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<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> -----Ursprüngliche Nachricht-----</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Von: x264-devel-bounce@videolan.org [mailto:x264-devel-</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> bounce@videolan.org] Im Auftrag von Ryan Dalzell</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Gesendet: Mittwoch, 17. Januar 2007 14:27</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> An: x264-devel@videolan.org</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Betreff: [x264-devel] Re: AW: Re: Error Concealment</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> On Wednesday 17 January 2007 12:38, List, Peter wrote:</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > -----Ursprüngliche Nachricht-----</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > Von: x264-devel-bounce@videolan.org [mailto:x264-devel-</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > bounce@videolan.org] Im Auftrag von Ryan Dalzell</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > Gesendet: Mittwoch, 17. Januar 2007 13:28</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > An: x264-devel@videolan.org</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > ></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > Betreff: [x264-devel] Re: Error Concealment</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > ></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > On Wednesday 17 January 2007 09:53, Awadh Bihari wrote:</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > > Please let me know how to detect the slice loss at
the decoder side.</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > > It can only be detected if active sps/pps is not
equal to sps/pps ?</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > Due to arbitrary slice order and the fact that slice
headers do not</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > tell</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > you how many macroblocks are in the slice (and assuming
you are</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > receiving</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > the video data over a network), I believe that the only
way is to</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > actually</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > decode each slice and count the number of macroblocks
that it</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > contributes</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > to a picture. Then, after a suitable period of time to
allow late</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > packets</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > to arrive, if you still haven't decoded all the
macroblocks of a</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > picture</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > > then you have lost some slices.</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> ></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > I dont see why you need to count anything. The slice always
tells you</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > where it's locates in the frame, so you just dump the
macroblocks to</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > that place. If you have arbitrary slice order, things get
more</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> difficult,</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > but in principle it should be the same. You should be able to
detect</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > when the next frame starts (by POC and/or frame_number). If
that happens</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > you can finalize the previous frame, and that's it. Am I
missing</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > something</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> > here?</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Yes, I think you are. Let's say that your receive six slices for a
picture</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> before a slice with a different POC arrives. Is this all the
slices for</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> that picture, or are there supposed to be seven and one got lost?
You</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>> can't tell, short of decoding all the slices and
counting the number of</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> macroblocks provided.</span></font></p>
<p class=MsoPlainText><font size=2 color=black face="Courier New"><span
style='font-size:10.0pt;color:black'> </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'>I was expecting that my network
interface would sort the packets for me. That may be naďve though. A delay
would be involved as well in this case, but I need a receiving buffer anyways,
right?</span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>> This gets even worse when slices can be out of
order across picture</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>> boundaries. I have searched high and low the spec
and I cannot find a</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> statement that precludes this from happening. (Of course, due to
the lack</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> of plain English in the spec it could be there.)</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'>I will check if that is
possible, but I definitely do not believe it is!</span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'>And yes, this standard is not that
easy to read </span></font><font color=blue face=Wingdings><span lang=EN-GB
style='font-family:Wingdings;color:blue'>J</span></font><font color=blue><span
lang=EN-GB style='color:blue'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> Also this could happen</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> when packets become reordered due to network jitter or taking
different</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> routes. Then you don't even know that you have the last slice you
are</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> going</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> to get when the POC changes. So you have to wait a while to see if
there</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> are more packets to arrive containing slices for the current
picture.</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> IMO, it's pretty horrible </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'> </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'>I have heard a lot of different
things about FMO (Flexible Macroblock Ordering). Some said it was absolutely easy
to implement (on PC: simply have more than one input-buffer, one for every
slice-group. Then, while decoding from left to right, top to bottom simply
switch to the right buffer). Some others said it was horrible. </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'>Could you comment? </span></font></p>
<p class=MsoPlainText><font size=2 color=blue face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:blue'> </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>> ASO is a good example of a little extra flexibility
with not much real </span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'>> value but with a high cost in real world systems.</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span lang=EN-GB
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText><font size=2 color=black face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;color:black'> </span></font></p>
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