Tuesday, March 05, 2019

Live Interpretation (Updated)

I had someone come to me today asking about the solution we are using for live interpretation.  Apparently news of this is starting to get around and this made me realize it's time to update the technical details and start posting some of my lessons learned.

Let's start with our current technology stack.  It's fairly similar to what we were using before, but we have managed to simplify it a bit.  Here's a list of tech:
The configuration is fairly straightforward:
  • Connect mic to mixer
  • Connect mixer to interface
  • Connect the interface to the laptop
  • Connect the laptop to router
  • Connect router to internet
  • Power everything on
  • Start Icecast
  • Start BUTT
  • Start streaming

I will create blog posts to describe how to configure the software and a description of Windows vs Linux as a server OS for this purpose.  However, this is meant to be an overview of what we're using and how.

I also wanted to provide a list of issues we've run into so far and things to keep in mind:
  • Internet connectivity is very important.  Our initial tests were on a local network with no internet connectivity and, while it worked, it did cause some issues.  Specifically, we started using TuneIn the streaming radio player and its initial setup required internet connectivity to move forward.  VLC doesn't, but you cannot assume the users will have enough data on their plan to download the software.  We now have a dedicated wireless network that does have internet connectivity
  • Wireless channel selection.  Right now we are having some issues with cross-talk between the various routers in the house.  (sound tech, ours and others).  I'm hoping we can get around to assigning dedicated channels for these, but we're not there yet
  • User friendliness: VLC, while a great app, isn't always the friendliest.  The iOS app will keep track of URLs you've listened to and that helps, but Android does not.  I'm hoping to eventually replace this with a dedicate app for CT, but that's a future enhancement.
  • Audio Processing: Our current mixer has limited audio processing, specifically no compression.  BUTT doesn't offer any dynamics either, so we are looking at other options to allow us to compress and boost the audio a bit.  Also, don't skimp on the choice of microphone.  You could use an inexpensive computer mic, but I would think it would result in poor sounding audio and not be pleasant to the listener.  We're using a Sennheiser mic (which is probably overkill), but at least a Shure SM58.  Ideally you'd have a good plosive filter too.
  • Dedicated space: one of the issues we have now is our interpreters are set up in the back of the theater.  This is for expediency sake at this point as they can see what's going on and hear the message.  There are two key downsides to this:
    • The interpreters can occasionally be heard by the congregation.  To avoid this, they often have to speak more quietly than they would and that causes the volume to fluctuate for the listener.
    • The listeners tend to hear the sound from the service flow into the feed we are sending.  This can be a bit distracting, especially given the lag.
  • Latency: while the technology appears to work well, it does suffer from a bit of latency.  Each step of the chain adds a small time buffer to smooth out any network loss.  The configurations I use tend to reduce this, but it still adds up.  At best, we tend to see 3 second latency between when words are spoken to when they are delivered.  At worst, I've seen 10 seconds or more.  With VLC, you can simply stop and restart the stream to reduce that back down, but it's still something to keep in mind.
  • Avoid Windows 10 (for now): I personally use Windows 10 and have since about the time it came out. (In fact, I'm writing this post on a Windows 10 Pro machine).  However, when I tried to use Icecast on Windows 10, something went wrong.  It worked in testing, but in production use, somehow the networking stack in Windows (be it the firewall or something) ended up killing all active connections.  It was so bad that I had to quickly restart into Linux just to continue the service.  We're currently using Windows 7 and it works just fine, so until I can figure out what happened, I'd avoid 10.
  • GDPR: One thing Icecast will do is create log files.  Under GDPR you will need to make sure you handle those with care and follow your organization's privacy guidelines.  And if you don't have guidelines for compliance ... bring it up as it does matter.
At the end of the day, it's not the most perfect setup, but the price of starting up is fairly inexpensive.  Assuming you have a PC or laptop available, simply add the dedicated wireless router, mixer and microphone and you're up and running.

As we continue on, I will publish more thoughts and details.

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