Subject: [AVT] MPEG-4 BIFS in the packet loss environment

From: "Lim, Young-Kwon" <[email-masked]>
Date: Sat, 23 Mar 2002 00:17:16 +0900

Dear all,

I was little bit suprised about the comments on the MPEG-4 Simple payload
format raised at the last meeting. It was about MPEG-4 BIFS data in the
packet loss environment. As I commented in the meeting difference encoding
mechanism of MPEG-4 BIFS is not different from any other delta encoding
method. As we all clearly know, if we loose some packets containing delta
information such as P-frames of video bitstream decoder needs to be
resynchronized at the next synchronization points such as I-frame of video
bitstream. This also same to the case of MPEG-4 BIFS. If we loose packets
containing BIFS update which is difference from the current scence
description we need to resynchronize the scene at the next BIFS command
which contains whole scene description. In addition, the size of BIFS packet
is relatively smaller than audio or video packets. So, we can duplicate
without wasting large bandwith. And there are also carouselling mechanism
repeatedly sending the BIFS command. So, loosing the MPEG-4 BIFS packets
shouldn't be a issue.

Sincerely,
Young.

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: "Zvi Lifshitz" <[email-masked]>
Date: Sat, 23 Mar 2002 22:24:08 +0200

Young,

Loosing MPEG-4 BIFS packets is an issue for the reasons explained in M7816.

Regards,

z
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-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Lim,
Young-Kwon
Sent: Friday, March 22, 2002 5:17 PM
To: [email-masked]
Cc: [email-masked]
Subject: MPEG-4 BIFS in the packet loss environment

Dear all,

Sincerely,
Young.

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From: "Marshall Eubanks" <[email-masked]>
Date: Sat, 23 Mar 2002 19:53:33 -0500

On Sat, 23 Mar 2002 22:24:08 +0200
> Loosing MPEG-4 BIFS packets is an issue for the reasons

Dear Zvi;

What does M7816 refer to ? In
http://www1.ietf.org/mail-archive/working-groups/avt/current/index.html
the messages are not numbered.

Regards
Marshall Eubanks

---

From: "Zvi Lifshitz" <[email-masked]>
Date: Sun, 24 Mar 2002 09:56:43 +0200

Attached please find M7816 for the benefit of those who don't have access to
MPEG repository.

Regards,

z

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Marshall Eubanks
Sent: Sunday, March 24, 2002 2:54 AM
To: Zvi Lifshitz; 'Lim, Young-Kwon'; [email-masked]
Cc: [email-masked]
Subject: Re: [AVT] RE: MPEG-4 BIFS in the packet loss environment

Dear Zvi;

Regards
Marshall Eubanks

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From: Colin Perkins <[email-masked]>
Date: Sun, 24 Mar 2002 11:58:53 -0600

Is this still the case with things like MPEG-J?
Colin

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From: Stephan Wenger <[email-masked]>
Date: Sun, 24 Mar 2002 21:06:38 +0100

I have two problems with BIFS:

1. Re-synchronization: For video, you have many option after a packet loss: 
accept the artifacts, use error concealment, rely on built-in error 
resilience to clean up the errors.  Only the most trivial decoders stop 
displaying video and wait for the next key frame.  But the analogy of that 
is precisely what you have to do when you loose a BIFS packet.  You cannot 
expect a presentation engine that handles datra structures to be as 
tolerant as the human visual system.

2. BIFS has multi-session control protocol capabilities.  I feel uneasy to 
send such critical information over an unprotected link.

I don't have any problems with BIFS-Anim.  This seems to be a media format 
like any other.  If this is your primary concern, then I would not object 
if we allow only BIFS-Anim but not BIFS-Command.

Would it be possible to send BIFS Command messages well before their first 
use and become effective only at a certain point in time, or do they have 
to be sent synchronously?  Maybe you can use an argumentation similar to 
the one I use for PUP packets in the JVT payload design?

Stephan

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From: Vishy Swaminathan <[email-masked]>
Date: Tue, 26 Mar 2002 07:01:16 -0800

All,

MPEG-J data has the same issues as BIFS with packet loss. Fragments of 
received data cannot be used when some fragments are lost. However, 
mechanism for sending MPEG-J data ahead of time is clearly defined and 
it does not have to be sent synchronous with media data. Ofcourse, 
repetitive sending will also help.

However, I dont think the packet loss of BIFS or MPEG-J can be equated 
to packet loss of video.

Regards,
Vishy Swaminathan