MrsWatson is a command-line audio plugin host. It takes one or more plugins, sends an audio signal to them for processing, and saves the resulting output. Although the plugins think they are running in realtime, processing is actually done offline (this is not the same as the “offline” processing in VST terminology). This makes MrsWatson ideal for developing or debugging plugins, or processing audio on a server.
In 2009 I sold the exclusive rights to MissWatson to a company interested in using it for server-side audio processing. As per the terms of our agreement, I made one last public release, and removed the code from my website. Since then, I have received numerous emails and inquiries regarding the project, mostly from plugin developers or people interested in VST technology. Though I have no regrets about discontinuing the original MissWatson (particularly since I didn’t have time to properly maintain it), I felt that it was a useful utility which should be made available and open-sourced.
In 2011, my NDA with the aforementioned company expired, and I started working on a new MissWatson. MrsWatson is the result of this labor.
As I no longer have the source code for MissWatson, MrsWatson is a black-box implementation. They share only the name and concept in common. The two programs are incompatible and have fundamentally different behavior. They are also written in different languages (the original in C++, MrsWatson in C), and have completely different internal architecture.
If you have built some system which used the original MissWatson, then you will likely have to make some big changes to migrate to MrsWatson. Likewise, if you were using some of the original MissWatson code in your project, you will not be able to replace it with MrsWatson without significant work on your end.
Say you have an audio file which you would like processed through a group of mastering plugins.
mrswatson --input mysong.pcm --output out.pcm --plugin plugin1;plugin2
This will print the following output:
- 00000000 000000 Plugin 'plugin1' is of type VST2.x - 00000000 000000 Plugin 'plugin2' is of type VST2.x - 00000000 000000 MrsWatson version 0.1.0 initialized - 00000000 000000 Opening VST2.x plugin 'plugin1' - 00000000 000029 Opening VST2.x plugin 'plugin2' - 00000000 000144 Processing with samplerate 44100, blocksize 512, 2 channels - 03532800 000204 Total processing time 60ms, approximate breakdown by component: - 03532800 000204 plugin1: 38ms - 03532800 000204 plugin2: 11ms - 03532800 000204 MrsWatson: 11ms - 03532800 000204 Read 3528000 frames from mysong.pcm, wrote 3532800 frames to out.pcm - 03532800 000204 Shutting down - 03532800 000210 Closing plugin 'plugin1' - 03532800 000212 Closing plugin 'plugin2' - 03532800 000212 Goodbye!
To see more or less logging output, use the
--quiet options, respectively. MrsWatson generates colored output (if your terminal supports it) with two times per line, the first for the current sample and the second for the time in milliseconds since processing began. The sample time also changes colors after every 44100 samples to help visually break up processing times. This value can be changed with the
To process a MIDI file through an instrument, you’d do something like this:
mrswatson --midi-file mysong.mid --output out.pcm --plugin piano,soft.fxp
Like the first example, a list of plugins separated with semi-colons can be given here so that the audio generated by the instrument can be processed through any number of effects. Each plugin name can be followed by a comma and the location to a preset file to be loaded before processing.
Complete help for MrsWatson can be found by running the program with no arguments, or with
--help switch prints quite a lot of output, so you can also use
--options to see all supported options and their default values.
Currently, MrsWatson loads plugins by their short name by searching in the standard installation locations for your platform, as well as the current working directory and by absolute path. Use the
--list-plugins option to see the order of locations searched and the plugins found there.
While MrsWatson has some understanding of getting and setting plugin parameters, it does not extend this functionality to the end user. Rather than passing a huge list of parameters on the command line, one should instead create a preset for the plugin and load it with the comma-separated syntax as shown above.
As MrsWatson is a new codebase, there are lots of missing features, some more important than others. To encourage a quick initial release, the following features are not yet present in MrsWatson, but may be added at some point in the future:
- AudioUnit plugins on Mac OSX
- File support for compressed audio
- Resampling of input source if desired
- True realtime mode
I have also tried to identify incomplete areas of the code and log them to the console, which means that we are aware that this feature is missing and will be added soon. If you see some other missing functionality or experience a crash or other bug, please report an issue on the project page.
MrsWatson can be built either from the command line or with a few popular IDE’s. For the command line builds, you will need the following:
- A relatively recent automake
- A relatively recent autoconf
- Mingw (on Windows)
On Windows, MrsWatson can also be built with Visual Studio, which is preferred as this offers better performance. After cloning the source code, run the
setup-build.sh script, then
make as usual. Please report any build problems on the project page.
As MrsWatson is a 32-bit executable, which is needed to support 32-bit plugins (of which are the vast majority in the plugin world), you may also need some 32-bit compatibility libraries installed on your system. On linux, you may need to install the following packages to build MrsWatson from source:
Alternately, MrsWatson can be built with a few popular IDE’s. Build files are included in the
projects directory under the project sources root. Distribution builds of MrsWatson are always made with
make, except for on Windows.
As mentioned, MrsWatson is fully functional but needs a lot of polish. If you find areas of the code which are incomplete or not compatible with some plugins, please make a pull request.
Likewise, if you want to help out without programming, the best way to do so is to test and report any problems with given plugins or platforms.
If you are using MrsWatson to do something cool, please send me a link to your project! If you appreciate MrsWatson and would like to donate money, please instead make a donation to a charity on our behalf, and let us know about it. The organizations which have helped us the most are:
- EFF: Without the EFF, programs like MrsWatson would be significantly harder to create and distribute.
- Wikipedia: Writing MrsWatson involves a lot of research as well as coding, and Wikipedia is an essential part of this.
Big additional thanks to:
- Andrew McCrea (@thrusong)
MrsWatson is made available under the BSD license. For more details, see the
LICENSE file distributed with the source code. MrsWatson also uses the following third-party libraries, which are licensed under the respective agreements: