MediaPortal Audio renderer - better video playback quality (3 Viewers)

[tourettes]

New version available for testing: https://forum.team-mediaportal.com/637138-post3.html

Initial version of the audio HW based reference clock. No other changes. Following setting can be used to toggle between the reference clock "source"

HWBasedRefClock

Toggles between the audio HW based reference clock and system time based reference clock. Audio HW based reference clock is the default value (1).

EVR presenter stats have new "Aud. sys. drift:" debug stat that shows the drifting between audio HW clock and system clock. On my dev PC that is approx 1.00006x

 

[disaster123]

AW: MediaPortal Audio renderer - better video playback quality

tourettes
could you explain a little bit in which cases it makes sense to change the value to 0 (system clock)?

 

[red5goahead]

on my htpc Aud. sys. drift show 0,9996.....

 

[tourettes]

Re: AW: MediaPortal Audio renderer - better video playback quality

@tourettes
could you explain a little bit in which cases it makes sense to change the value to 0 (system clock)?

In theory newer, since the A/V sync shouldn't be drifting anymore if the system clock and audio clocks are running different speeds. But if there are some more severe issues spotted then it is worth to test the system clock as reference. Also it is not yet 100% sure that the audio clock related code is able to cure the slowly drifting A/V sync.

 

[Redemption80]

Great to see something new to test, will give this a bash now, and report any issues etc..

Thanks again for this.

 

[red5goahead]

Re: AW: MediaPortal Audio renderer - better video playback quality

@tourettes
could you explain a little bit in which cases it makes sense to change the value to 0 (system clock)?

In theory newer, since the A/V sync shouldn't be drifting anymore if the system clock and audio clocks are running different speeds. But if there are some more severe issues spotted then it is worth to test the system clock as reference. Also it is not yet 100% sure that the audio clock related code is able to cure the slowly drifting A/V sync.

Some A/V synch problem with audio HW based reference clock. Watching Covert Affairs after some pauses and some stops play lost A/V synch. video delay for maybe 500-750 ms.

 

[davidf]

tourettes you need the code within the TODO because of audio clock starting half way through a period which would give a high adjustment rate incorrectly (although this depends on the code within the audio renderer so I can't be sure).

Added adjustment for completeness - the correction code is in integer maths which used to be quicker but probably isn't anymore, you have the bias to worry about which is a double anyway.

SetTimestamps(LONGLONG systemTime,LONGLONG rendererTime, bool rendererInUse)
{

if (m_lastRendererInUse && rendererInUse) 
  {
    // only set samples from here to remove pause/unpause inconsistency
    SetSampleError(systemTime-rendererTime,rendererTime-m_lastrendererTime); //the first 2 might be the wrong way round
    m_referenceClock+=rendererTime-m_lastrendererTime; //only use audio renderer time if in use throughout
  }
else m_referenceClock+=systemTime-m_lastsystemTime;
m_lastRendererInUse=rendererInUse;
m_lastrendererTime=rendererTime;
m_lastsystemTime=systemTime;
} 

LONGLONG GetCurrentTime()
{
return m_referenceClock+CorrectDelta(GetCurrentSystemTime()-m_lastsystemTime); 
}

LONGLONG m_llTotalSampleDuration=1; //stop div by zero
LONGLONG m_llTotalSampleError=0;
//stop adding after 10 mins as it's pretty accurate by that point
#define MAX_SAMPLE_DURATION 60000000000 

void SetSampleError(LONGLONG sampleError, LONGLONG sampleDuration)
{
  if (m_llTotalSampleDuration<MAX_SAMPLE_DURATION)
  {
    m_llTotalSampleDuration+=sampleDuration;
    m_llTotalSampleError+=sampleError;
  }
}

LONGLONG CorrectDelta(LONGLONG delta)
{
  return (delta*(m_llTotalSampleError+m_llTotalSampleDuration))/m_llTotalSampleDuration;
}

double Adjustment()
{
  return (double) (m_llTotalSampleError+m_llTotalSampleDuration)/m_llTotalSampleDuration;
}

 

[davidf]

I can't see what's wrong yet (how is m_dAdjustment calculated?) but the figures are not what I expected. The stats on my machine show a constant 1.0003 which would add up to a clock drift of just over 1 second per hour or 24 seconds per day. It could be in the Audio Clock I suppose but I'm certainly not seeing my clock go off by 3.5 minutes per week.

From your previous samples I calculated the multiplier over the 100 seconds and got

1.025641026
1.033352838
0.988735232
1.001775899
0.995644405
1.001562247
1.000780999
1.001797268
1.000702905
1.001494482
1.000596414
0.998207012
0.999618143
1.000012975
1.000043739
0.974490926
0.999941171
1.000030931
1.000012306
1.000063017
1.000029069
1.000061145
0.999831872
0.999821214
0.999520431
0.999628714
1.00001548
1.000051558
1.000002572
0.999973146
1.000040886
1.000033127
0.999562469
1.000042323
1.000054706
1.000017365
0.999964128
1.000018537
0.999796572
1.000038036
1.000047515
1.000048656
1.00004625
1.000046214
1.000003538
1.000042427
1.000025842
1.000045783
0.999837386
1.00004325
1.000025625
0.999894569
0.999987454
1.000037607
1.000030734
0.999826985
1.000033887
1.000033856
0.999831319
0.999735537
0.999789313
1.000015096

as the system clock multiplier which is less than you got. Also there is a fair amount of variation over this time which I didn't see in the stats when I tried it last night, the figure was a constant 1.0003.

I'll have a look tonight after I give up on trying to fix my RAID disk which failed while I was on holiday - wish I hadn't used RAID 0 now :-(

 

[Truri]

AW: Re: MediaPortal Audio renderer - better video playback quality

on my htpc Aud. sys. drift show 0,9996.....

Same here.
New version seems to work without problems so far.
I will report if I find something

 

[disaster123]

AW: MediaPortal Audio renderer - better video playback quality

davidf
never use Raid 0 except for temporary data