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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>Von:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> mahesh k
[mailto:maheswarreddy.k@gmail.com] <br>
<b><span style='font-weight:bold'>Gesendet:</span></b> Dienstag, 7. August 2007
14:24<br>
<b><span style='font-weight:bold'>An:</span></b> Mailing list for x264
developers<br>
<b><span style='font-weight:bold'>Betreff:</span></b> Re: [x264-devel]
Regarding disabling 4x4 in JM code</span></font></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Dear peter,<br>
I am talking about decoder only. I will explain u my problem more clearly.<br>
<br>
Right now our decoder works properly with our encoder. Now we need to make this
decoder standardised in the sense that it should accept any other bitstream(for
example i want to decode JM encoders output with my decoder). <br>
<br>
</span></font><span lang=EN-GB>After reading the syntax elements as per
baseline standard I need to check whether this is implemented or not in my
decoder and return the error still needs to be implemented. the intent was that
the code shouldnot crash in such situations instead return proper error code. </span></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'>Obviously you will need to decode the COMPLETE mb_type than. For
values of ‘0’ in Intra-frames and values of ‘5’ in
P-Frames and ‘23’ in B-Frames you produce your error message. </span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
<br>
I went through the section that u told me. </span>But my doubts were,<br>
i dont understand what 0_0_0 signify in name of MB type. </font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'>The 1. number in x_x_x corresponds to column 5 of table 7-11</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'>The 2. number….
column 6</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'>The 3. number
column 7</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'>Search for the label-text of these table-columns to get their exact meaning</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'> </span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>Also in table
7.13 mb_types for P slices, what do we mean by inferred type.</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><i><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red;font-style:italic'>Inferred</span></font></i><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'> means <i><span style='font-style:italic'>deduced</span></i>. I
simply says: if a macroblock does not appeare in the bitstream (because it is
skipped due to ‘mb_skip_run’ it automatically has the type P_Skip
and is 16x16 ….</span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
Also tell me can we idetify the prediction mode from mb_type itself? <br>
</span></font><font size=2 color=red face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:red'>Yes, every possible mode
is part of the tables! Somewere in 7.4.5 you find the note that you have to add
the I-Table at the bottom of the P and B tables, to signal Intra MB’s in
P and B-frames. </span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color=red
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial;
color:red'> </span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
</span>thanks in advance,<br>
mahesh.</font></p>
<div>
<p class=MsoNormal><span class=gmailquote><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>On 8/7/07, <b><span style='font-weight:bold'>List,
Peter</span></b> <<a href="mailto:Peter.List@t-systems.com">Peter.List@t-systems.com</a>>
wrote:</span></font></span> </p>
<div link=blue vlink=blue>
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<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>Dear Mahesh,</span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>if you are talking about a DECODER intra 4x4 is a
must, if you want to be standard conform in all cases (for any profile). </span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>If you are talking about ENCODERS you don't
need to implement intra-4x4 but only use intra-16x16 (resulting in very poor
intra performance).</span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'> </span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>I don't understand what you mean with:</span></font></p>
<p style='margin-bottom:12.0pt'><font size=3 face="Times New Roman"><span
lang=EN-GB style='font-size:12.0pt'>But we want to decode any standard
bitstream that is as per standard but return the error code accordingly . </span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>About mb_type read in "Recommendation
H.264" (ISO/IEC 14496-10) paragraph 7.4.5</span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'> </span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'>Peter</span></font></p>
<p><font size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy'> </span></font></p>
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<p><b><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;
font-weight:bold'>Von:</span></font></b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'> mahesh k [mailto:<a
href="mailto:maheswarreddy.k@gmail.com" target="_blank">maheswarreddy.k@gmail.com</a>]
<br>
<b><span style='font-weight:bold'>Gesendet:</span></b> Dienstag, 7. August 2007
11:22<br>
<b><span style='font-weight:bold'>An:</span></b> Mailing list for x264
developers<br>
<b><span style='font-weight:bold'>Betreff:</span></b> Re: [x264-devel]
Regarding disabling 4x4 in JM code</span></font></p>
</div>
<div><span id="q_1143fb44a94c6eff_3">
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'> </span></font></p>
<p style='margin-bottom:12.0pt'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>thanks for ur reply. Plz tell me whether intra 4x4 is
must in base line profile or it is an optional.<br>
Can't we run the baseline profile decoder without 4x4 as per standard?<br>
I need this because at present we have not implemented this 4x4 mode But we
want to decode any standard bitstream that is as per standard but return the
error code accordingly . <br>
Also I am confused with the syntax element mb_type. <br>
What values does mb_type should have if i need to check whether this is an 4x4
or 16x16.<br>
Also plz tell me in clear about this mb_type and ma_mde.<br>
If possible refer some good document on this. <br>
<br>
Thanks in advance.</span></font></p>
<div>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>On
8/7/07, <b><span style='font-weight:bold'>List, Peter</span></b> <<a
href="mailto:Peter.List@t-systems.com" target="_blank">Peter.List@t-systems.com</a>>
wrote:</span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'><br>
> mahesh k wrote:<br>
> > I want a baseline ecoded bit stream in which intra4x4 predition mode<br>
> > should not be present.<br>
><br>
> Note (but you probably already know it): of course intra4x4 is part of <br>
> baseline.<br>
<br>
Also note that intra4x4 is NOT some fancy add on for intra-coding like<br>
some people think 4x4 motion estimation is.<br>
Intra4x4 is the basic intra coding mode! It is usually used for the<br>
majority of intra-macroblocks. Intra-16x16 is only used for very uniform <br>
macroblocks like blocks from a blue sky or something like that.<br>
Regards, Peter<br>
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