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• ffmpeg decode example using vda acceleration ?

  18 mars 2015, par Bill Yan

  I’m testing the vda hw accelerated decoder of ffmpeg, but have no luck so far.

  the command line I use is this :

  ./ffmpeg -hwaccel vda -i ~/Downloads/big_buck_bunny_720p_surround.avi -c:v rawvideo -pix_fmt yuv420p out.yuv

  (the input video can be downloaded here : http://mirrorblender.top-ix.org/peach/bigbuckbunny_movies/big_buck_bunny_720p_surround.avi)

  but it uses the sw decoder, instead of the requested vda hw decoder.

  I debugged ffmpeg.c, and found out that in the function get_format :

  if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
  
      break;

  the desc->flag isn’t set with AV_PIX_FMT_FLAG_HWACCEL, so it skips the hw acceleration initialization.

  the reason is because the pix_fmt is set to AV_PIX_FMT_NONE for some reason, instead of yuv420p as specified by the command.

  I then changed the command to this :

  ./ffmpeg -hwaccel vda -i ~/Downloads/big_buck_bunny_720p_surround.avi -c:v rawvideo -pix_fmt vda_vld out.yuv

  but what I got was :

  Impossible to convert between the formats supported by the filter 'format' and the filter 'auto-inserted scaler 0'
  
  
  
  
  
  Error opening filters!

  Can you please show me an example of using ffmpeg to dump the above video into yuv using the vda hw decoder ?

  UPDATE from the ffmpeg mailist.

  I was told to try the following command instead :

      ./ffmpeg -vcodec h264_vda -i ~/Downloads/big_buck_bunny_720p_surround.avi out.yuv

  but this is what I got :

  ./ffmpeg -vcodec h264_vda -i ~/Downloads/big_buck_bunny_720p_surround.avi out.yuv
  
  
  
  ffmpeg version 2.6.1 Copyright (c) 2000-2015 the FFmpeg developers
  
  built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
  
  configuration: 
  
  libavutil      54. 20.100 / 54. 20.100
  
  libavcodec     56. 26.100 / 56. 26.100
  
  libavformat    56. 25.101 / 56. 25.101
  
  libavdevice    56.  4.100 / 56.  4.100
  
  libavfilter     5. 11.102 /  5. 11.102
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  1.100 /  1.  1.100
  
  [10:20:50.169] vtDecompressionDuctCreate signalled err=-8973 (err) (Could not select and open decoder instance) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.107/Sources/VideoToolbox/VTDecompressionSession.c line 1181
  
  [h264_vda @ 0x7f9feb034600] Failed to init VDA decoder: -12473.
  
  [avi @ 0x7f9feb00da00] Failed to open codec in av_find_stream_info
  
  [NULL @ 0x7f9feb034600] missing picture in access unit with size 9960
  
  [10:20:50.252] vtDecompressionDuctCreate signalled err=-8973 (err) (Could not select and open decoder instance) at /SourceCache/CoreMedia_frameworks/CoreMedia-1562.107/Sources/VideoToolbox/VTDecompressionSession.c line 1181
  
  [h264_vda @ 0x7f9feb034600] Failed to init VDA decoder: -12473.
  
  [NULL @ 0x7f9feb034600] missing picture in access unit with size 457

  the reason I wanted to try this was because I wanted to use vda with libavcodec in the first place. but the problem I saw was exactly the above. looks like ffmpeg has the same issue.

• MP4 videos in Firefox and IE not respecting rotation

  17 novembre 2015, par jnevelson

  We have a webpage that plays back a faststart MP4 in a <video></video> tag - pretty simple, and it works great in Chrome and Safari. However, it seems as though Firefox 36 and IE10 are not respecting the rotation of the video, so they end up playing either upside down or rotated 90*.

  Here is what ffprobe says about one of the videos :

  ╰─$ ffprobe test
ffprobe version 2.6 Copyright (c) 2007-2015 the FFmpeg developers
 built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
 configuration: --prefix=/usr/local/Cellar/ffmpeg/2.6_1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libvorbis --enable-libvpx --enable-libfaac --enable-nonfree --enable-vda
 libavutil      54. 20.100 / 54. 20.100
 libavcodec     56. 26.100 / 56. 26.100
 libavformat    56. 25.101 / 56. 25.101
 libavdevice    56.  4.100 / 56.  4.100
 libavfilter     5. 11.102 /  5. 11.102
 libavresample   2.  1.  0 /  2.  1.  0
 libswscale      3.  1.101 /  3.  1.101
 libswresample   1.  1.100 /  1.  1.100
 libpostproc    53.  3.100 / 53.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test':
 Metadata:
   major_brand     : qt
   minor_version   : 512
   compatible_brands: qt
   date            : 2015-03-03T15:57:38-0800
   date-eng        : 2015-03-03T15:57:38-0800
   encoder         : Lavf56.25.101
 Duration: 00:00:06.29, start: 0.000000, bitrate: 25699 kb/s
   Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 25862 kb/s, 59.98 fps, 60 tbr, 19200 tbn, 38400 tbc (default)
   Metadata:
     rotate          : 180
     handler_name    : DataHandler
     encoder         : H.264
   Side data:
     displaymatrix: rotation of 180.00 degrees
   Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
   Metadata:
     handler_name    : DataHandler

  I’ve Googled around and haven’t found any information or bug reports on this, so I’m wondering if it’s something we’re missing or doing wrong. The video itself is only run through ffmpeg to make it faststart so we can stream it - no other encoding/transcoding is done.

  I’m hoping there’s a better solution than to return the rotation alongside the video and transform it via CSS - especially because it’s rotated properly in Chrome and Safari.

  Thanks !

• Evolution #4149 (Nouveau) : UI System Fonts pour l’espace privé

  10 juin 2018, par Peet du

  Un article qui peut donner des idées : https://www.smashingmagazine.com/2015/11/using-system-ui-fonts-practical-guide/

  (Note : Ouverture de ce ticket suite à la suggestion de https://core.spip.net/issues/4148#note-14)