LSL6: Games may restore with muted music or broken volume fade-out

[RayKoopa]

• ScummVM 2.6.0git6340-g974c51b4cd1 (Jun 5 2022 09:42:22)
• Game language: English
• Game version: Hi-Res 1.000.000
• Windows 11 21H2 10.0.22000.675

Steps to reproduce (not 100% sure yet):

• Leave a room which causes a 5 second volume fade-out of the previous room's background music before starting the new room's music (for example, when entering the hotel interior from the pool).
• Save the game while the fade is in progress.
• Restore this game.
• Notice that there's a chance of the previous room's music now being stuck at the volume at the time of saving.

In DOSBox, the behavior is different: The fade-out of the previous room's music "restarts" at full volume and full 5 second duration, and then properly starts the current room's music.

I cannot reproduce this every time yet. It may be required to quickly move "one room further" before the fade-out ends (e.g. in the above example, to a 2nd hotel interior) and then quickly save the game. I attached a save game where this happened exactly like that.

Another possibly related issue is that LSL6HIRES sometimes starts or restores games with music turned "off" - even after returning to the game selection and starting the game anew.

[RayKoopa]

Note about moving one room further possibly needed

[RayKoopa]

Probably related: I noticed that sometimes the music completely mutes out when restoring a game. Using Music On / Off does not bring it back, and the music volume dial does nothing. I have to enter a room with other music to restore it.

[RayKoopa]

Add note about music being off when starting / restoring game

[sluicebox]

Fixing #7073 fixes this, at least the part I was able to reproduce: ​https://github.com/scummvm/scummvm/commit/6e5b1e31f0f9672cb979a7fa12d4bed35a4f6bf1

The problem occurs when a fade completes while you have the menu open and then you click Save.

One way to reproduce:

• Walk from the pool into the hotel
• Open the menu during the music fade and keep it open until the fade is finished (very low volume)
• Click the Save menu item and save the game
• New music will start at expected volume (it was waiting for the game to unpause)
• Load the save
• Previous room's music is at very low volume and stays that way

The fix was to include some missing sound data in the save files. Only new saves will be fixed. This changes the save game format (they have version numbers) so SCI saves created after this commit won't be usable by versions of ScummVM before the commit. Old saves can still be used by the newer version.

Please test this when you have a chance. Thanks!

[RayKoopa]

I can confirm the fix and I'm pretty sure my many saving attempts had the same "File Menu > Click Save" timing :)

[RayKoopa]

I just played a fresh game on 2.7.0git2368-g37379daf724 (Aug 27 2022 16:01:24), and restored a save in the locker room, and the music was super silent / "almost muted" again. The music wasn't fading at the time I saved - I fully let Larry undress. It's the save I attached on issue #13804.

Clicking "Music On/Off" in the options instantly enables it again, as if the game knows it is off.

EDIT: I just closed the window of a LoRes game session and started a HiRes game without completely exiting ScummVM - the music was muted from the start in the HiRes game session!.