Jconv - Convolution Reverb for Jack
Installing Jconv
Puppy Linux
- Download puppy-jconv.zip from http://www.puppylinux.ca/members/DAW/puppy-jconv.zip.
- Decompress the zip file.
- Click on puppy-jconv.pet.
- Click on Install Package.
- Click OK or close the Success screen by clicking on the
X on the upper right corner.
- Two directories have now been created within the /root folder: ir-conf
and ir-wavs. These contain the configuration files and the impulse
response recordings.
Ubuntu Studio (and other Debian
based systems)
- Download ubuntu-jconv.zip from
http://www.puppylinux.ca/members/DAW/ubuntu-jconv.zip.
- Decompress the zip file.
- Double click on libzita-convolver0_0.1.0-0.pm.1_i386.deb to install the convolution library.
- If any dependancy issues are reported resolve them by installing the required packages.
- Double click on jconv_0.2.0-0.pm.2_i386.deb to install the jconv
binaries.
- If any dependancy issues are reported resolve them by installing the required packages.
- Some standard sample impulse response recordings and configuration files can now be found in /usr/share/jconv.
- Save the /ir-conf and /ir-wavs subdirectories
to your user area (these contain the sample configuration files and impulse response
recordings that I have used so far).
- Open the .conf files located in /ir-conf within the text editor and change the path
location of the /ir-wavs directory to match your system (i.e. change '/cd /root/ir-wavs'
to '/cd /home/user/ir-wavs'). See the next section for more information.
Configuration Files
Jconv uses configuration files to gather all the information needed to perform the
convolution reverb magic. A .conf file will contain information about how many audio
channels are involved as inputs and outputs, what impulse response recrodings are
used, the location of those recordings, and the gain level, delay level, and offset
value for each reverb channel created. See https://bb.linuxsampler.org/viewtopic.php?f=7&t=52
for more details.
The configuration file is fairly simple. Let's use an example from the sample configuration
files created for this project. Open the file navigator and go to /ir-conf.
Click on chapel16b44k.conf to open it in the text editor.
The first line (remembering that '#' at the beginning of a line comments it out
- making it invisible to jconv) will look like this...
/cd /root/ir-wavs
This changes the directory to the one containing the impulse repsponses so
that we don't have to repeat the whole absolute path further down.
The next line looks like this:
-
/convolver/new 2 2 512 80000
This informs jconv that we're creating a new convolver with two input and two output
channels, the partition is 512 samples (the same as the JACK period for zero latency)
and the last number is the maximum amount of memory (RAM) an impulse will use (we
will use a default value that is larger than most of the impulse response files).
The next two lines work together...
-
/impulse/read 1 1 0.5 0
0 0 1 chapel_16b44k.wav
/impulse/read 2 2 0.5 0
0 0 2 chapel_16b44k.wav
These lines tell jconv to load the impulses into each channel. The values are: input, output, gain, delay, offset, length and channel, respectively. So the above simply
applies a stereo IR to a pair of channels. Delay and offset can be used to shave of
samples to get rid of any direct sound and make the signal completely 'wet'.
I have included sample conf files for three impulse responses - Chapel,
Great Hall, and York Minster. These were modified
for our purposes from Fons Adriaensen's work (he created jconv). Many thanks Fons!
The 16b44k and 24b48k refer to the sample rate of the wave file - 16bit 44.1 kilohertz
and 24bit 48kilohertz respectivly. Use the sample rate that best matches your sound
configuration.
Other Impulse Response files are freely available on the internet, and some professional
quality IR files are also available for purchase.
Get the IR recording of the Lafeyette Theater (donated by E. Hayek)
from Kent Allman's site at http://72.29.87.235/filesupload/LafayetteReverb1.zip
Starting Jconv
- Open a Terminal/Console window by clicking on console icon.
- Type in jconv /root/ir-conf/chapel16b44k.conf at the command line.
- Minimize the window in which jconv is running.
Scripting with Qjackctl to start Jconv
Still to come... automatically starting jconv when starting Qjackctl by using scripting.
See https://bb.linuxsampler.org/viewtopic.php?f=2&t=165
Jack Connections
- Once jconv is started, click on the connections button in Qjackctl and map the connecitons
from LinuxSampler -> jconv -> system
Still to come - Using Persistent connections.
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