[Mp4-tech] Query regarding Microsoft MPEG-4 Reference Decoder
toMr. Stefan A. Goor
Stefan A. Goor
stefan.goor ucd.ie
Tue Jul 6 19:25:39 EDT 2004
Hi Saru,
I think those questions should be directed to Dicas:
dicas digital image coding GmbH
Holsteinische Stra?e 39
D-12161 Berlin,
Germany
Phone: +49 - 30 - 85 07 43 04
Fax: +49 - 30 - 85 07 43 06
http://www.dicas.de/ or
http://www.mpegable.com/
Hope this helps,
Best Regards,
Stefan
> -----Original Message-----
> From: mp4-tech-bounces lists.mpegif.org
> [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of MALHOTRA VINKY
> Sent: 03 July 2023 15:45
> To: mp4-tech lists.mpegif.org
> Subject: RE: [Mp4-tech] Query regarding Microsoft MPEG-4 Reference
> Decoder toMr. Stefan A. Goor
>
>
> 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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