How about simulating a dolby b decode?

  • Thread starter Thread starter mixsit
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mixsit

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I'm doing some cassette transfer to cd and as often, overall it sounds better with n.r. off, except where some of the songs are quieter or have lower recorded level the high end is doing a bit of that 'swimming.
I'm thinking maybe a dynamic eq (a plug I don't have) in a light expansion mode? It'd be cool if it had just enough effect to partially counter it.
Wha'da ya think?
 
:DYo Mix:

The key of B is too tough for me to play in.


:pGreen Hornet


Happy New Year:rolleyes:
 
rayc said:
vinyl - waverepair - THE BEST. See the link below for an explanation:
http://www.homerecording.com/bbs/showthread.php?t=256352
Click to expand...
Hey thanks. That looks great for the vinyl projects. I'm suprised I didn't come across that on searches before. 16bit only but that's no problem since I'll be collecting in Sonar anyway.
I found this (haven't tried it out yet) for multi-band'. It does up or downward comp or expansion. http://www.platinumears.com/freeplugins.html

There's this one that aims right at dolby b but looks like it's only for playback in Winamp'.
http://www.hansvanzutphen.com/stereo_tool/

Looks like fun.:rolleyes:
 
IMHO the only Dolby B decoder software I would use (if it was available) is a REAL Dolby B decoder, ie: one that has been designed to track just as the Dolby decode specification requires, and described (probably) on the Dolby website.

Until someone markets one, I'll stick with a standard Dolby B analog decoder. Even a decoder out of an old cassette deck will IMHO lick trying to guess your way through using off the shelf noise reduction software.

If you want to simulate the Dolby B decode thing, understand what it needs to do. It has to be a sliding band dynamic low pass filter that works as per the Dolby B standard. It also has to be calibrated to the tape playback level just like the analog decoders had to be calibrated.

A properly decoded Dolby A, B, C, S or SR tape should have few or no audible artifacts. If anyone can achieve that by guesswork, using products not specifically designed for that purpose, I salute them. They have a lot more patience than me.

Cheers Tim
 
Tim Gillett said:
IMHO the only Dolby B decoder software I would use (if it was available) is a REAL Dolby B decoder, ie: one that has been designed to track just as the Dolby decode specification requires, and described (probably) on the Dolby website.

Until someone markets one, I'll stick with a standard Dolby B analog decoder. Even a decoder out of an old cassette deck will IMHO lick trying to guess your way through using off the shelf noise reduction software.

If you want to simulate the Dolby B decode thing, understand what it needs to do. It has to be a sliding band dynamic low pass filter that works as per the Dolby B standard. It also has to be calibrated to the tape playback level just like the analog decoders had to be calibrated.

A properly decoded Dolby A, B, C, S or SR tape should have few or no audible artifacts. If anyone can achieve that by guesswork, using products not specifically designed for that purpose, I salute them. They have a lot more patience than me.

Cheers Tim
Click to expand...
I agree mostly. What would be cool (maybe) is if om the tape deck you could adjust the decode action so that when it comes back 'dull on or shishy' off you could dial in somewhere in between.
And I didn't know it was also sliding the effect up/down in frequency.
 
Record a pass with NR and one without and edit together the best sounding parts.
 
Dolby doesnt work like that, at least not on most types of music and speech.

Dolby tracks the level and frequency changes of the program dynamically, in time with the music so to speak. So the Dolby effect can be fully "on" for 10milliseconds and then fully "off" for the next, and oscillating many times a second as the music plays.

The only way to get it to sound "unDolby" is to properly decode it, with a Dolby standard decoder. You fight fire with fire and Dolby with Dolby. In decoding, whatever processing the encoder did to the signal, gets equally processed in the opposite direction, many times a second. That's what the double D Dolby symbol is about. You reverse the processing by counteracting it.

As the Dolby website says, the problem with decoding is when the tape system itself no long accurately maintains the original program's level and frequency response exactly. The problem is not so much the Dolby system but errors in the tape record and playback system, which Dolby decoding tends to magnify, causing mistracking.
Once you understand that, you are well on the way to working out how to make the Dolby decoder track properly, even on tapes that no longer track, and maybe never tracked from the moment they were recorded.
Cheers Tim
 
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