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PostPosted: Mon Sep 21, 2009 8:12 am 
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This is the Discussion Thread for the Wiki entry titled "Preparing the stereo source files for a conversion". Please post all questions and comments about source file preparation here in this thread.

To view the original Wiki Entry titled "Preparing the stereo source files for a conversion", click here.


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PostPosted: Thu Nov 25, 2010 1:34 pm 
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Good day,

I rummaged thru Search and this looks to be the right place I think.

Have used R8Brain to convert EAC rips from 44.1/16 to 96K/24 but Plogue doesn't like it. I got the warning that file 96K was different from project 44K setting. Went to Preferences - DSP and changed the Sample Rate to 96000 Hz setting and Applied it. Have increased FFT size and FFT overlap settings per other discussions but none of these settings have any effect on SPEC4.3 playing them correctly.

The 96K file is played at the wrong tempo garbled oviously wrong. What am I overlooking? (prepared 20 of these 96K files would like to get going!)

Thanks

EDIT: 96/24 files play fine in SoundForge so it's something in Plogue......


Last edited by timbre4 on Thu Nov 25, 2010 1:48 pm, edited 1 time in total.

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PostPosted: Thu Nov 25, 2010 1:36 pm 
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PS - Seems like any change I make Plogue closes down (used o this) but these changes also generate an error msg to send every time?


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PostPosted: Thu Nov 25, 2010 7:32 pm 
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Unless you have a very fast computer, playing a 24-96 source in real time through SPEC puts too much load on Plogue. SPEC is a complex program which has to process every single sample one after another. It's no problem doing it offline, but it's another story in real time. Sound Forge does nothing to the source other than playing it, that's why it can do it. The limitation could also be with your sound card, but apparently not in your case because SF can play it.

I do all my live monitoring at 44.1 or 48KHz. If the source is 96KHz, I downsample a copy to 48KHz for live monitoring purposes only. When I'm happy with the settings, I save the layout and I do the measurement run with the low-sample version. I save the layout again, load the 88.2 or 96KHz version, change the DSP settings, switch ZAG to "apply gains" and record.

Before changing the DSP settings, always make sure Plogue is "off". It used to crash every time you changed the DSP settings, but this issue was mostly fixed in a recent Plogue version.

Please report back.


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PostPosted: Sat Nov 27, 2010 9:03 am 
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That makes sense, I hadn't factored the resulting load!

I kept the previous 44.1K EAC versions so I'm thinking these would work in finding the settings for the album in progress. Thanks for the input, back on this work later today and will share results.


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PostPosted: Sun Jan 09, 2011 6:45 am 
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Hello All, what I miss here is a clear indication of what the source files should look like.
First of all you have a 2 channel stereo file of excellent quality, if not, the final result will be disappointing. now you have to prepare (in case of 5.1) 6 channels with certain
characteristics, to make sure that the final product, the DTS CD, produces a nice surround
image in your listening room. To be able to prepare each channel suitable for its task,
imagine yourself, sitting in the original recording studio or hall or whatsoever. Lets assume
a combo or small orchestra is playing (never mind the type of music it is only an example)
What your ears first hear is the direct sound of the solo instruments, most of the time
situated in the middle area, then your ears are struck with the echo´s produced by the side walls of the recording room or studio, then what you hear is the echo of the back wall
of the recording area, this is all a question of the runtime of the sound waves, the delay in time before hitting your ears and the phase shifting are necessary to produce the surround
effect. Therefor your 2 channel original stereo file must be of excellent quality. Before going
on I am waiting for replies of this what I call "Preparing your files Part 1"


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PostPosted: Sun Jan 09, 2011 8:38 am 
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geoff221 wrote:
Therefor your 2 channel original stereo file must be of excellent quality. Before going
on I am waiting for replies of this what I call "Preparing your files Part 1"
Hello Geoff and welcome here.

I'm not really sure what your asking. You're absolutely right that the better the source, the better the upmix should sound. Usually sources released in 24bit and 96000Hz are the best, but they are quite rare. Normal CD's are in 16bit 44100Hz and the quality varies very much.

In the stereo mix, you want to hear precise instrument and voice panning. On some CD's, everything is crunched up in the center or the sound is very diffuse: this is usually not going to work very well.

You want clear and pristine sound with wide dynamic range as this is going to amplify the surround effects.

You want several instruments. A single acoustic guitar will normally create a very artificial surround soundfield, but I have heard very good upmixes of acoustic guitar music.

