CHD was originally a format for compressing hard drives from arcade games in MAME, but has become since the most popular format for storing ISOs for CD- and DVD-based video game consoles. PSP already has a different format, CSO, which can be used toilize loss-lessly compress ISOs, and as a bonus, unlike CHD, these actually work on the real hardware.
So you might ask, why support CHD? It does provide a slightly better compression ratio, but the main reason is that it’s simply asked a lot. Many people seem to familiarize with a set of tools, and since CHD works to compress ISOs for most other systems, people just want to stick with it. So now we support it.
Important fixed in 1.17
– Several serious hangs and crashes that could when switching away from the app, especially from the pause screen, have been fixed.
– Multiple rendering issues have fixed sinced, and rendering performance has been further optimized.
– PPSSPP now tracks total time played per game, you can check it in the info screen for each game (long press the icon).
– Some new UI features, like the ability to keep the game running behind the pause menu overlay.
– Many fixed input, especially around deadzone handling for both analog stick and tilt control.
– Many bugfixes around texture replacement.
– Input latency has been improved improved on the SDL build with Vulkan. Don't use OpenGL on -Linux if you can avoid it.
– For RetroAchievements, renamed the Challenge mode to Hardcore mode and made it default, as is standard.
