Tom Lucas wrote:

> "Isaac Bosompem" <x86asm@gmail.com> wrote in message 

>> Your mention of compression reminded me of a discussion I had with a
>> co-worker during my summer job. He does some music production so he 
>> was
>> pretty knowledgable of audio technology terminology (filtering, etc.).
>> He told me about a case in which he used "compression" and described
>> what it does. But I must ask what is the difference between 
>> compression
>> and attenuation?
> 
> I think that the compression that mp3 uses also causes some attenuation 
> of certain frequencies that the algorithm considers are inaudible. This 
> might explain the noise artifacts that are audible on very high and very 
> low notes such as I'm hearing on the GP2X. I'd have to plug it into my 
> hifi to be sure that the problem is not with the headphones. 

I think you'll find that the term 'compression' in this case referred to
"audio compression"  - certainly in the context of a comparison with
'attenuation'.

Audio compression is quite different to the compression of digital data
such as mp3 (or zip, jpeg etc) uses - it refers to reducing the dynamic
range of a signal; i.e. the range between the loudest and softest sounds
in a piece of music etc.

Attenuation is simply reducing the level of a signal.

You could, for example, 'compress' a signal so that the softer volume
levels are actually increased towards the loudest, whilst leaving the
loudest unchanged. In this case, there would be no attenuation at all.

Regards,

-- 
Mark McDougall, Engineer
Virtual Logic Pty Ltd, <http://www.vl.com.au>
21-25 King St, Rockdale, 2216
Ph: +612-9599-3255 Fax: +612-9599-3266

"Isaac Bosompem" <x86asm@gmail.com> wrote in message 
news:1159312388.360971.228900@k70g2000cwa.googlegroups.com...
>
>> I guess the bulk of the work is done by the PC then - does it have a
>> fairly wide range of supported formats? I suppose you just have to 
>> leave
>> it to Sony to get it onto the PSP unless you want to work out their
>> mechanisms. This is what infuriates me about the iPod too - 
>> everything
>> is proprietory and you have to go a long way out of your way to get
>> around it. My plan for the GP2X is to get wireless LAN into it 
>> somehow
>> and then stream movies from my server to wherever I am in the house. 
>> To
>> have to convert all the movies into a GP2X format would be highly
>> inconvenient and a waste of disc space.
>
> Yup pretty much any format can be converted. I guess as long as you
> have the codec installed. The iPod, although a really nice player, is
> probably the last MP3 player I would ever buy. There are hacks
> available though so you dont have to use that iTunes application 
> (which
> unfortunately is bundled with QuickTime player now).

Tell me about it, the girlfriend has a seperate WinXP login on which she 
has updated her iTunes (I try to keep is away fro my login) and the damn 
thing has smeared itself and quicktime over everything I hold dear. It's 
worse than the old AOL days when it used to take control of everything 
on your PC and your underpants if you stood too close.

> Maybe you can get
> an SDIO WiFi card for the GP2X? Maybe there is a driver available or
> something. My Zire 71 unfortunately doesnt work with most cards. Seems
> like only one card is listed as working.

Might be an option. The breakout board allows a USB dongle to be used 
too - assuming that the driver can be made to work. Perhaps an SDIO WiFi 
could be an idea and I'm sure someone has written a driver for linux for 
one - I'll have to have a look.

> I did use MMPlayer on the Zire 71 and it played a 160x160 video quite
> well, no dropped frames and quite smooth. I don't think that is too 
> bad
> for a 144Mhz ARM9. There was some exaple 320x320 videos but I don't
> think those would go over too well. Might be worth a shot.

My Sopranos are at least 640x480 and I've never seen a frame dropped. 
The lip-sync can wander from time to time but that could well have been 
a problem at encoding time.

>> The mp3 player on the GP2X is a little lacklustre. There are a 
>> variety
>> of equalizer settings but it is not that brilliant and the 
>> compression
>> is very apparent on deep bass notes.
>
> The GP2X looks like a bigger device so I thought it would have some
> good audio hardware.
> I remember looking over some code for the GP2X, the way it sets its
> output sample rate was quite strange, definitely don't remember it
> being standard way of doing it (setting up some clock divider).

I'm using reasonably good quality sony headphones but perhaps I should 
plug it into my hifi for a true opinion of the sound. The audio hardware 
may have been compromised for their TV-out white elephant or to make 
room for the loudspeakers.

> The Zire 71 (DioPlayer app to be exact) has a graphic EQ. Once that is
> turned on though it becomes quite sluggish.

I've never managed to get the GP2X to do anything that remotely affected 
its reposne time and that includes fastforwarding and rewinding through 
big videos.

