Since Resource::makeStream returns a MemoryReadStream which will
not attempt to free the resource memory, it is fine to always
dispose those streams and get rid of the separate resourceStream
property, which was a holdover from some past WIP resource design
which no longer exists.
The previous code for attenuating audio channels was not accurate,
so samples were quieter than they were supposed to be when mixed
together. Robots were also being mixed without attenuation, which
was incorrect.
1. Unlocking all resources of a type using a resource ID of -1 is
gone in SCI32;
2. Audio locks need to be serialized starting in GK2 for the game's
modified kDoAudio(1) call;
3. Audio locks in SCI3 must work more like SSCI, since at least
Lighthouse's `BackMusic::fade` method will attempt to unlock
audio that was never locked by a script. In SSCI (and now in
ScummVM too) this is a no-op; previously in ScummVM, it would
remove Audio32's own lock on the audio resource, resulting in a
use-after-free;
4. kDoAudio(1) starting in GK2 returns the number of active
*not-in-memory* channels being played, not the total number of
active channels.
Fixes Trac#9675.
SCI3 changes the way that monitored channel works. In SCI2/2.1,
when a channel is monitored, it is the only audible channel. In
SCI3, monitored channels mix normally.
This is very noticeable in LSL7, where music disappears totally
during speech if the monitored channel is the only channel played
back.
This patch includes enhancements to the ScummVM integration with
SCI engine, with particular focus on SCI32 support.
1. Fixes audio volumes syncing erroneously to ScummVM in games
that modify the audio volume without user action (e.g. SCI1.1
talkies that reduce music volume during speech playback). Now,
volumes will only be synchronised when the user interacts with
the game's audio settings. This mechanism works by looking for
a known volume control object in the stack, and only syncing
when the control object is present. (Ports and planes were
researched and found unreliable.)
2. Fixes audio syncing in SCI32 games that do not set game
volumes through kDoSoundMasterVolume/kDoAudioVolume, like GK1,
GK2, Phant1, and Torin.
3. Fixes speech/subtitles syncing in SCI32 games that do not use
global 90, like LSL6hires.
4. Fixes in-game volume controls in SCI32 games reflecting
outdated audio volumes when a change is made during the game
from the ScummVM launcher.
5. Fixes SCI32 games that would restore volumes from save games
or reset volumes on startup, which caused game volumes to be
out-of-sync with ScummVM when started.
6. ScummVM integration code for audio sync has been abstracted
into a new GuestAdditions class. This keeps the ScummVM-
specific code all in one place, with only small hooks into the
engine code. ScummVM integrated save/load code should probably
also go here in the future.
Fixes Trac#9700.
Using the one from SCI2.1mid makes fades very slow because SDL has
a larger audio buffer than SSCI DOS. This new algorithm is based on
wall time so will always fade at the correct speed, although the
larger buffers will have a coarser granularity so the fades may
not be as smooth as in the original engine. If anyone cares, the
fade volume could be mixed into individual samples in `readBuffer`
instead of applying just once per complete buffer. SSCI did not
do this, however, so this implementation should be pretty accurate.
This provides a complete implementation of kDoAudio through
SCI2.1mid, plus partial implementation of SCI3 features.
Digital audio calls shunted through kDoSound have also been
updated to go through the SCI32 audio mixer, though these shunts
are a bit hacky because the ScummVM implementation of kDoSound
does not currently match how SSCI kDoSound is designed.
It is probably possible in the future to just replace the SCI1.1
audio code (audio.cpp) with the new SCI32 code, since the major
differences seem to be that (1) SCI1.1 only supported one digital
audio playback channel (this is configurable already), (2) it
had extra commands for CD audio playback and queued sample
playback.
