[sdlgit/SDL-Site.git] / pages / SDL-Audio.html-inc

<div class="pod">
<!-- INDEX START -->
<h3 id="TOP">Index</h3>

<ul><li><a href="#NAME">NAME</a></li>
<li><a href="#CATEGORY">CATEGORY</a></li>
<li><a href="#CONSTANTS">CONSTANTS</a></li>
<li><a href="#METHODS">METHODS</a>
<ul><li><a href="#open">open</a></li>
<li><a href="#pause">pause</a></li>
<li><a href="#get_status">get_status</a></li>
<li><a href="#load_wav">load_wav </a></li>
<li><a href="#free_wav">free_wav </a></li>
<li><a href="#convert">convert</a></li>
<li><a href="#mix">mix</a></li>
<li><a href="#lock">lock</a></li>
<li><a href="#unlock">unlock</a></li>
<li><a href="#close">close </a></li>
</ul>
</li>
<li><a href="#AUTHORS">AUTHORS</a>
</li>
</ul><hr />
<!-- INDEX END -->

<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="NAME_CONTENT">
<p>SDL::Audio - SDL Bindings for Audio</p>

</div>
<h1 id="CATEGORY">CATEGORY</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="CATEGORY_CONTENT">
<p>Core, Audio</p>

</div>
<h1 id="CONSTANTS">CONSTANTS</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="CONSTANTS_CONTENT">
<p>The constants are exported by default. You can avoid this by doing:</p>
<pre> use SDL::Audio ();

</pre>
<p>and access them directly:</p>
<pre> SDL::Audio::AUDIO_S16SYS;

</pre>
<p>or by choosing the export tags below:</p>
<p>Export tag: ':format'</p>
<pre> AUDIO_U8
 AUDIO_S8
 AUDIO_U16LSB
 AUDIO_S16LSB
 AUDIO_U16MSB
 AUDIO_S16MSB
 AUDIO_U16
 AUDIO_S16 
 AUDIO_U16SYS
 AUDIO_S16SYS

</pre>
<p>Export tag: ':status'</p>
<pre> SDL_AUDIO_STOPPED
 SDL_AUDIO_PLAYING
 SDL_AUDIO_PAUSED

</pre>

</div>
<h1 id="METHODS">METHODS</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="METHODS_CONTENT">

</div>
<h2 id="open">open</h2>
<div id="open_CONTENT">
<pre>  use SDL;
  use SDL::Audio;

  SDL::init(SDL_INIT_AUDIO);

  my $desired = SDL::AudioSpec-&gt;new();

  my $obtained;

  SDL::Audio::open( $desired, $obtained );

  # $obtained-&gt;... (A new SDL::AudioSpec now);

</pre>
<p>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.</p>
<p>To open the audio device a desired SDL::AudioSpec must be created.</p>
<pre>  my $desired = SDL::AudioSpec-&gt;new();

</pre>
<p>You must then fill this structure with your desired audio specifications.</p>
<dl>
	<dt>The desired audio frequency in samples-per-second. </dt>
	<dd>
<pre>    $desired-&gt;freq

</pre>
	</dd>
	<dt>The desired audio format. See <a href="SDL-AudioSpec.html">SDL::AudioSpec</a></dt>
	<dd>
<pre>    $desired-&gt;format

</pre>
	</dd>
	<dt>The desired channels (1 for mono, 2 for stereo, 4 for surround, 6 for surround with center and lfe). </dt>
	<dd>
<pre>    $desired-&gt;channels

</pre>
	</dd>
	<dt>The desired size of the audio buffer in samples. This number should be a power of two, and may be adjusted by the audio driver to a value more suitable for the hardware. Good values seem to range between 512 and 8192 inclusive, depending on the application and CPU speed. Smaller values yield faster response time, but can lead to underflow if the application is doing heavy processing and cannot fill the audio buffer in time. A stereo sample consists of both right and left channels in LR ordering. Note that the number of samples is directly related to time by the following formula: ms = (samples*1000)/freq </dt>
	<dd>
<pre>    $desired-&gt;samples

