[Blink] 0.19.1: request: [4] lower audio bandwidth: control speex quality & complexity settings

cerieljacobs cerieljacobs at gmail.com
Sat Jul 10 13:26:19 CEST 2010


Op 10 jul 2010, om 11:52 heeft Adrian Georgescu het volgende geschreven:

> 
>>> 4. Feature request: have lower audio bandwidth consumption during call, by allowing codec (quality) preferences
>>>  ========================
>>>  When being mobile on expensive € 0.18 - € 12 /MB, 3G GSM network data connections,
>>>  you would like to transfer as few bits as possible while calling,
>>>  current blink 0.19.1 gives only the option to choose a coded.
>>>  What is needed next, are more options to set the codecs (quality) preferences, to reduce bandwidth to the bare minimum.
> 
> You may want to try GSM codec, it has about 30Kbit/s, if the other end point support it you may put this as your first preference. Same for iLBC.
> 
> Codecs are negotiated by both end-points and are not depending on Blink alone. Then most of the codecs that feature compression have usually a license that is incompatible with a free software like Blink. The codecs are not part of Blink but belong to libraries that Blink uses so the chance of this happening is very low also for this reason. 

I did not mean to switch to a different codec, but to set the quality parameters for the codec, like:

pjmedia_codec_speex_init: quality (0-10, default=8) & complexity (1-10, default=2)

An experiment found with 8KHz:
 - quality 2 => bitrate 5.9 Kbps  
 - quality 3 and 4 => bitrate 8 Kbps
 - quality 5 and 6 => bitrate 11 Kbps
 - quality 7 and 8 => bitrate 15 Kbps
 - quality 9 => bitrate 18.2 Kbps

I want to lower quality and increase complexity.

From Blink I'd wish to be able to select the quality and complexity values for the speex codec.




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