PS1 Playback

Generally

ARK supports playback of custom-made PS1 games in EBOOT.PBP format stored in the /PSP/GAME/ folder.

The classic app used to convert PS1 games into PSP format was PSX2PSP, however the new pop-fe app is highly recommended, as it not only supports other platforms such as PS2 and PS3, but it also has improved compatibility with converted games thanks to the use of custom configuration files.

On PSP

Games can be launched via the XMB or the Custom Launcher without any further configuration.

You can make use of the PopsLoader plugin to extend compatibility with PS1 games. This plugin allows you to load older versions of the emulator on the newest firmware version.

On PS Vita

Games can be launched in three ways: Adrenaline, ARK-X or PEOPS.

• ARK-X applies the minimum amount of patches needed to load PS1 custom games to offer a more original experience.
• Adrenaline offsers a wide-range of mods that not only extend the functionality of the emulator, but it also makes the experience more closely similar to that of the original PSP.
• PEOPS is an Open Source PS1 SPU (Sound Processing Unit) plugin made to be portable to many different emulators. Efforts of the scene allowed the plugin to be used on the original PSP POPS emulator for use on the PS Vita. It is the only way to have sound playback on PS1 games without requiring native Vita modifications as it runs on regular PSP emulator (which can be hacked on Official Vita Firmware via PBOOT.PBP and ChovySign). This configuration is available on ARK-4 standalone (ePSP mode), though it is generally not recommended due to possible sound glitches and lower image quality, though it has a more stable and useful memory card manager than the official VitaPops.

As a final note, while ARK (and Adrenaline) offer the necessary CFW features for a PopsLoader to be possible on PS Vita, no actual Vita-compatible PopsLoader has been made and the one for PSP does not work as-is.

CDDA

CDDA stands for CD Direct Audio and it was one of the methods (along with the proprietary XA format) to encode sound in PS1 games. Games that use CDDA are usually separated into different tracks, with the first one being the main data track and the rest being CD audio tracks. Many regular CD players were capable of playing these audio tracks when a PS1 disc was inserted.

The PS1 emulator was originally coded to use CD audio tracks packaged into the eboot itself, however on later firmware revisions, Sony decided to replace those CDDA tracks with equivalent tracks encoded (and compressed) in AT3 format, which the PSP could also decode and play, this was done to drastically reduce the size of some PS1 games that used a lot of the disc space for CDDA.

Though Sony replaced CDDA with AT3, they didn't really remove the ability to play CDDA-encoded games, they just disabled it. A plugin known as cdda_enabler developed by thefl0w was released to re-enable CDDA functionality in the PS1 emulator, allowing games encoded with the older format to be playable with full working sound (whereas before they would produce no sound).

The patch to re-enable CDDA has been added into ARK's PopCorn module (the custom PS1 driver), meaning that it is not necessary to use the cdda_enabler plugin on either PSP or PS Vita. However, when using PopsLoader on PSP it is necessary to also use cdda_enabler when running certain POPS versions as ARK's PopCorn module will have been replaced by the one in PopsLoader.

Custom Config

The PS1 emulator for PSP/Vita (POPS) allows for custom configuration to be injected in the structure of the PBP, allowing per-game fixes. With ARK you can implement these custom patches in a single external file CONFIG.BIN, stored alongside the EBOOT.PBP without the need to be injected into it as the CFW will do that for you on-the-fly.

For more information on research into POPS configuration files: https://gbatemp.net/threads/pops-on-psp-vita-config-research.607286/

You can find a collection of custom configs here: https://github.com/sahlberg/pop-fe/tree/master/pspconfigs

Anti-LibCrypt patch

ARK contains a patch to defeat libcrypt protection for known games without requiring to rebuild the PBP. This patch is applied automatically on games detected to need it and does not require any configuration from the user.