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Subject: Slashdot questions and answers
From: Björn Stenberg (bjorn_at_haxx.se)
Date: 2002-06-04


There has been some questions posted (and answered) on Slashdot this
morning, and to avoid you having to go search for them I'm posting them
here too:

----------
The question is...

by neksys on Tue June 04, 4:27 (Score:3, Insightful) (#3636165)
(User #87486 Info) [ Neutral ]

Is that legal? I mean, I'd just hate to see something like that challenged
under the DMCA in all its ridiculousness. Any thoughts or ideas?
----------
Re:The question is...

by Björn Stenberg on Tue June 04, 12:08 (Score:2) (#3637213)
(User #32494 Info) http://bjorn.haxx.se

I would say we are in the green. We are not voilating anyone's copyright
and we are not circumventing any copy protection scheme.

This has been a big point for me from the beginning. Some people wanted us
to distribute patched versions of the original firmware (language fixes,
charset fixes etc), but that would have violated Archos' copyright so we
never did that.
----------

----------
Re:The question is...

by plierhead on Tue June 04, 5:04 (Score:1) (#3636324)
(User #570797 Info) [ Neutral ]

Kind of confusing statement here in the story:

Every tiny bit was reverse engineered, disassembled and then re-written
from scratch

If it was rewritten from scratch then why was it first reverse-engineered
and disassembled ? Instead this sounds more like someone disassembled it
then used the understanding that they gained to create a new version,
which is not quite the same as "from scratch". That may be skating on thin
ice as far as being legal goes.
----------
Re:The question is...

by Björn Stenberg on Tue June 04, 12:43 (Score:3, Informative) (#3637265)
(User #32494 Info) http://bjorn.haxx.se

Don't confuse the terms.

Reverse engineering means examining a product to find out how it works.
Disassembling the firmware is merely one tool used in that examination.
Oscilloscopes and logic analyzers are other tools we have used.

We have written every single byte of the Rockbox firmware. But we could
not have written the software without first researching how the hardware
was put together, i.e. reverse engineer it.

All of this is completely legal.

If you define "from scratch" as writing software without first researching
the surrounding interfaces, then no software has ever been written from
scratch.
----------

----------
Arbitrary formats

by BlueFall on Tue June 04, 5:01 (Score:2, Interesting) (#3636314)
(User #141123 Info) [ Neutral ]

This is indeed very cool! Congrats to Rockbox!

Lots of other people have mentioned that they want Ogg support on their
player and a few others have pointed out the FAQ answer that says it's
probably too hard to do on this device. What I would like to see is a
portable device that can be easily extended to arbitrary formats. For
example, my current audio format of choice is FLAC which has no portable
hardware support (though there apparently is a car player that supports it
-- rock!). I doubt that it will become very popular though, because it's a
lossless codec and therefore must take up more room than lossy codecs. But
that's beside the point -- if someone makes a new audio format that is
truly cool and does some things that certain people like or want, it would
be neat if you could carry around that music without custom hardware.

Just a thought...
----------
Re:Arbitrary formats

by Björn Stenberg on Tue June 04, 12:19 (Score:2) (#3637228)
(User #32494 Info) http://bjorn.haxx.se

We can play any format if only we can write code for the DSP to decode it.
The MAS 3507 (and 3587) are generic DSPs that simply have MP3 codecs in
ROM. We can download new codecs in them and I'm the first to hooray if we
can get OGG or FLAC or anything into these DSPs.

Unfortunately, we have no docs or tools for writing new MAS DSP code and
Intermetall is very secretive about it. If anyone can help, please get in
touch!

The 12 MHz SH7034 CPU is unfortunately much too slow to handle decoding in
software.
----------

----------
whoa whoa WHOA! slow down!

by Lord Omlette on Tue June 04, 6:00 (Score:4, Insightful) (#3636485)
(User #124579 Info) http://www.omlettesoft.com/ [ Neutral ]

Slow down there big boy! Not a single one of those has actually been
implemented! Calling this thing v1.0 is really misleading. These guys are
like Microsoft, yeah, they got 1.0 out the door, call me when they get
3.11 for Workgroups, k?

