How to convert from Wav to MP3

solarbean · #1 01-22-2006, 08:54 AM

I have been doing some recording lately and I typically encode the recording in mp3 format prior to posting on the web. Lately I have noticed that if I compare the original wav file to the mp3 file, the amplitude is significantly lower in the mp3 than in the original wav file.

I have tried encoding using Audacity with Lame and using the built-in encoder in Stienberg Cubase SX.

Here's the signal chain: Mic->Mixer->Emu 0404 Sound Card -> EMU Patchmix Driver -> Recording Software.

Does anyone have an idea what could be happening? Does he MP3 encoding process always reduce amplitude?

ljguitar · #2 01-22-2006, 09:00 AM

Hi SB...
Things do happen when we compress files by 85% - 90%.

I just use iTunes to convert .wav to mp3, and it works fine, and while there is some loss, it isn't critical to most listeners. Except for high end audiophiles - who prefer a plastic disc with grooves in it - most folks don't have the gear to know the difference. Or they don't have the ear to detect what you are hearing.

They just like to hear us play guitar.

woodyboyd · #3 01-22-2006, 09:50 AM

I use SX and have not had this problem. What rate/bit are you encoding at?

12strings2hands · #4 01-22-2006, 10:41 AM

Quote:

Originally Posted by solarbean

Lately I have noticed that if I compare the original wav file to the mp3 file, the amplitude is significantly lower in the mp3 than in the original wav file.

I have tried encoding using Audacity with Lame and using the built-in encoder in Stienberg Cubase SX.

Try lame from the command line. There is a '--scale' option and a '--clip-detect' option that will allow you to max the sound just up to clipping.
Art

rick-slo · #5 01-22-2006, 11:00 AM

I use dBPowerAmp Music Converter. It does a nice job. You want a bit rate of 192 or higher in the mp3. I have never notice a VOLUME reduction in the mp3 versus the original wav file. Perhaps if you were going from a 24 bit wav to a 16 bit mp3 and the orginal wav was peaking quite a lot in loudness, then some volume could be lost in the dithering to 16 bit. I don't know - I would have to hear it for myself. If you want you can private message me and send me the wav file (keep it under 10 megs) and I can convert it to an mp3 and let you know what happened.
Rick

solarbean · #6 01-22-2006, 12:49 PM

Thank you so much for all the input. I took a look at the Lame's command line - wow there are a lot of options there. Impressive!

Well - I definitely saw some attenuation when encoding, but now it seems like it is not so bad ???? I think the initial signal was just so low that a bit of attenuation really killed it.

I replaced my soundcard a few weeks ago, and I think that the input is slightly different on this new soundcard. I had been pulling the signal from the mixer's 'line-out" and today I am pulling from the "main out". I believe that the impedances between the two must be more favorable this way because I ma getting serious signals now. (And all the gains are set at 0db in the entire signal chain.)

Here are comparisons between wav and mp3 encoded. The wav is 10 meg, so don't kill yourself downloading, but I would appreciate it if anyone could at least listen to the mp3 and let me know if it has decent signal level on your system. Is it too low or too high? Many Thanks.

http://www.masolar.com/pub/test.mp3
http://www.masolar.com/pub/test.wav

rick-slo · #7 01-22-2006, 01:15 PM

Sound like the same loudness wav versus mp3. Wav is just a wee bit cleaner sounding. I checked it out with DIGICheck and the signal level is about perfect using the K-System 14 as a reference.
Rick

solarbean · #8 01-22-2006, 01:20 PM

This is great! Thanks for checking.

Hey Rick, are you the same Rick-Slo that did that "scamp" piece on APM? Nice stuff!

Timothy Lawler · #9 01-22-2006, 01:27 PM

I use the Musicmatch Jukebox mp3 player's converter function. Very simple and sounds good IMO. Came free on my laptop. I think it's a free download.

Tim

rick-slo · #10 01-22-2006, 01:33 PM

Quote:

Originally Posted by solarbean

This is great! Thanks for checking.

Hey Rick, are you the same Rick-Slo that did that "scamp" piece on APM? Nice stuff!

Yep, that's me and thanks. Visit my webpage (see link below). I have a new CD ("Could It Be"), it should show up on CDBaby anyday now (I sent them copies two days ago).
Rick