Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Sound › audio out of phase??? › I realize this is an old post
I realize this is an old post….not sure if you ever had a response to the issue so I thought I'd try to help. What the TV station is refering to by "out of phase" is not a "sync" problem, meaning the frames should not be out of sync with the audio. What they are referring to is audio issues with the L/R or frequency spectrum of the audio being out of phase – as in sine waves phasing polarity to cancel out certain qualities of the audio. This usually happens on the low end first which results in sound qaulity that sounds like is coming through an telephone from the 1920s.
If you sum your audio master to Mono and the sound quality (low, mid, high) characteristics change, you have "out of phase" audio. Another test is, use an audio mixer that has balance (L/R) pan controls on each channel, connected from your master output to another unit to record, like a tape recorder, etc. On the mixer make sure you have the left channel & right channels connected to their own input – such as Left on channel 1 & Right on channel 2 and ch 1 panned left, ch 2 panned right. Your sound from the mixer should be stereo to when listening (different characteristics in the left vs. right). Now pan both ch1 & 2 to center & listen for the audio characteristics to change when centered. If it does change and you loose qaulity, it means your Left/Right channels are out of phase with each other. If you've already been using a mixer to record your master output with Stereo – it's also possible that one of your connectors has the polarity reversed, forcing the signal to become out of phase, ie +/- vs -/+ rather than +/- vs +/-, etc.