Audacity Forum

Sometimes when I record from a USB microphone, the recorded file plays back too fast.
It as if it was recorded with a lower sample rate than it is played with. The strange part is it sometimes works ok and others it is the wrong speed.

I can make it playable by changing the speed -66.6

I am using Audacity 2.0.5 but I experienced the same thing with Audacity version 1.3.x

Attached is an actual recorded file that has the problem.

a USB microphone

Which one?

sometimes works ok and others it is the wrong speed.

You're a lot closer than we are. What's common about the successes and failures? What did you change?

What's the show? "Thank you for checking in" suggests you are recording a Skype conference or other community activity.

Are you by any chance trying to record an Audacity session with a computer also running Skype? Skype doesn't share well. The session will be the very definition of "unstable."

Koz

Which one?

I should have been more specific. It is actually built into a logitech webcam (sorry don't know exact model)

You're a lot closer than we are. What's common about the successes and failures? What did you change?

I don't really know. Infact, I just tried it and it recorded properly.
In all cases, I was using 44100 mono

What's the show? "Thank you for checking in" suggests you are recording a Skype conference or other community activity.

Are you by any chance trying to record an Audacity session with a computer also running Skype? Skype doesn't share well. The session will be the very definition of "unstable."

It is recorded off of radio not skype.
Nothing that uses the camera or microphone running

OK. I'm building this in my head. You play a web radio performance to your speakers and then you make Audacity record from the web cam and that's your show. You have to be very quiet so the room noise doesn't get into the capture, right? There are other ways to do that, but if your computer is fast enough for live audio, that does work.

Speed may be important. You can get a very fast capture if the recording process was running too slow. That can happen if the computer is only able to perform the capture if it's not busy doing anything else.

Could the difference be that you have other things or programs running when you get the damaged shows? It could be something wacky like it stops working if you open the video portion of the webcam. If you leave it closed, everything's fine.

Koz

kozikowski wrote:OK. I'm building this in my head. You play a web radio performance to your speakers and then you make Audacity record from the web cam and that's your show. You have to be very quiet so the room noise doesn't get into the capture, right? There are other ways to do that, but if your computer is fast enough for live audio, that does work.

Speed may be important. You can get a very fast capture if the recording process was running too slow. That can happen if the computer is only able to perform the capture if it's not busy doing anything else.

Could the difference be that you have other things or programs running when you get the damaged shows? It could be something wacky like it stops working if you open the video portion of the webcam. If you leave it closed, everything's fine.

Koz

Thanks for responding.
I am recording from a physical radio. No playback at all on the computer. The room is reasonably quiet but I don't really need high quality anyway.

One thing I noticed is today I woke the system from hibernate, switched windows from firefox to audacity and started recording and ended up with a bad recording.
I then made a recording right after that and it was perfect.

My system should be fast enough with a Core 2 Duo @ 2.66GHz

smeezekitty wrote:I am recording from a physical radio.

Does this radio have a headphones output? Does your computer have a line-in port (blue)? If so you may be able to connect the radio to the line-in and record from line-in.

smeezekitty wrote:One thing I noticed is today I woke the system from hibernate, switched windows from firefox to audacity and started recording and ended up with a bad recording.
I then made a recording right after that and it was perfect.

My system should be fast enough with a Core 2 Duo @ 2.66GHz

Try rebooting the computer. You can avoid reboots for some time with sleep or hibernate but ultimately you have to reboot.

What version of Windows is it? Have a look at this question about sample rate mismatches, especially if you are on Vista or later http://manual.audacityteam.org/o/man/fa ... .html#sync .

Note that when you record with a USB webcam mic and play back with the built in sound card, you have two different devices which almost certainly won't have the exact same clock speed. And if the speed is different at some times than others, this suggests a drivers problem (probably with the built-in sound device). Make sure the web cam and especially the built-in sound device have their latest intended drivers. Please see http://wiki.audacityteam.org/wiki/Updat ... ce_Drivers .


Gale

Gale Andrews wrote:

smeezekitty wrote:I am recording from a physical radio.

Does this radio have a headphones output? Does your computer have a line-in port (blue)? If so you may be able to connect the radio to the line-in and record from line-in.

Yes, but then I couldn't listen to the output.

Try rebooting the computer. You can avoid reboots for some time with sleep or hibernate but ultimately you have to reboot.

Meh I guess I will have to break down and reboot. I like to hibernate because I get everything set up how I like it

What version of Windows is it? Have a look at this question about sample rate mismatches, especially if you are on Vista or later http://manual.audacityteam.org/o/man/fa ... .html#sync .

It is windows vista

Note that when you record with a USB webcam mic and play back with the built in sound card, you have two different devices which almost certainly won't have the exact same clock speed. And if the speed is different at some times than others, this suggests a drivers problem (probably with the built-in sound device). Make sure the web cam and especially the built-in sound device have their latest intended drivers. Please see http://wiki.audacityteam.org/wiki/Updat ... ce_Drivers .

I am not worried about 100hz or less difference. The difference is 3x as if it is being recorded at 14700Hz.
You are probably right, it is likely a driver bug but it is hard to say

All other sound plays the correct speed, even if imported with Audacity. It ONLY happens if recorded over USB.

smeezekitty wrote:

Gale Andrews wrote:

smeezekitty wrote:I am recording from a physical radio.

Does this radio have a headphones output? Does your computer have a line-in port (blue)? If so you may be able to connect the radio to the line-in and record from line-in.

Yes, but then I couldn't listen to the output.

Yes you could. In Audacity, Transport > Software Playthrough (on/off). This will play the recording through your computer playback device.

Are you recording a high quality sound like music, or is this something like a walkie talkie radio? If it's music, then headphones out of the radio to line-in of the computer will give you a much better recording.

smeezekitty wrote:

Try rebooting the computer. You can avoid reboots for some time with sleep or hibernate but ultimately you have to reboot.

Meh I guess I will have to break down and reboot. I like to hibernate because I get everything set up how I like it

It's only a suggestion if you want to record with the webcam. USB devices can benefit from reboot. Or at least, try unplugging the web cam and reconnecting it.

Can you put the programs you want in your startup menu?

smeezekitty wrote:

What version of Windows is it? Have a look at this question about sample rate mismatches, especially if you are on Vista or later http://manual.audacityteam.org/o/man/fa ... .html#sync .

It is windows vista

Then go through that link above about sync carefully. Recording the mic with Windows DirectSound host in Audacity, 44100 Hz or 48000 Hz project rate, both Exclusive Mode boxes checked in Windows Sound Control Panel could solve it.


Gale

Yes you could. In Audacity, Transport > Software Playthrough (on/off). This will play the recording through your computer playback device.

Are you recording a high quality sound like music, or is this something like a walkie talkie radio? If it's music, then headphones out of the radio to line-in of the computer will give you a much better recording.

Too much latency with the software playthrough. There should be very little or no music so it isn't a big deal.

In any case it turns out my USB mic only supports 16KHz, 32KHz and 48 KHz. I will try recording at 32 or 48 KHz to see if it helps but the intermittent nature of the problem makes troubleshooting difficult.

I must say the support here is very good here. Some other software teams are akin to talking to a brick wall.

You can buy a small doubler adaptor for the headphones out of the radio that would still let you record into computer line-in (if you have one).

Recording a radio acoustically is very sub-optimal.


Gale