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#77734 - 04/03/2002 20:59 Front/back ?
dcosta
enthusiast

Registered: 04/02/2002
Posts: 277
Loc: Massachussetts
In the equalizer, if I set it to 4 channel operation, I get another equalizer menu feature called "Front/back" it's options are either "Front" or "Back". Now I'm pretty good at figuring stuff out, but this just isn't jumping out at me.
Anyone know what selecting "Front" or "Back" actually does ?
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#77735 - 04/03/2002 21:09 Re: Front/back ? [Re: dcosta]
Alan
member

Registered: 06/05/2000
Posts: 142
Loc: Cedar Grove , IN
Select back, then back up a few menus and you adjust the rear. Same for front. It's not the most user friendly menu.

Alan
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#77736 - 04/03/2002 21:26 Re: Front/back ? [Re: Alan]
dcosta
enthusiast

Registered: 04/02/2002
Posts: 277
Loc: Massachussetts
Not sure I get it, I am in 4 channel mode and I have them locked "Left=Right"
It's my understanding that the outer two 5-band eq's are for the rear and the inner two are for the front, or maybe it's vice versa.
But the point I'm trying to drive home is "cant you just use the right button to cycle through the first 5 to get to the second five ?"
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#77737 - 04/03/2002 21:49 Re: Front/back ? [Re: dcosta]
Alan
member

Registered: 06/05/2000
Posts: 142
Loc: Cedar Grove , IN
Front and rear aren't displayed at the same time on the screen. What you see is left and right, and they're locked together.
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#77738 - 04/03/2002 22:05 Re: Front/back ? [Re: Alan]
dcosta
enthusiast

Registered: 04/02/2002
Posts: 277
Loc: Massachussetts
I see 20 bands in 4 channel mode, 5 for each of 4 channels.
I have them locked left=right.
When I adjust 5-band eq #1 the adjusments are made to 5-band eq #4 and
when I adjust 5-band eq #2 the adjusments are made to 5-band eq #3.
That makes perfect sense to me, but
I still don't get the whole front/back thing...

Furthermore, I'd like to be able to use 2 channel mode so that I have a 10-band eq for the front and a 10 band eq for the rear, this makes the most sense, since left and right speakers usually match, but front and rear speakers are usually different.
anyone got an idea on how to pull that one off...


Edited by dcosta (04/03/2002 22:10)
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#77739 - 04/03/2002 22:19 Re: Front/back ? [Re: dcosta]
Alan
member

Registered: 06/05/2000
Posts: 142
Loc: Cedar Grove , IN
You got me on that, I have never seen that display in the car. Forcing DC with hijack I see what you mean. If it wasn't 15deg outside I'd go out and verify that I'm not loosing it
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#77740 - 04/03/2002 22:59 Re: Front/back ? [Re: dcosta]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
Rotate your connections 90 degrees and then your front becomes your left and your back becomes your right. You'll just have to get used to using your fader to balance right-to-left and use your balance to balance front-to-back (and other similar things).
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#77741 - 04/03/2002 23:04 Re: Front/back ? [Re: wfaulk]
dcosta
enthusiast

Registered: 04/02/2002
Posts: 277
Loc: Massachussetts
Thought of that,
But, what about the player, a song in stereo will have independant left and right signals, that will now come out front and rear... ca-ca poop - me no like.
any way to compensate for this in the software ?
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#77742 - 04/03/2002 23:22 Re: Front/back ? [Re: dcosta]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
Uhh. Duh. Very good (and, you'd think, obvious) point.
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#77743 - 05/03/2002 11:23 Re: Front/back ? [Re: dcosta]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31597
Loc: Seattle, WA
No, there is no way to compensate for it in the software. The DSP accepts only a left and a right input. Period. There is no way to alter what the front does independently of the back, except the EQ'ing as provided for inside the DSP.
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#77744 - 05/03/2002 21:20 Re: Front/back ? [Re: wfaulk]
Diznario
enthusiast

Registered: 17/10/2001
Posts: 265
Loc: Portland OR
Speaking of strange ways of wiring up the channels in a car...

Have any of you guys ever tried reversing the stereo on just one of either the front or back channels? So that the front left plays the same thing as the right rear?

I've experimented with this setup before... Leads to some *Very* interesting stereo imagery...
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MK2 in an Impreza 2.5RS

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#77745 - 06/03/2002 03:53 Re: Front/back ? [Re: Diznario]
peter
carpal tunnel

Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
Leads to some *Very* interesting stereo imagery...

A friend of mine, when he was a student, had a car cassette player whose read head wandered seriously out of alignment. First he had the left channel coming out of both speakers, then he had the left channel coming out of the right speaker and silence on the left, and ultimately he had the left channel coming out of the right speaker and the left channel of the other side of the tape coming out of the left speaker backwards. Now that was interesting stereo imagery, especially with all the unusual music he used to listen to.

