oggvorbis

简介

The OGG/Vorbis file format, as defined by » 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.

需求

This extension requires PHP >= 4.3.0, » libogg >= 1.0, and » libvorbis >= 1.0.

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

安装此 PECL 扩展库的信息可在手册中标题为 PECL 扩展库安装的一章中找到。 更多信息如新版本,下载,源文件,维护者信息以及更新日志等可以在这里找到: » http://pecl.php.net/package/oggvorbis

Context options

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。

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.


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