[mythtv-users] Video is behind audio, dropping frames to catch up (VDPAU, HD content)
Paul Gardiner
lists at glidos.net
Thu Feb 28 18:13:40 UTC 2013
On 28/02/2013 17:59, Joseph Fry wrote:
>
>
>
> On Thu, Feb 28, 2013 at 12:15 PM, Karl Newman <newmank1 at asme.org
> <mailto:newmank1 at asme.org>> wrote:
>
> On Thu, Feb 28, 2013 at 8:05 AM, Paul Gardiner <lists at glidos.net
> <mailto:lists at glidos.net>> wrote:
>
> On 28/02/2013 15:39, Mike Perkins wrote:
>
> On 28/02/13 12:15, Paul Gardiner wrote:
>
> On 28/02/2013 12:01, Mike Perkins wrote:
>
> On 28/02/13 08:23, Paul Gardiner wrote:
>
> On 27/02/2013 22:04, Thomas Börkel wrote:
>
> HI!
>
> I have now tried many things, but I am
> running out of ideas.
>
> * it happens usually every 2-10 minutes
> * it happens for HD h264 and SD MPEG2, just
> for HD a little more often
> * it happens with and without VDPAU
> * it happened on old and upgraded hardware
> (only sound card identical)
> * it happens on 0.26 and earlier versions
> * I have tried all VDPAU profiles
> * I have disabled logging over NFS (> /dev/null)
> * I have enabled realtime prio (but it is
> not mentioned in the log)
> * I have reniced mythfrontend to -2 and X to -12
> * I have set the GPU to max. frequency all
> the time, so no switching
> * I have disabled the often crashing
> mythlcdserver
> * I have tried different kernel and NVidia
> driver versions
>
> What else can I try? What more info should I
> provide?
>
> Probably, something needs a little CPU time
> every now and then and
> this
> probably causes that little "jump" in
> playback and the log entry from
> the subject, but I don't know what it is and
> why MythTV is so
> sensitive
> on such hardware specs (Core i3, 3.1 GHz)?
>
> Or does it probably have something to do
> with the fact that this is a
> diskless PXE frontend?
>
> Any hints would be greatly appreciated.
>
>
> None of the myth systems I've built have ever
> synchronized AV
> correctly.
> I've always had to pause and unpause every now
> and then to regain sync
> and even then it's to get it to a consitentish
> 100ms which I then
> correct within my AV receiver. It's odd, because
> every other player
> I've
> tried with my recordings or downloads show them
> correctly in sync.
>
> My diskless PXE frontend has never had problems with
> AV sync. I use NFS
> to mount the root but not for media directories. On
> the other hand, my
> sound comes out the TV. Perhaps it is the "AV
> receiver" which is the
> common variable?
>
>
> I have wondered that. I will test, although several of
> the myth systems
> I was referring to were connected direct to speakers,
> and the sync was
> always variable and depended on the last user command. I
> think my
> current frontend may be pretty much ok when I'm not
> using different
> screen modes for different video resolutions, but I'm
> not sure of that.
> Need to do more testing.
>
> What CPU are you running?
>
> My current front end is one of these:
>
> http://www.newegg.com/Product/__Product.aspx?Item=__N82E16813131663
> <http://www.newegg.com/Product/Product.aspx?Item=N82E16813131663>
>
> That outputs via HDMI. A previous incarnation had a C7 VIA
> chip which
> output using VGA and 3.5 mm stereo into the TV. No problems
> either way.
>
>
> Nice. Will that do HQ scaling and Advanced 2x deinterlacing? Maybe I
> should upgrade. In any case, you are using an Atom too, so the A/V
> sync problem isn't down to processing power.
>
> Just realised that with my current set up, it will be difficult to
> remove the AV receiver: it's my only AMP, and the TV has no
> speakers.
> I can try moving to HDMI audio from spdif again, but last time I
> tried that it made sync worse. I never have sync problems with
> my blu-ray player, so I sort of doubt it is caused by the amp,
> but I'd like to rule it out. I guess I just need to borrow a little
> mobile speaker from someone.
>
> BTW, do you know what the "playback details" display measures A/V
> sync in?
>
> P.
>
>
> Some TVs can do video processing which can induce delay. Usually
> there's a setting or a mode which disables this (something like Game
> Mode should do it). This may not be the cause of your problem, but
> it might be worth looking into.
>
>
> Indeed, if you split your audio and video signal to different devices,
> you are subject to any processing delays imposed by those devices. I
> have seen TV's that introduce well over 100ms of lag (a few whole frames
> of video) with some settings. The ability to adjust the sync is one
> feature I like about mythtv that I believe is completely overlooked by
> most folks. Even with a high end BlueRay player feeding a top of the
> line TV and Audio setup, you can end up with noticeably out of sync audio.
Yeah, but it seems constant with the Blu-ray. I adjusted it via the AV
receiver and it seems fine. With Myth, I have also adjusted it, but I
still need to pause and unpause every now and then when it falls out of
sync.
Also I had this problem back when I was using analogue audio and a
CRT TV. Of course, it is possible that there was a problem with mythtv
back then, which is now fixed, and my current problem is the AV
receiver or TV, but then why the variation over time, and not
with the blu-ray player.
Cheers,
Paul.
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