Files produced by encoder_example are not properly muxed
To reproduce:
$> ./encoder_example ~/Videos/akiyo_qcif.y4m -o akiyo.ogv
$> ffplay akiyo.ogv
[ogg @ 0x7f0448000bc0] Broken file, keyframe not correctly marked.
Input #0, ogg, from 'akiyo.ogv':
Duration: 00:00:10.01, start: 0.000000, bitrate: 66 kb/s
Stream #0:0: Video: theora, yuv420p, 176x144 [SAR 128:117 DAR 1408:1053], 29.97 tbr, 29.97 tbn, 29.97 tbc
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
[ogg @ 0x7f0448000bc0] Broken file, non-keyframe not correctly marked.
...Relevant parsing code from libavformat: