XCV. oggvorbis
简介
The OGG/Vorbis file format, as defined by http://www.vorbis.com/ and http://www.vorbis.com/, is a scheme for compressing audio streams by multiple factors with a minimum of quality loss. This extension adds Ogg Vorbis support to PHP's URL Wrappers. When used in read mode, compressed OGG/Vorbis data is expanded to raw PCM audio in one of six PCM encoding formats listed below.
运行时配置
本扩展模块在 php.ini 中未定义任何配置选项。
安装
oggvorbis is installed through the usual PECL package installation process.
$ pear install oggvorbis
Copy the resulting oggvorbis.so to an appropriate location and add extension=oggvorbis.so to your php.ini file or load it dynamically in your PHP script using dl('oggvorbis.so');
Context options
表格 1. OGG/Vorbis tuning options
| Option | Definition | Relevance | Default |
|---|---|---|---|
| pcm_mode | PCM byte encoding used. See constants below. | Read / Write | OGGVORBIS_PCM_S16_LE |
| rate | PCM Sampling rate. Measured in Hz. | Write only | 44100 |
| bitrate | Vorbis Average Bitrate Encoding / Variable Bitrate Encoding. Measured in bps (ABR) or Quality level (VBR: 0.0 to 1.0). 128000 ABR is rough equal to 0.4 VBR. | Write only | 128000 |
| channels | Number of PCM channels. 1 == Mono, 2 == Stereo. | Write only | 2 |
| serialno | Serial Number of stream within file. Must be unique within file. Because of the potential to select a duplicate serial number within a chained file, make efforts to manually assign unique numbers when encoding. | Write only | Random |
| comments | Associative array of file comments. Will be translated to strtoupper($name) . "=$value". Note: This context option is not available in oggvorbis-0.1 | Write only | array('ENCODER' => 'PHP/OggVorbis, http://pear.php.net/oggvorbis') |
预定义常量
以下常量由本扩展模块定义，因此只有在本扩展模块被编译到 PHP 中，或者在运行时被动态加载后才有效。
表格 2. OGG/Vorbis supports PCM encodings in the following formats
| Constant | Definition |
|---|---|
| OGGVORBIS_PCM_U8 | Unsigned 8-bit PCM. |
| OGGVORBIS_PCM_S8 | Signed 8-bit PCM. |
| OGGVORBIS_PCM_U16_LE | Unsigned 16-bit PCM. Little Endian byte order. |
| OGGVORBIS_PCM_U16_BE | Unsigned 16-bit PCM. Big Endian byte order. |
| OGGVORBIS_PCM_S16_LE | Signed 16-bit PCM. Little Endian byte order. |
| OGGVORBIS_PCM_S16_BE | Signed 16-bit PCM. Big Endian byte order. |
- 目录
- Usage -- Examples on using the ogg:// wrapper.