ardour creating its own noise after starting audio file

41 replies [Last post]
zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

Using Mandriva 2009.1. Ardour imports audio file just fine. Press play audio file plays just fine, at first. Then Ardour starts making its own "white noise" type sound, which is not in the audio file itself, and the noise starts low volume then increases in volume as it is allowed to play. I have to kill ardour to stop the horrific noise. If I put in a plugin in the post fader position, the same noise starts immediately. This is a single stereo audio file, 44100hz, 16 bit, premastered with no clipping or other distortions in the file itself. Ardour is creating the noise itself. Anyone else have this issue or know how to fix it ? John in KC, Missouri

peder
User offline. Last seen 49 weeks 4 days ago. Offline
Joined: 2007-05-08
Posts:

I'm guessing you have some plugin that causes the noise. Try disabling all of them and see if it goes away. It might also be some feedback loop or something.

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

It actually does it with no plugins running at all. I have pulse audio disabled thinking that might be the problem, but it does it with pulse audio running and disabled both. The file plays fine it Audacity, so I'm confounded as to what is causing this in Ardour. Jack it running fine with 5.8 seconds latency, no Xruns, etc. I'm scratching my head as to what this might be. I thought about the feedback loop too, but I've checked the mixer settings for the soundcard and nothing should be doing that. I have a soundblaster live 5.1 card. Old but still seems to work great in Linux. Thanks for the reply, I do appreciate it. John

peder
User offline. Last seen 49 weeks 4 days ago. Offline
Joined: 2007-05-08
Posts:

Hmm, what if you play it in Audacity, with Audacity in Jack mode or in Alsaplayer/Jack? Perhaps Jack is causing something.

FWIW Soundblasters aren't recommended for real audio work since they resample everything to 48kHz internally.

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

I agree about the sound blaster, but financially it's the only option I have for a while. I'll try the Jack options you mentioned. Thanks

UPDATE: Tried running Audacity with Jack running. Not a single problem. It seems to be tied to Ardour somehow, but I'll be da*ned if I can figure out what would be the cause of this. Mandriva 2010 is coming out first week of Nov. I'll do a fresh install and see if that helps. Guess I'm stuck with Audacity for now. CRAP ! I like Audacity, don't get me wrong, but it and Ardour are two different beasts with two different objectives. (sigh)

nickmurtagh
User offline. Last seen 1 year 15 weeks ago. Offline
Joined: 2007-01-22
Posts:

Does it happen with any file or just that specific one?

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

Any audio (wav) that I import into Ardour.

nickmurtagh
User offline. Last seen 1 year 15 weeks ago. Offline
Joined: 2007-01-22
Posts:

What version of ardour do you have? And have you tried any older or newer versions?

qharley
qharley's picture
User offline. Last seen 3 days 51 min ago. Offline
Joined: 2007-03-24
Posts:

I have found a similar problem with some creative sound cards.

To solve, I changed p=3. in stead of 2. It is a jack - ardour - creative combination issue as far as I can tell. The same system runs flawlessly on a RME hammerfall card, using all 18 in and out channels simultaneously.

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

QHarley, This sounds very interesting. I'm not clear as to what p=3, instead of 2 is. What is the "p" you're referring to ? It sounds like you have the answer to my problem if you could explain the "p" is that you are changing the value of. Thanks.

nickmurtagh
User offline. Last seen 1 year 15 weeks ago. Offline
Joined: 2007-01-22
Posts:

I think he means Periods/Buffer in your jack configuration (eg qjackctl)

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

Okay, tried that. Jack won't run with Periods/Buffer at 3. Thanks everyone for trying to help. What an odd thing. Cheers, John

zenbrowncoat
User offline. Last seen 4 years 26 weeks ago. Offline
Joined: 2006-08-29
Posts:

Peder had the clue that fixed this problem for me. I set everything to 48000 instead of 44100. Found a piece of freeware called r8Brain to resample my audio file from 44100 to 48000. Jack at 48000, Audacity at 48000. Bingo ! No noise with or without plugins. So I guess for Soundblaster live cards the key is 48000 and then resample the finished project to 44100 for cd. Thanks everyone, John

paul
paul's picture
User offline. Last seen 3 hours 36 min ago. Offline
Joined: 2006-03-16
Posts:

@zenbrowncoat: for sample rate conversion the tools of choice are sndfile-resample or sox, both of which are open source, free of charge and better quality than r8brain. Both will be available using standard Mandriva software install tools. Just a FYI.

