[theora] Do FPS affect bitstream?

xiphmont at xiph.org xiphmont at xiph.org
Mon Feb 7 19:06:27 PST 2011


On Mon, Feb 7, 2011 at 10:56 AM, Ralph Giles <giles at thaumas.net> wrote:
> On 7 February 2011 02:03, Andreas Engel <andreas.engel at bravis.eu> wrote:
>
>> does the frame rate in th_info have any actual effect on the resulting
>> bitstream? So for example do I get different results when encoding the
>> same video 2000kbit/s at 30fps or 1000kbit/s at 15fps?
>
> Currently libtheoraenc doesn't take the framerate into account when
> making encoding decisions, so I'd expect that to be true up to
> rounding error. Note that if you're comparing the streams, the header
> packet will be difference, since it signals the playback rate to the
> decoder.

...with the caveat that 1000kbps/15fps is harder to encode than
2000kbps/30fps because the motion isn't as smooth, so I would expect
the resulting frames to be noticably lower quality as well as less
smooth.

Monty


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