> Though the Zire 71 also has some weak audio output. I hooked it up
> through a tape adaptor to the tape deck in my 1997 Volvo 850 (I
> believe). The bass was very weak almost non-existant. Now the sound
> system in this car is quite impressive for a stock system.

I've had bad experiences of those tape adaptors before so that could be 
your weak link. Those volvos do have an excellent stereo though and if 
you want to get into car hifi in a big way then I've heard they are a 
good platform for an expensive system because they are built so solidly 
and don't rattle with big subs.

> Your mention of compression reminded me of a discussion I had with a
> co-worker during my summer job. He does some music production so he 
> was
> pretty knowledgable of audio technology terminology (filtering, etc.).
> He told me about a case in which he used "compression" and described
> what it does. But I must ask what is the difference between 
> compression
> and attenuation?

I think that the compression that mp3 uses also causes some attenuation 
of certain frequencies that the algorithm considers are inaudible. This 
might explain the noise artifacts that are audible on very high and very 
low notes such as I'm hearing on the GP2X. I'd have to plug it into my 
hifi to be sure that the problem is not with the headphones. 

Tom Lucas wrote:
> "Isaac Bosompem" <x86asm@gmail.com> wrote in message
> news:1159209254.082417.173050@i42g2000cwa.googlegroups.com...
> >> I use a 1GB SanDisk SD card. A divX episode of the Sopranos comes in
> >> at
> >> about 350Mb but, after all the applications, ROMs and mp3s, I only
> >> have
> >> about 200meg free. The movie player is pretty fussy about what it
> >> will
> >> play and some divX films just won't work at all. I've got virtual dub
> >> and a number of other open source video processing/DVD ripping tools
> >> that the GP2X wiki recommends so I should be able to fix them once I
> >> work it all out. It would be nice to have mpeg support right out of
> >> the
> >> box but I guess there are licensing issues. To be honest, mpeg is
> >> such a
> >> popular format that it would be worth putting a few dollars on the
> >> rrp
> >> to cover but I guess it would go against the open source philosophy.
> >>
> >> Does the PSP have better support? That weird little disc it uses
> >> seems
> >> like a good point of failure when watching movies but it does use
> >> those
> >> expensive memory cards as well which might alleviate that.
> >
> > The way the PSP works is qutie strange with video. Some commercially
> > released movies are available on the disc (UMD). But as usual, that is
> > a Sony proprietary format and it did not take off too well. There has
> > been announcements that the movie studios would stop releasing videos
> > for it.
> >
> > The PSP actually can only play MP4 files off the Memory Stick Pro Duo
> > card. The PSP requires that these files be named in a certain obscure
> > manner. The PC side software is responsible for transcoding it to the
> > MP4 file. It's not too bad actually, my P3 1.13Ghz took about a minute
> > or so to do a 40 sec MPG video. The quality of the video is quite good
> > (assuming it scales well to the 16:9 aspect ratio). It makes an
> > excellent MP3 player too and has good audio output. Also the GPU's
> > output is quite impressive as well. Quite impressed with it.
>
> I guess the bulk of the work is done by the PC then - does it have a
> fairly wide range of supported formats? I suppose you just have to leave
> it to Sony to get it onto the PSP unless you want to work out their
> mechanisms. This is what infuriates me about the iPod too - everything
> is proprietory and you have to go a long way out of your way to get
> around it. My plan for the GP2X is to get wireless LAN into it somehow
> and then stream movies from my server to wherever I am in the house. To
> have to convert all the movies into a GP2X format would be highly
> inconvenient and a waste of disc space.

Yup pretty much any format can be converted. I guess as long as you
have the codec installed. The iPod, although a really nice player, is
probably the last MP3 player I would ever buy. There are hacks
available though so you dont have to use that iTunes application (which
unfortunately is bundled with QuickTime player now). Maybe you can get
an SDIO WiFi card for the GP2X? Maybe there is a driver available or
something. My Zire 71 unfortunately doesnt work with most cards. Seems
like only one card is listed as working.

I did use MMPlayer on the Zire 71 and it played a 160x160 video quite
well, no dropped frames and quite smooth. I don't think that is too bad
for a 144Mhz ARM9. There was some exaple 320x320 videos but I don't
think those would go over too well. Might be worth a shot.

>
> The mp3 player on the GP2X is a little lacklustre. There are a variety
> of equalizer settings but it is not that brilliant and the compression
> is very apparent on deep bass notes.

The GP2X looks like a bigger device so I thought it would have some
good audio hardware.
I remember looking over some code for the GP2X, the way it sets its
output sample rate was quite strange, definitely don't remember it
being standard way of doing it (setting up some clock divider).

