Tuesday July 6, 2004

Panther Wrestling

Today, as a part of a research project I'm involved in, I was assigned some audio and video conversion tasks. In particular, a couple of months ago we made about four hours of recordings of people making odd speech-like sounds, and I have to transfer those from DAT tapes into audio data files. Fortunately, there's a new G5 Mac running Panther dedicated to the project, so the conversion was a snap.

Or so you'd think.

Getting the data off the DAT digitally required some cable and peripheral gymnastics involving a Tascam DAT player with RCA digital output into an M-audio 410 interface that output the signal via Firewire. That wasn't too much trouble, although the System Preferences widget for configuring the 410 was pretty cryptic. I gather it was designed to imitate the interface on an audio engineer's board, which I'm sure would have helped it I were an audio engineer. In any case, when we had that all set up, we had digital audio coming in on the Firewire cable. I figured the hard part was over.

Under Sound in System Preferences on the G5, there's a software level meter. When I selected Firewire as the audio input device, that meter displayed levels that agreed with the meter on the DAT player, proving that the audio was making it all the way into the computer. This meter was, during the coming hours, the touchstone to which I returned to convince myself that, yes, there really was audio data in a recognizable format coming in via Firewire. However, two different audio apps installed on the machine, Praat and Audacity, were unable to sample the data. Praat would allow me to record when Firewire was the input device, but it recorded only silence. Audacity wouldn't even let me record, giving the message: "Error while opening sound device. Please check the output device settings and the project sample rate." I tried all the sample rates, but no dice—and why should I have to worry about the output device when I'm recording, anyway?

My last bright idea was to look for a straightfoward hello-world audio recording utility (like Sound Recorder in—wait for it—Windows). Panther apparently comes with Quicktime, iTunes, and Garage Band, but none of those appeared to have the ability to record off Firewire. Thwarted, I turned to an older Mac in the lab running SoundEdit under OS 8.6 that I knew was capable of doing the recording (although it wouldn't be able to burn the data onto a DVD-ROM like the G5). I set up the recording, and left the machine alone for a few hours to record the 124 minute tape. When I got back, it had recorded 2 hour and 10 minutes (out of a maximum of 2:19, although the disk wasn't close to full) and locked up rock solid. Sigh. I rebooted and started poking around, hoping to find a complete or almost-complete temp file. It was there, but when I double-clicked on it, SoundEdit told me it wasn't in the right format—apparently SoundEdit can't read its own temp files. At this point it was late, and I went home.

So, an afternoon wasted, and I'm going back tomorrow to try again with the OS 8.6 Mac by sitting there and watching it for two hours in order to stop it after it finishes recording, but before it crashes. Grrrrrrr. What really bugs me is that the G5 running Panther wasn't able to handle the job. If a brand-new Macintosh running the prettiest, bestest version of the OS can't perform the simple task of sampling audio coming in via Apple's much-touted Firewire, what good is it? Mac devotees are always bragging about how the new machines are simple, intuitive, and stable, and Macs have always had a reputation for doing multimedia well, but for this task, apparently they're just shiny aluminum doorstops.

Can you tell I'm in a bad mood?

[Now playing: "Travels in Nihilon" by XTC]

[Update: I got Audacity working. Some Googling produced this description of somebody having the same problem with the same equipment (more or less). The trouble is that the M-audio 410 sends four channels out on the Firewire. 1 and 2 are always for the analog inputs, and 3 and 4 are always for the digital inputs, and since the audio is coming from a DAT via an RCA cable, it's going onto channels 3 and 4. Praat and Sound Recorder (suggested by Rosyna in the comments) both handle only two channels (stereo). However, if I tell Audacity to record four channels, it works, with the first two being empty—I guess I'll have to delete them later. Fortunately, the disk is big and mostly empty, with 118 hours of recording space available.

So, the OSX System Preferences dialog must be (confusingly) merging all audio channels coming in on the Firewire for display in the level meter, but it gives no indication that there are more than two, and that the first two channels are actually silent. None of the audio apps I tried gave any indication of this, either. It would be nice to be able to see exactly what's coming in via Firewire, and maybe to be able to map between channels, since it looks like apps that only handle two channels are never going to be able to record a digital signal from the M-audio interface. (I'll have to play around with the M-audio mixer, maybe it can do the mapping.) Fortunately for me, this isn't a task I need to do on this machine more than once or twice, so I can write it up and forget about it.]

I am The Tensor, and I approve this post.
11:58 PM in Web/Tech | Submit: | Links:

TrackBack

TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a00d8341c88ad53ef00d8342ef68153ef

Listed below are links to weblogs that reference Panther Wrestling:

Comments

I am your god now. Appearantly. SoundEdit 16 is HORRIBLY old and has a limit of 2gigs per file. That is likely why it locked up and why you cannot open the file.

You can use many different OS X apps for this job. http://www.monkeybreadsoftware.de/Freeware/SoundRecorder.shtml

You chose to try to solve this by using an application killed many, many years ago on a system it doesn't support using an interface that didn't exist when the application was created.

Posted by: Rosyna at Jul 7, 2004 12:39:42 PM

I only used SoundEdit on the old 8.6 system, because I knew it was stable and functional there. Audacity and Praat are both supposed to work on OS X, and they do with non-Firewire audio input, but neither can record from Firewire even when it's selected as the audio input.

Posted by: The Tensor at Jul 7, 2004 12:56:01 PM

Did you try that app I suggested? Oddly called Sound Recorder...

Posted by: Rosyna at Jul 7, 2004 2:16:08 PM

Just tried Sound Recorder. It behaves the same as Praat: it allows me to select Firewire as the input and then record, but it records only silence. Interestingly, the level meter in Sound Recorder shows nothing, but the level meter in System Preferences continues to show the incoming signal.

Thanks for the suggestion, by the way. All help is appreciated.

Posted by: The Tensor at Jul 7, 2004 4:03:44 PM

The error message from Audacity is just a typo ("output device" should be "input device"). Also, there will be a new version of Audacity available later this month that might work better...

Posted by: Matt Brubeck at Jul 7, 2004 4:58:08 PM

I got Audacity working—see update above.

Posted by: The Tensor at Jul 7, 2004 6:34:24 PM

Post a comment