Delay between streams with multiple soundcards

Reported by samotham on 2011-03-01
12
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Mixxx
High
Unassigned
1.10
High
Unassigned
1.9
High
Unassigned

Bug Description

my internal soundcard is 44100 Hz, my external is 48000 Hz.
When I try to use both at the same time (int : headphones, ext : master or reversed), there is a small delay between the 2 streams. Which makes this brand new promising option with 1.9 version unworkable for me at the moment.

my 2 cards are :
 0 [A5451 ]: ALI5451 - ALI 5451
                      ALI 5451 at 0x8400, irq 9
 1 [Aureon51MkII ]: USB-Audio - Aureon5.1MkII
                      TerraTec Aureon5.1MkII at usb-0000:00:0c.1-1, full speed

Intel(R) Pentium(R) 4 CPU 2.80GHz

RJ Ryan (rryan) wrote :

Hi Samotham,

When we open each of your soundcards, we open them at identical sample-rates. In general, when a soundcard's sample-rate is represented as a metric, that indicates the maximum sample-rate of the soundcard.

However, there is an issue with our multiple-soundcard support which if you are using two soundcards with slightly different crystals, they will both have a different sense of what 44100Hz is (for example). This is probably the reason that you are hearing a delay.

Have you tried this setup with other DJ software? Did the same problem exist then?

We are evaluating potential ways to compensate for sync-issues like this but we don't have anything for you to try at the moment. I'll let you know as things progress.

Thanks for taking the time to file a bug,
RJ Ryan

samotham (samotham) wrote :

I see

I forget to tell I am using Ubuntu 10.10.
I didn't try on Windows but I get it will be the same ?

the only other DJ software that I know is Traktor 2, which doesn't allow to have multiple soundcard IIRC.

To be more precise, in order to use multiple soundcards, I have to use 48 kHz samplerate cause my external soundcard doesn't support 44.1.

Bill Good (bkgood) wrote :

samotham,
Are you using any sort of ALSA buffered output for either of the cards? ("default", "dmix", etc.) I wouldn't think the tiny variations in sound card sample rates would cause a delay in output (if anything, they might cause a pitch shift, but at the variations I'm aware of this would be largely imperceptible to the human ear).

Unfortunately, multiple sound card support will never be perfect, due to the imperfections in sound cards RJ outlined (this is likely why NI doesn't support it). If you wish to professionally (or as a serious hobby) DJ with mixxx, I'd recommend finding a 4-channel+ interface.
Bill

RJ Ryan (rryan) on 2011-03-07
Changed in mixxx:
milestone: none → 1.9.1
Changed in mixxx:
milestone: 1.9.2 → none

Marking as duplicate of bug #667651 which is fixed for 1.9.2.

Bill Good (bkgood) wrote :

Reporter talks about audible signal delays between the two cards (like one's being buffered and/or processed additionally), not discontinuities in the signals as 667651 addressed.

Fair enough, but I have a feeling the fix for 667651 addresses this too. Samotham, please watch for Mixxx 1.9.2 which will include that fix to see if it helps this too.

samotham (samotham) wrote :

great, I can't wait for 1.9.2 !
is it expected soon ?

RJ Ryan (rryan) on 2011-10-05
tags: added: multi-soundcard
Changed in mixxx:
status: New → Triaged
importance: Undecided → High
RJ Ryan (rryan) on 2011-10-05
tags: added: needs-triage
RJ Ryan (rryan) on 2011-10-20
summary: - soundcards with different sample rates - no sync
+ Delay between streams with multiple soundcards
RJ Ryan (rryan) wrote :

Hi Samotham,

1.9.2 is out now -- please give it a try and let us know if this fixes anything.

Best regards,
RJ Ryan

samotham (samotham) wrote :

ok now i've got 1.9.2-1-ppa4~maverick1

it works perfectly if I put the external 48000 Hz soundcard as main output (+ the internal one as headphone) !

but it is still unsynchronized if I put the internal one as main output, using the external USB as headphone.
Probably due to the fact my USB card needs to be set 48000 Hz to run.

Do you hear the skipping or distortion in the master output when you set
the internal as master? We didn't fix this bug, rather we made it so that
the problems are only audible in the headphones.

On Sun, Dec 4, 2011 at 12:52 PM, samotham <email address hidden> wrote:

> ok now i've got 1.9.2-1-ppa4~maverick1
>
> it works perfectly if I put the external 48000 Hz soundcard as main
> output (+ the internal one as headphone) !
>
> but it is still unsynchronized if I put the internal one as main output,
> using the external USB as headphone.
> Probably due to the fact my USB card needs to be set 48000 Hz to run.
>
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> https://bugs.launchpad.net/bugs/726894
>
> Title:
> Delay between streams with multiple soundcards
>
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