GetSpeeds and VB

bbriggstkd · **Joined:** Mon Sep 06, 2004 1:45 pm **Posts:** 118

Don't understand results from GetSpeeds. The function seems to work ok. I get a return code of 0. However when I look at the values. I get

CurrentRead = 1410
MaxRead = 1410
CurrentWrite = 4226
MaxRead = 4226

What units are these numbers in? Bytes per second or something? I don't think I should be able to write faster than I can read.

Here is my declare:

Declare Function StarBurn_CdvdBurnerGrabber_GetSpeeds _
Lib "c:\windows\system32\StarBurn.dll" (ByVal ObjGrabber As Long, _
ByRef ExceptionText As String, ByVal TextSize As Long, _
ByRef SystemError As Long, _
ByRef PCDB_Fail_Info As CDB_Failure_Type, _
ByRef CurrentRead As Long, ByRef MaxRead As Long, _
ByRef CurrentWrite As Long, ByRef MaxWrite As Long) As Long

VB doesn't have a ULONG, I'm using a long. That may be a problem but I don't know for sure.

alexey (staff) · **Joined:** Mon May 31, 2004 6:22 am **Posts:** 134

Hi,

Yes, it's in KB per second.
There are some constants:

Code:

//
// 1X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_1X                       176


//
// 2X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_2X                       353


//
// 2.2X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_2P2X                     387


//
// 3X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_3X                       528


//
// 4X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_4X                       706


//
// 8X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_8X                       1400


//
// 16X CD/DVD speed constant
//

#define CDVD_SPEED_IN_KBPS_16X                      2800


//
// Other CD/DVD speeds are just multiplier of 
// ( CDVD_SPEED_IN_KBPS_1X * N ) where N is drive speed
//

bbriggstkd · **Joined:** Mon Sep 06, 2004 1:45 pm **Posts:** 118

Using your constants, these numbers don't add up. That gives me a read speed of 8.011 and a write speed of 24.011. Is that correct. They aren't exact multipliers.

Why is the write speed faster than the read speed. Usually, the read speed is faster than the write, isn't it?

anton (staff) · **Posted:** Thu Sep 16, 2004 2:15 pm

This is b/s we're dealing with integers and there is no way to represent absolutely exact speeds. In any case when applied drive would pick up the one (speed) most close to passed.

No. Write speed can be larger then read speed. And some of the drives report read speed as cooked (in 150 KBps increments) and write speed as raw (in 176 KBps increments). This can also spoil life a bit.

bbriggstkd wrote:

Using your constants, these numbers don't add up. That gives me a read speed of 8.011 and a write speed of 24.011. Is that correct. They aren't exact multipliers.

Why is the write speed faster than the read speed. Usually, the read speed is faster than the write, isn't it?

bbriggstkd · **Joined:** Mon Sep 06, 2004 1:45 pm **Posts:** 118

Well, it sounds like my call is working then. I went to the support web site for my Sony laptop and noticed they even say the speeds as 8.1X on some of them.

Once Again, thank you for your help and your prompt response.

anton (staff) · **Posted:** Thu Sep 16, 2004 3:18 pm

Nice to know this issue is sorted out :-)

bbriggstkd wrote:

Well, it sounds like my call is working then. I went to the support web site for my Sony laptop and noticed they even say the speeds as 8.1X on some of them.

Once Again, thank you for your help and your prompt response.

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GetSpeeds and VB

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