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Subject: Re: Mp3 technical jargon

Re: Mp3 technical jargon

From: Linus Nielsen Feltzing <linus_at_haxx.se>
Date: Sat, 28 Feb 2004 10:41:30 +0100

Nathan Gray wrote:
> First, where's a good index of terminology some of you appear very
> comfortable in using?

Not that i know of. However, the bitswapping is entirely an Archos
issue, and has nothing to do with MP3 playback in general. The reason is
that the serial controller in the CPU sends the least significant bit
(bit 0) first, while the MAS decoder wants the MSB first. therefore we
have to reverse the bit order of every byte of MP3 data. This is what we
call "bitswapping".

> Second, what kind of data structure is used to bit-swap an mp3 from file
> into main memory for playing from buffer rather than spin-up and read
> from disc again?

Just load the MP3 data into the buffer and call bitswap() with the
appropriate arguments. After that, just call mp3_play_data() using the
same buffer over and over again.

You need to declare a function that can be called by the MP3 thread that
gives it more data to play. The pointer to this function is passed to
mp3_play_data().

I guess you can check out the video plugin for more details.

Linus

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Received on 2004-02-28

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