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I'm using OS X Mavericks (10.9.4) and installed ffmpeg from homebrew.

When executing this command (assuming input file exists):

ffmpeg -i ololo.wmv -vf scale=500:-1 -auto-alt-ref 1 -lag-in-frames 20 -pass 1 ololo.webm

I get this output:

ffmpeg version 2.3 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jul 18 2014 22:48:21 with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid
  libavutil      52. 92.100 / 52. 92.100
  libavcodec     55. 69.100 / 55. 69.100
  libavformat    55. 48.100 / 55. 48.100
  libavdevice    55. 13.102 / 55. 13.102
  libavfilter     4. 11.100 /  4. 11.100
  libavresample   1.  3.  0 /  1.  3.  0
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Unrecognized option 'auto-alt-ref'.
Error splitting the argument list: Option not found

Why? According to this page on webmproject.org, this option should be there.

1 Answer 1

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The problem is that by default ffmpeg does not include libvpx.
after executing brew reinstall ffmpeg --with-libvpx the problem is gone. This answer helped me: https://stackoverflow.com/a/13629348/1418097

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    For the future try to always specify the encoder you want rather than having ffmpeg auto-select one. Then you would've gotten "unknown encoder libvpx".
    – slhck
    Jul 28, 2014 at 6:53
  • @slhck of course, now I understand. I just used a template from an online guide for creating WebMs and (obviously) were knowing almost nothing about ffmpeg. But it turned out, one needs to understand what's going on, otherwise it won't work. :D Jul 28, 2014 at 7:08
  • Ah, I see. It's not your fault, of course. I'd rather say the online guide needs a bit of an update then — do you have a link? You don't necessarily have to understand everything as long as the description is also aimed at people with less experience.
    – slhck
    Jul 28, 2014 at 8:01
  • @slhck it's in russian language... and not really a complete guide. just some examples for people who can guess everything from them. Maybe I will write another guide at some day. Jul 28, 2014 at 8:54
  • There's also trac.ffmpeg.org/wiki/Encode/VP8 (shameless plug, I wrote it :P)
    – slhck
    Jul 28, 2014 at 9:54

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