[Live-devel] where can i get dynamic payload type's implementation mechanism

[xinzhang cao]

2005/11/18, Ross Finlayson <finlayson at live555.com>:
> At 10:38 PM 11/17/2005, you wrote:
> >Hi£º
> >      I am study RTSP,RTP,RTCP for some days. when the payload type's
> >is dynamic, where could i get the doc for description it.
> >          for example: when I use helix to streaming MP3 file, it use
> >X-MP3-draft-00.
> >where could i get document about X-MP3-draft-00 protocol.
>
> The issue is not that this RTP payload type is
> 'dynamic' (all RTP payload types defined in the
> last few years are dynamic).  The issue is that
> the "audio/X-MP3-draft-00" MIME type is a
> proprietary hack, defined only by
> RealNetworks.  If you want a document that
> defines it, you'll have to ask RealNetworks.
>
> However, in this case, the "audio/X-MP3-draft-00"
> MIME type is a RTP payload format that's similar
> to the (IETF standards track) RFC 3119 payload
> format, except that (i) there is only one ADU
> frame in each RTP packet, and (ii) there is no
> special header in the RTP packet.
>
> The "LIVE555 Streaming Media" code is able to
> handle this payload format (by converting the
> incoming data to regular MP3 frames).  See "MediaSession.cpp".
>
>
>        Ross Finlayson
>        Live Networks, Inc. (LIVE555.COM)
>        <http://www.live555.com/>
>
>
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>
Hi Ross:
    thanks for you replay.
    Now I have some question about rfc3119 and realnetworks about mp3 payload.
    Question 1:
    would you give me more detail about the backpointer. Now I know
the from MP3 frame to ADU frame the backpointer is very important.
    Question 2:
    about RealNetWorks you told me:
>(i) there is only one ADU frame in each RTP packet, and
     Is it that there is no ADU descriptors data.
>(ii) there is no special header in the RTP packet.
     Is it that the ISN code == 0xFFE. MP3 convert to ADU do not use
interleaved ADU frames