OpenAL
OpenAL aims to provide a standardized API for something called '3D' sound, just like OpenGL does for '3D' video rendering.
The fun part of OpenAL is that it does all the DSP for you, so you don't need to know a lot about audio. Since OpenAL comes from Creative Labs, it supports hardware rendering of audio with most if not all SoundBlaster audio controllers. They come with chips from EMU-systems and are specifically designed to mix down multichannel audio with DSP effects like reverb and chorus, which could consume a lot CPU speed.
The downside of OpenAL is that (at this time of writing) it is focus on games only. It doesn't do MIDI at all, it doesn't record anything, it doesn't work like a synthesizer. The only thing you can do with OpenAL is play sounds in a simulated 3D environment.
It probably doesn't work on the web.
To use OpenAL you need to read the documentation about OpenAL.
Note concerning audio users: there's no such thing as '3D' audio with speakers. Technically, when people have only two ears, they really can't distinguish sound from above or below, even in front or from behind. To achieve this people merely hear volume, the brightness of sound and the phase difference. One should be able to hear more '3D' sound with only two quality-class speakers than with a consumer class 5.1-set.
OpenAL 関数
目次
- openal_buffer_create — OpenAL バッファを生成する
- openal_buffer_data — バッファのデータを読み込む
- openal_buffer_destroy — OpenAL バッファを削除する
- openal_buffer_get — OpenAL バッファのプロパティを取得する
- openal_buffer_loadwav — .wav ファイルをバッファに読み込む
- openal_context_create — 音声処理コンテキストを作成する
- openal_context_current — 指定したコンテキストを現在のコンテキストにする
- openal_context_destroy — コンテキストを削除する
- openal_context_process — 指定したコンテキストを処理する
- openal_context_suspend — 指定したコンテキストをサスペンドする
- openal_device_close — OpenAL デバイスを閉じる
- openal_device_open — OpenAL 音声レイヤを初期化する
- openal_listener_get — リスナーのプロパティを取得する
- openal_listener_set — リスナーのプロパティを設定する
- openal_source_create — ソースリソースを生成する
- openal_source_destroy — ソースリソースを削除する
- openal_source_get — OpenAL ソースのプロパティを取得する
- openal_source_pause — ソースを一時停止する
- openal_source_play — ソースの再生を開始する
- openal_source_rewind — ソースを巻き戻す
- openal_source_set — ソースのプロパティを設定する
- openal_source_stop — ソースの再生を停止する
- openal_stream — ソースのストリーム再生を開始する
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User Contributed NotesOpenAL 関数
Tjeerd
02-Feb-2007 05:37
02-Feb-2007 05:37
cweiske at cweiske dot de
06-Sep-2006 10:31
06-Sep-2006 10:31
I made a PHP-Gtk2 OpenAL demo which allows you to define as many sound sources as you like and position them relative to the listener by drag and drop: http://gnope.org/p/Tools_OpenALdemo
cweiske at cweiske dot de
21-Jul-2006 08:29
21-Jul-2006 08:29
Playing a wav file:
<?php
function printok($b) {
echo $b ? " ok\n" : " error\n";
}
echo "Opening device";
$device = openal_device_open();
printok($device);
echo "Creating context";
$context = openal_context_create($device);
printok($context);
echo "Making context the current";
printok(openal_context_current($context));
//where we are
//echo "Setting listener position";
//printok(openal_listener_set(AL_POSITION, array(0, 0, 0)));
//echo "Setting listener orientation";
//printok(openal_listener_set(AL_ORIENTATION, array(0=>0,1 => 1, 2=>0, 3=> 0, 4=>4, 5=>5)));
echo "Creating buffer";
$buffer = openal_buffer_create();
echo "Loading wav";
printok(openal_buffer_loadwav($buffer, '/data/shared/vmware/newmessage.wav'));
echo "buffer stats\n";
echo " Frequency: " . openal_buffer_get($buffer, AL_FREQUENCY) . "\n";
echo " Bits : " . openal_buffer_get($buffer, AL_BITS) . "\n";
echo " Channels : " . openal_buffer_get($buffer, AL_CHANNELS) . "\n";
echo " Size : " . openal_buffer_get($buffer, AL_SIZE) . "\n";
echo "Creating source";
$source = openal_source_create();
echo "Setting source buffer";
printok(openal_source_set($source, AL_BUFFER, $buffer));
//echo "Setting source position";
//printok(openal_source_set($source, AL_POSITION, array(1, 0, 0)));
echo "Playing source";
printok(openal_source_play($source));
echo "sleeping\n";
//sleep(1);
//we wait 300msecs beause the sound
// has no time to be played otherwise
//since playing sound is done concurrently
// to the script
usleep(300000);
echo "Destroying source";
printok(openal_source_destroy($source));
echo "Destroying buffer";
printok(openal_buffer_destroy($buffer));
echo "Destroying context";
printok(openal_context_destroy($context));
echo "Closing device";
printok(openal_device_close($device));
?>
ganswijk at xs4all dot nl
01-Feb-2005 02:20
01-Feb-2005 02:20
There is no explanation about what OpenAL actually is and you first have to follow quite a lot of links and download an SDK (from the Creative site) to get information about what OpenAL actually is, but here is what I understand it is:
It's a new standard to create a kind of 3D sound landscape in the way that OpenGL creates a visual 3D landscape. It's not a general sound card interface (as I was looking for). It doesn't handle MIDI and it can't handle sound input (yet).
I was hoping that I could experiment with a kind of homebrewed VoIP with this library but that's not the case.
BTW. The "links to the DLL", don't actually lead to an DLL and finding one is very hard and I haven't found one yet, but at least I know now that I don't have to search any further.
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