Peter

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#77746 - 06/03/2002 04:48 Re: Front/back ? [Re: peter]
smu
old hand

Registered: 30/07/2000
Posts: 879
Loc: Germany (Ruhrgebiet)
Hi.

That reminds me:
Does anyone know if it is possible (probably only with some effort, if at all) to play an mp3 file backwards?

cu,
sven
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#77747 - 06/03/2002 07:47 Re: Front/back ? [Re: smu]
tonyc
carpal tunnel

Registered: 27/06/1999
Posts: 7058
Loc: Pittsburgh, PA
Does anyone know if it is possible (probably only with some effort, if at all) to play an mp3 file backwards?


"The music is reversible, but time is not. Turn back! Turn back!"

"It's fun to smoke marijuana!"

"Turn me on dead man!"


Sorry, but I couldn't resist. Anyway, I've never done it, but it seems to me playing an MP3 backwards would just be an exercise in starting at the end, decoding the last frame, reversing it, and lining it up with the "next" (actually previous) frame in the output stream.

Though I think backwards playing functionality on the Empeg may open SonicBlue up to lawsuits from parents who think that there are evil hidden messages in their kids' music.
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my empeg stuff

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#77748 - 06/03/2002 08:11 Re: Front/back ? [Re: tonyc]
tms13
old hand

Registered: 30/07/2001
Posts: 1115
Loc: Lochcarron and Edinburgh
In reply to:

Anyway, I've never done it, but it seems to me playing an MP3 backwards would just be an exercise in starting at the end, decoding the last frame, reversing it, and lining it up with the "next" (actually previous) frame in the output stream.


It's a bit harder with VBR files than forwards decoding, as you need to search for the beginning of each frame. In effect, you're always unsynchronised with the stream.

I think you could probably reverse an MP3 file losslessly without fully decoding it, now I think about it (and you can parse it forwards if you're willing to write the output backwards).
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#77749 - 06/03/2002 09:03 Re: Front/back ? [Re: tms13]
peter
carpal tunnel

Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
I think you could probably reverse an MP3 file losslessly without fully decoding it, now I think about it

The bit reservoir carries bits forward in time only, so I don't think you could do it properly without decoding to PCM and reversing the PCM.

Peter

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#77750 - 06/03/2002 09:25 Re: Front/back ? [Re: peter]
tms13
old hand

Registered: 30/07/2001
Posts: 1115
Loc: Lochcarron and Edinburgh
Good point - I'd totally forgotten about bit reservoir issues.
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#77751 - 06/03/2002 18:25 Re: Front/back ? [Re: smu]
msaeger
carpal tunnel

Registered: 23/09/2000
Posts: 3608
Loc: Minnetonka, MN
you could do it with sound play on beos
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#77752 - 07/03/2002 01:49 Re: Front/back ? [Re: smu]
jane
enthusiast

Registered: 10/10/2000
Posts: 350
Loc: Copenhagen SW, Denmark
I seem to remember that the Empeg standard includes
optional frames that will enable reverse playback (for searching). I don't know wether this appiles to the soundtrack as well (mp3)

Marius (Escort Cab + Mark II)

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#77753 - 07/03/2002 10:08 Re: Front/back ? [Re: peter]
smu
old hand

Registered: 30/07/2000
Posts: 879
Loc: Germany (Ruhrgebiet)
Hi Peter.

I thought about the bit reservoir, and I wonder if the bit reservoir could be sufficiently filled by decoding (only) the previous mp3-frame. That is if an mp3 file consists of frames A,B,C,D,E,F and I don't have enough memory to decode it completely to reverse it, would it be possible to
decode E to get the correct bit reservoir for F, decode F and reverse (play) it.
decode D to get the correct bit reservoir for E, decode E and reverse (play) it.
...

Would that seem sensible (apart from the fact that you decode 2n-1 frames to play n frames)?

cu,
sven
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#77754 - 07/03/2002 10:32 Re: Front/back ? [Re: smu]
peter
carpal tunnel

Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
Would that seem sensible (apart from the fact that you decode 2n-1 frames to play n frames)?

I think so. If you needed more than one previous frame to get the bit reservoir right, seeking would never work.

Peter

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#77755 - 07/03/2002 14:36 Re: Front/back ? [Re: smu]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
I've written some software that read data from the middle of an MP3 file, and that was definitely the answer to the problem there.
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#77756 - 08/03/2002 01:15 Re: Front/back ? [Re: jane]
jane
enthusiast

Registered: 10/10/2000
Posts: 350
Loc: Copenhagen SW, Denmark
The MPEG standard of course... not "Empeg standard".
(And why Can't edt my post?)

Marius (Escort Cab + Mark II)

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#77757 - 08/03/2002 05:24 Re: Front/back ? [Re: jane]
mtempsch
pooh-bah

Registered: 02/06/2000
Posts: 1996
Loc: Gothenburg, Sweden
I think the edit option is only available for a limited period of time after you've submitted the post. Actually it's in the BBS FAQ, here

/Michael
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