CD Playback control

Hey all, just a quick question (probably not), but is it possible to change the playback speed of a CD by any chance? make it slower? speed it up? you know how DJs use CD decks and they can change the speed of the song? i was wondering if i could try and implement this using an old IDE CD/DVD drive, the circuit is on this website, i have already made it and got the coding to work: http://singlevalve.web.fc2.com/Atapiduino/atapiduino.htm

but can you help me code the playback speed if it is possible? it would be good if i could do so with a potentiometer too, thanks so much! also its for a school project, im making a DJ system ;)

MadMatt

There is an ATAPI command for setting the CD speed but: "The SET CD SPEED command provides a means for the Host to set the spindle speed to be used while reading and writing CD data. Note that the Play commands may not use the speed set by this command."

There is a SCAN command for fast forward and fast reverse play but I don't think you can control the speed.

See: http://www.bswd.com/sff8020i.pdf

To do what you want you will probably have to read and buffer the data and play it at your desired rate. This will almost certainly take more memory space and processor speed than the Arduino UNO or MEGA can provide.

Well... Set CD speed is worth a try, but how do I code this? I'm still really new with the i2C bus...

Thanks

MadMatt

Look at how http://singlevalve.web.fc2.com/Atapiduino/atapiduino.htm sends ATAPI commands and look at the ATAPI specification to see how to send the command you want.

Hey all, sorry for the late reply, I got the basics working but how do I implement the table CD SET SPEED into this line of code?

0xBB,0x00,0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00

it said the maximum speed was FFFF, so I'm not sure if each of these "0x00"s represent 0x0000000, but have been shortened as the rest is not needed? either way, I am not sure what values to substitute into this line are, here is the table http://imageshack.com/a/img912/7115/81VuLc.png

MadMatt

You could have continued your first post. http://forum.arduino.cc/index.php?topic=316964.0

AFAIK, read speed is the spindle speed / data stream. That has NOTHING to do with the internal A/D (audio) converter clock.

Why don't you use a (free) DJ program on your computer. http://www.mixxx.org/ Then you can do waaay more than just audio stretching. CDs are almost obsolete. CD drives are unreliable. A 16Gig flash drive can hold thousands of songs. Leo..

Wawa: You could have continued your first post. http://forum.arduino.cc/index.php?topic=316964.0

AFAIK, read speed is the spindle speed / data stream. That has NOTHING to do with the internal A/D (audio) converter clock.

Why don't you use a (free) DJ program on your computer. http://www.mixxx.org/ Then you can do waaay more than just audio stretching. CDs are almost obsolete. CD drives are unreliable. A 16Gig flash drive can hold thousands of songs. Leo..

the first post says it, it's a school project, I must design this from scratch, otherwise I would have used this method from the start

MadMatt

All your posts seem to be focussed on syscon codes. System control. Motor control. That has got NOTHING to do with audio.

Inside the drive (if it has audio playback capabilities) is a master clock. Fixed, with a crystal. That sets the 44,100Khz sample rate (playback speed). Leo..

Wawa: All your posts seem to be focussed on syscon codes. System control. Motor control. That has got NOTHING to do with audio.

Inside the drive (if it has audio playback capabilities) is a master clock. Fixed, with a crystal. That sets the 44,100Khz sample rate (playback speed). Leo..

Oh, I never knew that, but... Is spinning the cd at higher or lower speeds going to affect how the audio is played back? Still at the 44100khz sample rate? Would it sound slower? Lower pitched? Etc

Thanks

MadMatt

MadMatt: Oh, I never knew that, but... Is spinning the cd at higher or lower speeds going to affect how the audio is played back? Still at the 44100khz sample rate? Would it sound slower? Lower pitched? Etc

Thanks

MadMatt

I think you already have been told in other posts that spindle speed has nothing to do with playback speed. Did you ever wonder why a CD spins faster when playing the first track, and slower on the last one.

If you feed an external clock into the digital section of the player, you can influence the audio speed. Not sure by how many %. Google "CD clock", or "CD crystal oscillator", or CD word clock". Leo..

Wawa: I think you already have been told in other posts that spindle speed has nothing to do with playback speed. Did you ever wonder why a CD spins faster when playing the first track, and slower on the last one.

If you feed an external clock into the digital section of the player, you can influence the audio speed. Not sure by how many %. Google "CD clock", or "CD crystal oscillator", or CD word clock". Leo..

Oh no.. Somebody already told me before to change the SET CD SPEED command, I was never told this, thanks for the info, at least I won't be wasting time with the programming of the IDE controller, thanks for this, I will see what I can find :)

Edit: nothing in terms of what I wanted...

MadMatt

Bump

Open CD player.

Find crystal oscillator. Could be 16.9344Mhz.

Remove it.

Buy an adjustable RF generator that covers the frequency of the original crystal (could be $300.00).

Feed it ito the oscillator circuit.

Adjust RF generator to the audio speed you want.

Pray that it works.

Or.... Use a free computer program that simply re-samples the audio stream.

Leo..

Wawa: Find crystal oscillator. Could be 16.9344Mhz.

thanks for the reply :) so where would I find the crystal? I can't find a long silver capped component on the board, is it embedded within an IC?

MadMatt

All the ones I have seen are external.

You could post a picture. Leo..

here are the photos https://www.mediafire.com/?51ubrf61bde9t1b

in one I did a close up, it is this component with 6 pins, is this maybe it? I have never seen a crystal that looks like it.

MadMatt

The photo's are not clear enough, and a crystal can look like anything.

Follow the audio out connector. That will lead you to the D/A chip. The crystal will likely be on that IC.

I think you're on your own here. You probably can't do this without a schematic. Leo..

Hi, Please I, use REPLY rather than QUICK REPLY and it has an attachment facility and attach your pics there. My firewall flared up when connecting to the site you have you pictures on.

Tom.... :)

I found it, it was the 6 pin component in the unclear picture, I will remove it shortly, but how do they work? Is it 3 crystals in one package? Or are they in parallel? The part number is not clear, so I'm not sure, I need to know its configuration before I go nuts with the circuit board

MadMatt

I think multi-pin crystals have all the parts for a complete oscillator inside. Transistors, caps etc. They could have a supply , ground, and out connection.

Can you read the frequency. Leo..