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Subject: Re: MPEG Audio format

Re: MPEG Audio format

From: Bluechip <csbluechip_at_gmail.com>
Date: 2006-01-14

>>>CHANNELS? Eg. Some frames are 48KHz and other frames are 44.1KHz ...or
>>>some frames in Stereo, some in Joint-Stereo?
>
>Dumb question since I've never really looked into how they're processed,
>but isn't this what VBR (variable-bit-rate) MP3 files are? Each frame of
>audio will vary in bitrate depending on the type of audio at that moment
>for best overall compression?
>
>-id

No such thing as a dumb question. Only dumb answers.

VBR files change in BITRATE, that does not mean a change in CHANNEL MODE,
SAMPLERATE, MPEG-VERSION or MPEG-LAYER

This example output may help it all make more sense:

@0x0021625C+0.1, 4721566 - 7835 MPEG audio frames
| ,--
| | MPEG Version : MPEG Version 1 (ISO/IEC 11172-3)
| | MPEG Layer : Layer III
| | Samplerate : 44100 Hz
| | Bitrate : VBR @ ABR = 184807 bpS [Match: 192 Kbps]
| | Samples/Frame : 1152
| | Frame Time : 26.122449 mS
| |
| | Frame Count : 7835 -> 68.2% (of ALL frames)
| | Frame Time : 0:03:24.669
| `-v
| | (%'s below are for this block only)
| |
| +-- Channels : Joint Stereo [Xing index: 36]
| | 35 -> 0.4% @ JS (only)
| | 7800 -> 99.6% @ JS +M/S
| |
| +-- Emphasis : 7835 -> 100.0% @ No Emphasis
| |
| | --- Enabled ---- -+- --- Disabled ---
| +-- Original : 7835 -> 100.0% | 0 -> 0.0%
| +-- Copyright : 0 -> 0.0% | 7835 -> 100.0%
| +-- Private : 0 -> 0.0% | 7835 -> 100.0%
| | |
| +-- Protected : 7835 -> 100.0% | 0 -> 0.0%
| +-- Padding : 0 -> 0.0% | 7835 -> 100.0%
| | ^
| `-- Bitrate : 1761 -> 22.5% @ 160 KbpS
| 6074 -> 77.5% @ 192 KbpS [ABR Match]
Received on Sat Jan 14 03:49:42 2006


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