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#36403 - 12/08/2001 12:22 Dynamic Volume Control from Engine?
nickdiaz
new poster

Registered: 09/12/2000
Posts: 4
Loc: Silicon Valley, CA
I'm the proud new owner of a RioCar player. My wonderful girlfriend bought one for me for our 1 year anniversary. I had it installed the same day, and the next day we were on a week long road trip vacation. The player is fantastic.

The only thing I miss from my stock radio system is the dynamic volume control. I would typically keep the knob on the second to lowest sensitivity, and the volume was just always right, whether I was sitting at a stoplight, or redlining my engine.

I've done searches, but have found no reference to anyone trying to get this functionality out of the empeg. Any ideas?


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#36404 - 12/08/2001 14:34 Re: Dynamic Volume Control from Engine? [Re: nickdiaz]
mardibloke
addict

Registered: 14/08/2000
Posts: 468
Loc: Penarth, UK
If you ever split up from your girlfriend do let us know

- --
Rod, UK Mk2 64gig Red S/No.341 2xDell RioReceiver
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Rod, UK

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#36405 - 12/08/2001 20:23 Re: Dynamic Volume Control from Engine? [Re: nickdiaz]
msaeger
carpal tunnel

Registered: 23/09/2000
Posts: 3608
Loc: Minnetonka, MN
what kind of car does it have a double din radio opening if it does maybe you could run the empeg thorugh the old head unit

32Gig MK2 In 2001 VW Golf TDI
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Matt

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#36406 - 13/08/2001 01:50 Re: Dynamic Volume Control from Engine? [Re: nickdiaz]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31600
Loc: Seattle, WA
Congratulations on your new toy!

The car docking sled has a microphone connector (assuming your installers didn't cut it off-- some installers have been known to do that sort of thing).

This connector isn't currently used. In the future, it will be used for voice-recognition software. But in the meantime, there have been discussions about using it for road-noise-based volume control. You know, use a small, cheap microphone to sample the ambient noise from, say, the engine compartment, and scale the volume accordingly.

To do it, someone would have to write what's known as a kernel hack, a third-party rewrite of the empeg's boot kernel. This isn't as complicated as it sounds, actually, other kernel hacks have already been done.

Since people have already talked about doing the noise-based-volume before, I'm surprised no one has done it yet. Anyone want to give it a whirl?

In the meantime, there's another kernel hack already available that you might want to try. It's called the "Volume Adjustment Kernel", or "Voladj" for short, and it's essentially a dynamic compressor. It increases the volume on quiet musical passages so they can be heard above the car's noise floor. This isn't exactly the same as what you're requesting. Voladj isn't based on the car noise, it's based on how quiet the song is at any given moment. Richard Lovejoy (its author) has mentioned the idea of integrating Voladj and some sort of microphone-based system together into one kernel hack, although it has not been done yet.

For mor information on installing kernel hacks, please read the entry in the FAQ forum of this BBS called "How do I put custom logos or kernels into my player?".

Also, you can do a search on this BBS for "picker and voladj for dummies", which is a slightly more complicated trick allowing the empeg to boot with a menu that allows you to select whether voladj is turned on or off.

Again, welcome, and congratulations on your new toy.

___________
Tony Fabris
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Tony Fabris

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#36407 - 13/08/2001 22:12 Re: Dynamic Volume Control from Engine? [Re: tfabris]
johnmcd3
enthusiast

Registered: 19/04/2001
Posts: 369
Loc: Seattle, WA (formerly Houston,...
Some cars (e. g. BMWs) have a line that goes to the radio that tells of car speed then the stock BMW radios adjust volume. There is a way to change how much the volume is altered due to speed as well. I haven't put a multimeter to the line yet, but its probably a sliding voltage or something. Trouble is I don't know enough to write a kernal hack to take advantage of this yet (although I have a EE/CS double major at duke, maybe in 2 or three years). In the mean time, if I gave information on the voltage, might someone be able to right something to accept that wire from the serial port? Preferably I would be able to adjust a config file to change how much volume adjustment there is. I am just a college student, but maybe I could provide some incentive/favor to someone . . . .

