[asterisk-dev] adjusting the playback speed of voicemail messages.

[Travis Hein]

Hello,

I’ve been looking at app_voicemail in an effort to find a way to address a
requirement that has come up recently. One of our customers previously had
an old Avaya system that allowed them to speed up or slow down the actual
speed of the voicemail they are listening to (i.e. – pitch shift). I was
hoping that there would be a way within asterisk to alter the sample rate
on the fly (i.e. – so when listening to a voicemail message #/* would
alter the sample rate to achieve the same effect instead of skipping
forward or back) but there doesn’t appear to be any way to do so.



I’m hoping I’m missing something and there is some easy way, but after
looking at the code, it appears that the sample rate for the ast_frame is
assumed to be 8 kHz. The formats/format_wav.c seems to also assume 8 kHz
always as well, and the ast_format does not seem to have an
 int (*set_sample_rate)(struct ast_filestream *, int new_rate);
either, which I was thinking would need something like that so that the
ast_control_streamfile() (that is called by the voicemail playback) could
adjust the sample rate by a given amount, just like it currently does for
the skipms value to the seek() function.



If anyone has any ideas that would be great.
-- 
Travis