[mythtv-users] Frontend hardware confusion.

[Andre]

On 24 Mar 2011, at 13:57, Kenni Lund wrote:

> 2011/3/23 Terjesen Jens Peder <Jens.Peder.Terjesen at devoteam.com>:
>> If the results from the qvdpautest reported in this thread on the Nvidia Linux forum are correct it looks like it is only a slight difference between ION and ION2.
>> http://www.nvnews.net/vbulletin/showpost.php?p=2392864&postcount=364
>> http://www.nvnews.net/vbulletin/showpost.php?p=2352362&postcount=327
>> 
>> If I understand this correctly it looks like the ION2 should be able to do Advanced 1X on HD, both 50 and 60 Hz, whereas the ION can not.
> 
> My Zotac Zbox HD-ID41 performs the same in qvdpautest as the AT5IONT-I
> above. I'm not sure how this should be interpreted, AFAIK "MIXER
> TEMPORAL_SPATIAL" is the result to look at when talking about the
> advanced deinterlacer in MythTV. But do you compare the result with
> the refresh rate (eg. 50Hz for PAL) or the frame rate of the video
> source (eg. 25 frames/sec)?

For mpeg2/h264 decoding it's frame rate that matters (25 or 29.97), for de-interlacing we are dealing with the field rate so 50 or 60hz for Euro or US.

I've found that Myth needs a good headroom above what qvdpautest reports.

> 
> MPEG DECODING (1920x1080): 68 frames/s
> MPEG DECODING (1280x720): 161 frames/s
> H264 DECODING (1920x1080): 62 frames/s
> H264 DECODING (1280x720): 137 frames/s
> VC1 DECODING (1440x1080): 79 frames/s
> MPEG4 DECODING (1920x1080): 72 frames/s

Loads quick enough, even when 1080p60 comes along it will be just ok.

> 
> MIXER TEMPORAL (1920x1080): 190 fields/s

Temporal 2x would need 60 so that's way beyond, that will be fine.

> MIXER TEMPORAL_SPATIAL (1920x1080): 65 fields/s

H'mm, this is why people aren't sure, 65 isn't much headroom over 60, start rendering on screen graphics or subtitles and maybe there is not enough bandwidth left to de-interlace!

Advanced 1x would be fine as that needs 25 or 30 but as JYA says temporal 2x will look better almost all of the time.


> MIXER TEMPORAL_SPATIAL + IVTC (1920x1080): 53 fields/s

Definitely not enough, probably not even enough for Euro 25 frames but no-one uses inverse telecine (IVTC) with MythTV, I tried it for a while but it didn't seem to add anything and caused lots of problems.


> MIXER TEMPORAL_SPATIAL + SKIP_CHROMA (1920x1080): 72 fields/s

This might be fine, needs Advanced 2X with vdpauskipchroma as a parameter, this might make enough difference and the poorer chroma resolution might not be noticeable. 

As always, need to give it a go, if it's jerky, especially when OSD graphics appear or subtitles are on then it needs a faster graphics clock. I think there were some different clock speed versions of the ION maybe it's possible to get a slightly overclocked ION2?