janwas
8792731c5c
timer: greatly speed up TIMER_ACCRUE by having it gather raw ticks and only converting those to wall-clock time at exit when displaying the values. old codepath remains and can be restored via TIMER_USE_RAW_TICKS This was SVN commit r3241.
270 lines
11 KiB
C
Executable File
270 lines
11 KiB
C
Executable File
// OpenAL sound engine
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//
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// Copyright (c) 2004-5 Jan Wassenberg
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// Contact info:
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// Jan.Wassenberg@stud.uni-karlsruhe.de
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// http://www.stud.uni-karlsruhe.de/~urkt/
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#ifndef SND_H__
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#define SND_H__
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#include "../handle.h"
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/*
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[KEEP IN SYNC WITH WIKI]
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overview
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--------
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this module provides a moderately high-level sound interface. basic usage
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is opening a sound and requesting it be played; it is closed automatically
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when playback has finished (fire and forget).
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any number of sound play requests may be issued; the most 'important' ones
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are actually played (necessary due to limited hardware mixing capacity).
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3d positional sounds (heard to emanate from a given spot) are supported.
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active sound instances are referenced by Handles, so changing volume etc.
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during playback is possible (useful for fadeout).
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sound setup
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-----------
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OpenAL provides portable access to the underlying sound hardware, and
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falls back to software mixing if no acceleration is provided.
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we allow the user to specify the device to use (in case the default
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has problems) and maximum number of sources (to reduce mixing cost).
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performance
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-----------
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much effort has been invested in efficiency: all sound data is cached,
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so every open() after the first is effectively free. large sound files are
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streamed from disk to reduce load time and memory usage. hardware mixing
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resources are suballocated to avoid delays when starting to play.
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therefore, the user can confidently fire off hundreds of sound requests.
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finally, lengthy initialization steps are delayed until the sound engine
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is actually needed (i.e. upon first open()). perceived startup time is
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therefore reduced - the user sees e.g. our main menu earlier.
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terminology
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-----------
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"hardware voice" refers to mixing resources on the DSP. strictly
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speaking, we mean 'OpenAL source', but this term is more clear.
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voice ~= source, unless expensive effects (e.g. EAX) are enabled.
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note: software mixing usually doesn't have a fixed 'source' cap.
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"gain" is quantified volume. 1 is unattenuated, 0.5 corresponds to -6 dB,
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and 0 is silence. this can be set per-source as well as globally.
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"position" of a sound is within the app's coordinate system,
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the orientation of which is passed to snd_update.
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"importance" of a sound derives from the app-assigned priority
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(e.g. voiceover must not be skipped in favor of seagulls) and
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distance from the listener. it's calculated by our prioritizer.
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"virtual source" denotes a sound play request issued by the app.
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this is in contrast to an actual AL source, which will be mixed
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into the output channel. the most important VSrc receive an al_src.
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"sound instances" store playback parameters (e.g. position), and
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reference the (centrally cached) "sound data" that will be played.
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*/
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//
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// device enumeration
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//
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// prepare to enumerate all device names (this resets the list returned by
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// snd_dev_next). return 0 on success, otherwise -1 (only if the requisite
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// OpenAL extension isn't available). on failure, a "cannot enum device"
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// message should be presented to the user, and snd_dev_set need not be
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// called; OpenAL will use its default device.
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// may be called each time the device list is needed.
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extern LibError snd_dev_prepare_enum();
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// return the next device name, or 0 if all have been returned.
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// do not call unless snd_dev_prepare_enum succeeded!
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// not thread-safe! (static data from snd_dev_prepare_enum is used)
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extern const char* snd_dev_next();
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//
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// sound system setup
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//
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// tell OpenAL to use the specified device in future.
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// name = 0 reverts to OpenAL's default choice, which will also
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// be used if this routine is never called.
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//
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// the device name is typically taken from a config file at init-time;
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// the snd_dev* enumeration routines below are used to present a list
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// of choices to the user in the options screen.
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//
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// if OpenAL hasn't yet been initialized (i.e. no sounds have been opened),
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// this just stores the device name for use when init does occur.
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// note: we can't check now if it's invalid (if so, init will fail).
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// otherwise, we shut OpenAL down (thereby stopping all sounds) and
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// re-initialize with the new device. that's fairly time-consuming,
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// so preferably call this routine before sounds are loaded.
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//
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// return 0 on success, or the status returned by OpenAL re-init.
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extern LibError snd_dev_set(const char* alc_new_dev_name);
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// set maximum number of voices to play simultaneously,
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// to reduce mixing cost on low-end systems.
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// return 0 on success, or 1 if limit was ignored
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// (e.g. if higher than an implementation-defined limit anyway).
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extern LibError snd_set_max_voices(uint cap);
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// set amplitude modifier, which is effectively applied to all sounds.
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// must be non-negative; 1 -> unattenuated, 0.5 -> -6 dB, 0 -> silence.
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extern LibError snd_set_master_gain(float gain);
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//
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// sound instance
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//
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// open and return a handle to a sound instance.
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//
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// if <snd_fn> is a text file (extension ".txt"), it is assumed
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// to be a definition file containing the sound file name and
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// its gain (0.0 .. 1.0).
