Odd echoes of recording repeated every 6 secs

[mr-b]

Hi

I'm using 1.3.12 on Win7 and I've found that intermittently when using the Append Record (Shift-Record) feature that I see the playback meters blip every 6 secs or so (duration of around half a second) and I hear echoes of the music that's just gone bleed through into the recording. I thought at first that it was some kind of very weird bleed-through from some dodgy tapes until now when I clocked the playback meters bursting into life during a record (good job they are separate)! During speech this sounds like a couple of previously words are repeated over the top every 6 secs.

Any ideas what's happening?

[Gale Andrews]

One other user e-mailed recently suggesting append-record in 1.3.12 was "reproducing previous bits" but I could not get any elaboration. There isn't enough detail in your report as to your tracks and recording device setup and what you are trying to do. I assume it's an overdub recording (Transport > Overdub is checked), but how is rogue playback getting captured in the recording unless you are recording stereo mix or are using loudspeakers instead of headphones? If pre-existing audio is being captured in the recording, is it coming from the same track that is being recorded into, from a point on the timeline prior to where you started the append-record?

A screen capture would help (ALT + PrtScr) so we can see the tracks and selections, and track and project sample rates. If you can reproduce the problem in a short saved project (tracks of only about a minute long) then that project might be very useful to us.

Thanks



Gale

[mr-b]

Appreciate it's hard to debug this without repro steps, but as befor it's intermittent. I'd say 1 in 100 so far ... I'm 100% sure though that it's only ever happened while using Append-Record.
Overdub is checked, but only because it's the default. This is just recording line in from an M-Audio 2496 sound card. Playback and Recording are using the sound card's Line devices. I'm using 44.1 currently but it has also happened at 96k. 32 bit float, single audio track.

The pre-existing audio is coming from the same track that is being recorded and is a few seconds behind. It's not from before the append-record timeline. So after the first track has been recorded and append record is started, it's like the same tape is being recorded from a second line in but the 2nd tape is a few secs behind the main tape and about every 6s its fader is flicked up then down.
Let me know if you need any more info.

[Gale Andrews]

Thanks for the answer. So, although you only have one track and are appending to that (so you are not playing anything while recording) you are still getting flashes on the green playback meter while you are recording? And at the exact time these flashes occur, you get part of the current append record that has just been laid down on the track duplicating itself in that recording?

If it wasn't for the playback meter flashes and the possibility that this is specific to append-recording, I'd have said this was a fairly typical problem of not having the computer resources to write the Audacity .au files properly - if you are recording in stereo at 44100 Hz, this happens every 6 seconds. Or, a problem with the M-Audio drivers. Could you upload a short demo file somewhere if this happens again, and post a link to it here? There are lots of free sites you can upload to, like http://www.sendspace.com.

It would be an idea to also glance at Managing Computer Resources and Drivers to satisfy yourself that some problem such as virus scanning of the .au files might not be responsible.


Gale

[mr-b]

Thanks for the answer. So, although you only have one track and are appending to that (so you are not playing anything while recording) you are still getting flashes on the green playback meter while you are recording? And at the exact time these flashes occur, you get part of the current append record that has just been laid down on the track duplicating itself in that recording?

Exactly.

If it wasn't for the playback meter flashes and the possibility that this is specific to append-recording, I'd have said this was a fairly typical problem of not having the computer resources to write the Audacity .au files properly - if you are recording in stereo at 44100 Hz, this happens every 6 seconds. Or, a problem with the M-Audio drivers. Could you upload a short demo file somewhere if this happens again, and post a link to it here? There are lots of free sites you can upload to, like http://www.sendspace.com.

It would be an idea to also glance at Managing Computer Resources and Drivers to satisfy yourself that some problem such as virus scanning of the .au files might not be responsible.

My PC is a quad core 3GHz with 4GB RAM so it should have enough horsepower. I'll def snag the audio next time it happens.
RE: the AV, I'm using Microsoft's Security Essentials and it is possible to exclude certain file types, so I'll consider adding .au - unless you'd prefer me to try and capture this happening again.