Turo
Turo's picture
User offline. Last seen 2 weeks 6 days ago. Offline
Joined: 2013-08-06
Posts:

In my Alesis io4 (which has a switch for 24 bits or 16 bits mode) the problem get solved when I switch it to 16-bit and restart. Then I reconfigure Jack (trough Cadence) to have 4 inputs and 4 outputs (instead of 2 and 2, because in 16bits-mode the 4 chanels are available for recording) and the interface just works fine.
The problem appears as it also get solved in Ardour and Audacity and I would expect in any other software, by using 24-bits or 16-bits. I would say it has something to do with conections made through jack and Bit-depth, but no idea how to handle bit depth through Jack. Any idea?
I'm using DreamStudio 12.04.3 LTS with kernel 3.8.0.26-lowlatency and pulseaudio 1.1 and I have found problems with this Alesis io4 interface in the past with distros with relases below 12.04 (like UbuntuStudio, Ubuntu and KXStudio) perhaps because of ALSA driver or Pulseaudio.
I hope this information to be valuable to others :)

Matt Francomb
Matt Francomb's picture
User offline. Last seen 7 hours 51 min ago. Offline
Joined: 2006-09-12
Posts:

I've found something similar when importing 16-bit files that I've rendered (with dithering) into a new session. I assumed that it was the dithering noise - if my understanding of how you would convert a 16-bit file to 24-bit or floating-point is correct, that noise would be audible because it's now affecting the 9th bit of each 24-bit sample, as opposed to the bottom bit of a 16-bit one (i.e. at about -96dB). So I just don't do that any more. This is based on the assumption that you convert a 16-bit sample to a 24-bit on simply by adding 8 bits of zeros at the bottom end (i.e. the converse of how you would convert 24 bits to 16 without dithering), because scaling the 16 bits to 24 would change the dynamics.

linuxdsp
linuxdsp's picture
User offline. Last seen 1 day 17 hours ago. Offline
Joined: 2009-02-04
Posts:

@MattFrancomb:

I assumed that it was the dithering noise..

Think of increased bit depth / resolution as effectively extending the lower limit of dynamic range e.g. below 0dBFS.

linuxdsp
linuxdsp's picture
User offline. Last seen 1 day 17 hours ago. Offline
Joined: 2009-02-04
Posts:

Think of increased bit depth / resolution...

e.g. the available dynamic range is greater for greater bit depth, but your 0dBFS ref should still be the same.

Matt Francomb
Matt Francomb's picture
User offline. Last seen 7 hours 51 min ago. Offline
Joined: 2006-09-12
Posts:

Yes, that's how I do look at it 0dB (the top bit) stays the same, as does the bottom bit (-96dB in 16-bit) and everything in between, but the noise floor drops from -96dB to -144dB, meaning that the dithering (at -960B to -96dB) becomes audible in quiet passages. And I think it's likely that this is what's happening for the OP, particularly since he says the noise goes away if he plays it in a 16-bit setup.

Or were you correcting something I'd said? I don't see a difference.

linuxdsp
linuxdsp's picture
User offline. Last seen 1 day 17 hours ago. Offline
Joined: 2009-02-04
Posts:

Maybe I misread your original post - when I read it (quickly) I thought you were implying that dither at the original noise floor [or some kind of signal, which just happens to be noise] at -96dBFS would somehow become substantially louder / or more noticeable if you increased the bit depth / resolution to 24Bit.

paul
paul's picture
User offline. Last seen 3 hours 36 min ago. Offline
Joined: 2006-03-16
Posts:

there are no bit depth options with JACK. It uses the largest bit depth the hardware will support when reading and writing to/from the hardware. It also offers the option to dither when converting back to hardware format, since the internal format used by all JACK clients (and almost all audio software in this day and age) is 32 bit float, which has an implicit 24 bit depth. You do not dither when converting to a deeper bit format, only when reducing the bit depth.

linuxdsp
linuxdsp's picture
User offline. Last seen 1 day 17 hours ago. Offline
Joined: 2009-02-04
Posts:

You do not dither when converting to a deeper bit format, only when reducing the bit depth.

agreed.

This video provides a good explanation of all things to do with A/D or D/A conversion, including dithering etc

http://www.youtube.com/watch?feature=player_embedded&v=cIQ9IXSUzuM

seablade
User offline. Last seen 6 hours 28 min ago. Offline
Joined: 2007-01-22
Posts:

I agree with LinuxDSP on that video, excellent and becoming part of my coursework for my students to watch it and the companion to it.

