PlayStation 4 BD-J (PS4 Blu-ray Java) Homebrew Answers by Mr_lou

A few years back we saw some PS4 BD-J Homebrew ports followed more recently by PS4 Webkit Emulators, a BDLive Bug and a PS4 JavaScript Emulator demonstration video with some answers to common questions recently by musician and coder Mr_lou.

To quote: Hello all. Just signed up here, and thought I'd introduce myself (in this thread because BD-J dev is the main reason I signed up, and I don't actually own any PlayStations).

Been working on a BD-J project for 5 years now. Info at www.8bitmemoirs.com

Got the HDCookBook for my birthday, and have studied BD-J a lot. Very little info online about it indeed. Some Japaneese sites are rather good, but requires Google Translate.

Is anyone here still interested in BD-J? I think I can answer a few questions from this thread (although it's old), so here goes:

From Lucif3r: Would make more sense if the PS4 supported such a thing from a USB stick or similar... Wasting a blueray disc for a java app? No ty... o.o

Yea, Sony blocked the possibility of booting a Blu-ray Disc from USB, as we all know. But I believe it's still possible to run BD-J stuff from a USB - if you boot from a disc.

So yea, you will still need to burn a disc - but you can settle for having this one disc for booting, and then run whatever Xlets you have on your USB.

I admit I haven't tried this myself yet (because I'm using a Dune HD Smart D1 for testing which lets me run my stuff from harddisk), but from what I've read in HDCookBook it should be possible, because:

• Xlets can start other Xlets
• The disc filesystem gets merged with the USB filesystem (for BD-Live).

So, you could (theoretically) "waste" this one boot disc, and then just use USB sticks for various homebrew. But yes, using a re-writable disc is also an option. It'll have a looong life due to the very small size of JAR files.

And of course, while developing, you can use a software player like PowerDVD from Cyberlink. (Other software media-players are also getting BD-J support these days, like VLC and Kodi).

From FreePlay: There's no audio. But I think we already knew that.

I don't think this is because you can't have audio with BD-J. I think it's more a question of the developers didn't bother to port the audio-system to a BD-J compatible one.

From what I've read, the whole Java Media Framework (JMF) should be available in BD-J. I admit I don't have any experience with JMF myself, but a quick look at the docs tells me that it supports playback of Linear PCM WAV, which as far as know, is a RAW format.

The dynamic audio generators usually uses raw format (I think), so it should "just" be a matter of finding a way to feed dynamically generated audio into JMF.

Not claiming this is possible. Just saying I think it can be done, somehow. I'm a musician, and a coder, but I have never experimented with dynamic audio generation yet. But this whole dynamic audio generation is only interesting for emulators.

When we're talking homebrew games, you can always add audio in the form of video-playback. This is what I'm doing in my own project. Plenty of audio there.

From FreePlay: Something else I forgot to mention that you might have noticed in the video: emulators run REALLY FAST on this. Like, around 400% speed. I don't know why.

Without having tried the NES emulator, my guess is that it was created for PS3 with a "dumb" timing setting, which is the easiest way of doing it. The PS4 obviously having a faster CPU will result in a faster execution.

I suppose you could say that the emulator should just have been coded slightly differently.

From incognita: May be you can't hack the PS4 but I think you can do a lot of interesting hombrews.

Absolutely I think so too. My project "8-bit Memoirs" has been a very interesting one so far. Learning a lot of what's possible.

I admit I'm not as much focused on the PS3 as such, but rather Blu-ray Players in genereal (which is why my project has been tested on A LOT of different players).

If you only target PS3, you'll have it easy. Because getting stuff to run on all players requires a lot of patience and work. Blu-ray Players are just as different and buggy as JavaME enabled cellphones.

I would like to add the following. Some people say that Blu-ray Disc Java (BD-J) obviously isn't as powerful as native coding on the PlayStation - and they're of course absolutely right.

You shouldn't expect to be able to code full-blown 3D shooters. BD-J was created for simple menu stuff for Blu-ray movies.

That being said, you shouldn't underestimate what you can do with BD-J either. Take a look at this BD-J demo for example:

Finally, from GregoryRasputin comes the following summary and related BD-J files:

Download: Blu Ray Java

Here are some facts:

• This is NOT a hack.
• This is NOT anything major and will not lead to anything major.
• This will NOT let you run PS4 “backups”.
• This will NOT give you any access to the PS4’s OS system files.
• This is NOT illegal.
• This does NOT void your warranty.
• This will NOT let you run PC games on your PS4.
• This will ONLY let you run Java software.
• This WILL give you Homebrew.
• This IS totally doable.

Cheers to @GregoryRasputin for the update and @raedoob for the heads-up in the PSXHAX Shoutbox!

 

[misthalu]

Regarding my idea of running BD-J homebrew off of USB by first booting from a bootdisc:

As part of BD-Live. BD-J Xlets can download files and put them onto the "Binding Unit Data Area (BUDA)", and subsequently merge these files with the file-system of the disc, thus be able to update the content of the disc. (Well not really, as you obviously can't write to a disc. But the content would get added to the Virtual File System, and thus accessible as if they were on the disc).

This is what I wanted to use. But rather than downloading files, you would manually put your BD-J homebrew onto the USB, and the bootdisc would then merge them.

Theoretically possible - but sadly useless on the PS3/PS4 - because unlike other blu-ray players PS3/PS4 don't use a USB storage device for BUDA, but rather stores everything internally - not easily accessible for the user.

