Scratching MP3's & WAV's

I went to this huge music store quite a few times, usually playing the synthesizers since I'm a keyboard kind of guy, and I went to the DJ department of the store and saw a few CD scratchers (which support CD's, CDR's, CDRW's, and also run MP3's off the CD's as well). They were expensive to all hell though, like $1000+. So I came up with an idea of creating my own software to do this.

Here is my plan. I will be using DirectX8 on VB to display two 3D turntables with a mixer in the middle. It will allow the user to load one audio file into one turntable, and another onto the other turntable. When they are loaded, Vinyls are displayed. The user can turn on any of the turntables and it will run the audio as the Vinyl spins. Using the mouse, the user can scratch the vinyl, which should also cause the music to sound as though it has scratched, only not a fake scratch. A real scratch. My theory on how scratching is produced is that it is a combined sound of a scratch sound when the needle rubs along the surface of the vinyl and the speed of the sound the vinyl makes (forward as well as in reverse) when the DJ manually rotates the viny back and forth to scratch. That and some effects you can do using the crossfader, which I plan on controlling using the mouse wheel.

The physics behind it seem like common sense. Depending on the speed the vinyls rotating will depend on the speed of the sound, whether it is playing forwards, backwards, fast, or slow. When the DJ scratches, you can hear the music playing at the speed the vinyls manually being rotated back and forth, plus the sound of the scratch.

Is it possible to control the sound speed of MP3's and WAV's in real time using DirectSound and DirectShow? It seems very possible. And I'm supprised to not see any music programs have a feature like this.

If it is possible, sites that contain tutorials and source code on scratching or controlling the sound speed in real time would be a plus.

Is it possible at all?

Yes it is possible. All the Gatecrasher CDs are mixed like that. I was once in a Dj competition and I came on second because the winner had digitally mixed his mix tape. I ran away with the prize before they noticed it.


Well I can't remember the name of any of those apps, think one of them was called Dj Pro or something.

Well as you said the only thing is to pitch the track up as hell....I have seen diffrent apps do it. But I am pretty sure you can pitch up and down a track in DX (maybe not that much tho'), but I am not sure if you can get that reversed agin. At leat not with help from DX. I am not an expert on these things in DX. Sorry.

Here is an example:

http://www.softjam.co.uk/downloadsto...189&pubid=2869

This one looks even free...;)

http://www.analogx.com/contents/down...io/scratch.htm


well I am off. See you.

Thanks a lot NoteMe for the info. I just only hope that I can do it in my app. That would rock!

That free scratch program made one mistake. When you scratch in real life, you are moving the sound backwards as well as forwards. In the program, the only way it scratches is moving the speed of the sound backwards and forwards. I'll try to figure it out when I get my DJ program going.

[Edit] Nevermind on the mistake, I just had to click within the wav window.

Only have gone to a few RAVE here in Canada.
Only have been to maybe 1 bar in my city which has a live DJ mixin live...I do not have the top knowledge.

But what I've always figured is what you said.

If you want a more indepth look, grab a record player and some vinyl. Scratch forwards and backwards and see if you can figure out what is going on.

It is a combination of the sound just as the back-scratch began, the sound between the start and end of the scratch and in some case's as needed the sound of needle is also combined.

Using Dx it should be fairly simple.

If you wish to find such programs online, just search for Easy DJ.

In the program I plan on making, it's going to involve REAL scratching in real time. Also that Easy DJ program was a lousy example of what I was looking for. The records don't rotate at all. They are 2D, not 3D. And the scratches are as fake as a 3 dollar bill. Sound samples of scratches are totally not what I was looking for. But thanks for trying Halsafar.

hi, I'm also trying to create a dj scratching program
I got some theory from your program, but your program is not running
properly, I think it might be the "set position" that was used. maybe we can work on it together. I working on having my program
display a wave form just like the analog.com scratch program.
maybe using a good pointer to the memory might work, what do you think?
email me back at [email protected] or [email protected]

I think Jacob ended up making something like what he wanted. I remember downloading something similar and going "thats pretty cool".

It was 3D aswell.. probably his.

chem

I need help with my project writing a scratch program.