Hello everyone

Here is what I'm trying to do:

I figured out how to hook my mp3 player up to the pa system at the supermarket I work at. What they use is an airphone type deal where it looks like a regular phone, but there is a button right under the speaker that you have to press in order to talk over the system. I figured out a way to keep the button pressed in all the time, and put the right side of my headphones under the microphone part of the phone. The audio quality over the pa system was excellent.

But there are a few problems.

1) Since the right side of the headphones are under the speaker, only the right channel is heard through the pa system. This results in some songs sounding totally different since the music is on both the left and right channels. Is there a program out there that I could switch my mp3s over and force them to use just the right channel (make the left and right channels into one right channel)?

2) My mp3s are all different volumes. This means sometimes I have to run over to the side of the store the mp3 player is on and turning the volume up/down. I use MP3 Gain for these mp3s but there still is a huge difference in volume at times. I believe MP3 Gain uses the highest point of the song and normalizes that way instead of normalizing the whole song. Is there a program out there that converts mp3s to the same volume, I mean so there are no loud or soft parts - the WHOLE song is the same volume? I'd like every mp3 I have to be THE SAME volume instead of some songs having loud parts in the middle and quiet parts in the beginning and end.

1a) I have a feeling that would be impossible.

2a) Replay Gain doesn't do peak normalization based on the highest peak, but it does alter the overall volume of the whole song, like you said.

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If you don't mind having to rerip everything from CDs, then...

1b) You could create mono MP3s, by downmixing the sound to mono before encoding. Some encoders can do this for you.

2b) I think what you want is 'dynamics compression,' similar to what you would hear on the radio. You could make mono MP3s from dynamically compressed audio.

1) So if I convert everything to mono both left and right channels will be heard on the right side of the headphones?

2) Can you recommend software that uses dynamics compression?

1) In a way, yes, but it'll be heard on the left side too. If the mono sound was a downmix, a mono mix of L and R will be heard on both sides of the headphone.

I think it would be theoretically possible to get (or build) a single-sided headphone with a mono plug which does the downmixing for you, but I'm not sure.

2) Depending on what you expect from an audio player, foobar2000 can be an excelent choice.

http://www.foobar2000.org/components.html

There's a dynamics compressor component for it, which you can use for playback. You can also use it during conversion to MP3.

1) Simple solution - get a pair of cheap earbuds and position them both under the microphone, so you'll get a nice balance of L/R... instant "downmix" to mono.

2) When you mp3gained your files, were you using the track gain or album gain? You'll want to use track gain for this. Track gain will make all tracks of a consistent volume, whereas album gain preserves the relative volume differences in songs within an album.

If you want even volume throughout a song that is very dynamic, you'll have to do some dynamics compression before encoding it to mp3.