</pre>
	</dd>
	<dt>This should be set to a function that will be called when the audio device is ready for more data. It is passed a pointer to the audio buffer, and the length in bytes of the audio buffer. This function usually runs in a separate thread, and so you should protect data structures that it accesses by calling SDL::Audio::lock and SDL::Audio::unlock in your code. </dt>
	<dd>
		<p>THIS IS NOT READY YET</p>
<pre>    $desired-&gt;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-&gt;userdata

    This pointer is passed as the first parameter to the callback function. 

</pre>
	</dd>
</dl>
<p>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.</p>
<p>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 <a href="SDL-AudioCVT.html">SDL::AudioCVT</a>'s for converting loaded data to the hardware format.</p>
<p>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</p>
<p>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. </p>

</div>
<h2 id="pause">pause</h2>
<div id="pause_CONTENT">
<pre> pause( $bool )

</pre>
<p>This function pauses and unpauses the audio callback processing. It should be called with <code>$bool = 0</code> 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.</p>

</div>
<h2 id="get_status">get_status</h2>
<div id="get_status_CONTENT">
<pre> int get_status();

</pre>
<p>Returns either <code>SDL_AUDIO_STOPPED</code>, <code>SDL_AUDIO_PLAYING</code> or <code>SDL_AUDIO_PAUSED</code> depending on the current audio state. </p>

</div>
<h2 id="load_wav">load_wav </h2>
<div id="load_wav_CONTENT">
<pre> SDL::AudioSpec load_wav( $filename, $spec );

</pre>
<p>This function loads a WAVE file into memory.</p>
<p>If this function succeeds, it returns the given <code>SDL::AudioSpec</code>, filled with the audio data format of the wave data, and sets <code>buf</code> 
to a buffer containing the audio data, and sets <code>len</code> to the length of that audio buffer, in bytes. You need to free the audio buffer 
with <code>SDL::Audio::free_wav</code> when you are done with it.</p>
<p>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.</p>
<p>Example:</p>
<pre> use SDL;
 use SDL::Audio;
 use SDL::AudioSpec;

 SDL::init(SDL_INIT_AUDIO);

 # Converting some WAV data to hardware format

 my $desired  = SDL::AudioSpec-&gt;new();
 my $obtained = SDL::AudioSpec-&gt;new();

 # Set desired format
 $desired-&gt;freq(22050);
 $desired-&gt;channels(1);
 $desired-&gt;format(AUDIO_S16);
 $desired-&gt;samples(8192);

 # Open the audio device
 if( SDL::Audio::open($desired, $obtained) &lt; 0 )
 {
     printf( STDERR &quot;Couldn't open audio: %s\n&quot;, 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( &quot;Could not open sample.wav: %s\n&quot;, SDL::get_error() );
     SDL::Audio::close_audio();
     SDL::quit;
     exit(-1);
 }

 my ( $wav_spec, $wav_buf, $wav_len ) = @{$wav_ref};

</pre>

</div>
<h2 id="free_wav">free_wav </h2>
<div id="free_wav_CONTENT">
<pre> free_wav( $buffer )

</pre>
<p>After a WAVE file has been opened with <code>load_wav</code> its data can eventually be freed with <code>free_wav</code>. <code>buffer</code> is the buffer created 
by <code>load_wav</code>. </p>

</div>
<h2 id="convert">convert</h2>
<div id="convert_CONTENT">
<pre> SDL::Audio-&gt;convert( cvt, data, len )

