[M4IF Technotes] Help with MPEG-4 Visual/Natural reference so ftware

[Larry Pearlstein]

Hi Gary,
Thanks for checking into this.  I have now run the vcon-ge1.cmp Conformance
Test bitstream through the latest Microsoft software, and I still find
anomalous results.  I believe that the problem stems from the way the source
material was used in encoding.
This bitstream indicates rectangular dimensions of 720 x 576.  When the
bitstream is decoded, and pictures are examined assuming an output YUV12
file with a height of 576 lines the results are garbled.
On the other hand, if the resulting file is examined assuming that the
format is YUV12, at 720 x 480, then the resulting pictures appear as one
might expect.
I am guessing that a 720 x 480 YUV12 source file was fed into an encoder
configured to accept data in the 720 x 576 format.
This was quite confusing for me, since I was decoding one frame at a time,
and found very strange results looking at any given 720 x 576 output frame.
If my hypothesis can be confirmed then, for the sake of future MPEG-4 users,
I suggest that we issue a Corrigendum to the Conformance part, and recreate
the vcon-ge1.cmp bitstream, and any other bitstreams that may have been
similarly affected.
                Regards,
                Larry
-----Original Message-----
From: Gary Sullivan [mailto:garysull   microsoft.com]
Sent: Thursday, October 11, 2023 8:16 PM
To: Larry Pearlstein; technotes   lists.m4if.org
Subject: RE: [M4IF Technotes] Help with MPEG-4 Visual/Natural reference
software
I contacted the Microsoft software coordinator.  He says that the FDIS
version
1.0 software is pretty old stuff, and the final version 2 software can be
obtained
from  <http://numbernine.net/robotbugs/mpeg4.htm>
http://numbernine.net/robotbugs/mpeg4.htm as Microsoft-fdam1-2.3-001213.zip
and that is the most stable available version.  If the phenomenon persists
in the
version 2 software, then the question becomes more pertinent.
-Gary
-----Original Message-----
From: Larry Pearlstein [mailto:lpearlst   ati.com] 
Sent: Thursday, October 04, 2023 8:04 AM
To: 'technotes   lists.m4if.org'
Subject: [M4IF Technotes] Help with MPEG-4 Visual/Natural reference software
Hi, 
I've been playing with the MPEG-4 Visual Reference Software, FDIS version
1.0, Natural, decoder software from both Microsoft and MoMuSys.  I've built
and run both under Visual C++ under WinNT.
I have decoded the reference bitstream vcon-ge1.cmp, which contains the
ping-pong sequence. 
The VideoObjectLayer header specifies a rectangular format of 720 x 576. 
I trace both decoders, and I see the 720 x 576 dimension at the dump
routine.  But when I examine the output files (planar 4:2:0 YUV, with
multiple frames concatenated in one file) I find that both Microsoft and
MoMuSys seem to produce pictures formatted at 720 x 480.  Any ideas why this
might be happening?
Also, I have tried to subscribe to the MoMuSys reflector, but the EMAIL
address seems bad.  Is there still an active MoMuSys reflector?
                                Thanks, 
                                Larry 
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