[Live-devel] H264 H264VideoRTPSource

[Jeremy Noring]

On Mon, Jan 25, 2010 at 3:25 AM, Miguel Angel Arcos
<marcos at a5security.com>wrote:

> Dear Ross,
>
> I'm working with the class H264VideoRTPSource when I recieve RTP data
> information of an IP Camera and I have some questions.
>
> First, If I look my (subsession->(fVideoWidth y fVideoHeight)) and I can't
> extract video resolution because this values are 0. Then I'm looking to
> extract that information looking the SPS, Sequence Parameter Set, packets.
> On the live555 classes I have been looking and I can't find any parser of
> that data. Is possible extract that information using live555 or I need to
> search another parser to do that task?
>

Live555 doesn't have a parser for the sequence parameter sets.  Writing such
a parser isn't too hard, although it's not completely trivial because the
SPS info uses exponential golomb encoding (a form of variable length
encoding) for many parameters.  I'd read the H264 specification if you're
interested in parsing it; also read the wiki page on exponential golomb:

http://en.wikipedia.org/wiki/Exponential-Golomb_coding

(also note that the resolution is inferred from several different values in
the SPS set--it isn't just a single value for width/height)
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