I’ve recorded and produced 13 podcasts episodes in Audacity on my current system, and until now I’ve had no problems whatsoever. But yesterday I was about to start editing my 14th, and I found that the recording (made the day before) has lost some quality. It’s gone all stuttering and poppy (not sure if those are the right terms), and also the timeline is distorted (about 20 seconds too short on a 50 minute recording). The funny thing is that the quality is fine in parts of the recording, especially towards the end. Here’s a short sample from one of the noisier parts:
I searched around for other similar problems on the forum, but I wasn’t able to figure out whether this is the same problem as anyone else is having. I’m posting here looking for any precautions I can take to avoid these problems in the future, or steps I can take to isolate the problem.
- I’m running Ubuntu 12.04, with PulseAudio (standard install of Ubuntu, haven’t changed anything here).
- I have a Samson Q2U USB microphone, and I’m using Audacity 2.0.0 installed from the Ubuntu Software Center (standard apt repository I suppose).
- The computer is a pretty standard 3 year old desktop Acer with an i5 processor and 4 gigs of ram, no dedicated soundcard, mixer or anything like that.
- I record my own voice locally in Audacity while interviewing a guest over Skype (184.108.40.206-0maverick1) with video (video is not recorded). For redundancy, I also record the conversation using Skype Call Recorder (0.8+git.1-0ubuntu1~precise). Besides that the only thing I typically have running at the same time is Chrome with a few tabs.
- After recording, I save the project to an NTFS hard-drive (I occasionally want to access my storage from the Windows dual-boot). I’ve done this several times before and haven’t had any problems, as the Audacity’s temp (recording) folder is on the Ubuntu partition.
Here’s my partition table. The bottom one is where I saved the project (NTFS). The top one is where Audacity’s temp folder is.
➜ ~/>df -Th Filesystem Type Size Used Avail Use% Mounted on /dev/sda5 ext4 49G 22G 25G 48% / udev devtmpfs 1.9G 4.0K 1.9G 1% /dev tmpfs tmpfs 764M 1.1M 763M 1% /run none tmpfs 5.0M 0 5.0M 0% /run/lock none tmpfs 1.9G 6.8M 1.9G 1% /run/shm /dev/sda6 fuseblk 410G 297G 114G 73% /media/storage
…on what could suddenly have caused these problems:
- I regularly do automatic updates from Ubuntu. Some of these could have changed something about the audio behavior on the system
- I was busying around more with the machine than usual, using Chrome to look at some Google Docs. Usually I have Audacity and Skype in the front while recording, with Chrome running in the background.
So far, my attempts to reproduce the issue have been unsuccessful.
I’ve had a look at some resources regarding these problems, and these are the ideas on precautions I can take:
- Avoid running Chrome at the same time
- Increase Audacity’s process priority (I noticed in Ubuntu’s System Monitor that PulseAudio is already running with priority Very High - all others are running with Normal)
- Save the project directly to the “local” ext4 hard-drive, not to the NTFS partition
Is this sensible? Do you think there are any other variables I should tweak? I saw there are some recommendations about HW, but I’m not in a position to make any investments there.
Many thanks in advance for any help or advice here.