[asterisk-dev] AST_FRAME_DIGITAL

[Klaus Darilion]

Russell Bryant schrieb:
> 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?

That's the whole point - it should not interpret it at all.

>  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.

Thus, if I have 3G video call bridged by Asterisk from chan_zap to 
chan_misdn Asterisk should decode the 3G video and then reencode it - 
does not sound well engineered.

If Asterisk bridges a G4 fax call from chan_zap to chan_misdn Asterisk 
should decode the G4 fax into in an IMAGE and the reencode it to G4?

Klaus