[asterisk-dev] AST_FRAME_DIGITAL

[Russell Bryant]

Klaus Darilion wrote:
> Thus, why do we have a AST_FRAME_IMAGE? Why is IMAGE not treated as 
> VOICE? Obviously because Asterisk would transcode and the image is 
> broken - the same reason why I like AST_FRAME_DIGITAL.

I don't think that comparing IMAGE to DIGITAL is a valid comparison.  I can look
at the image in an IMAGE frame.  I can listen to the audio in a VOICE frame.
But what about DIGITAL?  How is Asterisk supposed to interpret a DIGITAL frame?
 It is completely arbitrary.

I'm not sure how many ways I can say this.  The stream you're dealing with is
_voice_ and _video_, both of which have explicit frame types in Asterisk.  The
stream should be decoded and passed into Asterisk using this method.  There are
good reasons for it being this way.  It is the whole reason that Asterisk is
able to bridge calls between completely different technologies - ISDN to IAX2 or
whatever the case may be.  Furthermore, by explicitly using the voice and video
frame types, Asterisk is able to handle transcoding if necessary.  If both ends
of the call are set up to use the same audio and video formats, Asterisk will
not touch the contents.

-- 
Russell Bryant
Software Engineer
Digium, Inc.