Mailing List Archive: MythTV: Users

Judder-free playback leads to bad audio sync?

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nico at youplala

Sep 5, 2010, 9:53 AM

Post #1 of 6 (273 views)
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Judder-free playback leads to bad audio sync?

Hello,

Since I followed the judder-free playback instructions here

http://www.mythtv.org/wiki/User_Manual:JudderFree

I have noticed that A/V sync is going bad as I watch content.

My googling brought some fellows with the same issue, but no clear
solution.

Am I missing something?

Thanks!

Nico

Ubuntu 10.04 Lucid x86_64 - up-to-date with security, backports,
updates, medibuntu and JYA (release testing)

Alsa S/PDIF output, no pulseaudio

VDPAU on GT220 - 256.52

MythTV Version : 26057
MythTV Branch : branches/release-0-23-fixes
Network Protocol : 23056
Library API : 0.23.1.201000710-1
QT Version : 4.6.2
Options compiled in:
linux debug using_oss using_alsa using_pulse using_jack
using_pulseoutput using_backend using_dvb using_firewire using_frontend
using_glx_proc_addr_arb using_hdhomerun using_hdpvr using_iptv
using_ivtv using_joystick_menu using_libudev using_lirc using_mheg
using_opengl_video using_opengl_vsync using_qtdbus using_qtwebkit
using_v4l using_x11 using_xrandr using_xv using_xvmc using_xvmc_vld
using_xvmcw using_bindings_perl using_bindings_python using_opengl
using_vdpau using_ffmpeg_threads using_libavc_5_3 using_live using_mheg

lists at laser-point

Sep 5, 2010, 11:01 AM

Post #2 of 6 (277 views)
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Re: Judder-free playback leads to bad audio sync? [In reply to]

On 05/09/2010 17:53, Nicolas Will wrote:
> Hello,
>
> Since I followed the judder-free playback instructions here
>
> http://www.mythtv.org/wiki/User_Manual:JudderFree
>
> I have noticed that A/V sync is going bad as I watch content.
>
> My googling brought some fellows with the same issue, but no clear solution.
>
> Am I missing something?

Every MythTv FE I've built has slowly run out of sync.
When it gets noticeable, I jump back 5s and that syncs
it up again.

Paul.
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

nico at youplala

Sep 5, 2010, 1:44 PM

Post #3 of 6 (275 views)
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Re: Judder-free playback leads to bad audio sync? [In reply to]

On Sun, 2010-09-05 at 19:01 +0100, Paul Gray wrote:

> On 05/09/2010 17:53, Nicolas Will wrote:
> > Hello,
> >
> > Since I followed the judder-free playback instructions here
> >
> > http://www.mythtv.org/wiki/User_Manual:JudderFree
> >
> > I have noticed that A/V sync is going bad as I watch content.
> >
> > My googling brought some fellows with the same issue, but no clear
> solution.
> >
> > Am I missing something?
>
> Every MythTv FE I've built has slowly run out of sync.
> When it gets noticeable, I jump back 5s and that syncs
> it up again.

Well, that may be the case, but my FE was OK, now it is really
noticeable.

Nico

lists at laser-point

Sep 5, 2010, 3:14 PM

Post #4 of 6 (267 views)
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Re: Judder-free playback leads to bad audio sync? [In reply to]

On 05/09/2010 21:44, Nicolas Will wrote:
> On Sun, 2010-09-05 at 19:01 +0100, Paul Gray wrote:
>> On 05/09/2010 17:53, Nicolas Will wrote:
>> > Hello,
>> >
>> > Since I followed the judder-free playback instructions here
>> >
>> > http://www.mythtv.org/wiki/User_Manual:JudderFree
>> >
>> > I have noticed that A/V sync is going bad as I watch content.
>> >
>> > My googling brought some fellows with the same issue, but no clear
>> solution.
>> >
>> > Am I missing something?
>>
>> Every MythTv FE I've built has slowly run out of sync.
>> When it gets noticeable, I jump back 5s and that syncs
>> it up again.
>
> Well, that may be the case, but my FE was OK, now it is really noticeable.

I imagine how quickly it drifts depends on subtleties in mode timings.
You may have just been lucky before. I wasn't trying to imply it
is nothing to worry about, just suggesting it's an inherent MythTv
problem.

Paul.
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

jppoet at gmail

Sep 5, 2010, 5:58 PM

Post #5 of 6 (266 views)
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Re: Judder-free playback leads to bad audio sync? [In reply to]

On Sun, Sep 5, 2010 at 2:44 PM, Nicolas Will <nico [at] youplala> wrote:

> On Sun, 2010-09-05 at 19:01 +0100, Paul Gray wrote:
>
> On 05/09/2010 17:53, Nicolas Will wrote:
> > Hello,
> >
> > Since I followed the judder-free playback instructions here
> >
> > http://www.mythtv.org/wiki/User_Manual:JudderFree
> >
> > I have noticed that A/V sync is going bad as I watch content.
> >
> > My googling brought some fellows with the same issue, but no clear
> solution.
> >
> > Am I missing something?
>
> Every MythTv FE I've built has slowly run out of sync.
> When it gets noticeable, I jump back 5s and that syncs
> it up again.
>
>
> Well, that may be the case, but my FE was OK, now it is really noticeable.
>
> Nico
>

I have noticed the same. If I keep playback at 60p (even for 24p material)
the sync stays perfect. If I use 24p playback then the A/V sync gets worse
and worse. Therefore, I have gone back to using 60p even for 24p material.

John
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

nico at youplala

Sep 6, 2010, 12:42 PM

Post #6 of 6 (247 views)
Permalink

Re: Judder-free playback leads to bad audio sync? [In reply to]

On Sun, 2010-09-05 at 18:58 -0600, John P Poet wrote:

> On Sun, Sep 5, 2010 at 2:44 PM, Nicolas Will <nico [at] youplala>
> wrote:
>
> > On Sun, 2010-09-05 at 19:01 +0100, Paul Gray wrote:
> >
> > On 05/09/2010 17:53, Nicolas Will wrote:
> > > Hello,
> > >
> > > Since I followed the judder-free playback instructions here
> > >
> > > http://www.mythtv.org/wiki/User_Manual:JudderFree
> > >
> > > I have noticed that A/V sync is going bad as I watch content.
> > >
> > > My googling brought some fellows with the same issue, but no clear
> > solution.
> > >
> > > Am I missing something?
> >
> > Every MythTv FE I've built has slowly run out of sync.
> > When it gets noticeable, I jump back 5s and that syncs
> > it up again.
> >
> >
> > Well, that may be the case, but my FE was OK, now it is really
> noticeable.
> >
> > Nico
> >
>
>
> I have noticed the same. If I keep playback at 60p (even for 24p
> material)
> the sync stays perfect. If I use 24p playback then the A/V sync gets
> worse
> and worse. Therefore, I have gone back to using 60p even for 24p
> material.

Call me greedy, but I'd like judder and lag free :o)

I could go back to 60 Hz, the judder is less problematic than the audio
lag for my own brain.

But I am sure that perfection could come out of this, and Jean-Yves made
the how-to for judder-free (if not the code) and is also working on
audio. There is a strong potential for synergy. (yes, I work for a large
company and I did a tour in marketing as well as product management,
shoot me!)

Nico

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