Jack latency and tempo changes.

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Jack latency and tempo changes.

detox.maestro

Hi.

I have installed jack with frames=256, freq=48kHz and periods=2 wich gives me about 10ms latency.

The problem is unexpected tempo changes when jack is connected to some syth: zynaddsubfx, qsynth or hydrogen.

That tempo changes can be hear more clearly when I set frames=4096 which gives about 170ms latency.

There are no tempo changes when I use for example lmms with built in instruments and also set frames=4096.

In lmms case the sound is only little delayed but all tracks plays with no tempo changes which is ok.

Even if I connect lmms with jack there are also no tempo changes.

So it seems that unexpected tempo changes are in case when I use outward synths like zynaddsubfx, qsynth or others.

Is it possible to fix it? How?

 

Also I've realised if I run zynaddsubfx without jack but directly with alsa - it seems that there are no tempo changes when I play some simple tracks from sequencer.

But unfortunatelly I can't run more than one synth program with only alsa, when I try tu run second program (for example hydrogen) I get error:

 

[ERROR]     Hydrogen          [createDriver] Error starting audio driver [audioDriver::init()]
[ERROR]     AlsaAudioDriver       ALSA: cannot open audio device hw:0: Device or resource busy

 

I tryed to run many dmix scripts - but that didn't solve it.

Also I can run other audio programs at the same time: for example two xine programs at the same time.

So it seems some audio programs can be runned twice (for example xine) but other not (for example zynaddsubfx).

Why? Is it possible to fix it? How?

 

Thanks in advance for reply.

Michael.

 



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Re: Jack latency and tempo changes.

Patrick Shirkey

On Thu, August 26, 2010 3:29 am, [hidden email] wrote:

> <style>blockquote {padding-left: 1ex; margin: 0px 0px 0px 0.8ex;
> border-left: #cccccc 1px solid;} p {margin: 0px;padding: 0px;} </style>
> <p>Hi.</p>
> <p>I have installed jack with frames=256, freq=48kHz and periods=2 wich
> gives me about 10ms latency.</p>
> <p>The problem is unexpected tempo changes when jack is connected to some
> syth: zynaddsubfx, qsynth or hydrogen.</p>
> <p>That tempo changes can be hear more clearly when I set frames=4096
> which gives about 170ms latency.</p>
> <p>There are no tempo changes when I use for example lmms with built in
> instruments and also set frames=4096.</p>
> <p>In lmms case the sound is only little delayed but all tracks plays with
> no tempo changes which is ok.</p>
> <p>Even if I connect lmms with jack there are also no tempo changes.</p>
> <p>So it seems that unexpected tempo changes are in case when I use
> outward synths like zynaddsubfx, qsynth or others.</p>
> <p>Is it possible to fix it? How?</p>
> <p>&nbsp;</p>
> <p>Also I've realised if I run zynaddsubfx without jack but directly with
> alsa - it seems that there are no tempo changes when I play some simple
> tracks from sequencer.</p>
> <p>But unfortunatelly I can't run more than one synth program with only
> alsa, when I try tu run second program (for example hydrogen) I get
> error:</p>
> <p>&nbsp;</p>
> <p>[ERROR]&nbsp;&nbsp;&nbsp;&nbsp; Hydrogen&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> &nbsp;&nbsp;&nbsp; [createDriver] Error starting audio driver
> [audioDriver::init()]<br />[ERROR]&nbsp;&nbsp;&nbsp;&nbsp;
> AlsaAudioDriver&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; ALSA: cannot open audio
> device hw:0: Device or resource busy</p>
> <p>&nbsp;</p>
> <p>I tryed to run many dmix scripts - but that didn't solve it.</p>
> <p>Also I can run other audio programs at the same time: for example two
> xine programs at the same time.</p>
> <p>So it seems some audio programs can be runned twice (for example xine)
> but other not (for example zynaddsubfx).</p>
> <p>Why? Is it possible to fix it? How?</p>
> <p>&nbsp;</p>
> <p>Thanks in advance for reply.</p>
> <p>Michael.</p>
> <p>&nbsp;</p><br />
>

Some older versions of zyn have realtime issues with jack. You could try
the Yoshimi fork or a newer version of zyn.


