[mythtv-users] VGA -SCART and interlace (2x)

John reidjr at btconnect.com
Thu Sep 24 20:35:21 UTC 2009


John wrote:
> Paul Gardiner wrote:
>> John wrote:
>>> Paul Gardiner wrote:
>>>> John wrote:
>>>>> Paul Gardiner wrote:
>>>>>> John wrote:
>>>>>>> Thanks for the reply.  What I was doing was moving between 
>>>>>>> autodetect, interlaced and progressive under the menu. The 
>>>>>>> picture looks the same with interlace (x2) and Progressive (no 
>>>>>>> -interlacer ) set. Same affect when I choose none as the 
>>>>>>> interlacer under the TV settings menu.
>>>>>>>
>>>>>>> Looks like I need another graphics card,
>>>>>>
>>>>>> I don't think you've quite got the point I was making. 
>>>>> You too :-)
>>>>>
>>>>> What I see is perfect "still" quality. The problem is interlacing 
>>>>> artefact's on  movement, just as you have clearly described. What 
>>>>> I was trying to say was that there was absolutely no reduction in 
>>>>> interlacing artefact's between interlaced 2x, and none. So 
>>>>> doubling the field rate, and repeating the fields does not lead to 
>>>>> a constant synchronization between recorded and displayed 
>>>>> interlacing.  The effect is disconcerting, and is clearly 
>>>>> noticable on all scene changes, as well as movement.
>>>>>
>>>>> VGA to scart gives excellent quality, and the quality is also 
>>>>> acceptable on movement using high quality deinterlacers, but the 
>>>>> whole point is that we shouldn't need to de-interlace to display 
>>>>> it :-)
>>>>
>>>> Ok, that makes more sense now I understand what you are seeing. You
>>>> need to get "none" working intermittently well before using 
>>>> "Interlaced x2".
>>>>
>>>> Do you see clear fine-lined combs, or a strange larger-scale sine-wave
>>>> type pattern on the edge of moving objects?
>>>>
>>>> P.
>>>>
>>>>
>>>
>>> I see "strange larger-scale sine-wave type pattern on the edge of 
>>> moving objects"  ..... is there hope for me Doctor ;-)
>>
>> Oh yes! :-) That's great news. That's what I see if for any reason the
>> video is scaled. One possibility is if you are scaling the menu to
>> counteract overscan; it's ok to do so, but you need to uncheck the
>> setting "Scale video to match GUI" (or something like that). Or
>> maybe you aren't getting a 720x576 mode (I'd guess that wasn't
>> the problem because you'd see it in the logs). Can't think of any other
>> reason at the moment, but any scaling in the vertical will cause those
>> funny sine curves, and also stop "Interlaced x2" from working (although
>> yadif will be fine).
>>
>> Cheers,
>>     Paul.
>>
>>
> Seems a relevant bit of the logs. I am not clear if this is a good or 
> bad thing.
>
>
> 2009-09-23 18:39:37.748 VideoOutputXv: CreateShmImages(32): video_dim: 
> 720x576
> 2009-09-23 18:39:37.788 VDP: SetVideoRenderer(xv-blit)
> 2009-09-23 18:39:37.788 VDP: SetVideoRender(xv-blit) == 
> GetVideoRenderer()
> 2009-09-23 18:39:37.789 VideoOutputXv: Chromakeying not possible with 
> this XVideo port.
> 2009-09-23 18:39:37.789 Snapping width to avoid scaling: width: 720, 
> left: 0
> 2009-09-23 18:39:37.790 Display Rect  left: 0, top: 17, width: 720, 
> height: 542, aspect: 1.67123
> 2009-09-23 18:39:37.790 Video Rect    left: 0, top: 0, width: 720, 
> height: 576, aspect: 1.7777
> 2009-09-23 18:39:37.796 Over/underscan. V: 0, H: 0
> 2009-09-23 18:39:37.796 Snapping width to avoid scaling: width: 720, 
> left: 0
> 2009-09-23 18:39:37.797 Display Rect  left: 0, top: 17, width: 720, 
> height: 542, aspect: 1.67123
> 2009-09-23 18:39:37.797 Video Rect    left: 0, top: 0, width: 720, 
> height: 576, aspect: 1.7777
> 2009-09-23 18:39:37.797 VDP: LoadBestPreferences(720x576, 25)
> 2009-09-23 18:39:37.797 NVP(1): LoadFilters(''..) -> 0x0
> 2009-09-23 18:39:37.798 OSD Theme Dimensions W: 640 H: 480
> 2009-09-23 18:39:38.183 NVP(1): ClearAfterSeek(1)
> 2009-09-23 18:39:38.183 VideoOutputXv: ClearAfterSeek()
>
> What is the display rectangle  and why is it 542 ?
>
YES !!! Thanks Paul, you put me on the right track. I understood the 
need not to scale, but as I had all the zooming scaling and aspect ratio 
turned off, and the Video res exactly matched the modeline, everything 
should work (a clue -- no ).

 I was setting the aspect ratio in Xorg to ensure aspect Ratio detection 
worked with
Option         "DPI" "75x100"

I changed that to

Displaysize 260 145

and now the Display rectangle matches the video rectangle. Not 
completely sure I understand this, as the picturee on the TV look the 
same, except as there is no scaling the "interlacing (x2)" works as 
advertised. Excellent !

VideoOutputXv: CreateShmImages(32): video_dim: 720x576
2009-09-24 21:04:34.987 VDP: SetVideoRenderer(xv-blit)
2009-09-24 21:04:34.987 VDP: SetVideoRender(xv-blit) == GetVideoRenderer()
2009-09-24 21:04:34.988 VideoOutputXv: Chromakeying not possible with 
this XVideo port.
2009-09-24 21:04:34.988 Snapping height to avoid scaling: height: 576, 
top: 0
2009-09-24 21:04:34.988 Snapping width to avoid scaling: width: 720, left: 0
2009-09-24 21:04:34.988 Display Rect  left: 0, top: 0, width: 720, 
height: 576, aspect: 1.77778
2009-09-24 21:04:34.988 Video Rect    left: 0, top: 0, width: 720, 
height: 576, aspect: 1.7777
2009-09-24 21:04:34.994 Over/underscan. V: 0, H: 0
2009-09-24 21:04:34.994 Snapping height to avoid scaling: height: 576, 
top: 0
2009-09-24 21:04:34.994 Snapping width to avoid scaling: width: 720, left: 0
2009-09-24 21:04:34.994 Display Rect  left: 0, top: 0, width: 720, 
height: 576, aspect: 1.77778
2009-09-24 21:04:34.994 Video Rect    left: 0, top: 0, width: 720, 
height: 576, aspect: 1.7777
2009-09-24 21:04:34.994 VDP: LoadBestPreferences(720x576, 25)



Now, all I need to do is get the xrandr switching to work, and all is 
well. I optimistically hoped that perhaps this might have fixed that as 
well, depending on what the xrandr changes actually key on, vid_dim 
Display Rect, or Video Rect, but thats another story.

:-)

John






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