Subject: [AVT] Comments on draft-xia-avt-mpeg2ts-preamble-01.txt

From: Eric Friedrich <[email-masked]>
Date: Thu, 14 Jan 2010 14:16:42 -0500

Hello,
   I have a few comments on the Xia MPEG2TS Preamble draft (http://www.ietf.org/id/draft-xia-avt-mpeg2ts-preamble-01.txt 
)
Section 5.3
- If you take an earlier PES header and place it in the preamble  
directly before the "Beginning of video frame encoding data", you may  
create a problem. Most likely the PTS (presentation time stamp) of the  
earlier PES header does not correspond to the actual PTS of the IDR/I- 
Frame.
- In addition to PAT/PMT/ECM important elements are also the PES  
Header, and Sequence Header or Sequence Parameter Set. You may want to  
consider including these as well.
- Which SSRC value is used on the preamble packets?
- Which RTP timebase and values are set on the preamble packets. Is  
there an RTP timestamp discontinuity with the RAMS burst? How is the  
MPEG2 timebase initialized on the client?
Section 5.4
    How do you signal presence of the preamble? I don't see any new  
SDP attributes added

Thanks,
Eric Friedrich

---

From: Peilin Yang <[email-masked]>
Date: Fri, 15 Jan 2010 14:06:47 +0800

Dear Eric,

Thank you very much for giving comments. Some of them are good suggestions.
Please see inline

Best regards,

Peilin

-----邮件原件-----
发件人: [email-masked] [mailto:[email-masked]] 代表 Eric
Friedrich
发送时间: 2010年1月15日 3:17
收件人: [email-masked]
主题: [AVT] Comments on draft-xia-avt-mpeg2ts-preamble-01.txt

Hello,
   I have a few comments on the Xia MPEG2TS Preamble draft (http://www.ietf.
org/id/draft-xia-avt-mpeg2ts-preamble-01.txt
)
Section 5.3
- If you take an earlier PES header and place it in the preamble directly
before the "Beginning of video frame encoding data", you may create a
problem. Most likely the PTS (presentation time stamp) of the earlier PES
header does not correspond to the actual PTS of the IDR/I- Frame.

Peilin: I found that in some cases there are no actual PTS of the
IDR/I-frame which I got from operators. In other words, there is no PES
header of the IDR/I-frame in these cases. Therefore, it is necessary to get
the earlier PES header for demultiplexing. Otherwise, the IDR/I-frame cannot
be decoding.   

- In addition to PAT/PMT/ECM important elements are also the PES Header, and
Sequence Header or Sequence Parameter Set. You may want to consider
including these as well.

Peilin: Good question. I am updating a new version which will add the
information of the sequence header and Sequence Parameter Set. Thank you
very much.

- Which RTP timebase and values are set on the preamble packets. Is there an
RTP timestamp discontinuity with the RAMS burst? How is the
MPEG2 timebase initialized on the client?
Section 5.4
    How do you signal presence of the preamble? I don't see any new SDP
attributes added
Peilin: Good questions. The new version will add a new section to introduce
the RTP header of the preamble packets and update SDP attributes. Thank you
very much.

Thanks,
Eric Friedrich
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Audio/Video Transport Working Group
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