>
> _______________________________________________
> Jack-Devel mailing list
> [hidden email]
> http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org
>


--
Patrick Shirkey
Boost Hardware Ltd.

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Re: Jack latency and tempo changes.

Paul Davis
In reply to this post by detox.maestro
2010/8/26  <[hidden email]>:

> Hi.
>
> I have installed jack with frames=256, freq=48kHz and periods=2 wich gives
> me about 10ms latency.
>
> The problem is unexpected tempo changes when jack is connected to some syth:
> zynaddsubfx, qsynth or hydrogen.
>
> That tempo changes can be hear more clearly when I set frames=4096 which
> gives about 170ms latency.
>
> There are no tempo changes when I use for example lmms with built in
> instruments and also set frames=4096.

there are several possible things going on. i'm not going to comment
on them all because both lmms and zyn and known to have poor JACK
support.

but at a deeper level, even with apps with "perfect" app support,
tempo changes in current JACK are quantized (that is, rounded) to
period-sized boundaries. the bigger the period, the more notable the
effect. there's nothing you can do about this until some bright spark
proposes the shared-tempo-map-in-shared-memory format to end all such
suggestions. it hasn't happened yet.

--p
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Re: Jack latency and tempo changes.

detox.maestro
Hmmmm... That's pity but I also don't have as much knowledge in how jack
is developed to have bright spark idea how to resolve this issue...
Anyway thanks for reply.


> 2010/8/26  <[hidden email]>:
> > Hi.
> >
> > I have installed jack with frames=256, freq=48kHz and periods=2 wich gives
> > me about 10ms latency.
> >
> > The problem is unexpected tempo changes when jack is connected to some
> syth:
> > zynaddsubfx, qsynth or hydrogen.
> >
> > That tempo changes can be hear more clearly when I set frames=4096 which
> > gives about 170ms latency.
> >
> > There are no tempo changes when I use for example lmms with built in
> > instruments and also set frames=4096.
>
> there are several possible things going on. i'm not going to comment
> on them all because both lmms and zyn and known to have poor JACK
> support.
>
> but at a deeper level, even with apps with "perfect" app support,
> tempo changes in current JACK are quantized (that is, rounded) to
> period-sized boundaries. the bigger the period, the more notable the
> effect. there's nothing you can do about this until some bright spark
> proposes the shared-tempo-map-in-shared-memory format to end all such
> suggestions. it hasn't happened yet.
>
> --p


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Re: Jack latency and tempo changes.

Gabriel M. Beddingfield-2
In reply to this post by detox.maestro


On Thu, 26 Aug 2010, [hidden email] wrote:

> The problem is unexpected tempo changes when jack is
> connected to some syth: zynaddsubfx, qsynth or hydrogen.

Tempo changes are a sequencer issue.  Zynaddsubfx and
QSyth are not sequencers... so they are not the problem.
Hydrogen is both sequencer and synth -- so it might be the
problem.

If you have set Hydrogen as "JACK Timebase Master," then
Hydrogen is creating the tempo changes and you'll need to
find out why.  It only does so as a response to user input,
or if some other program is the timebase master.

If not... then you need to tell us who is the timebase
master (also called "transport master").

Thanks,
Gabriel
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Re: Jack latency and tempo changes.

Paul Davis
On Thu, Aug 26, 2010 at 10:18 AM, Gabriel M. Beddingfield
<[hidden email]> wrote:

> If not... then you need to tell us who is the timebase master (also called
> "transport master").

these are not the same thing really. one of the key elements of JACK
is that there is only one timebase master, but that all apps can
control the transport. so in truth, there is no transport master.
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Re: Jack latency and tempo changes.

Gabriel M. Beddingfield-2


On Thu, 26 Aug 2010, Paul Davis wrote:

>> If not... then you need to tell us who is the timebase master (also called
>> "transport master").
>
> these are not the same thing really. one of the key elements of JACK
> is that there is only one timebase master, but that all apps can
> control the transport. so in truth, there is no transport master.

I do not disagree with this... BUT... I've seen it called
all kinds of things in different apps.  :-)

Heck, I've even said "transport master" to mean "timebase
master."

