Audacity Forum

I edit my podcast using Audacity. For transition clips between segments, I often splice in clips I grabbed using Clip Grab off of YouTube. Sometimes when I grab these clips they are downloaded in m4a format, but they show up fine and I am able to edit them.

When I finalize the podcast episode on my computer, everything sounds fine. However, then sometimes when people listen to the podcast on their podcast app or in iTunes, the spots where there is supposed to be the YouTube clips between segments are nothing but dead air.

Does anyone have any idea why it may happen? Is it the m4a format causing the error? And if so, why does the file play totally fine after I export it as an MP3 on my computer, but then have the dead spaces where I spliced in the clips on someone else's computer or podcast app?

Thank you!

Also I'm using Audacity 2.1.0. Just realized that's out of date so I'm updating. Maybe that was the issue?

Okay, and another update on the issue!

It turns out that some clips that I spliced in but kept in the SAME track DO play. However, the clips that I spliced in by putting them on a DIFFERENT track (because there is some overlap) are the ones that are NOT playing. The clips that aren't playing are in the top track, if that makes any difference.

What in the world is going on? After I export it all to an MP3, why would it play fine on my computer, but then not play when MULTIPLE people (not just one, so it's not some one off issue) tried to play it on their computer?

The top track was muted at the time you exported the audio?

Unfortunately, you can't check that after the facts...

No, they weren't muted. I would have noticed it being greyed out.

I did have the volume turned down. But I still don't understand why it would play on my computer, but it wouldn't on someone else's when we are both using THE SAME website, and clicking THE SAME play button (episode 31 at 13:30 mark and 36:30 mark):
http://whathappending.libsyn.com/

In any case, I tried re-mixing it and reduced the top track's volume through the Amplify plugin, rather than the volume toggle on the track itself. Hoping that fixes the problem.

Here we see two versions of your podcast. The upper stereo track is your podcast as downloaded from your site. Below it is the same file, but mixed to mono.
As you can see, there are places in the second version where the show almost disappears. The reason for this is that the left and right channels of the original stereo track are "out of phase". If we zoom in really close, we can see what that means. The upper (left) channel and the lower (right) channel of the stereo track are virtually identical, but "upside down" from each other (technical terms: "inverted" or "180 degrees out of phase"). When the two channels are added together ("mixed") to mono, the two waveforms cancel each other out (they sum to zero).
Mixing to mono is what usually happens when listening to a stereo show via a mono playback system. For anyone listening in mono, parts of your show "sum to zero", meaning that they mix down to silence.

Oh my gosh thank you so much! This has been driving me crazy.

How do I prevent the left and right channels from getting "out of phase" in the future for anyone who might listen in mono? I'm not sure why it happened in that part of the file when I pasted in those clips.

Actually, in a full stereo music system, those small portions will not sound perfect and normal. They might sound like they're slightly weird or coming from behind you.

This is a channel test I recorded including an "out of phase" segment. It's 39 seconds.

http://www.kozco.com/tech/LRMonoPhase4.wav

Open that in Audacity and you can hear what it sounds like when I flop the channels as part of the demonstration.

I'm going to go back and read through that again, but it's possible the on-line segments were recorded wrong. That's really easy to do if you have a half-professional and half-home style recording system. As as you noted, if you're only listening in stereo you might not catch it.

Koz

Go back and download one of those YouTube segments and open it up in Audacity cold before you do anything to it. Magnify the blue waves like crazy so you can get down to the individual sample dots. Are they the same or opposite?

If it's a good stereo show, the waves will not be the same, but they should go mostly the same direction. Find a portion with a solo singer. Those should show up better.

Koz

carlosross wrote:How do I prevent the left and right channels from getting "out of phase" in the future for anyone who might listen in mono? I'm not sure why it happened in that part of the file when I pasted in those clips.

My guess is that those clips had the problem before you pasted them.
Where did you get those clips? Do you still have the original versions?