<br><br><div><span class="gmail_quote">On 30/07/07, <b class="gmail_sendername">Tom Dexter</b> <<a href="mailto:digitalaudiorock@hotmail.com">digitalaudiorock@hotmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
>From: "Steve Smith" Date: Mon, 30 Jul 2007 12:32:00 +0100<br>><br>><br>>Never mind 1080i what about 576i (ignoring TVOUT chips which seem basically<br>>broken in this respect) ?!?!<br>><br>>It seems the simple problem is that FRAME sync (rather than FIELD sync)
<br>>just<br>>isn't working<br>>somewhere along the line...<br>><br>>We shouldn't need to deinterlace if we have an interlaced display (capable<br>>of the relevant resolution) available, full stop, period, end of story.
<br>><br>>The fact that we do means that the syncing system is not working<br>>somewhere along the line, maybe it's the card, maybe the nvidia driver,<br>>maybe Myth ... does anyone know?<br>><br>>Regarding bob deinterlace and "too small a refresh rate". There was a patch
<br>>posted on the list a few weeks ago by a guy called Viktor. Works well.<br>><br>>Cheers<br>><br>>Steve<br><br>The whole issue with getting bob deinterlacing working by adjusting the<br>refresh rate got me wondering...I couldn't remember why I wasn't using it
<br>with my original 1080i mode. Then I remembered that, for one thing, it<br>always gave me that error, and for another, I read in a number of places<br>that you simply shouldn't use bob with an interlaced display.<br>
<br>Out of curiosity, I tried that patch of Viktor's you mentioned (which is<br>here for anyone interested):<br><br><a href="http://svn.mythtv.org/trac/ticket/2903">http://svn.mythtv.org/trac/ticket/2903</a><br><br>I'm in the
U.S. by the way...from your posts and his I see you're dealing<br>with PAL frame rates. I'm running Gentoo and didn't feel like making a<br>custom ebuild just yet, so I simply installed manually using the Gentoo
<br>ebuild command editing in that code change between the unpack and compile<br>steps. The patch seemed to work just fine. Instead of disallowing bob<br>because the refresh rate was being reported at 33333, the refresh rate was
<br>reported as 16666, and bob worked just fine, and does look noticeable better<br>than kerneldint.<br><br>While I'm sure there are good reasons the devs didn't want to incorporate<br>the patch, one comment they made on Viktor's bug report confuses me:
<br><br>"You also don't want to use bob-deint with an interlaced display, use kernel<br>or linear blend when there is a resolution missmatch and no deinterlacing<br>when the source and destination line count matches.
<br><br>See mythtv-vid branch for configuring such a setup."<br><br>What do they mean by that last statement? Isn't deinterlacing always<br>disabled automatically when you view non-interlaced content? I'm running
<br>0.20.1 (svn 13344). Whenever I watch livetv or recording from stations such<br>as Fox or ABC, who broadcast in 720p, my logs (assuming I'm using -v<br>playback) show something like:<br><br>2007-07-30 14:25:58.936
Disabled deinterlacing<br><br>What are they talking about there? I don't understand that reference to the<br>mythtv-vid branch.<br><br>Tom<br><br>_________________________________________________________________<br>
<a href="http://newlivehotmail.com">http://newlivehotmail.com</a><br><br>_______________________________________________<br>mythtv-users mailing list<br><a href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</a>
<br><a href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br></blockquote></div>Tom,<br><br>After some hard thinking last night I realised a bit of what the developers were getting at:
<br><br> (1) If what you are trying to play is the same resolution as your TV ***line for line** then you should be able to<br> get away with no de-interlace...... that is if FRAME sync actually worked. Which it doesn't appear to.
<br><br> (2) If however you are doing some scaling then what you are outputing isn't line for line the same as the signal so some form of de-interlacing is needed. When does this happen?<br> One case is when you output a 16:9 format mpeg on a 4:3 TV. The mpeg has 576 (for PAL) lines, but to get the right aspect ratio,
<br> this is scaled to 0.75*576=432 lines. Now our fields don't match up so we need to modify the picture with some form of deinterlacing.<br><br> (3) Viktor's patch, although it works, is a bit of a sledgehammer. Really it should modify the bob code to double the refresh rate *that bob sees* only if bob has been requested and interlace is being used. However, it works in my case so I'm happy thanks Viktor! :-)
<br><br><br>So in conclusion using Viktor's patch with bob deinterlace seems to work best for me.<br><br>Cheers<br><br>Steve<br><br><br><br><br><br>