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// otherwise, <snd_fn> is taken to be the sound file name and
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// gain is set to the default of 1.0 (no attenuation).
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//
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// is_stream (default false) forces the sound to be opened as a stream:
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// opening is faster, it won't be kept in memory, but only one instance
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// can be open at a time.
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extern Handle snd_open(const char* snd_fn, bool stream = false);
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// close the sound <hs> and set hs to 0. if it was playing,
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// it will be stopped. sounds are closed automatically when done
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// playing; this is provided for completeness only.
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extern LibError snd_free(Handle& hs);
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// request the sound <hs> be played. once done playing, the sound is
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// automatically closed (allows fire-and-forget play code).
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// if no hardware voice is available, this sound may not be played at all,
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// or in the case of looped sounds, start later.
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// priority (min 0 .. max 1, default 0) indicates which sounds are
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// considered more important; this is attenuated by distance to the
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// listener (see snd_update).
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extern LibError snd_play(Handle hs, float priority = 0.0f);
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// change 3d position of the sound source.
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// if relative (default false), (x,y,z) is treated as relative to the
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// listener; otherwise, it is the position in world coordinates.
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//
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// may be called at any time; fails with invalid handle return if
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// the sound has already been closed (e.g. it never played).
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extern LibError snd_set_pos(Handle hs, float x, float y, float z, bool relative = false);
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// change gain (amplitude modifier) of the sound source.
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// must be non-negative; 1 -> unattenuated, 0.5 -> -6 dB, 0 -> silence.
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//
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// should not be called during a fade (see note in implementation);
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// fails with invalid handle return if the sound has already been
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// closed (e.g. it never played).
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extern LibError snd_set_gain(Handle hs, float gain);
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// change pitch shift of the sound source.
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// 1.0 means no change; each reduction by 50% equals a pitch shift of
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// -12 semitones (one octave). zero is invalid.
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//
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// may be called at any time; fails with invalid handle return if
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// the sound has already been closed (e.g. it never played).
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extern LibError snd_set_pitch(Handle hs, float pitch);
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// enable/disable looping on the sound source.
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// used to implement variable-length sounds (e.g. while building).
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//
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// may be called at any time; fails with invalid handle return if
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// the sound has already been closed (e.g. it never played).
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//
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// notes:
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// - looping sounds are not discarded if they cannot be played for lack of
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// a hardware voice at the moment play was requested.
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// - once looping is again disabled and the sound has reached its end,
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// the sound instance is freed automatically (as if never looped).
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extern LibError snd_set_loop(Handle hs, bool loop);
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enum FadeType
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{
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FT_NONE,
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FT_LINEAR,
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FT_EXPONENTIAL,
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FT_S_CURVE,
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FT_ABORT
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};
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// fade the sound source in or out over time.
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// its gain starts at <initial_gain> (immediately) and is moved toward
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// <final_gain> over <length> seconds. <type> determines the fade curve:
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// linear, exponential or S-curve. for guidance on which to use, see
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// http://www.transom.org/tools/editing_mixing/200309.stupidfadetricks.html
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// you can also pass FT_ABORT to stop fading (if in progress) and
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// set gain to the current <final_gain> parameter.
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// special cases:
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// - if <initial_gain> < 0 (an otherwise illegal value), the sound's
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// current gain is used as the start value (useful for fading out).
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// - if <final_gain> is 0, the sound is freed when the fade completes or
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// is aborted, thus allowing fire-and-forget fadeouts. no cases are
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// foreseen where this is undesirable, and it is easier to implement
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// than an extra set-free-after-fade-flag function.
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//
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// may be called at any time; fails with invalid handle return if
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// the sound has already been closed (e.g. it never played).
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//
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// note that this function doesn't busy-wait until the fade is complete;
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// any number of fades may be active at a time (allows cross-fading).
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// each snd_update calculates a new gain value for all pending fades.
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// it is safe to start another fade on the same sound source while
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// one is already in progress; the old one will be discarded.
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extern LibError snd_fade(Handle hvs, float initial_gain, float final_gain,
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float length, FadeType type);
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//
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// sound engine
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//
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// (temporarily) disable all sound output. because it causes future snd_open
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// calls to immediately abort before they demand-initialize OpenAL,
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// startup is sped up considerably (500..1000ms). therefore, this must be
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// called before the first snd_open to have any effect; otherwise, the
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// cat will already be out of the bag and we debug_warn of it.
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//
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// rationale: this is a quick'n dirty way of speeding up startup during
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// development without having to change the game's sound code.
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//
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// can later be called to reactivate sound; all settings ever changed
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// will be applied and subsequent sound load / play requests will work.
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extern LibError snd_disable(bool disabled);
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// perform housekeeping (e.g. streaming); call once a frame.
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//
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// additionally, if any parameter is non-NULL, we set the listener
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// position, look direction, and up vector (in world coordinates).
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extern LibError snd_update(const float* pos, const float* dir, const float* up);
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// free all resources and shut down the sound system.
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// call before h_mgr_shutdown.
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extern void snd_shutdown();
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#endif // #ifndef SND_H__
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