UPDATE : 4th May 2016 – I’ve added a video using the measured filters. This will be useful for auditioning the mixes before uploading them to YouTube.
So, I’ve been experimenting with YouTube’s Ambisonic to Binaural VR videos. They work, sound spacious and head tracking also functions (although there seems to be some lag, compared to the video – at least on my Sony Z3), but I thought I’d have a dig around and test how they’re implementing it to see what compromises they’ve made for mobile devices (as the localisation could be sharper…)
Cut to the chase – YouTube are using short, anechoic Head Related Transfer Functions that also assume that the head is symmetrical. Doing this means you can boil down the Ambisonics to Binaural algorithm to just four short Finite Impulse Response Filters that need convolving in real-time with the B-Format channels (W, X, Y & Z in Furse Malham/SoundField notation – I know YouTube uses ambiX, but I’m sticking with this for now!). These optimisations are likely needed to make the algorithm work on more mobile phones.
It’s always bugged me that the VU meters in Reaper are so small, which is particularly a problem if you’re working with large amounts of channels (which, when using Higher Order Ambisonics, is common!). So, I’ve knocked up a flexible multi-channel meter than can be made as big as you like so it should be useful for testing and monitoring when setting up etc..
The scaling is flexible (you can specify the minimum dB value to show) and so is the time window used for both the meter and the peak hold (which is individually held per channel). I’ve commented the code so if you don’t like the colour scheme etc. it should be a doddle for you to alter it yourself! The file can be downloaded below:
So, last week Google enabled head (phone!) tracked positional audio on 360 degree videos. Ambisonics is now one of the defacto standards for VR audio. This is a big moment! I’ve been playing a little with some of the command line tools needed to get this to work, and also with using Google PhotoSphere pics as the video as, currently, I don’t have access to a proper 360 degree camera. You’ll end up with something like this:
I’ve recompiled all the plug-ins so there are now 64-bit versions of WigWare for those who now use 64-bit hosts. All audio processing is un-changed. Several issues with the Mac graphical user interface occurred when switching to 64-bit (nothing had to change on Windows!) which I had to fix, so please let me know if there are any issues! Downloads are on the WigWare page, or below :
I’ve just realised that the plug-ins on the site weren’t the versions that I have fixed for Mavericks. I had fixed them almost as soon as Mavericks was released so my students could continue using them, so apologies for not sharing! I’ve replaced all the Mac versions on the WigWare page with the updated graphical versions (the DSP code worked fine, it was the gfx that had issues).
If anyone has any problems with these, please let me know!
Sounds in Space happened on 30th June this year and was an excellent day (the programme and details of the day can be found here). There are always things which could be done better, and hopefully we’ve got all these noted ready for next year (fingers crossed). If you weren’t able to make the event, then the details below may give you a glimpse of what you missed and whether you’d like to come next time!
The 27 speaker 3D surround sound setup was the best we’ve ever had, made possible with the help of recent graduates from Sound, Light and Live Event Technology and Richard and Mark, technicians in Electronics and Sound. Alex Wardle (graduate from Music Tech and Production) also created a video of the event which can be viewed at:
The surround sound Rosetta performance by Sigma 7 (at Derby Theatre, 7.30pm 7th June) will be streamed live with Binaural Audio (wear headphones for 3D audio) at http://sigma7rosetta.co.uk/ . Multi-channel Videos will also be available after the show, and they’ll also be a Sound on Sound article about the event in the future too! If you can’t make the event, the stream will be the next best thing!