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PostPosted: Thu Apr 20, 2006 10:58 am Reply with quote
Bigchris
 
Joined: 18 Apr 2006
Posts: 15




Another question - I chose to drive my pcHDTV3000 as a DVB card in Mythtv instead of using the preconfigured v4l setup. Any reason why that was the wrong choice? I figured that since the kernel drivers were already there it just made sense to use them...
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PostPosted: Thu Apr 20, 2006 3:55 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Bigchris wrote:
I suspect that our choice of ATSC while most of the rest of the world is using DVB is going to hurt acceptance of DT by pushing our costs up. I'm reminded of France's SECAM which worked - but so what! If the production volume isn't there you either have to drive the price down with tax subsidies or it doesn't get wide acceptance.

DVB-T works great in PAL countries that have already allocated an extra one or two Mhz per channel. DVB-T in 6 Mhz didn't quite have the bitrate they needed for acceptable 1080i ten years ago. It also tended to cause interference to NTSC since it doesn't use the bandwidth as evenly as VSB-8.

There are over a thousand ATSC (VSB-8) transmitters operating right now and several million ATSC receivers. That exceeds the rest of the DVB-T world at the moment. ATSC receivers are dropping in price as demand increases. VSB-8 transmitters are less expensive than DVB-T transmitters and use less electricity. Australia is the only country broadcasting HD over DVB-T right now (with about a million receivers).
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PostPosted: Thu Apr 20, 2006 4:01 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Bigchris wrote:
Another question - I chose to drive my pcHDTV3000 as a DVB card in Mythtv instead of using the preconfigured v4l setup. Any reason why that was the wrong choice? I figured that since the kernel drivers were already there it just made sense to use them...

Most people are doing that. I'm using the older pcHDTV drivers because that's what I've been using without any serious problems and I'd rather keep the driver as small as possible and keep complicated things like MPEG parsing in the application. I mean it isn't really a DVB card even if you can fool applications into thinking it is with a clever driver.
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PostPosted: Thu Apr 20, 2006 6:54 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




heh I remember a few years ago, that channel 11 chief engineer wenhtv during a Society of Broadcast Engineers field trip to Saddleback mountain facilities said: We have four viewers, and one in Andover MA that had four receivers.
I have pix of the facilities...It was a pain for all involved, but seems PBS stations have the best effort in hardware and support.

Music could be like this: Give good quality for free and beg for money after..it works. Not pay per play.

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PostPosted: Thu Apr 20, 2006 6:55 pm Reply with quote
Jim
 
Joined: 01 Mar 2005
Posts: 88
Location: Greater Portland ME joined jan'05




oops I posted in wrong group sorry..Jim

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PostPosted: Thu Apr 20, 2006 7:29 pm Reply with quote
Bigchris
 
Joined: 18 Apr 2006
Posts: 15




Scott,
You've been a big help and made me smarter in the bargain!
Thank you very much!
Chris
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PostPosted: Sat Apr 22, 2006 1:56 am Reply with quote
kmj0577
 
Joined: 03 Jan 2006
Posts: 57




Scott Larson wrote:
Another issue with deinterlacing 1080i is that most forms of deinterlacing will display 30 frames per second instead of 60 fields per second. The frames are deinterlaced so the jaggies are gone but 1080i motion won't look as smooth as 720p because the display is being updated at half speed. Motion in HD video (sports, Letterman, Leno and so on) will look choppy, more like a movie than video. When the display is updated for every field, 1080i looks almost as smooth as 720p. Obviously this isn't an issue with filmed content.

I know mplayer and xine don't update the display for every field and I have patches for them (it only works with XvMC though). I think MythTV does because I'm pretty sure that's where I stole the code to patch xine and mplayer.

