[Live-devel] Adding support for DV video

[Ben Hutchings]

On Sun, 2009-04-26 at 15:50 -0700, Ross Finlayson wrote:
[...]
> >In fact I use a whole DV frame (120000-576000 bytes), which will then be
> >split across a large number of packets.  I take it this is not the
> >correct way to use frames in liveMedia?
> 
> No, actually that is correct.  Those are very large frame sizes, though - yow!

Just to be clear, that is the encoded size in DV interchange format
(DIF) of a complete video frame.  This size is constant for any given
profile so it doesn't change in a valid DIF file or stream.  The 80-byte
blocks each have a header identifying their type and position in the
frame.  I have compiled a more detailed description at
<http://dvswitch.alioth.debian.org/wiki/DV_format/>.

[...]
> >How should the receiving application cope with packet loss?
> 
> Our RTP receiving code ("MultiFramedRTPSource") automatically 
> detects, and discards, frames that contain lost packets, so the 
> receiving application will get either complete frames, or no frame 
> data at all.

Nice and simple.  The regular structure of DIF does mean that it should
be possible for a more sophisticated application to make use of an
incomplete frame hthough.

Ben.

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