halexander9000@halexander9000-904HD:~$ ffmpeg -i test.ogv -vcodec copy -acodec copy -f mp4 output.mp4
ffmpeg version N-38318-g34210e8 Copyright (c) 2000-2012 the FFmpeg developers
  built on Feb 29 2012 00:50:33 with gcc 4.6.1
  configuration: --enable-gpl --enable-nonfree --enable-libx264 --enable-libtheora --enable-libvorbis
  libavutil      51. 41.100 / 51. 41.100
  libavcodec     54.  4.100 / 54.  4.100
  libavformat    54.  1.100 / 54.  1.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 62.101 /  2. 62.101
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  7.100 /  0.  7.100
  libpostproc    52.  0.100 / 52.  0.100
[ogg @ 0x9003aa0] Broken file, keyframe not correctly marked.
Input #0, ogg, from 'test.ogv':
  Duration: 00:00:43.66, start: 0.000000, bitrate: 3791 kb/s
    Stream #0:0: Data: none
    Stream #0:1: Video: theora, yuv420p, 640x480 [SAR 1:1 DAR 4:3], 15 fps, 15 tbr, 15 tbn, 15 tbc
    Stream #0:2: Audio: vorbis, 22050 Hz, mono, s16, 89 kb/s
[mp4 @ 0x904f5c0] track 0: could not find tag, codec not currently supported in container
Output #0, mp4, to 'output.mp4':
  Metadata:
    encoder         : Lavf54.1.100
    Stream #0:0: Video: theora, yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 15 fps, 90k tbn, 15 tbc
    Stream #0:1: Audio: vorbis ([221][0][0][0] / 0x00DD), 22050 Hz, mono, 89 kb/s
Stream mapping:
  Stream #0:1 -> #0:0 (copy)
  Stream #0:2 -> #0:1 (copy)
Could not write header for output file #0 (incorrect codec parameters ?)
halexander9000@halexander9000-904HD:~$ ffmpeg -i test.ogv -vcodec copy -acodec copy -f matroska output.mkv
ffmpeg version N-38318-g34210e8 Copyright (c) 2000-2012 the FFmpeg developers
  built on Feb 29 2012 00:50:33 with gcc 4.6.1
  configuration: --enable-gpl --enable-nonfree --enable-libx264 --enable-libtheora --enable-libvorbis
  libavutil      51. 41.100 / 51. 41.100
  libavcodec     54.  4.100 / 54.  4.100
  libavformat    54.  1.100 / 54.  1.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 62.101 /  2. 62.101
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  7.100 /  0.  7.100
  libpostproc    52.  0.100 / 52.  0.100
[ogg @ 0xa8ffaa0] Broken file, keyframe not correctly marked.
Input #0, ogg, from 'test.ogv':
  Duration: 00:00:43.66, start: 0.000000, bitrate: 3791 kb/s
    Stream #0:0: Data: none
    Stream #0:1: Video: theora, yuv420p, 640x480 [SAR 1:1 DAR 4:3], 15 fps, 15 tbr, 15 tbn, 15 tbc
    Stream #0:2: Audio: vorbis, 22050 Hz, mono, s16, 89 kb/s
Output #0, matroska, to 'output.mkv':
  Metadata:
    encoder         : Lavf54.1.100
    Stream #0:0: Video: theora, yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 15 fps, 1k tbn, 15 tbc
    Stream #0:1: Audio: vorbis, 22050 Hz, mono, 89 kb/s
Stream mapping:
  Stream #0:1 -> #0:0 (copy)
  Stream #0:2 -> #0:1 (copy)
Press [q] to stop, [?] for help
[ogg @ 0xa8ffaa0] Broken file, keyframe not correctly marked.
frame=  348 fps=  0 q=-1.0 size=   12824kB time=00:00:23.66 bitrate=4440.0kbits/Broken file, keyframe not correctly marked.
[ogg @ 0xa8ffaa0] Broken file, keyframe not correctly marked.
    Last message repeated 1 times
frame=  604 fps=575 q=-1.0 size=   19663kB time=00:00:40.73 bitrate=3953.9kbits/Broken file, keyframe not correctly marked.
frame=  637 fps=598 q=-1.0 Lsize=   20139kB time=00:00:43.27 bitrate=3812.2kbits/s
video:19627kB audio:484kB global headers:0kB muxing overhead 0.140059%
halexander9000@halexander9000-904HD:~$