-gabriel
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Re: Jack latency and tempo changes.

jordan johnston
In reply to this post by detox.maestro
Hi micheal,

> I have installed jack with frames=256, freq=48kHz and periods=2 wich gives
> me about 10ms latency.
>
> The problem is unexpected tempo changes when jack is connected to some syth:
> zynaddsubfx, qsynth or hydrogen.
>
> That tempo changes can be hear more clearly when I set frames=4096 which
> gives about 170ms latency.
>
> There are no tempo changes when I use for example lmms with built in
> instruments and also set frames=4096.

When using alsa-midi, you have to understand that it's midi
implementation isn't sample accurate.
So when using it with jack, the lower the frames the better, but it
still won't be 100% perfect. Jack-midi is much nicer to work with, as
far as that goes.

I typically use 2-3ms of latency, alsa-midi seems (mostly) accurate at
this setting.

> In lmms case the sound is only little delayed but all tracks plays with no
> tempo changes which is ok.
>
> Even if I connect lmms with jack there are also no tempo changes.

I was under the impression that LMMS and Jack don't really play all
that nice together, also.

> So it seems that unexpected tempo changes are in case when I use outward
> synths like zynaddsubfx, qsynth or others.
>

In seq24, you can adjust the tempo in realtime, however i do not know
if it would handle a split-second-fast tempo change, like going
straight from 90bpm to say 150bpm. you can however, manually adjust
it, as it is playing. ie: speed it up or slow it down. That is the
only program in Linux, i have ever seen that will use this behavior
correctly, but it's not being developed anymore, really.

> Also I've realised if I run zynaddsubfx without jack but directly with alsa
> - it seems that there are no tempo changes when I play some simple tracks
> from sequencer.
>
> But unfortunatelly I can't run more than one synth program with only alsa,
> when I try tu run second program (for example hydrogen) I get error:

> [ERROR]     Hydrogen          [createDriver] Error starting audio driver
> [audioDriver::init()]
> [ERROR]     AlsaAudioDriver       ALSA: cannot open audio device hw:0:
> Device or resource busy

Ideally, jack is what you should be using in this scenario - running
synths/drum machines/sequencers/fx together.
Alsa doesn 't do a good job at this, and as soon as you want to run an
app/plugin through another plugin/app, you will soon encounter some
big limitations.

jordan
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Re: Jack latency and tempo changes.

detox.maestro
In reply to this post by Gabriel M. Beddingfield-2
I send mail to you and to list also.
What I mean by tempo changes is that the percussion instruments are not
playing at fixed tempo but it should.
If I use 120bmp then at one moment it is little too fast (about 125
bpm?), next moment is little to slow (about 115bpm?).
So all record should have fixed tempo 120bpm, but it seems that there
are some unexpected random delays to play notes. Sometimes that delays
can be about 1/32 note, sometimes about 1/16 note and maybe sometimes
this can be even 1/8 note.
Especially if I set frames=4096 - then this random delays are bigger and
can be hear more clearly.
So the effect is like listening old EP record on old breaked gramophone
with broken enginge which not hold his own speed.

As I wrote this happen with renoise and rosegarden also.
I am connecting it in very simple way, for example:
renoise -> jack -> qsynth
or
rosegarden -> jack -> qsynth

Then the synths is automatically visible in sequencers.

About ALSA: I also tryed to connect synths directly to ALSA without jack.
And it seems that when I connect synths directly to ALSA then the tempo
seems to be ok.
But unfortunatelly I can't run more than one synth.

If I run zynaddsubfx and then run hydrogen I get error:
[ERROR]     Hydrogen       [createDriver] Error starting audio driver
[audioDriver::init()]
[ERROR]     AlsaAudioDriver   ALSA: cannot open audio device hw:0:
Device or resource busy

As I said earlier I can run some audio programs twice (for example xine)
but I can't run synth-programs twice like hydrogen, zynaddsubfx or
qsynth.





