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Subject: Re: MPEG Audio format

Re: MPEG Audio format

From: Bluechip <>
Date: Sat, 14 Jan 2006 02:51:22 +0000

>>Pretty much got a proper core written for an Audio file processor now.
>>I have another simple question about MPEG Audio files.
>>Am I ever likely to encounter an MPEG Audio file which will contain AUDIO
>>frames which differ in VERSION, LAYER, SAMPLERATE and/or CHANNELS? Eg.
>>Some frames are 48KHz and other frames are 44.1KHz ...or some frames in
>>Stereo, some in Joint-Stereo?
>>I have been unable to find any documentation which explicitly states
>>whether this should or shouldn't be allowed by the MPEG standard, and
>>nothing to say explicitly whether any players do or don't support this
>>type of change.
>When it comes to sample rate, layer and version switching, I think you're
>reasonably safe, though it is probably legal. Stereo mode I think you will
>find encoders may switch from frame to frame.

Thanks Thom et al.

Three people have said this now. So I will assume Ver/Lyr/Smp to be
constant and Chn to be variable.

As you say, there seems to be no reason for Ver/Lyr/Smp changes to be
ILLEGAL, but generating comprehensive statistics for such files would be an
output nightmare - so I would rather avoid it if it is relevantly obscure.

Received on 2006-01-14

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