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

Andy White andrewmarkwhite at hotmail.com
Wed Nov 16 04:18:39 PST 2005

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 

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.



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