ATC audio being recorded

[Keith Smith]

Here are the daily files for January 6.

Jan 6 app/center (mp3)
Jan 6 del/gnd/twr (mp3)

These only cover about 1/3 of the day because the voice server was restarted during the early afternoon due to a resource exhaustion issue on that machine (it's on the same machine as the drones, and the machine needs a reboot every 6 weeks or so).

[Keith Smith]

Here are the daily files for January 7.

Jan 7 app/center (mp3)
Jan 7 del/gnd/twr (mp3)

I think the unanswered radio checks at the start were before the published operating hours

[Orest Skrypuch]

Keith,

What software are you using to accomplish this? I have on/off looked for some simple windows software that could record the input/output of a USB mic, with voice activation to eliminate the dead spots.

* Orest

[Keith Smith]

Orest,

It's non-trivial. I wrote a client that connects to the voice server (much like the controlling client and pilot clients). There is an option to record the received audio as a 32-bit floating point raw PCM stream. We take that data and write it to a pipe which feeds into the 'sox' utility (Linux) to convert it to a 16-bit int PCM format. Every hour, the utility kicks off a background task which takes that file and pipes in into sox to create a WAV stream, and passes THAT into the MP3 encoder. The file is then copied with 'scp' up to our web server.

The silences are not being manually removed, it's just a nice artifact of the architecture. We are only passed the data when someone is actually talking, so the resulting file only contains the actual transmissions.

This took a long time to build, largely because of the format conversions (I tried to keep it simple, but the various converters didn't work, so I ended up with the long, complex chain that you see above). Only the last conversion is lossy, though, so quality-wise, we're in great shape, as you can hear by what's in the files now.

[Keith Smith]

Here are the daily files for January 8.

Jan 8 app/center (mp3)
Jan 8 del/gnd/twr (mp3)

If anyone has any issues playing either of those, let me know. I failed to restart the 'daily recorders' (that part is a manual process each morning) on Sunday morning. I actually assembled the daily recordings by concatenating the hourly recordings (which are humming along in an automated fashion) with some server-side utilities.

[Steven Winslow]

Now honestly, Keith, tell me you had to use a thesaurus to come up with "concatenating." Thanks for the vocab lesson!

[Keith Smith]

Must be a software developer thing That word comes up quite frequently, believe it or not!

[Andrew Miller]

Must be a software developer thing That word comes up quite frequently, believe it or not!

A day doesn't go by in my job where I don't use that word.

[Keith Smith]

Here are the daily files for January 9.

Jan 9 app/center (mp3)
Jan 9 del/gnd/twr (mp3)

They're pretty short, traffic was light during the day with a brief spike in the evening.

[AviatorScott]

Hey,
This is a great service, I joined to work on my clearance "correctness", the hardest part of flying IFR is getting that clearance correct, (and keeping the passengers from screaming on those approaches to minimums )! Thus listening to the shortened list of clearance requests is great. Question though, I see several posts about "new interface" and hourly recordings, do we have an idea on when that will become functional?

Thanks,
Scott