./ffmpeg -r 60 -i render/%04d.png -i dirty_paws.flac -acodec copy -c:v -profile:v high libx264 dirty_paws.mkv
ffmpeg version N-50389-ge20f2dc Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar  1 2013 05:22:59 with gcc 4.6 (Debian 4.6.3-1)
  configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
  libavutil      52. 17.103 / 52. 17.103
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.102 / 54. 63.102
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 41.100 /  3. 41.100
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[image2 @ 0x31ce600] max_analyze_duration 5000000 reached at 5000000 microseconds
Input #0, image2, from 'render/%04d.png':
  Duration: 00:11:00.88, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: png, rgb24, 960x540 [SAR 5906:5906 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
[flac @ 0x31cfa80] max_analyze_duration 5000000 reached at 5034667 microseconds
Input #1, flac, from 'dirty_paws.flac':
  Metadata:
    ARTIST          : Of Monsters and Men
    album_artist    : Of Monsters and Men
    ALBUM           : My Head Is an Animal
    track           : 1
    disc            : 1
    MEDIA           : 12_ Vinyl
    TITLE           : Dirty Paws
    DATE            : 2012-04-03
    MUSICBRAINZ_ALBUMID: 28b84dee-a132-4fc0-88ba-0fffa7c01845
  Duration: 00:04:35.32, bitrate: 2770 kb/s
    Stream #1:0: Audio: flac, 96000 Hz, stereo, s32
[NULL @ 0x32ba0a0] Unable to find a suitable output format for 'high'
high: Invalid argument