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

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Thu Nov 17 14:00:08 PST 2005

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


Le mercredi 16 novembre 2005 à 12:18 +0000, Andy White a écrit :
> 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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