</pre>
<p>Converts audio data to a desired audio format.</p>
<p><code>convert</code> takes as first parameter <code>cvt</code>, which was previously initialized. Initializing a <code>SDL::AudioCVT</code> is a two step process. 
First of all, the structure must be created via <code>SDL::AudioCVT-&gt;build</code> along with source and destination format parameters. Secondly, 
the <code>data</code> and <code>len</code> fields must be setup. <code>data</code> should point to the audio data buffer beeing source and destination at 
once and <code>len</code> should be set to the buffer length in bytes. Remember, the length of the buffer pointed to by buf should be 
<code>len*len_mult</code> bytes in length.</p>
<p>Once the <code>SDL::AudioCVT</code> structure is initialized, we can pass it to <code>convert</code>, which will convert the audio data pointed to 
by <code>data</code>. If <code>convert</code> fails <code>undef</code> is returned, otherwise the converted <code>SDL::AudioCVT</code> structure.</p>
<p>If the conversion completed successfully then the converted audio data can be read from <code>cvt-&gt;buf</code>. The amount of valid, converted, 
audio data in the buffer is equal to <code>cvt-&gt;len*cvt-&gt;len_ratio</code>. </p>
<p>Example:</p>
<pre> 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-&gt;new();
 my $obtained = SDL::AudioSpec-&gt;new();

 # Set desired format
 $desired-&gt;freq(22050);
 $desired-&gt;channels(1);
 $desired-&gt;format(AUDIO_S16);
 $desired-&gt;samples(8192);

 # Open the audio device
 if( SDL::Audio::open($desired, $obtained) &lt; 0 )
 {
     printf( STDERR &quot;Couldn't open audio: %s\n&quot;, 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( &quot;Could not open sample.wav: %s\n&quot;, 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-&gt;build( $wav_spec-&gt;format, $wav_spec-&gt;channels, $wav_spec-&gt;freq,
                                     $obtained-&gt;format, $obtained-&gt;channels, $obtained-&gt;freq); 

 # Check that the convert was built
 if( $wav_cvt == -1 )
 {
     warn( &quot;Couldn't build converter!\n&quot; );
     SDL::Audio::close();
     SDL::Audio::free_wav($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);

</pre>
<p><strong>TODO</strong>: What to do with it? How to use callback? See http://www.libsdl.org/cgi/docwiki.cgi/SDL_ConvertAudio</p>

</div>
<h2 id="mix">mix</h2>
<div id="mix_CONTENT">
<p>Mixes audio data</p>
<p><strong>Not implemented yet</strong>. See: <a href="http://www.libsdl.org/cgi/docwiki.cgi/SDL_MixAudio">http://www.libsdl.org/cgi/docwiki.cgi/SDL_MixAudio</a></p>

</div>
<h2 id="lock">lock</h2>
<div id="lock_CONTENT">
<pre> lock();

</pre>
<p>The lock manipulated by these functions protects the callback function. During a <code>lock</code> 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.</p>

</div>
<h2 id="unlock">unlock</h2>
<div id="unlock_CONTENT">
<pre> unlock();

</pre>
<p>Unlocks a previous <code>lock</code> call.</p>

</div>
<h2 id="close">close </h2>
<div id="close_CONTENT">
<pre> close();

</pre>
<p>Shuts down audio processing and closes the audio device.  </p>

</div>
<h1 id="AUTHORS">AUTHORS</h1><p><a href="#TOP" class="toplink">Top</a></p>
<div id="AUTHORS_CONTENT">
<p>See <a href="/SDL.html#AUTHORS">/SDL.html#AUTHORS</a>.</p>

