Flat MP3's

My car has a 5.1 HD surround sound in it. My local FM stations are superb when I turn the volume up. Rich bass great mid range an high notes. But when I put MP3’s on a stick they sound flat. No serious base, so so sound. I know that MP3’s strip some of the sound in compression. Is there a way that I can add some of the zip back into them through Audacity?

I know that MP3’s strip some of the sound in compression.

MP3 doesn’t strip out anything you’re likely to notice unless you carry compression to extremes or multiple compress. That last is relatively easy to do by accident. If someone produced the original song as an MP3 and then posted it on-line and the service compressed it again…and then you downloaded it and compressed it so it would fit on a stick. You don’t need golden ears to hear three passes through MP3. That can be pretty obvious.

And permanent.

I do think it’s much more likely the 5.1 system is adding “enhancements” to the music, volume companders, fidelity boosters, etc. 5.1 surround shows are pretty rare so they have to do something to justify the added cost.

There’s nothing in the 5.1 standard that says they have to heavily process the sound. That all happens when they make the 5.1 show, and if you’re enjoying a 5.1 movie while you’re driving around town, warn us so we can drive some other time.


and they are broadcasting in stereo?

and they are 5.1 multi-channel, or stereo?
What settings are you using for the MP3 encoding?

Is there a way that I can add some of the zip back into them through Audacity?

You can try the Equalization effect. Bass is on the left and highs are on the right. (IMO- The Graphic Equalizer mode is easier to experiment with than the Draw Curves mode.) Boosting the bass can boost the signal level into clipping (distortion) so it’s best to run the Amplify effect after EQ to bring the peaks back down to 0dB.

There is one issue you need to be aware of… Audacity (like all normal audio editors) has to decompress the MP3 before editing. If you re-export to MP3 (or other lossy format) you are going through another generation of lossy compression. There are special purpose MP3 editors that can edit without decompressing/re-compressing but they can’t do equalization.

You may not notice any quality loss but it’s something you should be aware of. And if you have the original CDs, it’s best to start-over by making/editing WAV files and then compress ONCE to MP3 if you want to use MP3s.

Steve - It is stereo and the Stations advertise stereo HD. I export the piece to mp3 320 KB stereo

Koz: 5.1 is what they advertise it as. I do not drive around watching movies, in fact I don’t think I can. It may be a meaningless feature as you say to justify the cost.

Most radio stations use dynamic compression for a “constantly loud” sound. They may also boost the highs & lows. And, songs on the radio may simply play louder than songs on the thumb drive… Often a little boost in loudness is perceived as an improvement in sound quality.

True “high fidelity” FM would sound exactly like the CD, and 320kbps MP3 will also usually sound identical to the CD (in a proper, blind, scientific, level-matched listening test). There are certain sounds that are hard to compress, but most listeners won’t hear a difference with most songs.

Thank you sir. I am getting an education here.

5.1 is what they advertise it as.

I wonder if you’re not listening to the broadcast radio transmitter, but instead listening to the on-line stream where it would be no trouble to transmit Dolby 5.1.

I have friends with entertainment systems that “fall back” to actual FM Radio if there are no other services available. Everything else is handled as a bitstream using up your minutes.

There’s nothing in Dolby 5.1 that says a show has to sound fantastically better than anything else, but there is production processing. For example, dialog is almost always handled by the C center channel, not any of the others. The “.1” is the LFE low frequency effects purely there to make your shirt move during bass notes.

And then there’s Dial Norm. Dial Norm is a volume manager which allows Dolby 5.1 to reproduce, in original, real-life volume, a jet taking off or a thunder storm. That’s probably one reason your MP3-on-a-stick sounds flat.

No, we can’t simulate Dial Norm, but there are companders out there which can boost some portions of music on the fly.