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Host Development / Host SDK: Thread Safety
« on: January 22, 2012, 14:56:14 »
Dear developers of Vamp and QM,
I am a developer of Mixxx (mixxx.org) the leading Open Source DJ software for Mac, Linux and Windows.
We have currently released Mixxx 1.10. To support beat tracking and better BPM detection in 1.11 Vamp and the QM
plugin set have already been successfully integrated in our development branch. The results are excellent and
I would like to take the chance to say thank you.
I think Vamp and QM may be improved further. We have faced the following two problems during development:
Vamp SDK and thread-safety
Thread safety is an important requirement for Mixxx. We have three threads accessing the PluginLoader class.
A brief look at the PluginLoader source code showed that PluginLoader::getInstance() is not thread-safe. Moreover,
PluginLoader::loadPlugin returns a " new Vamp::PluginHostAdapter "( PluginLoader.cpp:407 ). At this point, I think that we are a bit unsafe. Indeed, I do not know what can happen, since the threads appear to share the same PluginLoader instance and a thread may call it, while the second has not yet obtained it.
So our big question is: Could you guys please release a thread-safe version of the Vamp Host -SDK?
QM beat track and 4/4 signatures
I know this post refers to host development but I would like to give feed back about beat tracking. All QM beat trackers are flexible in a sense that they are not limited to music having a 4/4 signature. However, most dance music today is written in a 4/4 signature. I personally have analysed the raw beat positions of the QM beat tracker with hundreds of songs. It was found out that the resulting beat grid was not always correct which negatively affects the BPM. QM frequently gets confused when the rhythm pattern changes within a track. Luckily, we have "invented" a method to to correct the raw beat positions. It would be great to have a native QM beat tracker for 4/4 signatures. If you are interested I can describe "invented" method and point to the implementation.
Again thank you very much. The Mixxx team is happy to have better BPM and beat detection in future!
I am a developer of Mixxx (mixxx.org) the leading Open Source DJ software for Mac, Linux and Windows.
We have currently released Mixxx 1.10. To support beat tracking and better BPM detection in 1.11 Vamp and the QM
plugin set have already been successfully integrated in our development branch. The results are excellent and
I would like to take the chance to say thank you.
I think Vamp and QM may be improved further. We have faced the following two problems during development:
Vamp SDK and thread-safety
Thread safety is an important requirement for Mixxx. We have three threads accessing the PluginLoader class.
A brief look at the PluginLoader source code showed that PluginLoader::getInstance() is not thread-safe. Moreover,
PluginLoader::loadPlugin returns a " new Vamp::PluginHostAdapter "( PluginLoader.cpp:407 ). At this point, I think that we are a bit unsafe. Indeed, I do not know what can happen, since the threads appear to share the same PluginLoader instance and a thread may call it, while the second has not yet obtained it.
So our big question is: Could you guys please release a thread-safe version of the Vamp Host -SDK?
QM beat track and 4/4 signatures
I know this post refers to host development but I would like to give feed back about beat tracking. All QM beat trackers are flexible in a sense that they are not limited to music having a 4/4 signature. However, most dance music today is written in a 4/4 signature. I personally have analysed the raw beat positions of the QM beat tracker with hundreds of songs. It was found out that the resulting beat grid was not always correct which negatively affects the BPM. QM frequently gets confused when the rhythm pattern changes within a track. Luckily, we have "invented" a method to to correct the raw beat positions. It would be great to have a native QM beat tracker for 4/4 signatures. If you are interested I can describe "invented" method and point to the implementation.
Again thank you very much. The Mixxx team is happy to have better BPM and beat detection in future!