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Author Topic: Convolution and multiple samplerate in MC21  (Read 5658 times)

JAVA Alive

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Convolution and multiple samplerate in MC21
« on: September 10, 2016, 11:00:29 am »

Hi,

I want to use convolution for frequency response correction and I am facing contradictions between documentation and behavior of the convolver plugin. (By the way, I find documentation on convolution is very poor)

Documentation says that filters are only for one sample rate but when I test in JRiver, a 44.1khz filter is applied to 96khz files. No output format is done in JRiver. Is it normal ? What sample rate filter should I use so that it applies to all input formats with the best audio output ?

 In addition, when I try to use TXT config file, I can't setup 2 filters for 2 sample rates.

 This file works :
Code: [Select]
44100 2 2 0
0 0
0 0
C:\Impulses\impulse44100.wav
0
0.0
0.0
C:\Impulses\impulse44100.wav
0
1.0
1.0

This file works :
Code: [Select]
96000 2 2 0
0 0
0 0
C:\Impulses\impulse96000.wav
0
0.0
0.0
C:\Impulses\impulse96000.wav
0
1.0
1.0
This file (addition of both) doesn't work (message is "not valid" in status field) :
Code: [Select]
44100 2 2 0
0 0
0 0
C:\Impulses\impulse44100.wav
0
0.0
0.0
C:\Impulses\impulse44100.wav
0
1.0
1.0
96000 2 2 0
0 0
0 0
C:\Impulses\impulse96000.wav
0
0.0
0.0
C:\Impulses\impulse96000.wav
0
1.0
1.0

I tried to seperate the 2 block by empty line, does not work also.

Anyone can help ?

Thanks a lot.
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mattkhan

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Re: Convolution and multiple samplerate in MC21
« Reply #1 on: September 10, 2016, 02:40:32 pm »

https://wiki.jriver.com/index.php/Convolution explains how the resampling works and the cfg file name format rules
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JAVA Alive

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Re: Convolution and multiple samplerate in MC21
« Reply #2 on: September 10, 2016, 03:42:21 pm »

Hi,

 Thanks but i've read this page and linked pages.
 
 Regarding multiple sample rates it says "If you want more control over what happens with different sample rates and channel configurations, you can generate separate filters at each sample rate, and MC will automatically switch between them, but you must use the following naming format for your filters: Name2.0_441 or Name5.1_48, etc. The regular expression is: ^(.+)(\\d{1}.\\d{1})_(\\d{2,3}).cfg$, which outputs: Name Channels Sample rate"

 Well sorry, I understand nothing.
 
 On this linked page they say :

 "Filter list

In situations where you are using several different formats (eg, stereo 44.1kHz and 5.1 48kHz) it is convenient to be able to switch automatically between filters.

So a config file can also comprise of a list of

    filter specification config file names of the type described above; and
    WAV impulse response filenames

one per line.  The filter used will then be the first to match the current sound source (in terms of number of input and output channels and sample rate).  This allows you to play both stereo and 5.1 sources, say, without having to change the config file."

  Not sure to understand. Any example would help.

Thanks.
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mattkhan

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Re: Convolution and multiple samplerate in MC21
« Reply #3 on: September 10, 2016, 04:35:56 pm »

What exactly do you want to achieve? Use your own filter per sample rate instead of jriver resampling a single filter for you?

If so just put the 2 bits of config (one per sample rate) in different config files and use the naming convention given on the wiki page for the cfg files.eg myfilter2.0_441.cfg and myfilter2.0_96.cfg for the example you have combined into one file.

If you want to do something else then post exactly what you want to achieve.
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JAVA Alive

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Re: Convolution and multiple samplerate in MC21
« Reply #4 on: September 11, 2016, 04:37:48 am »

I am trying to have several configs for different input formats (sample rate or number of chanels).

I don't really understand what you mean by "2 bits of config". You mean I make 2 cfg files with 1 config per file, right ?
I name them, by example : myfilter2.0_441.cfg and myfilter5.1_48.cfg. Right ?
Then what do I put in settings of the convolution dsp studio ?

Thanks.
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mattkhan

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Re: Convolution and multiple samplerate in MC21
« Reply #5 on: September 11, 2016, 07:48:42 am »

Yes that is what i meant, 1 complete configuration per cfg file.

You would create a set of files with the same prefix (myfilter in that example) and choose one in dsp studio. JRiver should then auto select the correct cfg as appropriate to the actual signal.

However note that I don't think it gives any information about whether it is doing this correctly or not. http://yabb.jriver.com/interact/index.php?topic=102394.0 can also catch you out.
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JAVA Alive

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Re: Convolution and multiple samplerate in MC21
« Reply #6 on: September 11, 2016, 09:00:03 am »

Ok, thanks I'll try this.
Not too sure of how to call a 2.2 setup. 2.2 or 2.0 ?
I'll test it. You can know which file is used by creating fake files with filters you can recognize 100% by earing them. Example : a low pass and a high pass. Once you're sure which file is used, you can replace them by the real impulse files.

Works but not user friendly ...
Yes, JRiver convolution interface is very poor.
A graphic selection of files to be used for each config, a proper error message for wrong configs and a proper documentation would be much nicer.

According to what I see on the forums, the cables stupidity is going down and room is more and more considered as the most important thing.

Therefore room corrections like convolution will become more and more popular even if room treatment should come first.

Thanks a lot again for your answers.
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mattkhan

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Re: Convolution and multiple samplerate in MC21
« Reply #7 on: September 12, 2016, 03:06:16 am »

Ok, thanks I'll try this.
Not too sure of how to call a 2.2 setup. 2.2 or 2.0 ?
The auto config switcher is based on common input formats (2.0, 5.1, 7.1 I think) not output formats like 2.2 so if you had output format set to produce a stereo signal then your 2.0 file would apply and you would create the .2 output either in the convolver or a subsequent peq stage.
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JAVA Alive

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Re: Convolution and multiple samplerate in MC21
« Reply #8 on: September 12, 2016, 03:25:02 pm »

Yes, thanks a lot.
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