</div>
</div>
Commit	Line	Data
b82df135	1	<div class="pod">
	2	<!-- INDEX START -->
	3	<h3 id="TOP">Index</h3>
	4
	5	<ul><li><a href="#NAME">NAME</a></li>
8758037a	6	<li><a href="#CATEGORY">CATEGORY</a></li>
fb5f7900	7	<li><a href="#CONSTANTS">CONSTANTS</a></li>
8758037a	8	<li><a href="#METHODS">METHODS</a>
15c551d8	9	<ul><li><a href="#open">open</a></li>
e3282ccf	10	<li><a href="#pause">pause</a></li>
15c551d8	11	<li><a href="#get_status">get_status</a></li>
	12	<li><a href="#load_wav">load_wav </a></li>
	13	<li><a href="#free_wav">free_wav </a></li>
e3282ccf	14	<li><a href="#convert">convert</a></li>
15c551d8	15	<li><a href="#mix">mix</a></li>
e3282ccf	16	<li><a href="#lock">lock</a></li>
e3282ccf	17	<li><a href="#unlock">unlock</a></li>
c7e8d3c6	18	<li><a href="#close">close </a></li>
8758037a	19	</ul>
b82df135	20	</li>
c7e8d3c6	21	<li><a href="#AUTHORS">AUTHORS</a>
c7e8d3c6	22	</li>
b82df135	23	</ul><hr />
	24	<!-- INDEX END -->
	25
	26	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>
	27	<div id="NAME_CONTENT">
260482f9	28	<p>SDL::Audio - SDL Bindings for Audio</p>
b82df135	29
	30	</div>
	31	<h1 id="CATEGORY">CATEGORY</h1><p><a href="#TOP" class="toplink">Top</a></p>
	32	<div id="CATEGORY_CONTENT">
260482f9	33	<p>Core, Audio</p>
b82df135	34
b82df135	35	</div>
fb5f7900	36	<h1 id="CONSTANTS">CONSTANTS</h1><p><a href="#TOP" class="toplink">Top</a></p>
fb5f7900	37	<div id="CONSTANTS_CONTENT">
3549ee6a	38	<p>The constants are exported by default. You can avoid this by doing:</p>
3549ee6a	39	<pre> use SDL::Audio ();
fb5f7900	40
fb5f7900	41	</pre>
3549ee6a	42	<p>and access them directly:</p>
fb5f7900	43	<pre> SDL::Audio::AUDIO_S16SYS;
	44
	45	</pre>
	46	<p>or by choosing the export tags below:</p>
	47	<p>Export tag: ':format'</p>
	48	<pre> AUDIO_U8
	49	AUDIO_S8
	50	AUDIO_U16LSB
	51	AUDIO_S16LSB
	52	AUDIO_U16MSB
	53	AUDIO_S16MSB
	54	AUDIO_U16
	55	AUDIO_S16
	56	AUDIO_U16SYS
	57	AUDIO_S16SYS
	58
	59	</pre>
	60	<p>Export tag: ':status'</p>
	61	<pre> SDL_AUDIO_STOPPED
	62	SDL_AUDIO_PLAYING
	63	SDL_AUDIO_PAUSED
	64
	65	</pre>
	66
	67	</div>
8758037a	68	<h1 id="METHODS">METHODS</h1><p><a href="#TOP" class="toplink">Top</a></p>
	69	<div id="METHODS_CONTENT">
	70
	71	</div>
e3282ccf	72	<h2 id="open">open</h2>
e3282ccf	73	<div id="open_CONTENT">
e3282ccf	74	<pre> use SDL;
	75	use SDL::Audio;
	76
	77	SDL::init(SDL_INIT_AUDIO);
	78
	79	my $desired = SDL::AudioSpec->new();
	80
	81	my $obtained;
	82
15c551d8	83	SDL::Audio::open( $desired, $obtained );
e3282ccf	84
	85	# $obtained->... (A new SDL::AudioSpec now);
	86
	87	</pre>
e3282ccf	88	<p>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.</p>
	89	<p>To open the audio device a desired SDL::AudioSpec must be created.</p>
	90	<pre> my $desired = SDL::AudioSpec->new();
	91
	92	</pre>
	93	<p>You must then fill this structure with your desired audio specifications.</p>
	94	<dl>
	95	<dt>The desired audio frequency in samples-per-second. </dt>
	96	<dd>
	97	<pre> $desired->freq
	98
	99	</pre>
	100	</dd>
55bbf7a2	101	<dt>The desired audio format. See <a href="SDL-AudioSpec.html">SDL::AudioSpec</a></dt>
e3282ccf	102	<dd>
	103	<pre> $desired->format
	104
	105	</pre>
	106	</dd>
	107	<dt>The desired channels (1 for mono, 2 for stereo, 4 for surround, 6 for surround with center and lfe). </dt>
