www.pudn.com > g7x.rar > README_usage

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***              MPEG-4 Audio Reference Software                   ***
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Content of README_usage
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MPEG-4 Version 1:
0   General
1   HVXC
2   CELP
3   TwinVQ
4   AAC scalable


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0  General
==========

As soon as the MPEG-4 file format specification will be stable

  mp4audec -mp4ff bitstreamfilename -o ouputfilename          

will decode files in ".mp4" file format as specified in MPEG-4 Version 2.
No further swiches are necessary for paricular decoders since all necessary 
information is in the file itself.

Please note that the ".mp4" file format is not supported in the
MPEG-4 Version 1 Audio Reference Software!


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1   HVXC
========


HVXC encoding/decoding is carried out using the reference software.

Show below is example usages of the reference software
as a HVXC encoder/decoder.


1. Fixed rate 2000bps

Encode:
mp4auenc -eo .aif -r 2000 -c "m=hvx dm=0" -m par -pb encbit2k filename.aif 
Decode:
mp4audec -ed .aif -sf 1.0 -pf 1.0 -r 2000 -c "dm=1" encbit2k/filename.mp4 -o decout2k.aif


input:filename.aif
encoded bitstream: encbit2k/filename.mp4
decoded output: decout2k.aif
dm=0: low dealy mode encode
dm=1: normal delay mode decode
-pf: pitch control factor (default=1.0)
-sf: speed control factor (default=1.0)


2. Fixed rate 4000bps

Encode:
mp4auenc -eo .aif -r 4000 -c "m=hvx dm=0" -m par -pb encbit4k filename.aif  
Decode:
mp4audec -ed .aif -sf 1.0 -pf 1.0 -r 4000 -c "dm=1" encbit4k/filename.mp4 -o decout4k.aif

input:filename.aif
encoded bitstream: encbit4k/filename.mp4
decoded output: decout4k.aif
dm=0: low dealy mode encode
dm=1: normal delay mode decode
-pf: pitch control factor (default=1.0)
-sf: speed control factor (default=1.0)


3. Variable rate

Encode:
mp4auenc -eo .aif -vr -r 2000 -c "m=hvx dm=0 vr=1 ed=1" -m par -pb encbitvar filename.aif
Decode:
mp4audec -ed .aif -sf 1.0 -pf 1.0 -r 2000 -c "dm=1" encbitvar/filename.mp4 -o decout2k.aif

input:filename.au
encoded bitstream: encbitvar/filename.mp4
decoded output: decout2k.aif


4. Scalable decode

Encoded bitstream at 4000 bps can also be decoded at 2000 bps, where a subset of
4000 bps bitstream is used for decoding.

Encode:
mp4auenc -eo .aif -r 4000 -c "m=hvx dm=0" -m par -pb encbit4k filename.aif  
Decode:
mp4audec -ed .aif -r 2000 -sf 1.0 -pf 1.0 -c "dm=1" encbit4k/filename.mp4 -o decout2k.aif

input:filename.aif
encoded bitstream: encbit4k/filename.mp4
decoded output: decout2k.aif


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Shown below are the lists you can see by executing mp4auenc -h or mp4audec -h


Encoder switches:

usage: mp4auenc -switches