Diagnosing issues with games.

[ChrisR]

I am a collector fairly new to Dreamcast, and I already own approximately 20% of the system's North American library. To protect my investment in my games I create backup copies (in the form of .GDIs using .BIN tracks) using an SD card adaptor.

What I want to do is to find a means to check and make sure that:

A. The game discs I am copying from are in as good a condition as I believe them to be and are free of read errors.

And

B. The backups I am creating are likewise without error.

The program I use to create my backup copies is able to detect some read errors, but not all. I want to be able to ensure each of my games is without error because even a small error can adversely affect gameplay.

For example one error I was able to detect in the past was an unreadable sector in the 18th track of Virtual On. The track was an audio track and the impact it had on the gameplay was merely that it cased the affected audio track to skip when played. Fortunately in this case the problem caused was only minor and I chose to resell the game (disclosing the issue to the buyer) in hopes of finding another copy of the game in better condition.

I suspect what I need is a way to calculate the CRC hash value of the .GDI image and compare it to an existing database of what the CRC values for each game should be. Alternatively if anyone has already made a tool for simply verifying the game disc is error free prior to copying this could also work, but I have not found such a tool.

If anyone can help me figure this out I would greatly appreciate it. Though be warned I am quite new to much of this so the instructions you give me may need to be quite explicit so I don't get confused by the process.

I just want to make sure I get to enjoy the collection I am amassing for a very long time. Preferably with the original disc intact and working properly on the actual console, but in the event something happens to them (be it scratches, breakage, fire, ect) I want to ensure I have a suitable archive of them to fall back on. And I want to know with certainty that everything is in perfect working order.

I also want to be able to check new games I buy to ensure they are working correctly with no issues so that I might be able to catch read errors in them immediately and be able to return them to the seller and protect myself against buying games with potentially serious defects.

[Aleron Ives]

Download the TOSEC database and compare the checksums of your dumps to the ones in the database to ensure that your dumps are accurate. You can compare CRC, MD5, and SHA-1 hashes for ultra paranoid assurance of data integrity.

[ChrisR]

I figured as much, but the thing is I have never checked a CRC hash value before so I know very little about what I am doing. I also am curious about how I would go about hash checking a .GDI image given that it consists of multiple files. Also given that there are different image formats such as .ISO as well as .GDIs that use .ISO or . BIN tracks I don't know if the hash would be different based upon which format the image is in.

I suppose what I really need is for someone to walk me through the process at least once so I know I am doing it right.

[Aleron Ives]

A GDI is not an image; it's a plain text file that lists all the files of your rip and describes the sector format of each file. The nullDC emulator uses these files to reconstruct a GD-ROM in memory so as to emulate original discs more easily, and it's become the standard for archiving retail discs, as well.

If you want to rip your discs in TOSEC format, burn httpd-ack to a CD-R, put it in your DC, and then use a web browser on your PC to visit the IP address that httpd-ack tells you that your BBA has. You can use your browser to download the contents of the GD-ROM by clicking on the link for each track on the disc. Once you're done, you can use something like RapidCRC or rhash to calculate the checksums of the files you ripped in order to determine whether they match the files in TOSEC. If they do, then your rip is good.

[ChrisR]

Unfortunately I don't have a BBA and they are a bit expensive for me. That is why I used the SD card adaptor with DC SD rip. Is there no equivalent method utilizing the SD card adaptor that I already have?

[Aleron Ives]

You can probably make usable rips with the SD card adapter, but I don't think your rips will match what httpd-ack generates, so you might not be able to verify them against TOSEC.

[ChrisR]

If I use my PC to create a PC-DC server would I be able to do it that way? No doubt it would be slow, but at least it won't cost me as much as the BBA.

[Aleron Ives]

I'm pretty sure httpd-ack only works with the BBA. You'd be better off using the SD card adapter than trying to dump games with the modem.