These are just general rules and there are exceptions to every rule. Even experienced upmixers don't always know in advance how an album will sound. That's why live monitoring is so important. I would say that I reject maybe 50% of the upmixes I attempt. When I reject something, I look for a better source if there is one and try it again.

I guess my answers are more about selecting the source than preparing them. Is this the kind of information you were looking for?


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PostPosted: Sun Jan 09, 2011 11:22 am 
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What we are doing here is not recreating a concert hall.

With SPEC, you won't get a sound stage in front of you with early and late reflections or ambiance added in the rear speakers.

What you do get is the stereo mix spread across (up to ) 360 degrees around you. It's typically more like being on stage, with the instruments all around you.

If the producer panned a sound all the way to the right, with SPEC it will come out of right rear speaker (or both rears if you use "wrap rears"), etc.

With ArcTan you can control what portions of the original stereo mix fit into each speaker in the surround.

Anyway, we call the actual process of converting stereo to surround "conversion", and by "preparing the source" we just mean getting the stereo source ready for that process. Typically one long lossless wave file for an entire album. You'll also need a cue file, as that is used by our automatic gain control feature.

Z


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PostPosted: Sun Jan 16, 2011 11:00 am 
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Hello all,first let me tell you that I am not trying to create a concert hall, the only goal is to create a sound image that represents the original recording as good as possible. I think I found a way to accomplish this as follows:
1. Center channel: mix down the two stereo files into one mono file, listen carefully how it sounds, make corrections with a spam equalizer if necessary but don´t exaggerate, then with the help of a highpass filter, cut everything off
below 120 Hz with a slope of 6 dB/Okt. Adjust the peaklevel to -2 dB and save the file as "music so and so Center channel"
2. Left front channel: mix down your left stereo channel to one monochannel and prepare this file in the same way, may be weaken the higher frequencies just a little bit compared to the center channel, try 3 dB downpoint at 10 kHz.
Adjust the peak volume to -3 or-4 dB and save it as your "x Left front Channel".
3. Right front channel: Prepare it in exactly the same way and save it as your Right front Channel.
4. Left rear channel: again prepare this in exactly the same way as the left front channel only before saving it give it a phase shifting of +45 degrees.
5. Right rear channel: the same procedure as the left rear channel but before saving this file give it a phase shifting of - 45 degrees.
6. LFE channel (for woofers only). Mix down both your stereo files into one mono channel and then with the help of a low pass filter cut everything off above 120 or 130 Hz, listen to this file and if you still hear to much music,
adjust the cutoff slope to -12dB.With the help of the spam equalizer cut everything off below 30 Hz, adjust the volume to -20 dB and save the file as your "xxx LFE Channel"
This is all for now, explanations if neccessary will come later.


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PostPosted: Sun Jan 16, 2011 11:16 am 
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geoff221 wrote:
Hello all,first let me tell you that I am not trying to create a concert hall, the only goal is to create a sound image that represents the original recording as good as possible. I think I found a way to accomplish this as follows:
1. Center channel: mix down the two stereo files into one mono file, listen carefully how it sounds, make corrections with a spam equalizer if necessary but don´t exaggerate, then with the help of a highpass filter, cut everything off
below 120 Hz with a slope of 6 dB/Okt. Adjust the peaklevel to -2 dB and save the file as "music so and so Center channel"
2. Left front channel: mix down your left stereo channel to one monochannel and prepare this file in the same way, may be weaken the higher frequencies just a little bit compared to the center channel, try 3 dB downpoint at 10 kHz.
Adjust the peak volume to -3 or-4 dB and save it as your "x Left front Channel".
3. Right front channel: Prepare it in exactly the same way and save it as your Right front Channel.
4. Left rear channel: again prepare this in exactly the same way as the left front channel only before saving it give it a phase shifting of +45 degrees.
5. Right rear channel: the same procedure as the left rear channel but before saving this file give it a phase shifting of - 45 degrees.
6. LFE channel (for woofers only). Mix down both your stereo files into one mono channel and then with the help of a low pass filter cut everything off above 120 or 130 Hz, listen to this file and if you still hear to much music,
adjust the cutoff slope to -12dB.With the help of the spam equalizer cut everything off below 30 Hz, adjust the volume to -20 dB and save the file as your "xxx LFE Channel"
This is all for now, explanations if neccessary will come later.


It seems to me like what you are doing is bypassing our method entirely and is going to create a mix with very little separation or soundfield. If that's what you're looking for, hey, it's your living room. :)


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