Cross synthesis & time stretching in CSound

The goals:
1. Cross-synthesise the two sounds using Csound’s pvcross opcode.
2. Time-stretch and pitch-shift one of the sounds using Csound’s pvoc opcode

To use any of CSounds phase vocoding opcodes we need to first analyse the files we want to use: its not hard, but you need to know to do it. Open the "Utilites" tab:

Then select your analysis type "PVANAL" is the one we want, after that set your input & output filenames, samplerate, num channels, and a frame size of perhaps 1024.. or there abouts.

Now hit "Run PVANAL" and it should print out the following in the console.
PV analysis output:

util pvanal:
audio sr = 44100, monaural
opening WAV infile adrien.wav
analysing 119879 sample frames (2.7 secs)
1024 infrsize, 256 infrInc
466 output frames estimated
pvanal: creating pvocex file
20
40
[snip]
460
480

484 1-chan blocks written to adrien.pvx

Ok so we've analysed the files needed, now to use them in the .csd file:
Helpful docs online: http://www.csounds.com/manual/html/pvcross.html

Some code like beside here generated some inresting results, but I don't know what the end goal should sound like...

Probably not really like this :(

Time stretching is a bit easier:

see http://www.csounds.com/manual/html/pvoc.html

 

 Not sayin its fantastic but it works :)

DnB production: Mastering EQ

Ever listened to some drum and bass? Wondered how they got that sound? A fraction of that sound is what I'm going to explain today. Apart from a whole lot of drum programming, compression, reverb and filtering there's some other "last" steps to take. One of the interesting things I've noticed is quite a lot of "old school" dnb tracks have some hefty master EQing going on.

Check out "Terrorist" by Renegade: Its a DnB classic. First just listen, and estimate what EQing could have been applied. Then listen to the track routing the audio into JAAA (Jack/ALSA Audio Analyser) and checkout this:

You see that?? Wow. Bout -20dB cut all around 10kHz, and another starting around 15kHz all the way up to 17kHz. Sure you ear's response to highs isn't linear: but that's still a hell of an EQing going on. Its all about the brightness of the track right there: that crispy snare snap and ringing hats.

Now check Helicopter by Deep Blue Jungle: its got quite an even response. Note the heavy bass, and that its a sound that is quite transient: it appears, rings and then dims away until the next downbeats. Inbetween those downbeats there's substantial congas, hats, shakers etc going on. Has some high cut applied (possibly shelving) applied starting at just over 15kHz:

Then checkout Dj Hypes "The Chopper", and note that the song is all about the bassline. To make the bass more obvious, there's a -40dB high shelf applied at just over 11kHz, dimming all bright attention grabbing overtones of the fast drums. As the drums are never a very prominent part of the sound, they're just cut out constantly.

Finally we'll look at Badman's "War in '94": It features some quite low bass lines, some saxophone and drums. Also some pad sounds are prominent at certain stages during the song:

All in all what I'm going to do when producing some DnB track, is load up Fons & Nedko's fantastic 4 band parametric EQ with LV2 gui: http://nedko.arnaudov.name/soft/lv2fil/trac/

It provides a new way to listen to the same songs, but without that mastering EQ applied: just reverse it using the above filter (yes the 4th section is disabled in the screeny: turn it on / off to notice the huge difference in brightness in the track!

 Conclusion: Don't be afraid of some hefty EQing, it can really add that final shape to the song: either adding dramatic effect to a certain element of the mix, or reducing its impact to highlight the other parts of the song.

Why another blog?

This blog is dedicated to production techniques, tips & tricks using open source audio software, and the linux platform. More specifically, I'm using Arch linux, with the ArchAudio repos, and some custom compiled software. Its a little techy, but well worth the new and fancy features that are available when using the latest & greatest :)

Hopefully you'll enjoy all resources to be posted on the blog, and have some fun browsing around. Comment & sharing opinions welcome! -Harry