Webcast Sound Problem for Some

[davidbann]

Hi there,

We have started broadcasting sacrament services using the church webcast system. Everything is working fine, and for most members they receive the broadcast with no problem. Some people on the other hand have problems with the sound - they have reported that either the sound is scrambled (making strange noises) or that there is no sound at all, but they can still see the video. Important to note is that these people can all hear the prerecorded tabernacle choir music perfectly, and only when the broadcast begins do they have problems with sound.

Any ideas on what could be causing this, and why it would only be problematic for some people and not for others?

We are broadcasting via Teradek where the chapel main sound system is fed directly into the Teradek, and an IP camera displayed on a laptop screen in full screen mode, with HDMI output from the laptop to the Teradek. The Teradek is configured using the webcast XML config.

Regards,
David

[russellhltn]

We are broadcasting via Teradek where the chapel main sound system is fed directly into the Teradek

What kind of connection are you using? If it's a standard 3.5mm to 3.5mm cable, I'd suggest setting the Teradek to "left only". The chapel is a single channel feed and the Teradek is expecting stereo.

[davidbann]

Hi Russell,

Yes, it is 3.5 to 3.5 - I will check it out and see if I have set to left only yet or not. If not, would that potentially cause that some viewers get the correct sound while others don't?

[russellhltn]

If not, would that potentially cause that some viewers get the correct sound while others don't?

Possibly. It depends on how the Teradek interpreted it and how the receiving device processed it.

The basis of my thinking is a common problem in stereo sound if one channel is somehow 180 degrees out of phase. People listening in stereo will say it's fine, but people listening in mono will hear next to nothing. in that situation, the problem is with the "sender" (encoder end) not the "receivers" (viewers).

[jimncyn]

We've had the exact same problem reported in our stake transmissions. All users can hear the prerecorded music and other videos from the church website fine, but when the transmission starts, some hear garbled audio while the majority hear the sound just fine. I would love to be able to track down if there are some settings or browser versions I can tell people to turn on or off.
You mentioned maybe if the stereo channels were out of phase those listening in stereo could be fine while mono listeners could hear nothing. Is there a way to know if I am a stereo or mono listener in my computer's browser.

[russellhltn]

Is there a way to know if I am a stereo or mono listener in my computer's browser.

Sorry, no, I don't. I was taking a wild guess and suggesting to pay attention to the details of the wiring going to the Teradek. While a simple 3.5mm stereo cable would connect the "record out" to the Teradek, that would connect a mono (TR) source to a stereo (TRS) encoder.

A mono 3.5mm cable would result in a 'left channel" only situation. That shouldn't be much of a problem unless the computer's left speaker isn't working.

Either way, some kind of mono to stereo adapter is needed, or else set the Teradek to mono using only the left channel.

The other thing may be to make sure the settings for encoding are in line with that the church's recommended settings.

I'm not ruling out a problem with the church servers, but I am focusing on what's in the STS's control.

[davidbann]

We are broadcasting via Teradek where the chapel main sound system is fed directly into the Teradek

What kind of connection are you using? If it's a standard 3.5mm to 3.5mm cable, I'd suggest setting the Teradek to "left only". The chapel is a single channel feed and the Teradek is expecting stereo.

This solved it for us - thanks for your help!

[russellhltn]

This solved it for us - thanks for your help!

Thanks for the feedback. I'm glad my guess worked out.

[rknelson]

We had the same issue. Tech support said it was a known problem on smartphones and to recommend using a computer for listening. Sound was good for some viewers and bad for others even on computers. Then I found using a computer connected to a TV with surround enabled made the problem worse.

Yesterday I finally located the real issue.

Our 1 year old sound system rack installed by a church approved contractor was wired incorrectly. The BLU-100 DSP outputs are "Shield, + and -. They had the 1/8" TRS Vidiu input audio jack wired to the BLU100 mixer with;
Shield to Shield, Ring (Right) to "+", Tip (Left) to "-".
This is totally wrong as it places a balanced signal across left and right.
The correct wiring is:
Shield to Shield, both Tip and Ring to +, with "-" wired through a jumper to Shield.

Attached is from the BLU100 DSP installation manual.

That fixed the problem. Changing the Vidiu from Stereo to Mono as suggested above works around this issue also.

Pretty disappointing to see audio experts who built the rack in a workshop miss that issue. Someone needs to correct this misunderstanding with the contractors.

[russellhltn]

Interesting. In all of our chapels, a balanced output is sent to a jack that has a transformer in it. The result is a transformer isolated mono (tip and ring) output. I'd say the real issue is that they didn't use the right jack. The transformer isolation is nice because it prevents ground loops, resulting in hum.