[asterisk-dev] Question about audiohook.c and re-sampling

[Joshua Colp]

Dennis Guse wrote:
 > Hi,

Kia ora,

 > at the moment I am working on app_jack, so that it is not limited to
 > 8000Hz anymore. During the day I made some progress and found that for a
 > G722 I only get slin in app_jack instead of the expected slin16 (or even
 > higher).
 > I looked further and found that audiohook.c defines the internal
 > sampling rate used for each audio hook. The sampling rate is set to
 > 8000Hz...

There is an initialization flag, AST_AUDIOHOOK_MANIPULATE_ALL_RATES, you 
can set which will cause the code to provide signed linear in the sample 
rate of the source codec. In the case of G722 this would be slin16.

 > Due to a lack of documentation I am not quite sure how to change
 > audiohook.c, so that always the channel's native sampling rate, which
 > depends on the actual codec, is passed to app_jack.

Once enabling the above you would need to change app_jack to remove the 
assumption that it will always be dealing with AST_FORMAT_SLINEAR.

Cheers,

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org