module SDL2::Mix
Interface for “SDL_mixer.h”
Constants
- CHANNELS
The default mixer has 8 simultaneous mixing channels
- CHANNEL_POST
Special Effects API by ryan c. gordon.….
- DEFAULT_CHANNELS
- DEFAULT_FORMAT
- DEFAULT_FREQUENCY
Good default values for a PC soundcard
- EFFECTSMAXSPEED
- LibPaths
- MAX_VOLUME
Public Class Methods
Load a wave file or a music (.mod .s3m .it .xm) file
# File lib/sdl2/mixer.rb, line 151 def self.load_wav(filename) Mixer::load_wav_rw(RWops.from_file(filename, "rb"), 1) end
Play an audio chunk on a specific channel. If the specified channel is -1, play on the first free channel. If ‘loops’ is greater than zero, loop the sound that many times. If ‘loops’ is -1, loop inifinitely (~65000 times). Returns which channel was used to play the sound.
# File lib/sdl2/mixer.rb, line 536 def self.play_channel(channel,chunk,loops=-1) Mixer::play_channel_timed(channel,chunk,loops,-1) end
Public Instance Methods
Dynamically change the number of channels managed by the mixer. If decreasing the number of channels, the upper channels are stopped. This function returns the new number of allocated channels.
# File lib/sdl2/mixer.rb, line 134 api :Mix_AllocateChannels, [:int], :int
Add your own callback when a channel has finished playing. NULL to disable callback. The callback may be called from the mixer’s audio callback or it could be called as a result of Mix_HaltChannel
(), etc. do not call SDL_LockAudio() from this callback; you will either be inside the audio callback, or SDL_mixer will explicitly lock the audio before calling your callback.
# File lib/sdl2/mixer.rb, line 257 api :Mix_ChannelFinished, [:pointer, :int], :void
Close the mixer, halting all playing audio
# File lib/sdl2/mixer.rb, line 646 api :Mix_CloseAudio, [], :void
Change the expiration delay for a particular channel. The sample will stop playing after the ‘ticks’ milliseconds have elapsed, or remove the expiration if ‘ticks’ is -1
# File lib/sdl2/mixer.rb, line 577 api :Mix_ExpireChannel, [:int, :int], :int
# File lib/sdl2/mixer.rb, line 556 api :Mix_FadeInChannelTimed, [:int, Chunk.by_ref, :int, :int], :int
Fade in music or a channel over “ms” milliseconds, same semantics as the “Play” functions
# File lib/sdl2/mixer.rb, line 550 api :Mix_FadeInMusic, [Music.by_ref, :int, :int], :int
# File lib/sdl2/mixer.rb, line 553 api :Mix_FadeInMusicPos, [Music.by_ref, :int, :int, :double], :int
Halt a channel, fading it out progressively till it’s silent The ms parameter indicates the number of milliseconds the fading will take.
# File lib/sdl2/mixer.rb, line 583 api :Mix_FadeOutChannel, [:int, :int], :int
Query the fading status of a channel
# File lib/sdl2/mixer.rb, line 589 api :Mix_FadingMusic, [], :fading
Free an audio chunk previously loaded
# File lib/sdl2/mixer.rb, line 182 api :Mix_FreeChunk, [Chunk.by_ref], :void
Free music previously loaded
# File lib/sdl2/mixer.rb, line 186 api :Mix_FreeMusic, [Music.by_ref], :void
Get the Chunk
currently associated with a mixer channel
# File lib/sdl2/mixer.rb, line 642 api :Mix_GetChunk, [:int], Chunk.by_ref
Get a pointer to the user data for the current music hook
# File lib/sdl2/mixer.rb, line 248 api :Mix_GetMusicHookData, [], :pointer
Find out the music format of a mixer music, or the currently playing music, if ‘music’ is NULL.
# File lib/sdl2/mixer.rb, line 216 api :Mix_GetMusicType, [Music.by_ref], :music_type
Get a list of chunk/music decoders that this build of SDL_mixer provides. This list can change between builds AND runs of the program, if external libraries that add functionality become available. You must successfully call Mix_OpenAudio
() before calling these functions. This API is only available in SDL_mixer 1.2.9 and later.
