[Live-devel] Low Frame-rate Panoramas

[Ross Finlayson]

> I’m working on distributing live panoramas and was wondering if live555 is suited to this application. Some particulars:
>  
> Frames are 2160 x 1080.
> Frame rate is around 1/second.
> I’ll be using either MPEG4 or H264 for encoding.
>  
> Is this do-able with live555? If so, any “gotcha’s” I should be aware of?

I don’t see any reason why this should not work, provided that your codec (MPEG-4 or H.264) supports frame rates that low.  For video quality this high, I suggest using H.264 rather than the (older, less efficient) MPEG-4 codec.

The biggest ‘gotcha’ - and it’s a big one - is that your frames (most if not all of which I assume will be ‘key frames’) will be very large (in terms of the number of bytes that they will take up).  As I’ve noted on this mailing list many times:

—————
I recommend that you reconfigure your encoder so that each key frame is encoded as a sequence of ’slice’ NAL units, rather than as a single NAL unit.

People often have trouble streaming H.264/H.265 video with extremely large key frames, if each key frame gets encoded as a single NAL-unit.  The problem with this is that these NAL units get sent as a (very long) sequence of RTP packets - and if even one of these RTP packets gets lost, then the whole NAL (key frame in this case) will get discarded by the receiver; see
	http://lists.live555.com/pipermail/live-devel/2011-December/014190.html
	http://lists.live555.com/pipermail/live-devel/2012-August/015615.html
	http://lists.live555.com/pipermail/live-devel/2013-May/016994.html
	http://lists.live555.com/pipermail/live-devel/2014-June/018426.html
	http://lists.live555.com/pipermail/live-devel/2014-June/018432.html
	http://lists.live555.com/pipermail/live-devel/2014-June/018433.html
	http://lists.live555.com/pipermail/live-devel/2014-June/018434.html
	http://lists.live555.com/pipermail/live-devel/2015-March/019135.html
	http://lists.live555.com/pipermail/live-devel/2015-April/019228.html
For streaming, it’s better to encode large key frames as a sequence of ‘slice’ NAL units.

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/