Audio tick sound with 59.94 configuration

Hello, I’m developing playout server with casparcg
Thanks for distributing a great program for free.

I found audio problem with decklink and 59.94i (NTSC) configuration.
Here’s how to reproduce problem

  1. Create colorbar & -50dB tone with NLE (1080i59.94, 48kHz)
  2. Setup casparCG with 1080i59.94, decklink output
  3. Load and playback colorbar / tone.
  4. Monitor HD-SDI embedded audio with headphone.
  5. You can hear tick. tick sound for every frame.

If you setup casparCG with 1080i5000, Decklink output sound is perfect (no problem. even with 59.94i clip playback)
Also, setup casparCG with 1080i6000 does not produce audio problem.

If you setup casparCG with NTSC, you can hear very loud tick tick sound from decklink output.

So my conclusion is that casparCG is good for PAL country, but not goot for NTSC(59.94, 29.97) country

I have changed casparCG version (up to very recent version) or change decklink driver, but does not solve this problam.
I hope this will be fixed in the next version.

Tested version :
2.3.0 d442a8f8 dev ~ d49b5bc8f
Decklink 10.11.4 ~ 11.5.1

Is it similar to this issue? If not, please open a new issue at GitHub.

Thank you for fast response. It’s different issue.
I’ll open a issue at GitHub.

Reproduction is very simple, create test signal with ffmpeg.

ffmpeg -f lavfi -i testsrc2=rate=29.97:duration=60:size=1920x1080 -f lavfi -i sine=frequency=1000:sample_rate=48000:duration=60 -af volume=-30dB -c:v mpeg2video -b:v 20000k -c:a pcm_s16le

setup casparCG with decklink, NTSC or 5994 (not PAL or 50, 60)

play 1-1 tone

You can hear abnormal tone