EMULAB Forum
clrmamepro [English] => clrmame Discussion => Topic started by: binarybin on 21 January 2022, 20:08
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Would it be possible to get some kind of support for RVZ Compression? Something like the CHDMan. Dolphin comes with a CLI Tool called DolphinTools that can verify a file. This would be for GC and Wii dats, which have crc32 on the .iso formats of the files. The tool calculates the internal data of the .rvz which will match the original data crc.
dolphintool.exe verify -i "SomeGame.rvz" -a crc32
From what i can see it could almost look like your CHDMan setup under Compressor.
Executable: dolphintool.exe
Verify: verify -i %1 -a crc32
It can also do md5 and sha1, but i think crc32 would be enough.
This outputs a CRC32 Value of the internal compressed data. Which matches the official released dat of the .iso's
Having RVZ Support in a tool for verification would be awesome. Hoping for consideration :)
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Sorry but this is currently not planned. Would be interesting to see why RVZ was considered over CHD....since both seem to use LZHA and both are just a compressed container. Why reinventing the wheel?
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While I in general agree that any new format introduced needs to be carefully weighed against the upheaval it causes, it appears the RVZ format has gained much traction and continues to grow. I'm no programmer, but I do understand you have to balance the time cost/benefit of adding something like this. In this case, if it's not too in-depth beyond adding the compression profile, I think it would be invaluable. Here's a quote I found from someone scratching the surface of the problems with CHD:
"MAME is sometimes so disappointing, they create the only cd image format that has delta encoding, then they do absolutely nothing to make it easy to use with the current state of the world (which for romhacks in particular is xdelta patches on the binary track). They're even considering 'reworking' chd to a 'more accurate' format - to be clear, this probably would require redumps of absolutely everything, and i can think of no finer way to kill the format."
..and finally, a hearty thanks for the years of effort on this software. It is greatly appreciated!
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Here's a link to a new open source CLI tool that may be of interest. It simply verifies an RVZ file(s) against a redump dat. It's limited in its scope and a poor substitute for integration in clrmamepro, but for now it appears one of the only options.
https://github.com/j68k/verifydump (https://github.com/j68k/verifydump)
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...and just to make my case/belabor the point a bit further, I grabbed a GC ROM ("18 Wheeler - American Pro Trucker (USA)") to run a quick informal test. All settings were default, except for the zip which I set to Ultra for the hell of it. All in KB.
| Original: | 1,425,760 |
| RAR: | 1,284,808 |
| chdman: | 1,308,705 |
| ZIP: | 1,303,626 |
| RVZ: | 159,917 |
Not bad for a lossless format! Clearly results on other games will vary, but overall I think it's close to a 40% compression ratio.