Audacity freezing while recording more than one track.

[stinni3]

Im using Audacity 1.3.9 (Unicode) and Im having trouble while recording. I am using MobilePre USB interface. Recording the first track works fine but when I start recording the second or third track it records for one or two second and freezes than. I have unchecked the Software playthrough button but it still doesnt work. I found out that if I uncheck the Overdub button also i can record as many tracks as I want to. But how am I supposed to be able to record while I cant hear the other tracks?

[stinni3]

I forgot to tell that I am using Linux Ubuntu 9.10 the Karmic Koala.

[stinni3]

Now, I have found out that it freezes when I try to use the USB Interface both as input and output device. When I plug my headphones into to the headphone plug on the computer and use the soundcard in the computer everything works fine. Does anyone know why I cant use my Interface both as input and output device?

[steve]

It sounds like your USB port cannot handle the amount of data. If you are recoding and playing back simultaneously over USB, the amount of data that the USB port has to handle is double. Try running it at 44100/16 bit (CD quality) and see if that works.

[stinni3]

But why does that happen? I haven't tried this but when I was using Windows everything worked fine, but after I installed Linux this happened. The USB port hasn't changed..

[steve]

The USB port hasn't changed..

The drivers have changed and your default Audacity settings may have changed.

Do you have "PulseAudio Mixer" ? It is necessary for setting up recording on a default Ubuntu system, but for some reason was not installed by default on Ubuntu 9.04 (I don't know if they have included it as a default in 9.10)

[stinni3]

No I don't have it, do you know where I can get it?

[steve]

Through Synaptic (the Package Manager).

Setting up Audacity and PulseAudio correctly can take a bit of working out, but if you look through some previous posts on this forum there are several write-ups about how to do it. The exact details are likely to be different depending on your hardware so a bit of experimentation will probably also be needed.

[stinni3]

Yes I have PulseAudio installed but I have no idea how to use it. When I am about to start recording a new track this window opens and says

Latency Correction setting has caused the recorded audio to be hidden before zero.
Audacity has brought it back to start at zero.
You may have to use the Time Shift Tool (<---> or F5) to drag the track to the right place.

why is that? Everything stops and nothing is recorded.

[steve]

It is a misleading message. Audacity has detected that the recording has stopped, but is not aware that it stopped prematurely.

If Audacity tries to use two different Hosts at the same time, then recording will stop within a few seconds and you will see that message. The message is actually correct - it is just informing you that Audacity has compensated for "latency". The problem is unrelated to the message - the problem is that recording has stalled.

Without using the PulseAudio Volume Control it is difficult to see exactly what is going on, and there are many possibilities. The most likely scenario is that Audacity is trying to access one device through PulseAudio and a different device through ALSA (your USB device and your ordinary computer sound card).

Here's some possible configurations for you to try. Go into Audacity "Edit menu > Preferences > Devices" to make the changes:

1)
Host > ALSA
Playback Device > Default
Recording Device > Default
This should set Audacity to use PulseAudio and PulseAudio will then control which physical devices are connected to Audacity.

2)
Host > ALSA
Playback Device > hw:0,0
Recording Device > hw:0,0
This should set Audacity to communicate with your computer sound card through ALSA

3)
Host > ALSA
Playback Device > hw:1,0
Recording Device > hw:1,0
This should set Audacity to communicate with your USB device through ALSA

The above set-ups are not guaranteed as your system may be different from mine.

The main advantage of using PulseAudio is that PulseAudio allows you to record sounds that are playing on your computer. For example, you can play streaming audio in Firefox and record directly into Audacity without using a microphone or linking the output socket to the input socket with a lead.

The disadvantage to using PulseAudio is that it is possible to configure PulseAudio to use settings that are invalid, for example to try and record from an input that does not exist.

To set up PulseAudio,

• Set Audacity to use the Default recording and playback devices (on some systems Pulse is specified, on others there is just the option for "Default").
• Click on the Recording meter in Audacity to activate it (or right click on the meter and select "Start Monitoring)
• Open PulseAudio Volume Control and go to the "Recording" tab.
• You should see Audacity listed (probably "ALSA Capture") and there is a little down arrow at the right of it.
• Click on the down arrow for a drop down menu and select "Move Stream"
• Select your desired input (The Mobile-Pre USB - do NOT select "USB Monitor")
• Now switch to the Playback tab - there should be nothing listed apart from "System Sounds"
• Go to Audacity and generate a 30 second tone (Generate menu).
• Press "Play" and then "Pause"
• Now back to the PulseAudio Volume Control - you should now see Audacity listed in the playback section.
• Use the drop-down menu to move the output stream to the required device (probably your USB device, but choose whichever you want).

Audacity is now set up.
These settings should persist unless you change them, although if you use Skype it is possible that Skype could change the settings without telling you.

In PulseAudio Volume Control you can set the default recording and playback devices. Just go to the "Input" and "Output" tabs and use the drop down menus to set which input and output you want as the default.

The PulseAudio Volume control does not set individual inputs and outputs on audio devices, it just deals with the device as a whole. For example, on my computer sound card I have a built-in microphone and an external microphone socket. PulseAudio Mixer does not control these, it just controls the sound card as a whole. I would use the ordinary Gnome Mixer to select which microphone I wish to use.