Sunday, March 13, 2011

GPP 038: A Conversation with Julia Sherred

This is my longer episode of the podcast to date, clocking in at almost two and a half hours. I have dropped the MP3 bit rate to 160Kbps (down from my usual 320) on the grounds that people may not want to download an MP3 file that is over 350 MB!

MP3 File

Show Notes

I mention the books Annals of the Former World by John McPhee and Starfish by Peter Watts. You can find Watts' novels in electronic form here. Get a taste of them, or download the whole things. I generally prefer to read books in print form but Behemoth (printed on paper as two volumes) is a large novel as the title implies, is out of print, and paper copies are going for collector prices. I will probably read that one on-screen. Note that if you don't want to buy dead tree editions, or just prefer e-books, you might still be able to leave Mr. Watts a tip using his donation link.

Oh, the video game we could not remember is Katamari Damacy.

Technical Information for Audio Geeks Only

Jules and I had this conversation over Skype, while simultaneously recording our separate ends of the conversation. She then sent me her end of the conversation in the form of a .WAV file and I assembled the two parts in Logic. There was a technical glitch: for reasons not entirely clear to me, her file was 0.0268% faster than mine. This meant that even though we were perfectly in sync at the beginning, by the end of the interview the files were about two and a half seconds out of sync, which jumbles up the conversation and results in a lot of cross-talk.

I was able to figured this out because prior to applying a noise gate, I was able to faintly hear my audio part in her headphones, and vice-versa. This allowed me to note how the "echo" got longer and longer, and determine that by the end of the file her audio was 2.348 seconds earlier than mine. The entire file was about 2 hours 26 minutes, or 8,760 seconds. The ratio comes out to be 0.000268. So to fix this, I used the "time stretch" function in Soundtrack Pro to stretch her audio file to 100.0268% of its original length, and the two parts then stayed together perfectly.

To make this kind of thing easier to fix in future interviews over Skype, I should remember to get my conversation partners to clap or count simultaneously at the beginning of the interview, and also at the end. This should make it easier to align the start of the files and also to determine whether the audio clocks have drifted apart by the end of the recordings and by how much, without having to rely on guesswork or being lucky enough to hear the sound leaking from headphones. I am not sure exactly what went wrong, but suspect that it has something to do with my using an Apogee Ensemble, which has a fairly high-end clock, while Jules was using a more ordinary PC sound card, which may derive its audio clock from I-don't-know-where -- maybe the PCI bus clock?


Joe Covenant said...

Well... canadian's are usually a little aheads of y'awl 'murkins anyway, eh?
;' )))

philosophywithfries said...

you're right. it was a clock issue.