I'm not sure how much CPU usage it eats up (a lot less than any other deinterlacer I've tried though), but -vf tfields=4 with mplayer gives very good results (even though the man page claims it'll only work properly with MEncoder and I do believe that to some extent since most any value other than 4 will give weird colors) and doubles the output framerate. I believe it's similar to bob in that it splits fields into frames, although I don't get the shimmering I did when I was on XvMC.
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PostPosted: Sat Apr 22, 2006 8:37 am Reply with quote
Bigchris
 
Joined: 18 Apr 2006
Posts: 15




FWIW, I'm using the latest Nvidia driver, 8756, and it really does seem to have improved XvMC as well as allowing OpenGL V sync to work. The only artifacts I'm seeing now is what I'd describe as "color noise" around small text and even that is so infrequent that it would be hard to call it "objectionable". When watching a live broadcast, the impression is less of seeing television or a movie, more seeing a 35mm photo that moves. Sweet!
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PostPosted: Mon Apr 24, 2006 6:26 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




kmj0577 wrote:
I'm not sure how much CPU usage it eats up (a lot less than any other deinterlacer I've tried though), but -vf tfields=4 with mplayer gives very good results (even though the man page claims it'll only work properly with MEncoder and I do believe that to some extent since most any value other than 4 will give weird colors) and doubles the output framerate. I believe it's similar to bob in that it splits fields into frames, although I don't get the shimmering I did when I was on XvMC.

I used tfields one time when I converted 4:3 1080i video into 480p at 60 frames per second. The filters were:

Code:
crop=1392:1064:250:16,tfields,spp=2,scale=640:480:0:0:20


I don't really remember what all that stuff was for but I remember it worked really well. The motion was smooth, the filters covered up the interlacing and there were no funky colors.
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PostPosted: Mon Apr 24, 2006 6:29 pm Reply with quote
kmj0577
 
Joined: 03 Jan 2006
Posts: 57




Scott Larson wrote:
kmj0577 wrote:
I'm not sure how much CPU usage it eats up (a lot less than any other deinterlacer I've tried though), but -vf tfields=4 with mplayer gives very good results (even though the man page claims it'll only work properly with MEncoder and I do believe that to some extent since most any value other than 4 will give weird colors) and doubles the output framerate. I believe it's similar to bob in that it splits fields into frames, although I don't get the shimmering I did when I was on XvMC.

I used tfields one time when I converted 4:3 1080i video into 480p at 60 frames per second. The filters were:

Code:
crop=1392:1064:250:16,tfields,spp=2,scale=640:480:0:0:20


I don't really remember what all that stuff was for but I remember it worked really well. The motion was smooth, the filters covered up the interlacing and there were no funky colors.

Yeah, the default value for tfields is 4 (which is the one you want to use anyways) which doesn't seem to give funky colors. I just experimented with different values and settled on thd efault.
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PostPosted: Mon Apr 24, 2006 7:07 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




My system isn't fast enough for tfields to work real time (and XvMC doesn't accept filter buffers) but I like the simple concept. However tfields has to assume that the field order won't change and I've found the hard way that some stations switch between odds first and evens first. Why, I have absolutely no idea, but turns into a shaky mess when the order changes.
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Nvidia XvMC deinterlacing patches?
PostPosted: Tue Aug 29, 2006 7:15 pm Reply with quote
nr
 
Joined: 16 Aug 2005
Posts: 18
Location: Malden, MA




Scott Larson wrote:
Another issue with deinterlacing 1080i is that most forms of deinterlacing will display 30 frames per second instead of 60 fields per second....
I know mplayer and xine don't update the display for every field and I have patches for them (it only works with XvMC though).


Any chance you could post these patches somewhere?
I have Nvidia hardware and would be thrilled to get some hardware deinterlacing with XvMC. (My Sempron 3300+ needs all the help it can get.)
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PostPosted: Wed Aug 30, 2006 2:01 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Look at this long thread for the mplayer patches.

I have a patch for xine here but I don't know if it's up to date.
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1080i playback - What does it take?
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