I wanted to add this functionality on the ISO with Ukko's Journey, but I don't see the point now. Because in order to access the BUDA dir, you need a jailbroken console. And as far as I understand, there's a big chance that a jailbroken console allows you to play a blu-ray disc folder structure from harddisk anyway. If this is true, you might as well just copy the whole structure onto HD, and run your homebrew like that.

Currently waiting for Centrino and/or GritNGrind to get back to me with some test results. Everyone seems to agree that you can run disc-stuff off of harddisk. But I wanna see someone test if that also applies to blu-ray discs before believing it.

I think there's a chance it only applies to actual game-discs.

 

[Centrino]

I did some testing, but due to setting up my decr for linux, otheros takes the majority of hdd space and leaves only 20gb for gameos. It can also be vice versa (20gb otheros and remaining for gameos) something i may do with more free time.

I could have ripped all of the disc, but its near 40gb.

I navigated into bdmv and copied the jar folder to where it should have gone on the hdd. Its not setup to just run jar files unfortunately, im fairly sure it will need a disc booted (or the whole disc dumped) so the system uses the files correctly. Maybe these files can be edited to include more jar/xlets or even replace with our own?

Either way, im saying its a partial sucess...i couldnt actually start the disc, it almost did but threw an error ( could be down to decr cfw or certain settings i have turned on for other non related tests)

The thing with decrs is they never were able to play bd films, only due to the recent cfw it supposedly can, maybe bd films worked on other decr fw but I havent seen nor heard of this

 

[GritNGrind]

You can include more jar/xlets. I've actually just got a small game up and running myself. As far the virtual file system, you have 1gb of storage you can use is what i've read. I do not have sound and this is what seems to have killed it back in the PS3 days because things suck without sound.

You said u were able to get sound now?

 

[misthalu]

I navigated into bdmv and copied the jar folder to where it should have gone on the hdd. Its not setup to just run jar files unfortunately, im fairly sure it will need a disc booted (or the whole disc dumped) so the system uses the files correctly

No it's not setup to just run whatever JAR file is in the BDMV/JAR folder. There's a bit more to it.

To get things running you must copy the whole disc folder structure.
You can test with the "Funky Fresh" demo:
http://www.pouet.net/prod.php?which=59098
Or the "Metal Skin Slidetro" one:
http://www.pouet.net/prod.php?which=60784

The downloads are ISO files. Extract these to folders and copy to the harddisk of the PS3. If either of those then runs, then it's party time!

You can include more jar/xlets. I've actually just got a small game up and running myself. As far the virtual file system, you have 1gb of storage you can use is what i've read. I do not have sound and this is what seems to have killed it back in the PS3 days because things suck without sound.

This game of yours, can you run it from the harddisk of your Playstation, or are you running from disc? If running from disc, can you copy the folder structure to harddisk and run from there?

It is true that the 1 gb of VFS storage could be used to add more Xlets to a disc later yes, but we probably won't be doing it that way. I'm thinking, if blu-ray disc folder structures can run off of harddisk, then users with a jailbroken Playstation will simply copy folder structures to their harddisks.

Users with non-jailbroken Playstations will need a disc, which is fine. In my opinion, only developers "need" to be able to test from harddisk (to avoid needing to burn a disc for each test).

You said u were able to get sound now?

It has always been possible to have sound. Look at the "Funky Fresh" and "Metal Skin Slidetro" demos. For my BD-J port of "Ukko's Journey" I have both music + sound-effects.

The thing about BD-J (and many other platforms) is that you gotta do it a certain way. You can't just play an mp3 file for example. You gotta encode the audio using a supported codec etc. It's no problem once you know which codec to use and such.

 

[Centrino]

K, ill test the isos if i have time tonight. Ill probably revert the hdd partitions too as it drives me mad only having the 2 options stated above.

Ill also make sure all cfw settings are default and go from there

 

[GritNGrind]

I've saved a file to local, and now found the path it saves in as well. I'll try to modify the code to see if execution is possible once there. Also, see below...good tool.

https://github.com/oliverlietz/bd-j/tree/master/DiscCreationTools/net.java.bd.tools.bdjo

 

[Centrino]

Common/ by any chance?

Funky fresh iso works on hdd on my decr

 

[GritNGrind]

Common/ by any chance?

Funky fresh iso works on hdd on my decr

No, doesn't dump to common directory. I'm going to see if I can control where it goes, but I may not have time until this weekend to test that.

 

[GritNGrind]

both ISO's also work on PS4 when burned to a disk

 

[misthalu]

both ISO's also work on PS4 when burned to a disk

That's great, but I didn't doubt that.

What would be more interesting to test, is running the ISO on a CFW via multiMAN.
Centrino has tested the Funky Frensh ISO on his DECR and reports that it works fine.
SockNastez has tested the same ISO on his non-DECR but can't get it running.

It would be nice with more tests to confirm whether an ISO runs from harddisk or not.
Here's she short guide on how to test, written by Centrino, edited by me:

1. Copy BD-J ISO file to USB stick
2. Open multiMAN and use multiMAN File Browser
3. Navigate to the BDISO folder on the harddisk
4. Copy your ISO file into the BDISO folder
5. Double-click the ISO file to mount it
6. System will boot back to the XMB, and the disc should now appear in the video column

Being able to run BD-J ISO's from harddisk will obviously make development more interesting.