// usage… int i; const int total = Mix_GetNumChunkDecoders
(); for (i = 0; i < total; i++)
printf("Supported chunk decoder: [%s]\n", Mix_GetChunkDecoder(i));
Appearing in this list doesn’t promise your specific audio file will decode…but it’s handy to know if you have, say, a functioning Timidity install.
These return values are static, read-only data; do not modify or free it. The pointers remain valid until you call Mix_CloseAudio
().
# File lib/sdl2/mixer.rb, line 208 api :Mix_GetNumChunkDecoders, [], :int
Finds the first available channel in a group of channels, @returns -1 if none are available.
# File lib/sdl2/mixer.rb, line 516 api :Mix_GroupAvailable, [:int], :int
Attach a tag to a channel. A tag can be assigned to several mixer
channels, to form groups of channels. If ‘tag’ is -1, the tag is removed (actually -1 is the tag used to represent the group of all the channels). Returns true if everything was OK.
# File lib/sdl2/mixer.rb, line 507 api :Mix_GroupChannel, [:int, :int], :int
Assign several consecutive channels to a group
# File lib/sdl2/mixer.rb, line 511 api :Mix_GroupChannels, [:int, :int, :int], :int
Returns the number of channels in a group. This is also a subtle way to get the total number of channels when ‘tag’ is -1
# File lib/sdl2/mixer.rb, line 521 api :Mix_GroupCount, [:int], :int
Finds the “most recent” (i.e. last) sample playing in a group of channels
# File lib/sdl2/mixer.rb, line 529 api :Mix_GroupNewer, [:int], :int
Finds the “oldest” sample playing in a group of channels
# File lib/sdl2/mixer.rb, line 525 api :Mix_GroupOldest, [:int], :int
Halt the playing of a particular channel
# File lib/sdl2/mixer.rb, line 569 api :Mix_HaltChannel, [:int], :int, {error: true}
Add your own music player or additional mixer function. If ‘mix_func’ is NULL, the default music player is re-enabled.
# File lib/sdl2/mixer.rb, line 233 api :Mix_HookMusic, [:mix_func], :void
Add your own callback when the music has finsihed playing. This callback is only called if the music finishes naturally.
# File lib/sdl2/mixer.rb, line 244 api :Mix_HookMusicFinished, [:music_finished], :void
Loads dynamic libraries and prepares them for use. Flags should be one or more flags from MIX_InitFlags OR’d together. It returns the flags successfully initialized, or 0 on failure.
# File lib/sdl2/mixer.rb, line 50 api :Mix_Init, [:init_flags], :int, {error: true, filter: OK_WHEN_NOT_ZERO}
Load a wave file or a music (.mod .s3m .it .xm) file
# File lib/sdl2/mixer.rb, line 161 api :Mix_LoadMUS, [:string], Music.ptr, {error: true, filter: OK_WHEN_NOT_NULL}
Load a music file from an SDL_RWop object assuming a specific format
# File lib/sdl2/mixer.rb, line 170 api :Mix_LoadMUSType_RW, [RWops.by_ref, :music_type, :int], Music.ptr
Load a music file from an SDL_RWop object (Ogg and MikMod specific currently) Matt Campbell (matt@campbellhome.dhs.org) April 2000
# File lib/sdl2/mixer.rb, line 166 api :Mix_LoadMUS_RW, [RWops.by_ref, :int], Music.ptr
Load a wave file
# File lib/sdl2/mixer.rb, line 147 api :Mix_LoadWAV_RW, [RWops.by_ref, :int], Chunk.ptr
Open the mixer with a certain audio format
# File lib/sdl2/mixer.rb, line 125 api :Mix_OpenAudio, [:int, :uint16, :int, :int], :int, {error: true}
Pause/Resume a particular channel
# File lib/sdl2/mixer.rb, line 594 api :Mix_Pause, [:int], :void
Pause/Resume the music stream
# File lib/sdl2/mixer.rb, line 600 api :Mix_PauseMusic, [], :void
The same as above, but the sound is played at most ‘ticks’ milliseconds
# File lib/sdl2/mixer.rb, line 542 api :Mix_PlayChannelTimed, [:int, Chunk.by_ref, :int, :int], :int
# File lib/sdl2/mixer.rb, line 546 api :Mix_PlayMusic, [Music.by_ref, :int], :int, {error: true}
Check the status of a specific channel. If the specified channel is -1, check all channels.
