SDL::Audio -- SDL Bindings for Audio
+SDL::Audio - SDL Bindings for Audio
TODO, Core, Audio
+Core, Audio
The constants are exported by default. You can avoid this by doing:
+use SDL::Audio (); ++
and access them directly:
+SDL::Audio::AUDIO_S16SYS; ++
or by choosing the export tags below:
+Export tag: ':format'
+AUDIO_U8 + AUDIO_S8 + AUDIO_U16LSB + AUDIO_S16LSB + AUDIO_U16MSB + AUDIO_S16MSB + AUDIO_U16 + AUDIO_S16 + AUDIO_U16SYS + AUDIO_S16SYS ++
Export tag: ':status'
+SDL_AUDIO_STOPPED + SDL_AUDIO_PLAYING + SDL_AUDIO_PAUSED +
Opens the audio device with the desired parameters.
+use SDL; + use SDL::Audio; + + SDL::init(SDL_INIT_AUDIO); + + my $desired = SDL::AudioSpec->new(); + + my $obtained; + + SDL::Audio::open( $desired, $obtained ); + + # $obtained->... (A new SDL::AudioSpec now); + ++
This function opens the audio device with the desired parameters, and returns 0 if successful, placing the actual hardware parameters in the structure pointed to by obtained. If obtained is NULL, the audio data passed to the callback function will be guaranteed to be in the requested format, and will be automatically converted to the hardware audio format if necessary. This function returns -1 if it failed to open the audio device, or couldn't set up the audio thread.
+To open the audio device a desired SDL::AudioSpec must be created.
+my $desired = SDL::AudioSpec->new(); + ++
You must then fill this structure with your desired audio specifications.
+$desired->freq + ++
$desired->format + ++
$desired->channels + ++
$desired->samples + ++
THIS IS NOT READY YET
+ $desired->callback
+
+ my $callback = sub{ my ($userdata, $stream, $len) = @_; };
+
+ $userdata is a reference stored in the userdata field of the SDL::AudioSpec.
+ $stream is a pointer to the audio buffer you want to fill with information and $len is the length of the audio buffer in bytes.
+
+ $desired->userdata
+
+ This pointer is passed as the first parameter to the callback function.
+
+
+ SDL::Audio::open reads these fields from the desired SDL::AudioSpec structure passed to the function and attempts to find an audio configuration matching your desired. As mentioned above, if the obtained parameter is NULL then SDL with convert from your desired audio settings to the hardware settings as it plays.
+If obtained is NULL then the desired SDL::AudioSpec is your working specification, otherwise the obtained SDL::AudioSpec becomes the working specification and the desired specification can be deleted. The data in the working specification is used when building SDL::AudioCVT's for converting loaded data to the hardware format.
+SDL::Audio::open calculates the size and silence fields for both the $desired and $obtained specifications. The size field stores the total size of the audio buffer in bytes, while the silence stores the value used to represent silence in the audio buffer
+The audio device starts out playing silence when it's opened, and should be enabled for playing by calling SDL::Audio::pause(0) when you are ready for your audio callback function to be called. Since the audio driver may modify the requested size of the audio buffer, you should allocate any local mixing buffers after you open the audio device.
Pauses and unpauses the audio callback processing
+pause( $bool ) + ++
This function pauses and unpauses the audio callback processing. It should be called with $bool = 0 after opening the audio device to
+start playing sound. This is so you can safely initialize data for your callback function after opening the audio device. Silence will
+be written to the audio device during the pause.
Gets the current audio state
+int get_status(); + ++
Returns either SDL_AUDIO_STOPPED, SDL_AUDIO_PLAYING or SDL_AUDIO_PAUSED depending on the current audio state.
Loads a WAVE file
+SDL::AudioSpec load_wav( $filename, $spec ); -
Frees previously opened WAV data
+ +This function loads a WAVE file into memory.
+If this function succeeds, it returns the given SDL::AudioSpec, filled with the audio data format of the wave data, and sets buf
+to a buffer containing the audio data, and sets len to the length of that audio buffer, in bytes. You need to free the audio buffer
+with SDL::Audio::free_wav when you are done with it.
This function returns NULL and sets the SDL error message if the wave file cannot be opened, uses an unknown data format, or is corrupt. +Currently raw, MS-ADPCM and IMA-ADPCM WAVE files are supported.
