[Asterisk-Dev] IAX2 trunk really should send timestamps as part of iax2_meta_trunk_entry..

[Andrew Kohlsmith]

On January 20, 2005 07:07 pm, Steve Kann wrote:
> To play devil's advocate against my own suggestion (I've thought about
> this a bit since I wrote that), the problem is that you now have two
> choices:

> 1) Put the timestamps at the beginning of the frame:
>       This will likely end up meaning copying stuff around when we send,
> because we won't know how big the timestamp stuff is.    But, it's easy
> for the receiver to deal with..

> This could be solved if there's a writev-equivalent way to send packets
> from discontinuous areas of memory...

> Or, we could just eat the memmove :)

Well the entire basis behind Zaptel (and asterisk in general) is that CPU 
power is cheap.  While we can't be flippant about it, I really don't think 
that a simple memmove or few per trunk frame is going to be all that 
terrible.

> 2) Put the timestamps at the end of the frame:
>      This is easy to send, but then the receiver needs to walk through
> all the meta entries to the end, to see _if_ there's timestamps there,
> and then read them, before processing all the meta entries..

My personal opinion is that #2 is better.  The receiver would copy the trunk 
frame's "master" timestamp to each demuxed channel and then, upon finding the 
meta entry could copy the "per channel" timestamp from the meta entry to the 
appropriate channel's timestamp.  That should not be any different from the 
normal operation unless a meta entry is detected.

-A.