[Speex-dev] Determine number of 20ms frames in packet - without decoding

[Steve Kann]

Jean-Marc Valin wrote:
> David Hogan wrote:
>   
>> Does anyone know a practical way to determine the number of 20ms speex
>> frames in a given speex packet without actually looping on speex_decode* ?
>>     
>
> There's no ready-made function for that. You'd have to write a function
> that inspects the bits, determines what mode is involved, and jump the
> right number of bits until a terminator is found or there's no more
> bytes. The narrowband decoder already does something similar when it
> encounters wideband data it doesn't want to decode.
>   
We've written code to do just this, actually.  It's included in 
iaxclient and asterisk in the speex codec modules.  I've also written 
about it to this list (probably with code excerpts).  Google is your friend.

http://mlblog.osdir.com/audio.compression.speex.devel/2006-01/index.shtml

Someone's even ported it to Java, it seems, here:

http://www.koders.com/java/fidAEF1846C82020C9EDC1E49EF2C3F2663BC99A242.aspx

-SteveK


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