[Speex-dev] 8.4kbps data rate in 8kbps nb mode

Jean-Marc Valin
2005-11-17T14:00:47Z

I'm not aware of this. How did you measure this value? Note that in
practice, there is a small overhead to Ogg packets.

	Jean-Marc

Le mercredi 16 novembre 2005 ? 12:18 +0000, Andy White a ?crit
:
> I know that most of the narrow band submodes don't have an exact
multiple of
> eight bits in each frame
>
> 79 bits for 3.95kbps
> 119 bits for 5.95kbps ...etc
>
> This means that you have a few unused bits when transporting Speex in the
Ogg
> format (you can achieve a lower number of unused bits if you change the
number
> of frames per Ogg packet to suit the mode).
>
> However, in 8kbps mode, the number of bits per frame is 160. I would have
> expected this to fit into an Ogg segment 20 bytes long. However, when I use
> (speexenc -n --quality 3) to encode at 8kbps the Ogg segments are each 21
bytes
> long.
>
> Is this an error, or is there extra information put in the 21st byte?
>
> I'll have a hunt through the code, but thought someone might have come
across
> this before.
>
> Regards,
>
> Andy
>
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