> Did you mean to send this direct to me... and not the list?
>
> On Thursday, August 26, 2010 12:18:35 pm you wrote:
> > Hmmm... I don't think that tempo changes are sequencer
>
> Then I don't understand what you mean by "tempo changes."
> To me, a tempo change means that the song is going along at
> 120 beat/min, and all of the sudden starts playing at 80
> beats/min.
>
> > When I use in renoise embeded instrument and only play it
> > through jack - then everynthing is ok.
> > But when I connect some outward synth and play it from
> > renoise through jack then there are unexpeceted tempo
> > changes.
>
> Does this happen with any other program besides Renoise?
> This sounds like a Renoise bug... but it's more likely a
> setup issue.
>
> How are you connecting Renoise to the sytns?  If you're
> using QJackCtl... are you doing it on the ALSA MIDI or JACK
> MIDI tabs?
>
> Thanks,
> Gabriel


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Re: Jack latency and tempo changes.

Gabriel M. Beddingfield-2


On Thu, 26 Aug 2010, [hidden email] wrote:

> As I wrote this happen with renoise and rosegarden also.
> I am connecting it in very simple way, for example:
> renoise -> jack -> qsynth
> or
> rosegarden -> jack -> qsynth

How are you making these connections?  Can you send a screen
shot?

I can think of about 4 different ways to do "renoise -> jack
->qsynth" -- and each one is totally different.  :-)

-gabriel
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Re: Jack latency and tempo changes.

jordan johnston
In reply to this post by detox.maestro
> I send mail to you and to list also.

oh sorry, maybe i hit "reply" instead of "reply all" in gmail. im not sure.

> What I mean by tempo changes is that the percussion instruments are not
> playing at fixed tempo but it should.
> If I use 120bmp then at one moment it is little too fast (about 125
> bpm?), next moment is little to slow (about 115bpm?).
> So all record should have fixed tempo 120bpm, but it seems that there
> are some unexpected random delays to play notes. Sometimes that delays
> can be about 1/32 note, sometimes about 1/16 note and maybe sometimes
> this can be even 1/8 note.
> Especially if I set frames=4096 - then this random delays are bigger and
> can be hear more clearly.

That's what i am saying, alsa-midi isn't accurate, and the higher the
frames, the more obvious it becomes. I was using other examples, also,
but they still play into the same issue. That's why i said if i use it
around 2-3ms of latency, when i am playing my keyboard with X plugins,
i wont notice any latency. but myself, i actually use jack-midi more,
now than alsa midi and a2j to expose alsa-mid to jack-midi where i
need to.

> So the effect is like listening old EP record on old breaked gramophone
> with broken enginge which not hold his own speed.
>
> As I wrote this happen with renoise and rosegarden also.
> I am connecting it in very simple way, for example:
> renoise -> jack -> qsynth
> or
> rosegarden -> jack -> qsynth
>
> Then the synths is automatically visible in sequencers.

don't you mean either:

 renoise -> qsynth(hosted by renoise) -> jack ?         (or qsynth
possibly running outside renoise directly to jack?)
or rosegarden -> qsynth(hosted by roegarden) -> jack          (either
way jack is at the end).

> About ALSA: I also tryed to connect synths directly to ALSA without jack.
> And it seems that when I connect synths directly to ALSA then the tempo
> seems to be ok.
> But unfortunatelly I can't run more than one synth.

it's probably not noticable, because you are running one synth, im not
really sure.
I use Jack all the time, for pretty much everything.

jordan
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Re: Jack latency and tempo changes.

jordan johnston
In reply to this post by Gabriel M. Beddingfield-2
hey,

> How are you making these connections?  Can you send a screen shot?
>
> I can think of about 4 different ways to do "renoise -> jack ->qsynth" --
> and each one is totally different. :-)

I can do that, just gimme a few minutes, i am only going to reply to
you though, as i am not sure if i should be posting pictures on
jack-dev.  I did that once, and for some reason i didn't feel very
good about it after....lol

My examples, wont be the same programs as you are using.. but you will
get the idea...

jordan
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Re: Jack latency and tempo changes.

detox.maestro
In reply to this post by jordan johnston
Thanks Jordan for your reply.
But I thinks that this issue depends much on frames and latency witch it
gives.
So this in not only midi issue.
It seems that if I get for example 170ms latency then the tempo changes
and note delays will not be greater than 170ms.
But the problem is like that the tempo is not fixed or synchronized.
If the latency would have fixed value 170ms in all tracks with good
synchronization - then everything would be ok.
But it seems that at one moment it is 170ms delay next moment for next
note it is 50ms delay,next note is about 110ms delay and so on...
So if I get smaller frame buffer for example 256 then the tempo changes
are also smaller, but still they are present and they are too big for
good record.
I can't get smaller frame buffer than 256 because then I get xruns.





