[Mp4-tech] Query regarding Microsoft MPEG-4 Reference Decoder to Mr. Stefan A. Goor

[MALHOTRA VINKY]

Mr. Stefan A. Goor
I have been working on a similar problem as mentioned by u and quoted below.
I m using MoMuSys encoder and as soon as I drop a frame from the enhancement layer
,the decoder is unable to decode it.
Did u find any solutions to the problem.
Kindly reply at your earliest convenience.
Saru Malhotra
> Hey All,
> Hopefully someone can help me with this.
> I have used the MPEG4IP tools to create hinted mp4 files that 
> contain mpeg4 bitstreams created with the MS Encoder 
> Reference Software and I have placed these files on the 
> Darwin Streaming Server to allow RTSP access. When I write 
> the payload of the packets received by the RTSP client to a 
> file, I can decode it with the MS Reference Decoder.  However 
> if I drop any packet, the decoder stops with a dialog box on 
> the screen that says "Debug Error!... ...abnormal program 
> termination..." and the decoder prints the following message 
> in the dos window:
> 
> Assertion failed: iMbType >= 0 && iMbType <= 3, file 
> d:\ms_om\sys\decoder\mbheaddec.cpp, line 476
> 
> >From what I understand, the MPEG-4 decoder should be able to handle 
> >losses
> and corruption (isn't one of the main goals of MPEG-4 to be 
> highly error resiliant?). Could anyone explain what the 
> problem may be and how I may get around it? I would like to 
> be able to decode content has been sent over a network and 
> that may have approximately 0.5% packet loss. Also, I assume 
> that each packet or at least an integer number of packets 
> corresponds to a single frame, is this true?
> >From RFC 1889 for RTP, I see that there is a marker bit that 
> generally
> indicates frame boundaries.  In MPEG-1 and 2 there was a 
> specific code that determined the start of a frame, is there 
> something similar for mpeg4 video stream? Any help with these 
> problems and questions would be greatly apreciated, Many 
> thanks, Stefan

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