From: TP Diffenbach <tp_at_diffenbach.org>
Date: Fri, 31 Jan 2003 23:42:20 -0500

> so it would have to be real-time analysis
> somehow before it goes through the DAC. Is there a clever trick we can
use
> to do this?

I strongly suspect the 30 second buffer goes through MP3 compression, as
that way continuing the recording is just a matter of continuing to
compress, rather than compressing the new bits and then compressing the
buffer.

I suppose if you wanted to test this, you might suddenly pop the batteries
during that 30 seconds, plug into the USB, and check out any fragmentary
records written to disk.

Not that I plan to perform this test, mind you. I'd much prefer to start a
consumer letter writing campaign to Archos, trying to convince them it's to
their competitive advantage to help bring about a better GUI for their
product.

-----Original Message-----
From: owner-rockbox_at_cool.haxx.se [mailto:owner-rockbox_at_cool.haxx.se]On
Behalf Of Matthew P. OReilly
Sent: Friday, January 31, 2003 11:26 PM
To: rockbox_at_cool.haxx.se
Subject: RE: Just an idea about the FM recorder...


>>
The MAS is the same type as on the older recorder models, AFAIK.

If that is the case, you are unfortunately completely wrong. The radio
is not played by the MAS. It is just connected to the ADC input of the
MAS, which routes the audio to the headphones. At least, that's how I
assume they are doing it.

/Linus
<<

The MAS is capable of real-time mp3 encoding, so I don't see that this is
necessarily the case. Also, considering that the FM recorder also buffers
30 seconds of radio time, I would assume that this is compressed - 30
seconds of uncompressed audio is not unfeasible, but I wouldn't bet on it.

Is it be possible to analyze the output and determine whether it is
compressed or uncompressed? We obviously can't save it since that would be
compressed almost definitely... so it would have to be real-time analysis
somehow before it goes through the DAC. Is there a clever trick we can use
to do this?

Matt
Received on 2003-02-01