Seablade

Matt Francomb
Matt Francomb's picture
User offline. Last seen 7 hours 51 min ago. Offline
Joined: 2006-09-12
Posts:

@linuxdsp - well, that is what I appeared to notice the one time that I re-imported a file that I'd rendered to 16-bit with noise-shaped dithering. I wouldn't say it became louder as such, but definitely became audible, in the sense that parts that sound silent when played back on a CD-player had a quality that I'd describe as sounding like "tape hiss" when imported to 24 bits. And it seems to me perfectly reasonable that it should do so, since true digital black is 48dB quieter than the dither level. I don't think we're disagreeing about anything, I was just suggesting it as a possible explanation that nobody seemed to have considered for the OP's observation. And of course, the effect of dithering /is/ noticeable when compared with an un-dithered version of the same file (if not audible as noise or hiss) - otherwise, why would you bother to do it?

linuxdsp
linuxdsp's picture
User offline. Last seen 1 day 17 hours ago. Offline
Joined: 2009-02-04
Posts:

@Matt Francomb: I don't think we fundamentally disagree. Dither would be expected to manifest as (very) low level noise, like tape hiss (as described in the link I posted). I guess I just interpreted your original comments wrongly.

veda_sticks
User offline. Last seen 8 hours 7 min ago. Offline
Joined: 2011-03-11
Posts:

I have the same problem with an mbox1 but i think my problem is clock related. burts of white noise every 5 seconds that last 10-15 seconds.

No combination of settings help for me, digidisign driver support though is non existant and there is only a patch that makes it work well it used to apperently but now only mbox 2 does

Why is it you have to have jack set to the sample rate set to the same sample rate as what your project is running in? I dont remember having to do that back in windows (mind you this was over 10 yeras ago) I have a couple of tracks that were recorded at 48khz but most as 44.1 so opening them up when jack is at the wrong sample rate causes playback speeed to be wrong.

Xperienced
User offline. Last seen 10 weeks 1 day ago. Offline
Joined: 2011-08-18
Posts:

When a DAW does not have JACK what it does is, more or less, load "JACK" when you open a project and close "JACK" when you close the project. Obviously you don't need to tell it what rate, but you also don't have JACK's functionality (software interconnection).

I'm not sure if that's what you're getting at, but if you meant that on Windows DAWs you can have files of multiple sample rates in the same project without being asked to resample them, that means the resampling is being done on the fly. That's unprofessional. It works, but it's unprofessional and it is so for a variety of reasons. This is correct on playback applications only (ie. media players, PulseAudio).

Dithering /is/ unnoticeable. Most of the time, anyway. We do it out of correctness, as a lot of things are in the multimedia engineering world. The problems here have nothing to do with dithering. If any quality changed when you imported a 16bit file then something is broken, there's no reason for anything to change. Same as in the case of the interface that works better in 16bit mode - it's just broken (the driver or the interface).

Matt Francomb
Matt Francomb's picture
User offline. Last seen 7 hours 51 min ago. Offline
Joined: 2006-09-12
Posts:

OK, maybe dithering is unnoticeable, but it's more than just correctness - lack of dithering is definitely noticeable! I demonstrated this for a client who wanted "as little processing as possible" done on the final mixdown and wanted to hear the difference because she was very skeptical of my explanation that "adding noise" could possibly make it sound better - rendered the same mix twice onto a CD, once with dithering and once without, and let her listen to the two on her stereo without telling her which was which, and she chose the dithered one. I was listening very carefully, and knew which was which and could definitely hear, for example, that where reverb tails or sustained notes faded /to silence/, the un-dithered version starts to "crackle" just before becoming inaudible, whereas the dithered version fades completely smoothly into silence. This is a normal listening levels - turn it up loud and it's even more noticeable.

paul
paul's picture
User offline. Last seen 3 hours 36 min ago. Offline
Joined: 2006-03-16
Posts:
@Matt Francomb: this is required viewing: http://www.youtube.com/watch?v=BYTlN6wjcvQ
LeatusPenguin
User offline. Last seen 3 days 4 hours ago. Offline
Joined: 2010-12-16
Posts:

@Matt Francomb: this is required viewing: http://www.youtube.com/watch?v=BYTlN6wjcvQ

I'd like to add that Ethan's book, which developed from the ideas he talks about in the video, is also a very interesting read.

Matt Francomb
Matt Francomb's picture
User offline. Last seen 7 hours 51 min ago. Offline
Joined: 2006-09-12
Posts:

@paul - yes, I've had a look at that. As I pointed out, the listeners didn't know which version was which, but preferred the dithered version. Because I knew which was which, I didn't express an opinion until after they had. As I said before, why bother dithering if it doesn't have a perceptible effect?