The Zire 71 (DioPlayer app to be exact) has a graphic EQ. Once that is
turned on though it becomes quite sluggish.

Though the Zire 71 also has some weak audio output. I hooked it up
through a tape adaptor to the tape deck in my 1997 Volvo 850 (I
believe). The bass was very weak almost non-existant. Now the sound
system in this car is quite impressive for a stock system.

Your mention of compression reminded me of a discussion I had with a
co-worker during my summer job. He does some music production so he was
pretty knowledgable of audio technology terminology (filtering, etc.).
He told me about a case in which he used "compression" and described
what it does. But I must ask what is the difference between compression
and attenuation? 

-Isaac

"Isaac Bosompem" <x86asm@gmail.com> wrote in message 
news:1159209254.082417.173050@i42g2000cwa.googlegroups.com...
>> I use a 1GB SanDisk SD card. A divX episode of the Sopranos comes in 
>> at
>> about 350Mb but, after all the applications, ROMs and mp3s, I only 
>> have
>> about 200meg free. The movie player is pretty fussy about what it 
>> will
>> play and some divX films just won't work at all. I've got virtual dub
>> and a number of other open source video processing/DVD ripping tools
>> that the GP2X wiki recommends so I should be able to fix them once I
>> work it all out. It would be nice to have mpeg support right out of 
>> the
>> box but I guess there are licensing issues. To be honest, mpeg is 
>> such a
>> popular format that it would be worth putting a few dollars on the 
>> rrp
>> to cover but I guess it would go against the open source philosophy.
>>
>> Does the PSP have better support? That weird little disc it uses 
>> seems
>> like a good point of failure when watching movies but it does use 
>> those
>> expensive memory cards as well which might alleviate that.
>
> The way the PSP works is qutie strange with video. Some commercially
> released movies are available on the disc (UMD). But as usual, that is
> a Sony proprietary format and it did not take off too well. There has
> been announcements that the movie studios would stop releasing videos
> for it.
>
> The PSP actually can only play MP4 files off the Memory Stick Pro Duo
> card. The PSP requires that these files be named in a certain obscure
> manner. The PC side software is responsible for transcoding it to the
> MP4 file. It's not too bad actually, my P3 1.13Ghz took about a minute
> or so to do a 40 sec MPG video. The quality of the video is quite good
> (assuming it scales well to the 16:9 aspect ratio). It makes an
> excellent MP3 player too and has good audio output. Also the GPU's
> output is quite impressive as well. Quite impressed with it.

I guess the bulk of the work is done by the PC then - does it have a 
fairly wide range of supported formats? I suppose you just have to leave 
it to Sony to get it onto the PSP unless you want to work out their 
mechanisms. This is what infuriates me about the iPod too - everything 
is proprietory and you have to go a long way out of your way to get 
around it. My plan for the GP2X is to get wireless LAN into it somehow 
and then stream movies from my server to wherever I am in the house. To 
have to convert all the movies into a GP2X format would be highly 
inconvenient and a waste of disc space.

The mp3 player on the GP2X is a little lacklustre. There are a variety 
of equalizer settings but it is not that brilliant and the compression 
is very apparent on deep bass notes. 

> I use a 1GB SanDisk SD card. A divX episode of the Sopranos comes in at
> about 350Mb but, after all the applications, ROMs and mp3s, I only have
> about 200meg free. The movie player is pretty fussy about what it will
> play and some divX films just won't work at all. I've got virtual dub
> and a number of other open source video processing/DVD ripping tools
> that the GP2X wiki recommends so I should be able to fix them once I
> work it all out. It would be nice to have mpeg support right out of the
> box but I guess there are licensing issues. To be honest, mpeg is such a
> popular format that it would be worth putting a few dollars on the rrp
> to cover but I guess it would go against the open source philosophy.
>
> Does the PSP have better support? That weird little disc it uses seems
> like a good point of failure when watching movies but it does use those
> expensive memory cards as well which might alleviate that.

The way the PSP works is qutie strange with video. Some commercially
released movies are available on the disc (UMD). But as usual, that is
a Sony proprietary format and it did not take off too well. There has
been announcements that the movie studios would stop releasing videos
for it.

The PSP actually can only play MP4 files off the Memory Stick Pro Duo
card. The PSP requires that these files be named in a certain obscure
manner. The PC side software is responsible for transcoding it to the
MP4 file. It's not too bad actually, my P3 1.13Ghz took about a minute
or so to do a 40 sec MPG video. The quality of the video is quite good
(assuming it scales well to the 16:9 aspect ratio). It makes an
excellent MP3 player too and has good audio output. Also the GPU's
output is quite impressive as well. Quite impressed with it.

