[speex-dev] draft-herlein-speex-rtp-profile-01

Tom Grandgent tgrand at canvaslink.com
Tue Jul 1 16:55:10 PDT 2003


I have a question about section 3.4 of the RTP payload draft:

> Speex codecs [11] are able to detect the the bitrate from the
> payload and are responsible for detecting the 20 msec boundaries
> between each frame.

This suggests that you can encode some frames with Speex, pass the 
compressed bits to the decoder, and you'll get the output - without 
having to do external bookkeeping for compressed frame size.  (I'm 
thinking of VBR here where compressed frame size varies constantly.)

If this is true, how does one go about leaving this responsibility to 
the codec?  It seems like I have to pass the size of the compressed 
frame as the last parameter of speex_bits_read_from(), then call 
speex_decode() to decode one frame at a time.  This is how the sample 
code in the manual works, and the reference manual doesn't shed any 
light on this.

So basically, if I'm given an RTP packet with several back-to-back 
VBR-compressed Speex frames, how do I decode it?


--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'speex-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.

More information about the Speex-dev mailing list