# File lib/sdl2/mixer.rb, line 618 api :Mix_Playing, [:int], :int
Find out what the actual audio device parameters are. This function returns 1 if the audio has been opened, 0 otherwise.
# File lib/sdl2/mixer.rb, line 141 api :Mix_QuerySpec, [:pointer, :pointer, :pointer], :int
Load raw audio data of the mixer format from a memory buffer
# File lib/sdl2/mixer.rb, line 178 api :Mix_QuickLoad_RAW, [:pointer, :uint32], Chunk.ptr
Load a wave file of the mixer format from a memory buffer
# File lib/sdl2/mixer.rb, line 174 api :Mix_QuickLoad_WAV, [:pointer], Chunk.ptr
Unloads libraries loaded with Mix_Init
# File lib/sdl2/mixer.rb, line 57 api :Mix_Quit, [], :void
Register a special effect function. At mixing time, the channel data is
copied into a buffer and passed through each registered effect function. After it passes through all the functions, it is mixed into the final output stream. The copy to buffer is performed once, then each effect function performs on the output of the previous effect. Understand that this extra copy to a buffer is not performed if there are no effects registered for a given chunk, which saves CPU cycles, and any given effect will be extra cycles, too, so it is crucial that your code run fast. Also note that the data that your function is given is in the format of the sound device, and not the format you gave to Mix_OpenAudio(), although they may in reality be the same. This is an unfortunate but necessary speed concern. Use Mix_QuerySpec() to determine if you can handle the data before you register your effect, and take appropriate actions.
You may also specify a callback (Mix_EffectDone_t) that is called when
the channel finishes playing. This gives you a more fine-grained control than Mix_ChannelFinished(), in case you need to free effect-specific resources, etc. If you don't need this, you can specify NULL.
You may set the callbacks before or after calling Mix_PlayChannel(). Things like Mix_SetPanning
() are just internal special effect functions,
so if you are using that, you've already incurred the overhead of a copy to a separate buffer, and that these effects will be in the queue with any functions you've registered. The list of registered effects for a channel is reset when a chunk finishes playing, so you need to explicitly set them with each call to Mix_PlayChannel*().
You may also register a special effect function that is to be run after
final mixing occurs. The rules for these callbacks are identical to those in Mix_RegisterEffect, but they are run after all the channels and the music have been mixed into a single stream, whereas channel-specific effects run on a given channel before any other mixing occurs. These global effect callbacks are call "posteffects". Posteffects only have their Mix_EffectDone_t function called when they are unregistered (since the main output stream is never "done" in the same sense as a channel). You must unregister them manually when you've had enough. Your callback will be told that the channel being mixed is (MIX_CHANNEL_POST) if the processing is considered a posteffect.
After all these effects have finished processing, the callback registered
through Mix_SetPostMix() runs, and then the stream goes to the audio device.
DO NOT EVER call SDL_LockAudio() from your callback function!
returns zero if error (no such channel), nonzero if added.
Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 338 api :Mix_RegisterEffect, [:int, :effect_func, :effect_done, :pointer], :int
Reserve the first channels (0 -> n-1) for the application, i.e. don’t allocate them dynamically to the next sample if requested with a -1 value below. Returns the number of reserved channels.
# File lib/sdl2/mixer.rb, line 499 api :Mix_ReserveChannels, [:int], :int
Set the “distance” of a channel. (distance) is an integer from 0 to 255
that specifies the location of the sound in relation to the listener. Distance 0 is overlapping the listener, and 255 is as far away as possible A distance of 255 does not guarantee silence; in such a case, you might want to try changing the chunk's volume, or just cull the sample from the mixing process with Mix_HaltChannel().
