[Live-devel] Video & Audio Properties at RTP Receivers

[oscar lima]

2007/12/5, Ross Finlayson <finlayson at live555.com>:
> The properties that you're asking about - video width & height, video
> frame rate, audio sampling frequency, audio number of channels are
> almost always contained within the media data themselves, and are
> therefore accessed by your decoding software (or hardware), when it
> parses this media data.  (A reminder that the "LIVE555 Streaming
> Media" software does not include decoding software.)  I.e., it is the
> job of your decoder to parse the media data and extract this
> information.

Yes. It is just I am implementing the Livemedia inside a plugin for
Windows Media Player  where they are required *before* the begining of
data processing. I know it's a dshow design problem, so i will have to
wait for data and process the first packets to get them.

> One exception to this is that *some* simple audio codecs (e.g., PCM)
> do not include the audio sampling frequency and number of channels
> 'in band'.  For these codecs (only), these properties are carried
> separately, in the stream's SDP description, and can be accessed from
> the stream's "MediaSubession" object.
> >2. For H.264, is there any parser for the extra info returned by
> >parseH264ConfigStr ?
>
> This data is a sequence of H.264 NAL units, and are therefore
> parsed/interpreted by your H.264 decoder.

Just a suggestion... For MPEG4, and H264, these infos are in the SDP
so it is possible to have a parser in the livemedia stack I think.


Thanks for the answer again,

Oscar