-Isaac

"Uwe Hercksen" <hercksen@mew.uni-erlangen.de> wrote in message 
news:4517D3ED.5000904@mew.uni-erlangen.de...
>
>
> Tom Lucas schrieb:
>>
>> Speaking to a very old hairy-eared engineered once he told be that 
>> the ROM he used many many years ago was windings of copper wire with 
>> ferrite beads on them to represent data. Apparently they always used 
>> women to wind the wires because they were more accurate than men. But 
>> I digress....
>
> Hello,
>
> they needed personell which was able to handle very small ferrite 
> beads and thin copper wires.

Perhaps my girlfriend should apply? ;-) 

Tom Lucas schrieb:
> 
> Speaking to a very old hairy-eared engineered once he told be that the 
> ROM he used many many years ago was windings of copper wire with ferrite 
> beads on them to represent data. Apparently they always used women to 
> wind the wires because they were more accurate than men. But I 
> digress....

Hello,

they needed personell which was able to handle very small ferrite beads 
and thin copper wires.

Bye

"Isaac Bosompem" <x86asm@gmail.com> wrote in message 
news:1158956978.232754.178970@k70g2000cwa.googlegroups.com...
>
> Tom Lucas wrote:
>> >
>> > You got a GP2X? Cool!
>> > I wanted one of those but I decided instead to blow my money on a 
>> > Palm
>> > Zire 71
>>
>> How is the Zire? Was it the right decision? I'm delighted with my 
>> GP2X
>> but would like a bit more battery life - it doesn't appear to have 
>> any
>> power management at all. The chap who did all the power management 
>> for
>> the Fedora Core distribution is a good buddy so I've been bribing him
>> with beer and curries to see if he can put some time into GP2X power
>> management. He's back at university now so he should have plenty of 
>> time
>> available ;-)
>
> How is the battery life on the 2X? I was contemplating purchasing one
> maybe.
> The Zire 71 is for sure a bit more compact than the GP2X but it doesnt
> have nearly as much horsepower or video hardware. I use it as a MP3
> player haha, it also has a built in camera, but its resolution is
> 640x480 so the pics aren't exactly top quality.

The battery life is one of the weaker elements. The alkalines it came 
with lasted about 45 minutes and I got about an hour out of the 1200mAh 
NiMH cells from my girlfriends camera (I'd probably better give them 
back soon). I bought some Uniross 2400mAh NiMH cells after that and now 
I get about 2 and a half hours watching movies. I bought 4 so that I can 
have one set in use and one set on charge or spare and, to date, I have 
never been caught without power yet.

> It is based on a TI OMAP310 SoC (ARM9 @ 144Mhz). I havent seen any 
> TRUE
> 3D games on it since I have to pay money for 3D games and I am
> certainly not doing that ;).

I can't see anyone paying for games on an architecture where most are 
free. I guess if the games were really incredible and beyond the means 
of amateurs to write then there could be a small market but I think it 
would quickly be piratted into oblivion.

> I just was flipping over the PalmOS v5.x.x documentation. As it so
> happens the majority of applications are still compiled for the M68K
> derivative that was in the older Palms (VII, V, etc.). For places 
> where
> there is a need for performance they can be written in native ARM code
> (as "ARMlets") which you can invoke from the M68K code. Tons of 
> example
> code and a relatively well documented API. Though the PalmOS Developer
> Suite is a ~400MB download :-O!

Seems like normal run-of-the-mill legacy support bloat. Why not write 
the whole application in an ARMlet and get it really moving? Of course 
ARMlets mean that legacy support is lost so they might as well just have 
copiled for ARM anyway. Suprised by the big developer download - 
presumably the installed app is even bigger. Hopefully that is 399Mb of 
examples and 1 of compiler.

> I admit I am a heavy gamer, so I have both the PSP and the DS Lite. 
> But
> neither architecture is as "open" so to speak as the Palm or the GP2X.

The GP2X will appeal if you are into retro games but the native stuff is 
not all that hot really. Perhaps there will an increase in popularity 
soon.

>> There are 2 ARM9's in use and I believe one is for thinking and the
>> other is purely for handling graphics so there should be enough power
>> available for a bit of 3D - that would be a very interesting project 
>> and
>> might be something I could fancy having a crack at.
>
> That'd be neat! If I recall I don't think anything like that has been
> made for the GP2X. Mostly high quality 2D games (which are not bad at
> all).

