Mailing List Archive

Pixelation with VDPAU and one channel
Since December 2016 there has been a new broadcast channel in Boston for
NBC. It is using MPEG2 1080i.

When watching a recording from this channel with VDPAU decoding, every
15 seconds or so there is pixelation on 20% to 50% of the screen. I have
tried this on 4 machines all equipped with NVIDIA Geforce 210 and they
all show the problem. All other (MPEG2 and H264) channels are perfect.

If I change playback profile to Standard decoding (ffmpeg), the playback
of the same recording is perfect. On Raspberry Pi with OpenMAX (with
mpeg2 license), the same recording is perfect. If I transcode to H264,
then I can watch using VDPAU decoding and it is perfect.

If I watch the recording files with VLC, with VDPAU selected, I see the
same pixelation.

If I watch the same file again the pixelation is at the same places,
with MythTV and VLC.

This has happened continuously since that channel came on the air and
still happens.

Has anybody else seen this? Anybody have any ideas?

Peter


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Re: Pixelation with VDPAU and one channel [ In reply to ]
On Wed, Jul 5, 2017 at 11:50 PM, Peter Bennett <cats22@comcast.net> wrote:

> When watching a recording from this channel with VDPAU decoding, every 15
> seconds or so there is pixelation on 20% to 50% of the screen. I have tried
> this on 4 machines all equipped with NVIDIA Geforce 210 and they all show
> the problem.

I have this recollection that the GT218 (inside a branded GeForce 210)
is just "barely" able to perform decode/de-interlace 1080i. And as this
(newly) O&O NBC channel may have chosen to encode slightly
differently as part of the transition, you may have hit some limit with
that card with that encoding. If viable, I would try a (gen/rev 2) GT630
or GT730 to see if the problem persists (for they are (or were) cheap
and available in low profile silent configs, if you need that).
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Re: Pixelation with VDPAU and one channel [ In reply to ]
On 06/07/17 01:32, Gary Buhrmaster wrote:
> On Wed, Jul 5, 2017 at 11:50 PM, Peter Bennett <cats22@comcast.net> wrote:
>
>> When watching a recording from this channel with VDPAU decoding, every 15
>> seconds or so there is pixelation on 20% to 50% of the screen. I have tried
>> this on 4 machines all equipped with NVIDIA Geforce 210 and they all show
>> the problem.
>
> I have this recollection that the GT218 (inside a branded GeForce 210)
> is just "barely" able to perform decode/de-interlace 1080i. And as this
> (newly) O&O NBC channel may have chosen to encode slightly
> differently as part of the transition, you may have hit some limit with
> that card with that encoding. If viable, I would try a (gen/rev 2) GT630
> or GT730 to see if the problem persists (for they are (or were) cheap
> and available in low profile silent configs, if you need that).

Last week I replaced an old non-VDPAU nvidia card that used the
304-series legacy driver by a (cheap ~30 GBP) GT 710 / GK208 fanless
card using 375.66. The cpu is a Core 2 Duo at 2.66 GHz and I'm running
master pre-513 under fc25. Most of my recordings are SD mpeg2 and the
main display is via HDMI at 1080p/50 Hz on a Panasonic tv. The video
card is synced to that.

When using VDPAU the picture is generally good, but there is a slight
picture instability during pan/tilt that I don't see when using DLNA on
the same tv. Mythfrontend offers better playback controls, but for
linear playback DLNA seems marginally better. Of course, there may be
tweaks that I haven't yet explored.

John P



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