ranges in different periods which makes no
  
  sense whatsoever.
  To avoid the need for the range reduction, it is helpful to feed in
  
  arguments as close to the origin as possible for the trigonometric
  
  functions. In fact, this also makes sense from an accuracy point of view :
  
  IEEE floating point has far more resolution for small numbers than big ones.
  This patch does this for the Blackman-Nuttall filter, and yields a
  
  non-negligible speedup.
  Sample benchmark (x86-64, Haswell, GNU/Linux)
  
  test : fate-swr-resample-dblp-2626-44100
  
  old :
  
  18893514 decicycles in build_filter (loop 1000),     256 runs,      0 skips
  
  18599863 decicycles in build_filter (loop 1000),     512 runs,      0 skips
  
  18445574 decicycles in build_filter (loop 1000),    1000 runs,     24 skips
  new :
  
  16290697 decicycles in build_filter (loop 1000),     256 runs,      0 skips
  
  16267172 decicycles in build_filter (loop 1000),     512 runs,      0 skips
  
  16251105 decicycles in build_filter (loop 1000),    1000 runs,     24 skips
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libswresample/resample.c

• avformat/cache : Avoid int-overflow in cache compare function

  9 novembre 2015, par Bryan Huh

  avformat/cache : Avoid int-overflow in cache compare function
  cache protocol indexes its cache using AVTreeNodes which require a cmp
  
  function for inserting and searching new cache-entries. This cmp
  
  function expects a 32-bit int return value (negative, zero, or positive)
  
  but the cache cmp function returns an int64_t which can overflow the
  
  int, giving negative numbers for when it should be positive, vice versa.
  
  This manifests itself only for very large files (e.g. 4GB+)
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/cache.c

• FFMPEG hwaccel convert WEBM to MP4 video issue

  19 avril 2020, par Yen Nguyen

  I use FFMPEG to convert webm videos into mp4 format using a Nvidia GPU GeoForce GTX 1660 card on Windows 10. It has worked perfectly since the beginning for few months but now it's stopped working with strange error as below :

  



  [h264 @ 0000013d8b5eee00] missing picture in access unit with size 431
[extract_extradata @ 0000013d8b6aef40] No start code is found.
big-buck-bunny-trailer.webm: could not find codec parameters


  



  FFMPEG version and Nvidia driver version are the same as before it just crashed overnight without a clue. I tried Googling around and did update to the latest ffmpeg version as well Nvidia driver version but it still doesn't help.
If I switch to CPU decoder (without hwaccel arg) using libx264 it just works fine.

  



  Environment Windows 10 64bit | ffmpeg version git-2020-04-15-51db0a4 (latest) | Nvidia GeForce GTX 1660, 
 - Geoforce Game Ready Driver version:445.87 Release Date Apr 15, 2020

  



   ffmpeg -y -vsync 0 -hwaccel cuvid -c:v h264_cuvid -i big-buck-bunny-trailer.webm -c:v h264_nvenc output.mp4

ffmpeg version git-2020-04-15-51db0a4 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200328
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 42.102 / 56. 42.102
  libavcodec     58. 78.102 / 58. 78.102
  libavformat    58. 42.100 / 58. 42.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.101 /  7. 77.101
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[h264 @ 0000013d8b5eee00] missing picture in access unit with size 431
[extract_extradata @ 0000013d8b6aef40] No start code is found.
big-buck-bunny-trailer.webm: could not find codec parameters
WARNING: defaulting hwaccel_output_format to cuda for compatibility with old commandlines. This behaviour is DEPRECATED and will be removed in the future. Please explicitly set "-hwaccel_output_format cuda".
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, matroska,webm, from 'big-buck-bunny-trailer.webm':
  Metadata:
    encoder         : http://sourceforge.net/projects/yamka
    creation_time   : 2010-05-20T08:21:12.000000Z
  Duration: 00:00:32.48, bitrate: N/A
    Stream #0:0(eng): Video: h264, none, 640x360, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn (default)
    Stream #0:1(eng): Audio: vorbis, 44100 Hz, mono (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (h264_nvenc))
  Stream #0:1 -> #0:1 (vorbis (native) -> aac (native))
Press [q] to stop, [?] for help
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 66
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1339
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1415
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1908
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2123
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2504
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2294
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2684
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2468
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2622
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2867
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2737
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 3017
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2556
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 7811
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1880
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1722
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2309
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1215
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2080
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1775
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2247
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1782
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1945
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1529
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1807
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2015
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1568
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2159
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1861
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2397
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1627
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2364
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1821
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2282
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2068
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1699
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2129
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2268
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2197
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1981
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2169
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2888
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1600
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2958
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1518
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2738
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2319
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2421
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2841
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 1949
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2422
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2288
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2559
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2332
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2403
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2257
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2573
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2320
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2231
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2408
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2415
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2194
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2697
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2480
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2256
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2245
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2519
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2203
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2332
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2341
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2439
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2201
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2882
[NULL @ 0000013d8b5eee00] missing picture in access unit with size 2467
Too many packets buffered for output stream 0:1.
[aac @ 0000013d8b6bf5c0] Qavg: 115.929
[aac @ 0000013d8b6bf5c0] 2 frames left in the queue on closing
Conversion failed!


  



  Does anyone know how to fix it, i am getting stuck for few days ?
Much appreciated !