They complain about the shuffle. Dandy, everyone knows that no matter how
good an Archos product is, the shuffle is fucking ridiculous. Archos
wouldn't know what random is if random bit them in the bloody ass. But
Rockbox doesn't even have a shuffle feature yet! And if they do, it's not
mentioned in the release notes or available via the menu.

I'm sure these guys will do something great with this project, but call me
when they add even one of the features on that list.
----------
Re:whoa whoa WHOA! slow down!

by bagder on Tue June 04, 7:27 (Score:1) (#3636693)
(User #32513 Info) http://daniel.haxx.se [ Neutral ]

It is indeed true that Rockbox 1.0 lacks most of the feature every sane
user wants. No one said it is more feature-complete or better in any way
than the original firmware at this early point.

Still, this is a proof that our effort is going in the right direction,
that it works and it helps getting attention and more developers onto the
project. We meant the 1.0 release to be this.

Adding the missing features is now only a matter of time. If you join up,
we'll have them available even faster.
----------

----------
Re:What exactly is the big deal?

by pacc on Tue June 04, 10:13 (Score:2) (#3637017)
(User #163090 Info) http://slashdot.org/ [ Neutral ]

At first I was a bit sad that I owned the Creative DAP (Nomad) instead of
this, but then I might have been turned off by these shortcomings.

Whenever these guys are ready with the basic functionality that should
have been there in the first place, I'd suggest these features:
* HW-mod and SW to emulate various car CDchangers
* SID support (20GB of these babes)

Maybe the Creative Nomad Jukebox hacking project has made progress until
then, but it's currently hacking the chip firmware itself and replacing
that would probably leave you without a filesystem - the Archos project
seems to have avoided that.
----------
Re:What exactly is the big deal?

by Björn Stenberg on Tue June 04, 12:24 (Score:2) (#3637237)
(User #32494 Info) http://bjorn.haxx.se

Why not help us?

Car CD changers are very simple to handle in software, but we naturally
can't do the hardware ourselves since we don't have the head units.

SID support is perhaps possible. The main bottleneck is that we must
encode the sound data as mp3 before feeding it to the sound chip. Unless,
that is, someone manages to write a new DSP codec to play uncompressed PCM
data.
----------

----------
Firmware is scrambled?

by safiire on Tue June 04, 6:25 (Score:0) (#3636553)
(User #542553 Info) http://slashdot.org/ [ Neutral ]

From the site:
The archos.mod file is scrambled, but luckily not using encryption.

Each data byte is inverted and ROLed 1 bit. The data is then spread over
four memory segments. The two least significant bits of the address is
used as segment number and the rest as offset in the segment. So,
basically:

* segment number = address % 4
* segment offset = address / 4
* segment length = imgsize / 4

A 6-byte header is added to the beginning of the scrambled image:

* 32 bit length (big-endian)
* 16 bit checksum

The Rockbox people have written and made available a descrambler/scrambler
for it.
How is this any different from the DECSS program that is illegal? Not that
I really think DECSS should be illegal, but this seems to be near the same
to me. Why isn't this deemed encryption, even if it's not a really hard
tough form of encryption?
----------
Re:Firmware is scrambled?

by Björn Stenberg on Tue June 04, 12:33 (Score:2) (#3637251)
(User #32494 Info) http://bjorn.haxx.se

The difference is that the purpose of the CSS scrambling is to prevent you
from reading the files on the DVD and save them on another disk (or play
them in an "unauthorized" player). CSS is thereby a copy protection
scheme, which DMCA forbids circumventing.

The purpose of Archos' scrambling is obviously not to prevent copying,
since the files are very much copyable, and Archos themselves freely
distribute the files on the Internet. Thus, descrambling it does not
circumvent a copy protection scheme.
----------

-- 
Björn



Page was last modified "Jan 10 2012" The Rockbox Crew
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