[Asterisk-Dev] iax2 video frame timestamps

[Steve Kann]

On Apr 30, 2005, at 11:25 PM, Ben Lear wrote:

> Kenny Shumard wrote:
>> On 4/29/05, Jeff Grollo <jgrollo at horizonlive.com> wrote:
>>> The enlightening iax(2) spec released yesterday describes timestamps
>>> for meta video frames as 16 bits. However, the diagram for meta video
>>> frames displays a '?' as bit 0 in the timestamp. chan_iax2.c (line
>>> 7324) only uses the lower 15 bits of the timestamp to construct a
>>> full 32-bit timestamp:
>>>
>>>     fr.ts = (iaxs[fr.callno]->last & 0xFFFF8000L) | (ntohs(mh->ts) &
>>> 0x7fff);
>>>
>>> Is that bit of the timestamp reserved or should the full 16 bits be
>>> used in timestamp calculations?
>>>
>>> Jeff Grollo
>>>
>>
>> This was exactly my question, and why I had that '?' there.
>> Any insight from anyone on that bit?
>
> It would be nice if it is/could be used to indicate a complete image 
> frame,
> basically the equivilent of an RTP Headers "M" bit.

That's interesting;  I was thinking of sending I frames via full 
frames, as opposed to "mini-video" frames,  Which would implicitly do 
the same thing (and also get a retransmit/acknowledgment for them).    
My feeling was that it made sense to send them reliably, since 
otherwise the following P (or preceeding B) frames don't make much 
sense without the I frame.

-SteveK