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Unique Solutions for Video Production

20 Nov 2014

Little DARling Update: Wireless Control

Posted by Robert Rozak

So, everybody wants to know what happened to the Little DARling Distributed Audio Recorder that I showed at NAB this year. Well, I got more ideas of things I wanted to add to it. Specifically, wireless control. It was clear after many conversations at NAB, that the market adoption of the Little DARling would be limited until a couple of problems were first solved:

  • How to sync the audio from the Little DARling with the video, when the Little DARling audio could potentially be very different from the camera audio.
  • How to navigate within potentially very long DARling recordings.

My plan became to introduce both versions of the Little DARling of the same time, so they could share the same printed circuit board.  So, this meant pushing out the original DARling, to work on the wireless stuff. I also did not want to go public with this plan until I was far enough along with the design, where I knew I could fit the wireless receiver on the board.  Check out this brief introduction v-log:

So, that's pretty cool! The MCU for the wireless receiver sends a slate signal to the analog mixer that is part of the analog preamp chain before the codec. So, this gets captured by the codec ADC and recorded onto the DARling audio file. Additionally, the slate signal is split out (before the codec) to the DARling output jack. So, you can use an additional DARling on the camera, where the DARling slate output goes into the camera and is recorded on the camera's audio track. Now, when you hit the wireless transmitter slate button, all of the individual DARlings being worn by your talent as well as your camera get simultaneously slated, so you've got something to align all of your audio with your video. Additionally, you can use the slate (or a sequence of slates) to navigate within long recordings.

Not shown in the video is a new piezo buzzer addition to the DARling, which gives you audible feedback to let you know when the wireless command has been received.

There may be DARlings that you will use, where you may not want a particular one to buzz or slate. On the SD Card, the user will load a text configuration file. Every single parameter that you can think of that can be controlled in the DARling, can be specified in the Config File. This includes turning on/off the slate or buzzer function. From the front panel buttons on the recorder, the user will select which configuration to load.

The old Nagra recorders allowed for remote control to start/stop your recording. The Little DARling is no different, just wireless. So, instead of one long recording for the day, you could do individual recordings for your scenes or interviews.

However, at the end of the day, you're going to have a lot of clips in your computer to manage (many DARs, many clips per DAR, all of them named audio001.wav, and so on). We're also working on a PC/MAC program, that will automatically rename your files in your computer to something logical, so they can be managed. What you'll do is log the scene or interview name for each clip in a text file on your smartphone. Put all of the clips from each DAR into its own folder, and give the folder a logical name (like, the name of the person wearing the DAR, "Sue", or "Dave", or whatever). Place the scene name text file in the same directory as the "Sue" and "Dave" folders. The program will automatically rename each of the "audio001.wav" "audio002.wav" files in each of the folders to "Sue_scene1.wav". This is just an example of what can be done. It is flexible enough for the user to add other information, such as date, etc.

In this paragraph, I'm going to talk about a feature that we are not committing to doing. We are just thinking about this right now. I keep getting asked about timecode. Personally, it doesn't make sense to me. These are not going to be 0.1ppm clocks, so they're going to drift just like your camera. The Little DARling concept no longer makes sense if you're connecting a Lock-it Box to it.
The Little DARling has a clock. But, there is no way to set it (can't set it wirelessly, can't set it by the buttons, can't set it by the config file). When the unit powers up, it powers up at the time and date of "zero". The software works such that when the first recording starts, the clock resets (but not on any of the subsequent recordings), regardless of whether the recording was started wirelessly or from the buttons on the recorder itself. If the first recording was started wirelessly, then all the Little DARlings first recordings are starting at the same time "zero", and all subsequent recording start times reference from that point. After a few hours when the clocks drift (maybe, lunchtime?) power cycle the Little DARlings to reset the next recording with a fresh time "zero". Or, we could have one of the wireless transmitter buttons do either a software reset of the DSP, or have the Supervisor MCU power cycle the entire board, so you wouldn't have to physically gather up all of the DARs to power cycle them. This will have the effect of your first afternoon recording again starting at time "zero". With one of the slates to the camera, you could read off the timecode from the editor you are using in post. Then, offset the time in the DAR header files by that amount. We could add this time header offset function to the PC/MAC program we're developing for batch renaming of files. Although we could add this in firmware after product release, again, these are not committed features.

When will all this be available?  How much will it cost?  Well, we're done adding new stuff.  So, the path to product release is much more deterministic than when I put the release on hold after NAB until I got the wireless stuff added.  Still, we're doing a cleanup pass on the board, so there is some work that is ongoing.  The pricing spreadsheet is the last thing that I look at, so there is no definitive answer there either.  Subscribe to the blog.  That is were you will get notified.  Sorry, but an email to me will not get a response of better date or pricing granularity.  Thank you for your understanding ...


- Robert from juicedLink, 11/20/2014