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• all : move ff_exp10, ff_exp10f, ff_fast_powf to lavu/ffmath.h

  15 mars 2016, par Ganesh Ajjanagadde

  all : move ff_exp10, ff_exp10f, ff_fast_powf to lavu/ffmath.h
  The idea is to use ffmath.h for internal implementations of math functions.
  
  Currently, it is used for variants of libm functions, but is by no means
  
  limited to such things.
  Note that this is not exported ; use lavu/mathematics for such purposes.
  Reviewed-by : Ronald S. Bultje <rsbultje@gmail.com>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanag@gmail.com>
  

  • [DH] libavcodec/aacenc_utils.h
  • [DH] libavcodec/aacpsy.c
  • [DH] libavcodec/acelp_pitch_delay.c
  • [DH] libavcodec/cngdec.c
  • [DH] libavcodec/dcaenc.c
  • [DH] libavcodec/imc.c
  • [DH] libavcodec/on2avc.c
  • [DH] libavcodec/opus.c
  • [DH] libavcodec/wmadec.c
  • [DH] libavcodec/wmaenc.c
  • [DH] libavcodec/wmaprodec.c
  • [DH] libavfilter/af_anequalizer.c
  • [DH] libavfilter/af_compand.c
  • [DH] libavfilter/af_volume.c
  • [DH] libavfilter/f_ebur128.c
  • [DH] libavfilter/vaf_spectrumsynth.c
  • [DH] libavfilter/vsrc_testsrc.c
  • [DH] libavutil/eval.c
  • [DH] libavutil/ffmath.h
  • [DH] libavutil/internal.h

• How to trim webm video while preserving transparency

  27 octobre 2020, par vishwas.mittal

  I want to trim a transparent webm video using ffmpeg. Here's the ffprobe result for that video :

  


  Input #0, matroska,webm, from 'template.webm':
  Metadata:
    ENCODER         : Lavf58.29.100
  Duration: 00:00:05.24, start: -0.002000, bitrate: 2856 kb/s
    Stream #0:0: Video: vp8, yuv420p(progressive), 1573x900, SAR 1:1 DAR 1573:900, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      ALPHA_MODE      : 1
      ENCODER         : Lavc58.54.100 libvpx
      DURATION        : 00:00:05.240000000
    Stream #0:1: Audio: opus, 48000 Hz, mono, fltp
    Metadata:
      ENCODER         : Lavc58.54.100 libopus
      DURATION        : 00:00:05.241000000


  


  I tried

  


  ffmpeg -i template.webm -ss 1 -to 3 -c copy trimmed.webm


  


  but the trimmed video doesn't start (or sometimes end) at the exact times defined in the command so I tried re-encoding the video using libvpx

  


  ffmpeg -i template.webm -ss 1 -to 3 -c:v libvpx -c:a copy -crf 30 -b:v 0 trimmed.webm


  


  It solved the timing issue but this results in loss of transparency of output video. Here's the ffprobe :

  


  Input #0, matroska,webm, from 'trimmed.webm':
  Metadata:
    ENCODER         : Lavf57.83.100
  Duration: 00:00:02.00, start: -0.001000, bitrate: 1395 kb/s
    Stream #0:0: Video: vp8, yuv420p(progressive), 1573x900, SAR 1:1 DAR 1573:900, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      ALPHA_MODE      : 1
      ENCODER         : Lavc57.107.100 libvpx
      DURATION        : 00:00:02.000000000
    Stream #0:1: Audio: opus, 48000 Hz, mono, fltp
    Metadata:
      ENCODER         : Lavc58.54.100 libopus
      DURATION        : 00:00:02.001000000


  


  How should I trim the video while preserving the transparency ? Moreover, a fast solution will be extremely helpful.

  


• Installing ffmpeg on OSX 10.11

  14 mai 2016, par JulianJ

  I am trying to install ffmpeg and it’s libraries on a mac running osx.
  I’ve used homebrew to successfully install however its seems only ffmpeg is installed and not ffprobe or drawtext.

  I tried reinstalling with this command :

  brew install ffmpeg --with-fdk-aac --with-ffplay --with-freetype --with-frei0r --with-libass --with-libvo-aacenc --with-libvorbis --with-libvpx --with-opencore-amr --with-openjpeg --with-opus --with-rtmpdump --with-schroedinger --with-speex --with-theora --with-tools

  and I get this

  Warning:ffmpeg-3.0.2 already installed, it's just not linked

  Is there something I am missing / have to do ?

  Thanks.