> Hi micheal,
>
> > I have installed jack with frames=256, freq=48kHz and periods=2 wich gives
> > me about 10ms latency.
> >
> > The problem is unexpected tempo changes when jack is connected to some
> syth:
> > zynaddsubfx, qsynth or hydrogen.
> >
> > That tempo changes can be hear more clearly when I set frames=4096 which
> > gives about 170ms latency.
> >
> > There are no tempo changes when I use for example lmms with built in
> > instruments and also set frames=4096.
>
> When using alsa-midi, you have to understand that it's midi
> implementation isn't sample accurate.
> So when using it with jack, the lower the frames the better, but it
> still won't be 100% perfect. Jack-midi is much nicer to work with, as
> far as that goes.
>
> I typically use 2-3ms of latency, alsa-midi seems (mostly) accurate at
> this setting.
>
> > In lmms case the sound is only little delayed but all tracks plays with no
> > tempo changes which is ok.
> >
> > Even if I connect lmms with jack there are also no tempo changes.
>
> I was under the impression that LMMS and Jack don't really play all
> that nice together, also.
>
> > So it seems that unexpected tempo changes are in case when I use outward
> > synths like zynaddsubfx, qsynth or others.
> >
>
> In seq24, you can adjust the tempo in realtime, however i do not know
> if it would handle a split-second-fast tempo change, like going
> straight from 90bpm to say 150bpm. you can however, manually adjust
> it, as it is playing. ie: speed it up or slow it down. That is the
> only program in Linux, i have ever seen that will use this behavior
> correctly, but it's not being developed anymore, really.
>
> > Also I've realised if I run zynaddsubfx without jack but directly with
> alsa
> > - it seems that there are no tempo changes when I play some simple tracks
> > from sequencer.
> >
> > But unfortunatelly I can't run more than one synth program with only alsa,
> > when I try tu run second program (for example hydrogen) I get error:
>
> > [ERROR]     Hydrogen          [createDriver] Error starting audio driver
> > [audioDriver::init()]
> > [ERROR]     AlsaAudioDriver       ALSA: cannot open audio device hw:0:
> > Device or resource busy
>
> Ideally, jack is what you should be using in this scenario - running
> synths/drum machines/sequencers/fx together.
> Alsa doesn 't do a good job at this, and as soon as you want to run an
> app/plugin through another plugin/app, you will soon encounter some
> big limitations.
>
> jordan


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Re: Jack latency and tempo changes.

Gabriel M. Beddingfield-2
In reply to this post by jordan johnston


On Thu, 26 Aug 2010, jordan wrote:

>> How are you making these connections?  Can you send a screen shot?
>>
>> I can think of about 4 different ways to do "renoise -> jack ->qsynth" --
>> and each one is totally different. :-)
>
> I can do that, just gimme a few minutes, i am only going to reply to
> you though, as i am not sure if i should be posting pictures on
> jack-dev.  I did that once, and for some reason i didn't feel very
> good about it after....lol
>
> My examples, wont be the same programs as you are using.. but you will
> get the idea...
Actually, I was hoping to get a screen shot from
'detox.maestro', since he's the OP.  :-)

And yes, off-list is fine.

-gabriel

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Re: Jack latency and tempo changes.

jordan johnston
In reply to this post by detox.maestro
2010/8/26  <[hidden email]>:

> Thanks Jordan for your reply.
> But I thinks that this issue depends much on frames and latency witch it
> gives.
> So this in not only midi issue.
> It seems that if I get for example 170ms latency then the tempo changes
> and note delays will not be greater than 170ms.
> But the problem is like that the tempo is not fixed or synchronized.
> If the latency would have fixed value 170ms in all tracks with good
> synchronization - then everything would be ok.
> But it seems that at one moment it is 170ms delay next moment for next
> note it is 50ms delay,next note is about 110ms delay and so on...
> So if I get smaller frame buffer for example 256 then the tempo changes
> are also smaller, but still they are present and they are too big for
> good record.
> I can't get smaller frame buffer than 256 because then I get xruns.
>

Correct. It is not sample-accurate. so you are seeing latency on
sequenced or played notes that is "variable".
in that, it is not in sync, you are experiencing, almost a form of
jitter.  If you were able to use say 64 or 128 frames it would be less
and less obvious and persistent.