There's Quake and Duke Nukem but I think that is only really pseudo 3D. 
I do have a SNES StarFox ROM which I haven't tried yet but it would be 
interesting to see how they handle the hardware accelerator that used on 
the original console. That sort of game would be a good place to start 
in developing some good fast 3D polygon movement. The ARM is probably 
powerful enough for a bit of texturing too. I guess it all depends on 
how much control you can have over the graphics processor and whether it 
is wired up sensibly.

>> I worked with ARM a good bit so I'm fairly comfortable with the
>> processors but I have never coded for Linux before so I have a pretty
>> steep learning curve. This is the main reason I bought the GP2X 
>> (other
>> than for watching the Sopranos on the train) because I think I'll be
>> using Linux in my next product and I want to learn how to use it in
>> plenty of time. Also once I get the hang of Linux properly then I can
>> finally be shot of Windows, for which my patience is dwindling - how
>> many iterations of Outlook do they need to get it right?
>
> That seems like a good use for the GP2X. You must have a big SD for 
> the
> Sopranos episodes? I like the Sopranos as well. My Zire 71 probably
> doesn't have the horsepower to play anything like that buy my PSP for
> sure could.

I use a 1GB SanDisk SD card. A divX episode of the Sopranos comes in at 
about 350Mb but, after all the applications, ROMs and mp3s, I only have 
about 200meg free. The movie player is pretty fussy about what it will 
play and some divX films just won't work at all. I've got virtual dub 
and a number of other open source video processing/DVD ripping tools 
that the GP2X wiki recommends so I should be able to fix them once I 
work it all out. It would be nice to have mpeg support right out of the 
box but I guess there are licensing issues. To be honest, mpeg is such a 
popular format that it would be worth putting a few dollars on the rrp 
to cover but I guess it would go against the open source philosophy.

Does the PSP have better support? That weird little disc it uses seems 
like a good point of failure when watching movies but it does use those 
expensive memory cards as well which might alleviate that. 

"larwe" <zwsdotcom@gmail.com> wrote in message 
news:1158954593.340085.266520@m7g2000cwm.googlegroups.com...

Tom Lucas wrote:

> Talking of price, I see your new book is now available in Amazon UK 
> and
> is only &#4294967295;16.49 and has free delivery. You might have made a sale 
> there,
> particularly because I just get paid today and I'm going to be doing
> drunken internet shopping tonight :-)

> Drunken internet shoppers account for at least 80% of my royalties.

I didn't get it this weekend because I got too drunk and bought a 32" 
LCD TV instead :-O I have sent my wish-list to my girlfriend in hope 
though.

> When applying for my current job I wanted to bring along a printout of
> the amazon.com page for my first book. Luckily I noticed before I
> handed it over that the "people who bought this also bought..." 
> section
> was full of titles like "How to be a Porn Star", "Find Hookers in Any
> City", and blank DVD media.

And what I damn waste of money it was. I sent it all back fast than you 
can say "Goodness, you shouldn't have one of _those_" Err um did I say 
me I meant some guy I know...

David Brown wrote:
> msg wrote:
> > Tom Lucas wrote:
> >
> >
> >>
> >> Speaking to a very old hairy-eared engineered once he told be that the
> >> ROM he used many many years ago was windings of copper wire with
> >> ferrite beads on them to represent data. Apparently they always used
> >> women to wind the wires because they were more accurate than men. But
> >> I digress....
> >>
> >
> > Holy cow, it wasn't THAT long ago; I did a lot of transformer ROM
> > re-wiring (to change code).  --Still have devices running using
> > transformer ROM.
> >
> > Most transformer ROM used U-cores so that the assembly can be easily
> > opened for maintenance (rather than torroids).
> >
> > Regards,
> >
> > Michael Grigoni
> > Cybertheque Museum
>


> Some of the old mainframes had absolutely no ROM.  When you boot them,
> you have to code in the machine code instructions using a set of DIP
> switches until you've got enough to start booting (from disk, tape,
> punch card, or whatever).  Fortunately, these things were seldom
> switched off.

When I was working in Saudi (in Riyadh on the air traffic system), we
had, in one particular shack full of equipment, a Rolm communications
control processor. This was about 25 years ago :)

This device had 16 adddress switches (helpfully labelled '0' and '1' ;)
, 16 data switches also helpfully marked, a spring loaded 'load' switch
and a switch marked 'Run'.

The power up for this beast was to set address 0, set the data switches
appropriately from the manual and hit the 'load' switch. repeat at
successive addresses until the required 64 words were loaded.

Move the run switch to the RUN position. The 64 instructions were the
tape reader init code so it could boot from tape.

and people complain about boot times ;)

Cheers

PeteS