Autodesk 64006-051108-9001 User Guide - Page 206

MPEG-1 and MPEG-2 Audio Codecs, QuickTime Audio Codecs, Full Rate, Half Rate

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198 Chapter 8: Encoding MPEG-1 and MPEG-2 Audio Codecs MPEG Layer 1 The oldest and most widely supported MPEG CD-ROM audio standard. This audio codec is obsolete, and generally inferior to MPEG Layer 2. Available only for MPEG video. MPEG Layer 2 The MPEG audio codec for CD-ROM and DVD audio. It produces excellent audio quality. The high data rates it requires make it less suitable for network applications. Available only for MPEG video. Uncompressed PCM A format most often used for audio editing. Available only for MPEG video. QuickTime Audio Codecs Mace 3:1 A general purpose audio codec for music. Mace 6:1 A general purpose audio codec for speech. QDesign Music 2 A high quality, low data rate audio compressor. Qualcomm PureVoice The Qualcomm PureVoice audio codec is optimized for speech. It has two options: Full Rate - Produces larger, higher-quality files and delivers approximately 9:1 compression. Half Rate - Produces smaller files with its approximately 19:1 compression, but the quality is correspondingly lower. If you are producing audio files that are intended to be delivered via a streaming server, we also recommend that you check the Optimize compression for streaming option. This option removes all the zeros off the end of each audio packet, reducing the data rate for both Full Rate and Half Rate options. The amount of reduction varies significantly with the complexity of the audio. Note: You must use a sample rate of 8 kHz for good results when doing realtime streaming with a QuickTime Streaming Server. Any rate can be used for progressive-streaming files.

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Chapter 8: Encoding
198
MPEG-1 and MPEG-2 Audio Codecs
MPEG Layer 1
The oldest and most widely supported MPEG CD-ROM audio standard. This audio codec is
obsolete, and generally inferior to MPEG Layer 2. Available only for MPEG video.
MPEG Layer 2
The MPEG audio codec for CD-ROM and DVD audio. It produces excellent audio quality. The
high data rates it requires make it less suitable for network applications. Available only for
MPEG video.
Uncompressed PCM
A format most often used for audio editing. Available only for MPEG video.
QuickTime Audio Codecs
Mace 3:1
A general purpose audio codec for music.
Mace 6:1
A general purpose audio codec for speech.
QDesign Music 2
A high quality, low data rate audio compressor.
Qualcomm PureVoice
The Qualcomm PureVoice audio codec is optimized for speech. It has two options:
Full Rate
— Produces larger, higher-quality files and delivers approximately 9:1 compression.
Half Rate
— Produces smaller files with its approximately 19:1 compression, but the quality is
correspondingly lower.
If you are producing audio files that are intended to be delivered via a streaming server, we also
recommend that you check the Optimize compression for streaming option. This option
removes all the zeros off the end of each audio packet, reducing the data rate for both Full Rate
and Half Rate options. The amount of reduction varies significantly with the complexity of the
audio.
Note:
You must use a sample rate of 8 kHz for good results when doing realtime streaming with
a QuickTime Streaming Server. Any rate can be used for progressive-streaming files.