[mythtv-users] Video quality on 0.28 worse than it was on 0.21

[Allen Edwards]

I am using the same playback profile with both 0.21 and 0.28.

If rez > 0 0 -> ffmpeg & XVideo
xv-blit softblend
Bob(2x) Linear blend

This was available on the 0.28 menu so I assume it is supported.  Works
well in 0.21 but not in 0.28

When I had the 8600 care in and selected any of the VDPAU profiles, the
frontend would exit when I tried to play anything. Perhaps the nvidia
drivers were not really loaded though.

Allen


On Fri, Aug 24, 2018 at 9:12 AM, Stephen Worthington <
stephen_agent at jsw.gen.nz> wrote:

> On Fri, 24 Aug 2018 08:13:11 -0700, you wrote:
>
> >As the subject line suggests, playback is perfect on this exact same
> >hardware with 0.21 and is terrible with 0.28.  The video driver is
> >different.  Everything else I am able to check is the same.  I can just
> >switch the HD without touching anything in the hardware and the playback
> is
> >smooth as silk.  It is almost unwatchable with 0.28.
> >
> >If it is true that the video driver won't make a difference, then I need
> to
> >go back to 8.04.  I find that difficult to believe.  Perhaps there is some
> >other setting, maybe in the backend, I am missing that is different. But
> >the playback is terrible even when the backend isn't doing anything except
> >sourcing a recording.
> >
> >The card is a 6200.  I misspoke saying it was a 6600.
> >
> >Allen
>
> The 6200 and 6600 are similar - no VDPAU.  Cards from back then did do
> some sort of support for MPEG acceleration, which I think has been
> deleted from mythfrontend as VDPAU is now used to do the same.  So I
> would guess that your recordings are using MPEG1 or MPEG2 video
> streams, and in 0.21, were using that old acceleration method for
> playback.  If your recording sources have never used H.264 video, and
> you have not been playing back H.264 video files you have downloaded,
> you will not have noticed the lack of support for acceleration of
> other video formats, and the 6200 will have been fine.
>
> So if I am right, 0.28 will not support doing the old MPEG
> acceleration on a 6200 card - you need to use the 8600GT and get it to
> actually use VDPAU in mythfrontend, as your CPU is likely too small to
> do the full decoding itself, even for MPEG video files, as witnessed
> by your playback problems using the 8600GT without VDPAU.
>
> However, the VDPAU in the 8600GT is only feature set A.  That means
> that it does not do the best sort of hardware deinterlacing.  So it
> may mean that if you have a lot of interlaced recordings, the video
> will not be as smooth with VDPAU on the 8600GT as it was with 0.21
> using the old MPEG support on the 6200.  The best deinterlacing
> support only became available in VDPAU in the GT220 and above Nvidia
> cards with VDPAU feature set C.  That is why I moved to a GT220 card
> and pensioned off my old 8600GT - I used it in my Windows box until
> its fan died.
>
> You need to find out what is in your recordings to see if they need
> deinterlacing and what their video streams are.  The program ffprobe
> is normally installed on MythTV systems and can tell you.  This is
> what I get from one of my 1080i recordings:
>
> Input #0, mpegts, from '1003_20180824065900.ts':
>   Duration: 01:04:57.58, start: 78211.124622, bitrate: 7228 kb/s
>   Program 1
>     Stream #0:0[0x1c2]: Video: h264 (High) ([27][0][0][0] / 0x001B),
> yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k
> tbn, 50 tbc
>     Stream #0:1[0x190](eng): Audio: aac_latm (HE-AAC) ([17][0][0][0] /
> 0x0011), 48000 Hz, stereo, fltp
>     Stream #0:2[0x19a](eng): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz,
> 5.1(side), fltp, 384 kb/s
>     Stream #0:3[0x3eb]: Unknown: none ([11][0][0][0] / 0x000B)
>     Stream #0:4[0x3fc](eng): Subtitle: dvb_subtitle ([6][0][0][0] /
> 0x0006) (hearing impaired)
>     Stream #0:5[0x1f40]: Unknown: none ([5][0][0][0] / 0x0005)
>     Stream #0:6[0x3ec]: Unknown: none ([11][0][0][0] / 0x000B)
>
> On the Stream #0 line (the video stream), you can see "h264", "25 fps"
> and "50 tbr".  So it is H.264 video, interlaced, 25 frames per second.
> If it was not interlaced, it would say "25 tbr".
>
> Or you can install the "mediainfo" program and use it - it gives more
> intelligible output.
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