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

[MALHOTRA VINKY]

Hello Stefan,
 Your mail has been a great help.
 Thanx a ton.
 Can you just let me know,how can I 
 obtain Dicas SDK?Any idea if there 
 is some concession for Universities,
 I mean the University pricing of the 
 software?
Thanx,
Saru 
--- "Stefan A. Goor" <stefan.goor ucd.ie> wrote:
> Dear Saru Malhotra,
> Yes I have found a few solutions to this.
> The reason that the reference software doesn't work
> is because the decoders
> do not
> support error resilience:
> 
> "The syntax of MPEG-4 allows you to write
> error-resilient
> decoders. How you do build such decoders is not
> specified in the standard -
> it's an area where vendors can (and do) compete.
> Some decoders do not
> include any error robustness processing, and may
> indeed fail when
> confronted with errors."
> (Rob Koenen,
>
http://lists.mpegif.org/pipermail/mp4-tech/2004-January/003125.html)
> 
> However I have found that the microsoft decoder (and
> possibly the MoMusys
> one) will
> decode a sequence if a filtering process is used to
> ensure that only full
> frames are passed
> to the decoder. So if a packet is lost that contains
> an Access Unit (AU)
> segment rather
> than a complete AU, none of the segments for that AU
> are passed to the
> decoder.
> You can tell if an AU segment is in a packet from
> the RTP marker bit.
> 
> I have not tried this for enhancement layers but I
> guess that it may work.
> 
> Another alternative is to buy a codec that supports
> error resilience.  We
> obtained the
> Dicas SDK and have found it to be robust for lossy
> situations.
> 
> Hope this helps,
> Stefan
> 
> 
> 
> 
> 
>   -----Original Message-----
>   From: mp4-tech-bounces lists.mpegif.org
> [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf
> Of MALHOTRA VINKY
>   Sent: 01 July 2023 12:48
>   To: mp4-tech lists.mpegif.org
>   Subject: [Mp4-tech] Query regarding Microsoft
> MPEG-4 Reference Decoder to
> Mr. Stefan A. Goor
> 
> 
>   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 the! se
>   > problems and questions would be greatly
> apreciated, Many
>   > thanks, Stefan
> 
> 
> 
>
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