I am totally, understanding your problem - i have dealt with the same
issues at one point or another.

i'll be back in a few :)   if those screenshots, i just gotta run out
for a second, and i will post when i get back.


jordan
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Re: Jack latency and tempo changes.

jordan johnston
In reply to this post by Gabriel M. Beddingfield-2
oh sorry,

i thought you were asking me,

cheerz


jordan
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Re: Jack latency and tempo changes.

detox.maestro
In reply to this post by Gabriel M. Beddingfield-2
I have to send it once again - because I get message that mail can't be
bigger than 40KB.
So here are first screenshot.


>
> Actually, I was hoping to get a screen shot from
> 'detox.maestro', since he's the OP.  :-)
>
> And yes, off-list is fine.
>
> -gabriel

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Re: Jack latency and tempo changes.

detox.maestro
In reply to this post by Gabriel M. Beddingfield-2
And here are second screenshot.
One is AUDIO tab and second is ALSA tab, I didn't have any connections
in MIDI tab.
>
> Actually, I was hoping to get a screen shot from
> 'detox.maestro', since he's the OP.  :-)
>
> And yes, off-list is fine.
>
> -gabriel

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Re: Jack latency and tempo changes.

Gabriel M. Beddingfield-2


On Thu, 26 Aug 2010, [hidden email] wrote:

> And here are second screenshot.
> One is AUDIO tab and second is ALSA tab, I didn't have any connections
> in MIDI tab.

Thank you!

Is the audio output distorted... or are the notes just being
played at the wrong time?

IF DISTORTED:  This would be an issue with JACK.  By
distorted, I mean that there are gaps or overlaps in the
audio playback.  This would sound something like an XRUN.

IF NOTES PLAYED AT WRONG TIME:  This is an issue with the
applications themselves.  You are using ALSA for MIDI, so it
has nothing to do with JACK itself.  The fact that it
appears on the "JACK Control" dialog is just a convenience.
These are not "tempo changes" but "MIDI jitter."

SPECULATION:  What's probably happening is that one (or
both) of the applications does not have good synchronization
between their audio and MIDI code whenever they are using
JACK for audio.  The notes are accidentially getting
scheduled +/- one period size.  That's why it gets worse
when you make the period size larger.

-gabriel
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Re: Jack latency and tempo changes.

Rui Nuno Capela
On 08/26/2010 08:45 PM, Gabriel M. Beddingfield wrote:

>
>
> On Thu, 26 Aug 2010, [hidden email] wrote:
>
>> And here are second screenshot.
>> One is AUDIO tab and second is ALSA tab, I didn't have any connections
>> in MIDI tab.
>
> Thank you!
>
> Is the audio output distorted... or are the notes just being played at
> the wrong time?
>
> IF DISTORTED:  This would be an issue with JACK.  By distorted, I mean
> that there are gaps or overlaps in the audio playback.  This would sound
> something like an XRUN.
>
> IF NOTES PLAYED AT WRONG TIME:  This is an issue with the applications
> themselves.  You are using ALSA for MIDI, so it has nothing to do with
> JACK itself.  The fact that it appears on the "JACK Control" dialog is
> just a convenience. These are not "tempo changes" but "MIDI jitter."
>
> SPECULATION:  What's probably happening is that one (or both) of the
> applications does not have good synchronization between their audio and
> MIDI code whenever they are using JACK for audio.  The notes are
> accidentially getting scheduled +/- one period size.  That's why it gets
> worse when you make the period size larger.
>

check rosegarden's alsa-midi (aka alsa-seq) timer... if defaulting to a
pcm one, that's your trouble :)

hth
--
rncbc aka Rui Nuno Capela
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