[speex-dev] frame size

Marc Gimpel marc at wimba.com
Thu Oct 23 08:34:16 PDT 2003


Framesize always refers to the decoded data frame size in samples.
Framesize is dependent on the encoding mode
Narrowband (8kHz): framesize = 160 samples = 320 bytes of PCM
Wideband (16kHz): framesize = 320 samples = 640 bytes of PCM
Ultra Wideband (32kHz): framesize = 640 samples = 1280 bytes of PCM
The size of the encoded data depends on the quality setting, so if you 
know for instance that you are using quality 3 on narrowband, that is 
119 bits of encoded data per frame which is rounded to 15 bytes per 
frame (without counting the ogg headers). If you are using VBR then the 
number of bytes used to encode each frame (which says fixed in size) 
will vary.
If you have any other questions, don't hesitate to ask

    Good luck

    Marc Gimpel
    Head of research

Ulrich B. Staudinger wrote:

> hello,
> i have a simple question about speex frame size.
> i work with jspeex - but i think it's speex generic, the question i have.
> can i use any frame size i want? or does the size have be in a certain 
> ratio to other numbers? and what does the frame size in the decoder 
> mean? encoded or decoded packet frame size?
> how much data can i hand to the encoder to encode?
> if i hand i.e. 400 bytes to the encoder, what will i have in return? 
> 180 bytes of encoded data?
> in gsm it was all so simple... i have 320 bytes and get 133 in return 
> .... (i think those were the numbers).
> thanks for an answer,
> ulrich

--- >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