On Tue, Oct 30, 2007 at 10:26:02AM -0500, Kevin P. Fleming wrote: > Luigi Rizzo wrote: > > > ok thanks for the clarification. > > The absence of sequence number makes it slightly difficult to detect > > missing frames though... > > Not really... sequence numbers (especially in the video media world) > aren't a reliable way to order packets and check for missing packets > anyway, as sequence numbers can be 'consumed' by non-media frames in > some situations, and IIRC there are also video formats where multiple > frames can be sent with the same sequence number. > > Using the timestamps and duration of the frames allows the receiver to > determine if any time period is missing media.
I am a bit unclear on the following case: i encode a video frame (say an I-frame) and the result is a large chunk of data that needs to be transmitted over multiple UDP packets (containing in turn RTP or IAX frames). Now, for this video frame i have only one timestamp (in IAX they have 1ms resolution), and maybe 50+ packets. The timestamp for the next video frame is say 30 ms later. The only thing i can do here is send the individual IAX packets with the same timestamp, because i don't have enough different values before the next video frame. But then how can i detect missing or reordered fragments ? Surely if the fragmentation is done correctly i can leave it to the decoding code, which has more info (in the bitstream). Perhaps i should just forget about doing those checks in my code and leave it to the decoder. cheers luigi _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