For efficiency, the precision of this effect may be limited (distances 1
through 7 might all produce the same effect, 8 through 15 are equal, etc). (distance) is an integer between 0 and 255 that specifies the space between the sound and the listener. The larger the number, the further away the sound is.
Setting (distance) to 0 unregisters this effect, since the data would be
unchanged.
If you need more precise positional audio, consider using OpenAL for
spatialized effects instead of SDL_mixer. This is only meant to be a basic effect for simple "3D" games.
Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
the distance attenuation will be done to the final mixed stream before passing it on to the audio device.
This uses the Mix_RegisterEffect
() API internally.
returns zero if error (no such channel or Mix_RegisterEffect
() fails),
nonzero if position effect is enabled. Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 470 api :Mix_SetDistance, [:int, :uint8], :int
Stop music and set external music playback command
# File lib/sdl2/mixer.rb, line 626 api :Mix_SetMusicCMD, [:string], :int
Set the current position in the music stream. This returns 0 if successful, or -1 if it failed or isn’t implemented. This function is only implemented for MOD music formats (set pattern order number) and for OGG, FLAC, MP3_MAD, and MODPLUG music (set position in seconds), at the moment.
# File lib/sdl2/mixer.rb, line 613 api :Mix_SetMusicPosition, [:double], :int
Set the panning of a channel. The left and right channels are specified
as integers between 0 and 255, quietest to loudest, respectively.
Technically, this is just individual volume control for a sample with
two (stereo) channels, so it can be used for more than just panning. If you want real panning, call it like this: Mix_SetPanning(channel, left, 255 - left);
…which isn’t so hard.
Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
the panning will be done to the final mixed stream before passing it on to the audio device.
This uses the Mix_RegisterEffect
() API internally, and returns without
registering the effect function if the audio device is not configured for stereo output. Setting both (left) and (right) to 255 causes this effect to be unregistered, since that is the data's normal state.
returns zero if error (no such channel or Mix_RegisterEffect
() fails),
nonzero if panning effect enabled. Note that an audio device in mono mode is a no-op, but this call will return successful in that case. Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 400 api :Mix_SetPanning, [:int, :uint8, :uint8], :int
Set the position of a channel. (angle) is an integer from 0 to 360, that
specifies the location of the sound in relation to the listener. (angle) will be reduced as neccesary (540 becomes 180 degrees, -100 becomes 260). Angle 0 is due north, and rotates clockwise as the value increases. For efficiency, the precision of this effect may be limited (angles 1 through 7 might all produce the same effect, 8 through 15 are equal, etc). (distance) is an integer between 0 and 255 that specifies the space between the sound and the listener. The larger the number, the further away the sound is. Using 255 does not guarantee that the channel will be culled from the mixing process or be completely silent. For efficiency, the precision of this effect may be limited (distance 0 through 5 might all produce the same effect, 6 through 10 are equal, etc). Setting (angle) and (distance) to 0 unregisters this effect, since the data would be unchanged.
If you need more precise positional audio, consider using OpenAL for
spatialized effects instead of SDL_mixer. This is only meant to be a basic effect for simple "3D" games.
If the audio device is configured for mono output, then you won’t get
any effectiveness from the angle; however, distance attenuation on the channel will still occur. While this effect will function with stereo voices, it makes more sense to use voices with only one channel of sound, so when they are mixed through this effect, the positioning will sound correct. You can convert them to mono through SDL before giving them to the mixer in the first place if you like.
Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
the positioning will be done to the final mixed stream before passing it on to the audio device.
This is a convenience wrapper over Mix_SetDistance
() and Mix_SetPanning
().
returns zero if error (no such channel or Mix_RegisterEffect
() fails),
nonzero if position effect is enabled. Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 440 api :Mix_SetPosition, [:int, :int16, :uint8], :int
Set a function that is called after all mixing is performed. This can be used to provide real-time visual display of the audio stream or add a custom mixer filter for the stream data.