FYI I've also checked my PC's latency using DPC Latency Checker - http://www.thesycon.de/eng/latency_check.shtml. (I'll add this tool to the wiki)

[darius2]

FYI I've also checked my PC's latency using DPC Latency Checker - http://www.thesycon.de/eng/latency_check.shtml. (I'll add this tool to the wiki)

How to set message window refresh time to 2+ s to let me copy and paste this message ?
1 s refresh time cancells selected text every second, so no chance to get it copied.


Really excellent tool.

I am trying to diagnose audio signal drops-out in Asterisk for Windows + Celliax to play audio to a sound card.

Are you aware of one more professional Audio Channel Latency Checker ?

Darius

[Gale Andrews]

FYI I've also checked my PC's latency using DPC Latency Checker - http://www.thesycon.de/eng/latency_check.shtml. (I'll add this tool to the wiki)

How to set message window refresh time to 2+ s to let me copy and paste this message ?
1 s refresh time cancells selected text every second, so no chance to get it copied.

Do you mean capture a screenshot of the latency checker? Perhaps you could use a screen video capture utility like HyperCam or CamStudio?

Darius2, can you please quote the person who made the quote in your messages? It gets confusing if you attribute other people's quotes to yourself. The easiest way to quote properly is to click "Quote" when you want to reply, then the Forum software will attribute and nest the quotes properly.


Thanks


Gale

[Gale Andrews]

Thanks for the answer. So, although you only have one track and are appending to that (so you are not playing anything while recording) you are still getting flashes on the green playback meter while you are recording? And at the exact time these flashes occur, you get part of the current append record that has just been laid down on the track duplicating itself in that recording?

Exactly.

Can you uncheck Transport > Overdub and see if that stops it happening?

RE: the AV, I'm using Microsoft's Security Essentials and it is possible to exclude certain file types, so I'll consider adding .au - unless you'd prefer me to try and capture this happening again.

If you don't mind being irritated occasionally by this problem, perhaps don't change the anti-virus settings at the moment.

Another experiment you can try is to open Audacity from a command prompt. Navigate to the Audacity installation folder then type

audacity -blocksize 2127800

That will make each .au file 2 MB instead of 1 MB, so at 44100 Hz 32-bit float the write to .au will only be done every 12 seconds instead of every six seconds. If the problem still appears every six seconds, writing the .au files isn't the cause. An easy way to get a command prompt at the correct place on Windows Vista/7 is to SHIFT + right-click over the Audacity installation folder > Open command window here (or this registry hack to make that menu item appear on normal right-click as well). Only experienced users should mess with the Windows registry, of course, because mistakes can cause problems.




Gale

[mr-b]

Ok to make this a bit easier, I tried modifying the Audacity shortcut to add the blocksize option but Windows said that it was invalid.
So I created a batch file to run it with the option but it says:

D:"C:Program Files (x86)Audacity 1.3 Beta (Unicode)audacity.exe -blocksize 2127800"
'"C:Program Files (x86)Audacity 1.3 Beta (Unicode)audacity.exe -blocksize 2127800"' is not recognized as an internal or external command, operable program or batch file.

It works though running it from the cmd prompt directly.
How do I run it from a batch file (or shortcut)?


I'll hold off the other suggestions i.e.
- uncheck Transport > Overdub
- exclude .au files from AV real-time scanner

until I see the issue again (and will capture recording and screen grabs). It's not so much of an issue now I know to check for it.

[Gale Andrews]

Ok to make this a bit easier, I tried modifying the Audacity shortcut to add the blocksize option but Windows said that it was invalid.
So I created a batch file to run it with the option but it says:

D:"C:Program Files (x86)Audacity 1.3 Beta (Unicode)audacity.exe -blocksize 2127800"
'"C:Program Files (x86)Audacity 1.3 Beta (Unicode)audacity.exe -blocksize 2127800"' is not recognized as an internal or external command, operable program or batch file.

It works though running it from the cmd prompt directly.
How do I run it from a batch file (or shortcut)?

In the batch file, only wrap the path in quotes thus:
"C:Program Files (x86)Audacity 1.3 Beta (Unicode)audacity.exe" -blocksize 2127800

Similarly in the shortcut, the

-blocksize 2127800

has to go in the "Comment" box, not in the "Target" box.

Thanks for your help.


Gale