	108	<dd>
	109	<pre> $desired->channels
	110
	111	</pre>
	112	</dd>
	113	<dt>The desired size of the audio buffer in samples. This number should be a power of two, and may be adjusted by the audio driver to a value more suitable for the hardware. Good values seem to range between 512 and 8192 inclusive, depending on the application and CPU speed. Smaller values yield faster response time, but can lead to underflow if the application is doing heavy processing and cannot fill the audio buffer in time. A stereo sample consists of both right and left channels in LR ordering. Note that the number of samples is directly related to time by the following formula: ms = (samples*1000)/freq </dt>
	114	<dd>
	115	<pre> $desired->samples
	116
	117	</pre>
	118	</dd>
	119	<dt>This should be set to a function that will be called when the audio device is ready for more data. It is passed a pointer to the audio buffer, and the length in bytes of the audio buffer. This function usually runs in a separate thread, and so you should protect data structures that it accesses by calling SDL::Audio::lock and SDL::Audio::unlock in your code. </dt>
	120	<dd>
	121	<p>THIS IS NOT READY YET</p>
	122	<pre> $desired->callback
	123
15c551d8	124	my $callback = sub{ my ($userdata, $stream, $len) = @_; };
e3282ccf	125
	126	$userdata is a reference stored in the userdata field of the SDL::AudioSpec.
	127	$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.
	128
	129	$desired->userdata
	130
	131	This pointer is passed as the first parameter to the callback function.
	132
	133	</pre>
	134	</dd>
	135	</dl>
	136	<p>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.</p>
55bbf7a2	137	<p>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 <a href="SDL-AudioCVT.html">SDL::AudioCVT</a>'s for converting loaded data to the hardware format.</p>
e3282ccf	138	<p>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</p>
	139	<p>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. </p>
	140
	141	</div>
	142	<h2 id="pause">pause</h2>
	143	<div id="pause_CONTENT">
15c551d8	144	<pre> pause( $bool )
	145
	146	</pre>
	147	<p>This function pauses and unpauses the audio callback processing. It should be called with <code>$bool = 0</code> after opening the audio device to
	148	start playing sound. This is so you can safely initialize data for your callback function after opening the audio device. Silence will
	149	be written to the audio device during the pause.</p>
8758037a	150
8758037a	151	</div>
15c551d8	152	<h2 id="get_status">get_status</h2>
	153	<div id="get_status_CONTENT">
	154	<pre> int get_status();
	155
	156	</pre>
	157	<p>Returns either <code>SDL_AUDIO_STOPPED</code>, <code>SDL_AUDIO_PLAYING</code> or <code>SDL_AUDIO_PAUSED</code> depending on the current audio state. </p>
8758037a	158
8758037a	159	</div>
15c551d8	160	<h2 id="load_wav">load_wav </h2>
	161	<div id="load_wav_CONTENT">
	162	<pre> SDL::AudioSpec load_wav( $filename, $spec );
	163
	164	</pre>
	165	<p>This function loads a WAVE file into memory.</p>
	166	<p>If this function succeeds, it returns the given <code>SDL::AudioSpec</code>, filled with the audio data format of the wave data, and sets <code>buf</code>
