Subject: Re: [AVT] MPEG2TS preamble - where next

From: Peilin YANG <[email-masked]>
Date: Sat, 31 Jul 2010 05:44:00 +0800

Dear Sandy,

Thank you very much for thinking that this is also a good topic to discuss.

The design ideas of Xia's solution adopts a kind of loose coupling approach to avoid the influence between transport layer session module and application layer (codec). Its advantage is obvious, when you change one module, it doesn't affect another module.  
The example in previous email, I mean that if some unknowable preamble information has already supported by current codec chips, but it doesn't include in the current preamble information. At this time, our solution doesn't need to upgrade software code of STB, and only need to upgrade RS. This is different between two methods.

Best regards,

Peilin

----- 原邮件 -----
发件人: "Sandy (Alexander) MacInnis" <[email-masked]>
日期: 星期五, 七月 30日, 2010 上午5:45
主题: RE: [AVT] MPEG2TS preamble - where next
收件人: Peilin YANG <[email-masked]>
抄送: "[email-masked]" <[email-masked]>

Thanks, Peilin, this is also a good topic to discuss.
I've seen this point brought up before in this forum.

In my understanding, if some new PSI and/or CODEC format becomes a requirement in the future - something that we could not and did predict now - then all receivers that are supposed to receive this new format need to have at least some new software. (I say "at least" because they might have to be replaced.) This is true regardless of what kind of preamble is used, or even whether there is any preamble at all in use.

Do you agree? If not, how do the receivers process formats that were not known and not predictable at the time the receivers were designed and programmed?

So I don't see a difference between the two proposed preamble formats regarding receiving future multicast PSI and/or CODEC formats. It would be nice not to have to update the preamble spec itself, but that does not appear to make a difference to whether the receivers would need to be updated when new multicast formats need to be supported. Whether one or the other preamble format choice would result in more or less work to update receivers
 in the future, I can't predict, since by definition we can't predict what the future PSI or CODEC changes might be.

--Sandy

-----Original Message-----
From: Peilin YANG [mailto:[email-masked]] 
Sent: Thursday, July 29, 2010 1:36 PM
To: Sandy (Alexander) MacInnis
Cc: [email-masked]
Subject: Re: [AVT] MPEG2TS preamble - where next

Dear Sandy,

I am not an expert of codec chip, so I cannot carefully evaluate your comments. But I am completly sure that our current deployment is no problem for that.
Perhaps from the viewpoint STB, i am not sure, TOLV is slightly simple. 
But I think you ignore somewhere, from the viewpoint of operation, if some unknown and unknowable PSI and codec information emerge, Begen's solution needs to upgrade STB's software code. Our solution doesn't. For example, in our implemention, we found in few video stream, occasionally, the first packet of I frame doesn't include PES header. Though this seldom happens, but at this time, PES Header is also a kind of MPEG2-TS preamble informat

ion. I mean this is only an example. through this use case, our solution only needs to upgrade RS software code, we don't need to upgrade STB software code. But Begen's solution needs to upgrade both RS and STB software code. If it is necessary to upgrade software code of uncountable STBs, I think operators don't want to see it. IMHO, this is the advantage of our solution.

Best regards,

Peilin