[Live-devel] temporal reference and Picture types for TS streams

[Shaswata Jash]

Hi Mallikharjuna,

According to RFC-2250, encapsulation (i.e. adding MPEG1/2 specific fixed
headers) is done only on elementary streams. Even if MPEG -PS is used, live
first extracts the ES from it and then uses the encapsulation rule over it.
In fact according to the RFC, if a server would have directly streamed the
MPEG-PS, there is no need of any encapsulation (Ref: Section 2 of the RFC).
Similarly for MPEG-TS, the RFC states only that each RTP packet must contain
integral number of 188 bytes of MTS packets (Ref: Section 2 of the RFC) and
there is no need of MPEG specific headers until and unless the RTP packets
contains TS packets as it is.
So if the server is intelligent enough to extract the elementary stream from
a TS stream and then stream out following the encapsulating rule of
RFC-2250, then only in the client side those information can be found.
Another solution can be - let the server stream the TS packets, but the
client parses those packets to find the information of temporal reference
and picture type (because these informations can be found from the MPEG-bit
streams too).
Also, can we not use the virtual-function called processSpecialHeader()
(which can be accessed in classes derived from RTPSource) to get the each
RTP packet in the client side - in that case, will it not be cleaner design?

With regards,
Shaswata

----- Original Message ----- 
From: "Mallikharjuna Reddy (NAVT)" <ymreddy at ssdi.sharp.co.in>
To: "'LIVE555 Streaming Media - development & use'"
<live-devel at ns.live555.com>
Sent: Friday, September 08, 2006 2:00 PM
Subject: [Live-devel] temporal reference and Picture types for TS streams


>
> Hello All,
>
> We are trying to capture the temporal reference and picture types for TS
> streams from MPEG Video-specific header after parsing the RTP fixed
headers
> on the client side. We could able to do it for ES and PS streams in
> networkReadHandler() function. But the same functionality is not working
for
> TS streams. Also we observed that on the server side for TS streams, MPEG
> Video-specific header is not attached to each RTP packet after the RTP
fixed
> header. We are using testMPEG2TransportStreamer.cpp for streaming TS
files.
>
> Any clues on this.
>
> Thanks and Regards
> Y. Mallikharjuna Reddy
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