# File lib/sdl2/mixer.rb, line 226 api :Mix_SetPostMix, [:mix_func], :void
Causes a channel to reverse its stereo. This is handy if the user has his
speakers hooked up backwards, or you would like to have a minor bit of psychedelia in your sound code. :) Calling this function with (flip) set to non-zero reverses the chunks's usual channels. If (flip) is zero, the effect is unregistered.
This uses the Mix_RegisterEffect
() API internally, and thus is probably
more CPU intensive than having the user just plug in his speakers correctly. Mix_SetReverseStereo() returns without registering the effect function if the audio device is not configured for stereo output.
If you specify MIX_CHANNEL_POST for (channel), then this the effect is used
on the final mixed stream before sending it on to the audio device (a posteffect).
returns zero if error (no such channel or Mix_RegisterEffect
() fails),
nonzero if reversing effect is enabled. Note that an audio device in mono mode is a no-op, but this call will return successful in that case. Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 493 api :Mix_SetReverseStereo, [:int, :int], :int
Set/Get/Iterate SoundFonts paths to use by supported MIDI backends
# File lib/sdl2/mixer.rb, line 635 api :Mix_SetSoundFonts, [:string], :int
Synchro value is set by MikMod from modules while playing
# File lib/sdl2/mixer.rb, line 630 api :Mix_SetSynchroValue, [:int], :int
You may not need to call this explicitly, unless you need to stop all
effects from processing in the middle of a chunk's playback. Note that this will also shut off some internal effect processing, since Mix_SetPanning() and others may use this API under the hood. This is called internally when a channel completes playback.
Posteffects are never implicitly unregistered as they are for channels,
but they may be explicitly unregistered through this function by specifying MIX_CHANNEL_POST for a channel.
returns zero if error (no such channel), nonzero if all effects removed.
Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 361 api :Mix_UnregisterAllEffects, [:int], :int
You may not need to call this explicitly, unless you need to stop an
effect from processing in the middle of a chunk's playback.
Posteffects are never implicitly unregistered as they are for channels,
but they may be explicitly unregistered through this function by specifying MIX_CHANNEL_POST for a channel.
returns zero if error (no such channel or effect), nonzero if removed.
Error messages can be retrieved from Mix_GetError().
# File lib/sdl2/mixer.rb, line 348 api :Mix_UnregisterEffect, [:int, :effect_func], :int
Set the volume in the range of 0-128 of a specific channel or chunk. If the specified channel is -1, set volume for all channels. Returns the original volume. If the specified volume is -1, just return the current volume.
# File lib/sdl2/mixer.rb, line 563 api :Mix_Volume, [:int, :int], :int
This is a callback that signifies that a channel has finished all its
loops and has completed playback. This gets called if the buffer plays out normally, or if you call Mix_HaltChannel(), implicitly stop a channel via Mix_AllocateChannels(), or unregister a callback while it's still playing.
DO NOT EVER call SDL_LockAudio() from your callback function!
# File lib/sdl2/mixer.rb, line 290 callback :effect_done, [:int, :pointer], :void
This is the format of a special effect callback:
myeffect(int chan, void *stream, int len, void *udata);
(chan) is the channel number that your effect is affecting. (stream) is
the buffer of data to work upon. (len) is the size of (stream), and (udata) is a user-defined bit of data, which you pass as the last arg of Mix_RegisterEffect(), and is passed back unmolested to your callback. Your effect changes the contents of (stream) based on whatever parameters are significant, or just leaves it be, if you prefer. You can do whatever you like to the buffer, though, and it will continue in its changed state down the mixing pipeline, through any other effect functions, then finally to be mixed with the rest of the channels and music for the final output stream.
DO NOT EVER call SDL_LockAudio() from your callback function!
# File lib/sdl2/mixer.rb, line 280 callback :effect_func, [:int, :pointer, :int, :pointer], :void
This function gets the version of the dynamically linked SDL_mixer library.
# File lib/sdl2/mixer.rb, line 38 api :Mix_Linked_Version, [], Version.ptr
Callback: music_finished
# File lib/sdl2/mixer.rb, line 237 callback :music_finished, [], :void