	167	to a buffer containing the audio data, and sets <code>len</code> to the length of that audio buffer, in bytes. You need to free the audio buffer
	168	with <code>SDL::Audio::free_wav</code> when you are done with it.</p>
	169	<p>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.
	170	Currently raw, MS-ADPCM and IMA-ADPCM WAVE files are supported.</p>
	171	<p>Example:</p>
	172	<pre> use SDL;
	173	use SDL::Audio;
	174	use SDL::AudioSpec;
	175
	176	SDL::init(SDL_INIT_AUDIO);
	177
	178	# Converting some WAV data to hardware format
	179
	180	my $desired = SDL::AudioSpec->new();
	181	my $obtained = SDL::AudioSpec->new();
	182
	183	# Set desired format
	184	$desired->freq(22050);
	185	$desired->channels(1);
	186	$desired->format(AUDIO_S16);
	187	$desired->samples(8192);
	188
	189	# Open the audio device
	190	if( SDL::Audio::open($desired, $obtained) < 0 )
	191	{
	192	printf( STDERR "Couldn't open audio: %s\n", SDL::get_error() );
	193	exit(-1);
	194	}
	195
	196	# Load the test.wav
	197	my $wav_ref = SDL::Audio::load_wav('../../test/data/sample.wav', $obtained);
	198
	199	unless( $wav_ref )
	200	{
	201	warn( "Could not open sample.wav: %s\n", SDL::get_error() );
	202	SDL::Audio::close_audio();
	203	SDL::quit;
	204	exit(-1);
	205	}
	206
	207	my ( $wav_spec, $wav_buf, $wav_len ) = @{$wav_ref};
	208
	209	</pre>
8758037a	210
8758037a	211	</div>
15c551d8	212	<h2 id="free_wav">free_wav </h2>
	213	<div id="free_wav_CONTENT">
	214	<pre> free_wav( $buffer )
	215
	216	</pre>
	217	<p>After a WAVE file has been opened with <code>load_wav</code> its data can eventually be freed with <code>free_wav</code>. <code>buffer</code> is the buffer created
	218	by <code>load_wav</code>. </p>
8758037a	219
8758037a	220	</div>
e3282ccf	221	<h2 id="convert">convert</h2>
	222	<div id="convert_CONTENT">
	223	<pre> SDL::Audio->convert( cvt, data, len )
8758037a	224
e3282ccf	225	</pre>
8758037a	226	<p>Converts audio data to a desired audio format.</p>
fb2dc882	227	<p><code>convert</code> takes as first parameter <code>cvt</code>, which was previously initialized. Initializing a <code>SDL::AudioCVT</code> is a two step process.
fb2dc882	228	First of all, the structure must be created via <code>SDL::AudioCVT->build</code> along with source and destination format parameters. Secondly,
e3282ccf	229	the <code>data</code> and <code>len</code> fields must be setup. <code>data</code> should point to the audio data buffer beeing source and destination at
	230	once and <code>len</code> should be set to the buffer length in bytes. Remember, the length of the buffer pointed to by buf should be
	231	<code>len*len_mult</code> bytes in length.</p>
fb2dc882	232	<p>Once the <code>SDL::AudioCVT</code> structure is initialized, we can pass it to <code>convert</code>, which will convert the audio data pointed to
	233	by <code>data</code>. If <code>convert</code> fails <code>undef</code> is returned, otherwise the converted <code>SDL::AudioCVT</code> structure.</p>
	234	<p>If the conversion completed successfully then the converted audio data can be read from <code>cvt->buf</code>. The amount of valid, converted,
	235	audio data in the buffer is equal to <code>cvt->len*cvt->len_ratio</code>. </p>
