Posted: 10/25/2018 9:44 PM
Post subject: PS1 core feature request: CHD support
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eddie82
Joined: 10/19/2018
Posts: 4
Hi, ive been thinking that it would be great if BizHawk added support for .CHD file format! It is currently the best compression method for PS1 discs, and probably for other CD based systems aswell. The resultant file is usually smaller than 7z or RAR compression, and it is a playable format. Since last year, the mednafen beetlepsx core has support for CHD (at leas in Retroarch). Thanks for any reply, BizHawk is my favourite emulator nowadays!!! You guys are doing a marvelous job, i wish that more people knew about it. Cheers from Brazil \o/ PS: Also, does it support .pbp file ? .pbp is not that efficient but it is also nice and a lot of people already have entire libraries in .pbp format.
Posted: 10/25/2018 10:45 PM
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hegyak
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Joined: 3/31/2010
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Isn't CHD what MAME and possibly MESS use? I have also never heard of PBP Format myself. I am not stating that I will or the team will take on this task, just wanted to confirm a question I had about it.
When TAS does Quake 1, SDA will declare war. The Prince doth arrive he doth please.
Posted: 10/26/2018 1:39 AM
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Spikestuff
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Yeah, I know both of them and you literally just explained 'em. They're both compression rather than raw. Personally. Rather not have to deal with having to compress a bin/cue in order to sync/encode a TAS if it's submitted in this format. .pbp is a format for PS1 games on PSP as a side note and some PS1 emulators accept it (like the dodgy ePSXe).
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Posted: 10/26/2018 1:50 AM
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Sonia
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Joined: 12/6/2013
Posts: 435
Location: Brazil
This page has some good information, if anyone needs: http://emulation.gametechwiki.com/index.php/Save_Disk_Space_for_ISOs#CHD_Compression
Posted: 10/26/2018 2:15 AM
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eddie82
Joined: 10/19/2018
Posts: 4
mmm yes, saving disk space is the pont here... my hard drive is not that big and unfortunately my favourite systems are the CD ones (PS1, Sega-CD, PCE-CD, Saturn, Amiga...) What is special about the CHD format is that instead of compressing all disc data in the same way, it identifies the audio tracks and compresses them with FLAC (lossless), thats why it achieves a smaller size even compared to 7z or RAR. This is a great feat imo! .pbp is usually used by people who like to bundle multi-disc games into a single pbp file. Other than this pbp compression is not that special (is +- like the old .CDZ format sizewise). By the way, i see there is a function related to multi-discs in BizHawk but i never took the time to learn it, idk what it does. I personally never used BizHawk to TAS, and i understand that this whole project is TAS oriented so... if the compression of CDs would mess up stuff, then i guess its a bad idea :-/ Anyway thanks for the replies :-)
Posted: 10/26/2018 7:58 PM
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creaothceann
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Spikestuff wrote:
Personally. Rather not have to deal with having to compress a bin/cue in order to sync/encode a TAS if it's submitted in this format.
Why would compression alter the emulation?
Posted: 10/27/2018 1:04 AM
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Spikestuff
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creaothceann wrote:
Why would compression alter the emulation?
See Dolphin. Compressed Wii to wbfs and Compressed GameCube links to desyncs from what I've screwed around with in the past.
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Posted: 10/27/2018 9:23 AM
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JosJuice
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Location: Sweden
You will get desyncs in Dolphin if you trim disc images (i.e. move files around on the disc), and I think there might be a desync risk from editing the partition table of Wii games (which many WBFS writers do by default), but just blanking out unused data or using lossless compression shouldn't affect sync. CHD is lossless, right?
Posted: 10/29/2018 6:29 AM
(Edited: 10/29/2018 6:55 AM)
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eddie82
Joined: 10/19/2018
Posts: 4
Yes it is lossless. It only misses the subchannel, but it can be added as an .sbi file in case the particular game needs it. Most people use .cue+.bin anyway (without the .sbi subchannel data) and any .sub file from a ccd+img+sub set can be converted to .sbi . The difference in size is huge and the gameplay as far as i know is unaltered, same quality (i heard a small delay to load, but thats all). I played a few CHD PSX games on MAME and Retroarch and didnt even notice the loading delay. The CDDA audio tracks from multi-track discs played correctly, everything worked fine (On Retroarch. mame psx emulation is still buggy, i believe no cdda audio support) As far as i know the Mednafen emulator does NOT support CHD. I read somewhere that last year someone paid for the Retroarch team to include CHD support for their BettlePSX core. Anyway, since CHD is such a nice format and since its addtion to BettlePSX core is kinda new (2017) i decided to stop by and tell you guys this, since it really saves a lot of space (the guy had a 800GB psx collection using 7z compression and it changed to 430GB+- after he converted everyting to CHD) and since i prefer using BizHawk for gaming :-P Its just a suggestion, EmuHawk is already awesome anyway. Keep up the good job! cheers :-)
Posted: 10/29/2018 6:41 AM
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Spikestuff
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eddie82 wrote:
Most people use .cue+.bin anyway (without the .sbi subchannel data)
Hawk requires the SBI files for the games that require it. Otherwise the game crashes. Recent submission example.
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Posted: 10/29/2018 6:57 AM
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eddie82
Joined: 10/19/2018
Posts: 4
Yes i know. Thats why i mentioned that you can run CHD + .SBI . WHat i meant is that the chd does not contain the .sbi, i didnt mean you could not run it along ;-) As long as the .chd and the .sbi have the same name, the emulator will run them together, normally as it would sbi+cue+bin. I never TASed and do not know how it works, but since a few consoles have 2 core options, maybe the PSX one could have a TAS core (default) and a CHD core (secondary)... in case it does really affect the TAS. I believe maybe it wont, but again i just know how to play ^.^