Recherche avancée

Sur d’autres sites (11502)

• avformat/matroskaenc : Use native id V_FFV1 instead of V_MS/VFW/FOURCC

  25 mai, par Andreas Rheinhardt

  avformat/matroskaenc : Use native id V_FFV1 instead of V_MS/VFW/FOURCC
  Up until now, our muxer wrote FFV1 in video-for-windows
  
  compatibility mode out of concern for old demuxers that
  
  only support that (whereas the demuxer accepts V_FFV1).
  
  This commit switches to using native mode, because
  
  a) V_FFV1 is around long enough so that old demuxers
  
  should not be an issue (support in FFmpeg has been added
  
  in commit 9ae762da7e256aa4d3b645c614fcd1959e1cbb8d
  
  in March 2017/FFmpeg 3.3),
  
  b) using native mode uses fewer bytes for the CodecPrivate,
  
  c) the VfW extradata is zero-padded to an even length
  
  if necessary, but our demuxer forgot to undo the padding
  
  until very recently (92e310eb82e04713e55d248b65c22f0eb95afada),
  
  so that there are many versions of our demuxer around that
  
  are buggy wrt VFW, but not V_FFV1.
  
  This affects the FFV1 extradata checksums, specifically
  
  the (experimental) version 4 files with error check version 2*
  
  as created by
  
  ffmpeg -i ../fate-suite/mpeg2/sony-ct3.bs -c:v ffv1 \
  
   slices 16 -frames 1 -level 4 -strict experimental ffv1.mkv
  
  VFW files like the above created by this muxer before this patch
  
  would not work with an old demuxer.
  * : Without error check version 2, the CRC for the whole extradata
  
  is zero, which is not changed by appending a zero byte.
  Reviewed-by : compn <ff@hawaiiantel.net>
  
  Reviewed-by : Dave Rice <dave@dericed.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavformat/matroskaenc.c
  • [DH] tests/ref/fate/matroska-mastering-display-metadata

• libvpx 0.9.1 and FFmpeg 0.6

  18 juin 2010, par Multimedia Mike — VP8

  Great news : Hot on the heels of FFmpeg’s 0.6 release, the WebM project released version 0.9.1 of their libvpx. I can finally obsolete my last set of instructions on getting FFmpeg-svn working with libvpx 0.9.

  Building libvpx 0.9.1
  Do this to build libvpx 0.9.1 on Unix-like systems :

  • Download libvpx 0.9.1 from http://code.google.com/p/webm/downloads/list
  • Unpack, chdir to the source dir, ’./configure && make && make install’

  libvpx’s build system has been firmed up a bit since version 0.9. It’s now smart enough to install when said target is invoked and it also builds the assembly language optimizations. Be advised that on 32- and 64-bit x86 machines, Yasm must be present (install either from source or through your package manager).

  Building FFmpeg 0.6
  To build the newly-released FFmpeg 0.6 :

  • Install Vorbis through your package manager if you care to encode WebM files with audio ; e.g., ’libvorbis-dev’ is the package you want on Ubuntu
  • Download FFmpeg 0.6 from the project’s download page
  • Configure FFmpeg with at least these options : ./configure --enable-libvpx --enable-libvorbis --enable-pthreads ; the final link step still seems to fail on Linux if the pthreads option is disabled
  • ’make’

  Verifying
  Check this out :

  $ ./ffmpeg -formats 2> /dev/null | grep WebM
    E webm            WebM file format
  $ ./ffmpeg -codecs 2> /dev/null | grep libvpx
  
   DEV    libvpx          libvpx VP8
  

  That means that this FFmpeg binary can mux a WebM file and can both decode and encode VP8 video via libvpx. If you’re wondering why the WebM format does not list a ’D’ indicating the ability to demux a WebM file, that’s because demuxing WebM is handled by the general Matroska demuxer.

  Doing Work
  Encode a WebM file :

  ffmpeg -i <input_file> <output_file.webm>

  FFmpeg just does the right thing when it seems that .webm extension on the output file. It’s almost magical.

  For instant gratification that the encoded file is valid, you can view it immediately using ’ffplay’, if that binary was built (done by default if the right support libraries are present). If ffplay is not present, you can always execute this command line to see some decode operation :

  ffmpeg -i <output_file.webm> -f framecrc -

• Add partial_tukey and punchout_tukey apodization functions

  10 août 2014, par Martijn van Beurden

  Add partial_tukey and punchout_tukey apodization functions
  Adds two new apodization functions that seem to perform better than
  
  the apodization functions currently in the codebase and fixes three
  
  existing windows as well.
  Its important to note that this patch only affects the encoder stage
  
  that evaluates various possible predictors. Audio encoded with these
  
  new windows will still decode with existing legacy decoders.
  = Theory =
  
  These functions are used to window the  audio data at the predictor
  
  stage. These news functions enable the use of only part of the signal
  
  to generate a predictor. This helps  because short transients can
  
  introduce noise into the predictor. The  predictor becomes very good
  
  at prediciting one part of the  signal, instead of mediocre for the
  
  whole block.
  Signed-off-by : Erik de Castro Lopo <erikd@mega-nerd.com>
  

  • [DH] doc/html/documentation_tools_flac.html
  • [DH] include/FLAC/stream_encoder.h
  • [DH] man/flac.1
  • [DH] man/flac.sgml
  • [DH] src/libFLAC/include/private/window.h
  • [DH] src/libFLAC/include/protected/stream_encoder.h
  • [DH] src/libFLAC/stream_encoder.c
  • [DH] src/libFLAC/window.c