Thanks,

- John

P. S. Maybe in other cars you coud tap into the spedometer line or something for a similar effect.

30 GB - Mk2a (Rio Car) - BLUE, but I really want a red ar, msg me
_________________________
1998 BMW ///M3 30 GB Mk2a, Tuner, and 10 GB backup

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#36408 - 14/08/2001 02:28 Re: Dynamic Volume Control from Engine? [Re: nickdiaz]
altman
carpal tunnel

Registered: 19/05/1999
Posts: 3457
Loc: Palo Alto, CA
If it's PWM indicating the engine speed, this could be fed into the headlight/phone mute line and you could write a kernel driver to scale the volume accordingly.

Hugo



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#36409 - 15/08/2001 01:46 Re: Dynamic Volume Control from Engine? [Re: altman]
Dava
member

Registered: 06/12/2000
Posts: 192
Loc: Bucks UK
Having recently fitted a Nav system to my car, it appears that there are 2 ways that the vehicle speed is reported to the head unit/nav system.

One method uses a sliding voltage which I suppose is generated by some type of dynamo affair attached to the prop shaft or speedo cable.

The other uses a pulse (usually either 4 or 8 pulses per revolution).

My car had neither (deep joy) so I was forced to fit a small transducer in the speedo cable. This gives 4 PPR and the Nav system will autocalibrate this to the GPS signal over time so that in the event of GPS signal loss, the speedo sense allows the system to do dead reckoning in conjunction with the map overlay, gyroscope and compass it has built in.

It all seems very accurate and tells me that my cars speedo reads 100mph when I am really only doing 95. This is apparantly normal as the UK regs say -0% to +5% for speedo accuracy.

It is reported that in some makes of car this signal is factory routed to those 2 connector blocks that go into the back of the ICE unit.

I would like to volunteer Richard Lovejoy to the work for Speed Dependant Volume Control .His Voladj Kernal is superb and seems to do all the hard stuff, we just need a way to count 12V pulses on one of the serial pins and process the volume accordingly.

The other benefits of this connection could be a Speedo reading visual, trip computer with average speed, distance (or fastest 0-60 time for the boy racers) etc. The list goes on.

MK2 Red S/n 949
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MK2 smoked 32Gb S/n 090000949 MK2a Blue 20GB racked and out of sync

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#36410 - 15/08/2001 10:01 Re: Dynamic Volume Control from Engine? [Re: Dava]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31600
Loc: Seattle, WA
Having recently fitted a Nav system to my car (...)
I suppose is generated by some type of dynamo affair attached to the prop shaft (...)


Mr. Bond, you're not supposed to let that sort of information slip on the internet.

_
Q
_________________________
Tony Fabris

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#36411 - 15/08/2001 10:16 Re: Dynamic Volume Control from Engine? [Re: Dava]
johnmcd3
enthusiast

Registered: 19/04/2001
Posts: 369
Loc: Seattle, WA (formerly Houston,...
This idea interests me greatly. In the next day or so I'll find out which system bmws use.

30 GB - Mk2a (Rio Car) - BLUE, but I really want a red ar, msg me
_________________________
1998 BMW ///M3 30 GB Mk2a, Tuner, and 10 GB backup

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#36412 - 16/08/2001 01:37 Re: Dynamic Volume Control from Engine? [Re: johnmcd3]
Dava
member

Registered: 06/12/2000
Posts: 192
Loc: Bucks UK
My guess is that it is the pulse type, if this is the case then it should be very easy to interface to the serial port.

Once the connections are made you would need a piece of calibration software which simply counted and displayed the pulses over a 5 mile drive (no wheel spins now!).

Once you have this, in conjunction with the inbuilt clock you can calculate:

Distance
Speed
Acceleration
G- Force !


Oh, and adjust the volume as originally requested.


PS. I see that you are looking for an AR Red for your new beamer, I will swap mine for the blue you have if you want.


MK2 Red S/n 949
_________________________
MK2 smoked 32Gb S/n 090000949 MK2a Blue 20GB racked and out of sync

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