vcd, .dat files and isofs problem

vcd, .dat files and isofs problem

[David Chow]

I have problems reading the .dat files from VCD, here is the kernel 
logs. I think it is an fs issue, since I am not the only one having the 
same problem. In user space, read returns I/O error but I think it is an 
fs issue or a cd-rom
driver issue, I have tested with xine vcd player, the vcd can be played 
by directly accessing the block device but not through the fs. I tested 
the VCD under MS Windows using the same machine and disc and .dat files 
can be correctly read, even  I use vcdgear win32 to convert the .dat 
file to .mpg it is still fine. So it is sure it is not the CD or 
hardware problem.

Many VCD's are tested and result is the same. It is likely to be an fs 
specific problem. I am running 2.4.17 and lsmod shows isofs is in use. 
Here is my log messages.

kernel: hdd: command error: error=0x55
kernel: end_request: I/O error, dev 16:40 (hdd), sector 32300
kernel: hdd: command error: status=0x51 { DriveReady SeekComplete Error }
kernel: hdd: command error: error=0x55
kernel: end_request: I/O error, dev 16:40 (hdd), sector 32304
kernel: hdd: command error: status=0x51 { DriveReady SeekComplete Error }
kernel: hdd: command error: error=0x55
kernel: end_request: I/O error, dev 16:40 (hdd), sector 32308
kernel: hdd: command error: status=0x51 { DriveReady SeekComplete Error }
kernel: hdd: command error: error=0x55
kernel: end_request: I/O error, dev 16:40 (hdd), sector 32312
kernel: hdd: command error: status=0x51 { DriveReady SeekComplete Error }
kernel: hdd: command error: error=0x55
kernel: end_request: I/O error, dev 16:40 (hdd), sector 32316
kernel: hdd: command error: status=0x51 { DriveReady SeekComplete Error }

regards,

David

Re: vcd, .dat files and isofs problem

[Alan Cox]

> I have problems reading the .dat files from VCD, here is the kernel 
> logs. I think it is an fs issue, since I am not the only one having the 
> same problem. In user space, read returns I/O error but I think it is an 
> fs issue or a cd-rom

VCD .dat files are not normal "files". They are encoded in a different mode
to get more bytes/sector at the cost of lower error resistance (mpeg is
error resistant in itself...)

Alan

Re: vcd, .dat files and isofs problem

[Will Dyson]

Alan Cox wrote:
>>I have problems reading the .dat files from VCD, here is the kernel 
>>logs. I think it is an fs issue, since I am not the only one having the 
>>same problem. In user space, read returns I/O error but I think it is an 
>>fs issue or a cd-rom

Have a look at cdfs: http://www.elis.rug.ac.be/~ronsse/cdfs/

It will allow you to read those files. Of course, there are also userland 
  utilities for that. Just search freshmeat for vcd.

> VCD .dat files are not normal "files". They are encoded in a different mode
> to get more bytes/sector at the cost of lower error resistance (mpeg is
> error resistant in itself...)

I knew they were different, but not why. Learn something new every day.

-- 
Will Dyson