e3282ccf	236	<p>Example:</p>
	237	<pre> use SDL;
	238	use SDL::Audio;
	239	use SDL::AudioSpec;
	240	use SDL::AudioCVT;
	241
	242	SDL::init(SDL_INIT_AUDIO);
	243
	244	# Converting some WAV data to hardware format
	245
	246	my $desired = SDL::AudioSpec->new();
	247	my $obtained = SDL::AudioSpec->new();
	248
	249	# Set desired format
	250	$desired->freq(22050);
	251	$desired->channels(1);
	252	$desired->format(AUDIO_S16);
	253	$desired->samples(8192);
	254
	255	# Open the audio device
	256	if( SDL::Audio::open($desired, $obtained) < 0 )
	257	{
	258	printf( STDERR "Couldn't open audio: %s\n", SDL::get_error() );
	259	exit(-1);
	260	}
	261
	262	# Load the test.wav
	263	my $wav_ref = SDL::Audio::load_wav('../../test/data/sample.wav', $obtained);
	264
	265	unless( $wav_ref )
	266	{
15c551d8	267	warn( "Could not open sample.wav: %s\n", SDL::get_error() );
e3282ccf	268	SDL::Audio::close_audio();
	269	SDL::quit;
	270	exit(-1);
	271	}
	272
	273	my ( $wav_spec, $wav_buf, $wav_len ) = @{$wav_ref};
	274
	275	# Build AudioCVT
	276	my $wav_cvt = SDL::AudioCVT->build( $wav_spec->format, $wav_spec->channels, $wav_spec->freq,
	277	$obtained->format, $obtained->channels, $obtained->freq);
	278
	279	# Check that the convert was built
	280	if( $wav_cvt == -1 )
	281	{
15c551d8	282	warn( "Couldn't build converter!\n" );
e3282ccf	283	SDL::Audio::close();
	284	SDL::Audio::free_wav($wav_buf);
	285	SDL::quit();
	286	exit(-1);
	287	}
	288
	289	# And now we're ready to convert
	290	SDL::Audio::convert($wav_cvt, $wav_buf, $wav_len);
	291
e3282ccf	292	# We can freeto original WAV data now
	293	SDL::Audio::free_wav($wav_buf);
	294
e3282ccf	295	</pre>
e3282ccf	296	<p><strong>TODO</strong>: What to do with it? How to use callback? See http://www.libsdl.org/cgi/docwiki.cgi/SDL_ConvertAudio</p>
8758037a	297
8758037a	298	</div>
15c551d8	299	<h2 id="mix">mix</h2>
15c551d8	300	<div id="mix_CONTENT">
8758037a	301	<p>Mixes audio data</p>
15c551d8	302	<p><strong>Not implemented yet</strong>. See: <a href="http://www.libsdl.org/cgi/docwiki.cgi/SDL_MixAudio">http://www.libsdl.org/cgi/docwiki.cgi/SDL_MixAudio</a></p>
8758037a	303
8758037a	304	</div>
e3282ccf	305	<h2 id="lock">lock</h2>
e3282ccf	306	<div id="lock_CONTENT">
15c551d8	307	<pre> lock();
	308
	309	</pre>
	310	<p>The lock manipulated by these functions protects the callback function. During a <code>lock</code> period, you can be guaranteed that the callback
	311	function is not running. Do not call this from the callback function or you will cause deadlock.</p>
8758037a	312
8758037a	313	</div>
e3282ccf	314	<h2 id="unlock">unlock</h2>
e3282ccf	315	<div id="unlock_CONTENT">
15c551d8	316	<pre> unlock();
	317
	318	</pre>
	319	<p>Unlocks a previous <code>lock</code> call.</p>
8758037a	320
8758037a	321	</div>
e3282ccf	322	<h2 id="close">close </h2>
e3282ccf	323	<div id="close_CONTENT">
15c551d8	324	<pre> close();
	325
	326	</pre>
8758037a	327	<p>Shuts down audio processing and closes the audio device. </p>
	328
	329	</div>
c7e8d3c6	330	<h1 id="AUTHORS">AUTHORS</h1><p><a href="#TOP" class="toplink">Top</a></p>
c7e8d3c6	331	<div id="AUTHORS_CONTENT">
1dbe1697	332	<p>See <a href="/SDL.html#AUTHORS">/SDL.html#AUTHORS</a>.</p>
c7e8d3c6	333
c7e8d3c6	334	</div>
b82df135	335	</div>