Below are some diagnostic tests and possible solutions if you hear garbled audio when a file is played.
Garble audio can be caused by phase issues between the left and right audio or one of the left or right audio channels being empty in the played file.
Make sure it's not just bad audio in the file itself. Play the file on the PC using the WinLGX software preview player and see if it sounds garbled.
- Open the Storage Manager window (Tools/Storage Manager)
- Right-click the video file and select View.
- The file should play in the software preview monitor (volume slider on the right).
Out of Phase Audio
Garbled audio is often due to the file's left and right audio channels being out of phase. This is fine if all the devices downstream are stereo, but it is a problem if the left and right channels are combined in a mono device. Going from stereo to mono with phase issues could garble or cancel out the audio signal.
A possible diagnostic test would be downloading the file to your PC (that has speakers or headphones), playing it in the VLC media player, and setting the audio menu's stereo mode to MONO (AUDIO/Stereo Mode)/Mono) and see if it's garbled there.
This may be caused during a recording by the incoming audio connections being flipped, where the ground and the signal are switched on the left or right channel, making it out of phase with the other channel—or wiring the audio equipment involved in the wrong way. Be sure your audio cables are connected correctly throughout the whole length of upstream devices and connections that bring the audio signal to your recorder input.
Possible Solutions
The best solution would be to avoid creating these files in the first place.
- Avoid Mixing the Channels
- If possible, avoid any "Y" cabling or mono points where the left and the right audio signal is mixed together in your upstream or downstream equipment and cabling.
- Duplicate One Audio Channel on Both Channels
- In an editing software program, copy the left audio channel to the right audio channel, overwriting the right audio channel. Or copying the right to left will do just as well. This may only work if the channel you are copying over has complete sound. So test it on a copy of the file first.
- Only Use One Audio Channel
- If you must have a mono device, you can use the left channel output only by disconnecting the right audio channel connection from the analog terminal block. If using embedded SDI audio and an SDI to Analog converter, remove the right audio output connection from the converter.
Stereo Audio Missing a Channel
The garbled audio could be caused by the file having stereo audio, but only one of the left or right channels has audio, and the other is empty or low.
A possible diagnostic test would be downloading the file to your PC (that has speakers) and playing it in the VLC media player. Set the audio stereo mode to MONO from the Audio menu, left only, right only, and stereo and see if it's garbled there.
Possible Solutions
The best solution would be to avoid creating these files in the first place and make sure they have both left and right audio.
- Copy Good Channel to Empty Channel
- In an editing software program, copy the good audio channel (left or right) to the other audio channel, overwriting the bad audio channel.
Further Diagnostics
If the file has none of the above audio issues, it could be something downstream from the UltraNEXUS-HD introducing the audio issue. You'll need to check how you monitor the output and further diagnose the issue, as explained in our knowledge base article called "Video Output Distorted."