+Example:
+use SDL; + use SDL::Audio; + use SDL::AudioSpec; -
Audio Conversion Structure
+ SDL::init(SDL_INIT_AUDIO); + + # Converting some WAV data to hardware format + + my $desired = SDL::AudioSpec->new(); + my $obtained = SDL::AudioSpec->new(); + + # Set desired format + $desired->freq(22050); + $desired->channels(1); + $desired->format(AUDIO_S16); + $desired->samples(8192); + + # Open the audio device + if( SDL::Audio::open($desired, $obtained) < 0 ) + { + printf( STDERR "Couldn't open audio: %s\n", SDL::get_error() ); + exit(-1); + } + + # Load the test.wav + my $wav_ref = SDL::Audio::load_wav('../../test/data/sample.wav', $obtained); + + unless( $wav_ref ) + { + warn( "Could not open sample.wav: %s\n", SDL::get_error() ); + SDL::Audio::close_audio(); + SDL::quit; + exit(-1); + } + + my ( $wav_spec, $wav_buf, $wav_len ) = @{$wav_ref}; + +Initializes a SDL_AudioCVT - structure for conversion
+free_wav( $buffer ) + ++
After a WAVE file has been opened with load_wav its data can eventually be freed with free_wav. buffer is the buffer created
+by load_wav.
SDL::Audio->convert( cvt, data, len ) + +
Converts audio data to a desired audio format.
+convert takes as first parameter cvt, which was previously initialized. Initializing a SDL::AudioCVT is a two step process.
+First of all, the structure must be created via SDL::AudioCVT->build along with source and destination format parameters. Secondly,
+the data and len fields must be setup. data should point to the audio data buffer beeing source and destination at
+once and len should be set to the buffer length in bytes. Remember, the length of the buffer pointed to by buf should be
+len*len_mult bytes in length.
Once the SDL::AudioCVT structure is initialized, we can pass it to convert, which will convert the audio data pointed to
+by data. If convert fails undef is returned, otherwise the converted SDL::AudioCVT structure.
If the conversion completed successfully then the converted audio data can be read from cvt->buf. The amount of valid, converted,
+audio data in the buffer is equal to cvt->len*cvt->len_ratio.
Example:
+ use SDL;
+ use SDL::Audio;
+ use SDL::AudioSpec;
+ use SDL::AudioCVT;
+
+ SDL::init(SDL_INIT_AUDIO);
+
+ # Converting some WAV data to hardware format
+
+ my $desired = SDL::AudioSpec->new();
+ my $obtained = SDL::AudioSpec->new();
+
+ # Set desired format
+ $desired->freq(22050);
+ $desired->channels(1);
+ $desired->format(AUDIO_S16);
+ $desired->samples(8192);
+
+ # Open the audio device
+ if( SDL::Audio::open($desired, $obtained) < 0 )
+ {
+ printf( STDERR "Couldn't open audio: %s\n", SDL::get_error() );
+ exit(-1);
+ }
+
+ # Load the test.wav
+ my $wav_ref = SDL::Audio::load_wav('../../test/data/sample.wav', $obtained);
+
+ unless( $wav_ref )
+ {
+ warn( "Could not open sample.wav: %s\n", SDL::get_error() );
+ SDL::Audio::close_audio();
+ SDL::quit;
+ exit(-1);
+ }
+
+ my ( $wav_spec, $wav_buf, $wav_len ) = @{$wav_ref};
+
+ # Build AudioCVT
+ my $wav_cvt = SDL::AudioCVT->build( $wav_spec->format, $wav_spec->channels, $wav_spec->freq,
+ $obtained->format, $obtained->channels, $obtained->freq);
+
+ # Check that the convert was built
+ if( $wav_cvt == -1 )
+ {
+ warn( "Couldn't build converter!\n" );
+ SDL::Audio::close();
+ SDL::Audio::free_wav($wav_buf);
+ SDL::quit();
+ exit(-1);
+ }
+
+ # And now we're ready to convert
+ SDL::Audio::convert($wav_cvt, $wav_buf, $wav_len);
+
+ # We can freeto original WAV data now
+ SDL::Audio::free_wav($wav_buf);
+
+
+TODO: What to do with it? How to use callback? See http://www.libsdl.org/cgi/docwiki.cgi/SDL_ConvertAudio
Mixes audio data
+Not implemented yet. See: http://www.libsdl.org/cgi/docwiki.cgi/SDL_MixAudio
Locks out the callback function
+lock(); + ++
The lock manipulated by these functions protects the callback function. During a lock period, you can be guaranteed that the callback
+function is not running. Do not call this from the callback function or you will cause deadlock.
Unlocks the callback function
+unlock(); + ++
Unlocks a previous lock call.
close(); + +
Shuts down audio processing and closes the audio device.
See AUTHORS in SDL.
+ +