Recherche avancée

Sur d’autres sites (16586)

• Revision 58e0159c80 : Fix ssse3 quantize_fp functions while skip=1 In ssse3 functions, DEFINE_ARGS ma

  24 février 2015, par Yunqing Wang

  Changed Paths :
   Modify /vp9/encoder/x86/vp9_quantize_ssse3_x86_64.asm

  
  
  Fix ssse3 quantize_fp functions while skip=1

  In ssse3 functions, DEFINE_ARGS macro hard codes qcoeff and dqcoeff
  to r3 and r4. If skip is 1, qcoeff and dqcoeff need to be loaded
  from the stack, which doesn’t work because of the above definitions.
  Currently, skip=1 case is not used in the encoder. This patch fixed
  the issue, so it can be turned on later.

  Change-Id : I998d696b1a7a85dca2b3bcee790b21c21e039147

• Dealing with problems in FLAC audio files with ffmpeg

  15 janvier 2020, par Seamus

  I have gotten a set of FLAC (audio) files from a friend. I copied them to my Sonos music library, and got set to enjoy a nice album. Unfortunately, Sonos would not play the files. As a result I have been getting to know ffmpeg.

  Sonos’ complaint with the FLAC files was that it was "encoded at an unsupported sample rate". With rolling eyes and shaking head, I note that the free VLC media player happily plays these files, but the product I’ve paid for (Sonos) - does not. But I digress...

  ffprobe revealed that the FLAC files contain both an Audio channel and a Video channel :

  $ ffprobe -hide_banner  -show_streams "/path/to/Myaudio.flac"
  
  
  
  
  
      Duration: 00:02:23.17, start: 0.000000, bitrate: 6176 kb/s  
  
      Stream #0:0: Audio: flac, 176400 Hz, stereo, s32 (24 bit)  
  
      Stream #0:1: Video: mjpeg (Progressive), yuvj444p(pc, bt470bg/unknown/unknown), 450x446 [SAR 72:72 DAR 225:223], 90k tbr, 90k tbn, 90k tbc (attached pic)  
  
      Metadata:  
  
        comment         : Cover (front)  

  Cool ! I guess this is how some audio players are able to display the ’album artwork’ when they play a song ? Note also that the Audio stream is reported at 176400 Hz ! Apparently I’m out of touch ; I thought that 44.1khz sampling rate effectively removed all of the ’sampling artifacts’ we could hear. Anyway, I learned that Sonos would support a max of 48kHz sampling rate, and this (the 176.4kHz rate) is what Sonos was unhappy about. I used ffmpeg to ’dumb it down’ for them :

  $ ffmpeg -i "/path/to/Myaudio.flac" -sample_fmt s32 -ar 48000 "/path/to/Myaudio48K.flac"

  This seemed to work - at least I got a FLAC file that Sonos would play. However, I also got what looks like a warning of some sort :

  [swscaler @ 0x108e0d000] deprecated pixel format used, make sure you did set range correctly
  [flac @ 0x7feefd812a00] Frame rate very high for a muxer not efficiently supporting it.
  Please consider specifying a lower framerate, a different muxer or -vsync 2

  A bit more research turned up this answer which I don’t quite understand, and then in a comment says, "not to worry" - at least wrt the swscaler part of the warning.

  And that (finally) brings me to my questions :

  1.a. What framerate, muxer & other specifications make a graphic compatible with a majority of programs that use the graphic ?

  1.b. How should I use ffmpeg to modify the Video channel to set these specifications (ref. Q 1.a.) ?

  2.a. How do I remove the Video channel from the .flac audio file ?

  2.b. How do I add a Video channel into a .flac file ?

  EDIT :

  I asked the above (4) questions after failing to accomplish a ’direct’ conversion (a single ffmpeg command) from FLAC at 176.4 kHz to ALAC (.m4a) at 48 kHz (max supported by Sonos). I reasoned that an ’incremental’ approach through a series of conversions might get me there. With the advantage of hindsight, I now see I should have posted my original failed direct conversion incantation... we live and learn.

  That said, the accepted answer below meets my final objective to convert a FLAC file encoded at 176.4kHz to an ALAC (.m4a) at 48kHz, and preserve the cover art/video channel.

• ERROR : libvpx decoder version must be >=0.9.1 [install ffmpeg in CentOS 6.3]

  4 septembre 2017, par Hu Le

  I want to install ffmpeg in CentOS 6.3
  It needs to install libvpx.

  I install libvpx before. Its version is 0.9.7.

  When I install ffmpeg, it indicates :

  [root@hostname ffmpeg]# PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure —prefix="$HOME/ffmpeg_build" —extra-cflags="-I$HOME/ffmpeg_build/include" —extra-ldflags="-L$HOME/ffmpeg_build/lib -ldl" —bindir="$HOME/bin" —pkg-config-flags="—static" —enable-gpl —enable-nonfree —enable-libfdk_aac —enable-libfreetype —enable-libmp3lame —enable-libopus —enable-libvorbis —enable-libvpx —enable-libx264 —enable-libx265

  ERROR: libvpx decoder version must be >=0.9.1

  If you think to configure made a mistake, make sure you are using the latest
  version from Git. If the latest version fails, report the problem to the
  ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
  Include the log file "ffbuild/config.log" produced by configuring as this will help
  solve the problem.

  Now my rpm and yum is :

  [root@hostname ]# yum list libvpx

  Loaded plugins : fastestmirror

  Loading mirror speeds from cached hostfile

  • nux-dextop : li.nux.ro

  • rpmforge : mirrors.neusoft.edu.cn

  Installed Packages

  libvpx.x86_64 1.3.0-5.el6_5 installed

  Available Packages

  libvpx.i686 0.9.7.1-3.el6.nux nux-dextop

  I want to remove libvpx.i686 in this way :

  [root@hostname ffmpeg]# yum remove libvpx.i686

  Loaded plugins : fastestmirror

  Setting up Remove Process

  No Match for argument : libvpx.i686

  Loading mirror speeds from cached hostfile

  • nux-dextop : li.nux.ro

  • rpmforge : mirrors.neusoft.edu.cn

  Package(s) libvpx.i686 available, but not installed.

  No Packages marked for removal

  How to remove libvpx.i686 completely ?