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Audio CD's from mp3 and WAV sound different?
symbiont7
post Dec 28 2003, 21:52
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Here's my dilema. I have created identical compilation audio CD's but they sound quite different depending on the source, mp3 vs. WAV.

The audio CD's created from mp3 files have a stronger base tone to them, so much so that I have to turn the base significantly down in my truck CD player. Let's say on a scale of -10 to 10 it would have to be set at -3 or -4 for the music not to be overrun by base tones.

The audio CD's created from the WAV files sound normal, and I can have the base tuned approximately the same as I have for radio stations and commercial CD's. Same scale, maybe a 2 or 3.

I'm talking identical songs here. Rip song X to WAV, save it, then convert to mp3 (recommended lame version, at alt preset standard). Then make two seperate audio CD's, one from the mp3, one from the WAV file.

I use EAC for all the ripping and burning, although the couple times I've burned with BAO it does the same thing.

Basically, I want to save space on my hard drives. I'd like to rip and only save the mp3's, then mix and burn audio CD's at my leisure. But not if they produce that horrible overdrive of base! I have other needs for the mp3 format, so I do not want to use another format, lossless or not.

I don't suppose my EQ settings on my soundcard could affect all this? I thought that was just for playback. I am by no means an audiophile though, so I may be making a stupid mistake somewhere! smile.gif

Sorry for the long post, and thank you in advance for any help you may have.

sym7

This post has been edited by symbiont7: Dec 28 2003, 21:56
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tigre
post Dec 28 2003, 22:12
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The reason could be clipping. If the source CD is recorded at loud volume (= many sample values close to +/-32767) there are big chances that encoding-decoding causes clipping. This might lead to the results you describe. Try applying mp3gain to the files or use replaygain and a program capable of using replaygain information for decoding, e.g. foobar2000 (its Audio CD writer or Diskwriter + your favourite burning program).


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kennedyb4
post Dec 28 2003, 22:48
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What did you use to decode the mp3's?
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symbiont7
post Dec 29 2003, 01:08
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QUOTE (tigre @ Dec 28 2003, 01:12 PM)
The reason could be clipping. If the source CD is recorded at loud volume (= many sample values close to +/-32767) there are big chances that encoding-decoding causes clipping. This might lead to the results you describe. Try applying mp3gain to the files or use replaygain and a program capable of using replaygain information for decoding, e.g. foobar2000 (its Audio CD writer or Diskwriter + your favourite burning program).

I will give mp3gain a try, thank you.

Just for the record, the ripped WAV and subsequent encoded mp3 files sound exactly the same to my ears. It's not until the burning of audio CD's does a difference emerge.
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symbiont7
post Dec 29 2003, 01:09
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QUOTE (kennedyb4 @ Dec 28 2003, 01:48 PM)
What did you use to decode the mp3's?

Whatever EAC and BAO use.

I take the mp3 files and use those two programs to write the audio CD's.
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rickshaw
post Dec 29 2003, 01:31
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What is BAO?


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tigre
post Dec 29 2003, 01:34
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Burnatonce


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symbiont7
post Dec 30 2003, 15:21
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Okay, used mp3gain on a few test files and yes indeed, mp3gain did the trick! It said there was clipping in 6 of the 8 test tracks I used, I then saved the volume changes, and reburned. The tracks sound not only quieter, but as you turn up the volume the bass is in the proper proportions. Funny, the 2 tracks that didn't have clipping I never really thought suffered from the "bass overload", I just stuck them on there for more of a comparison/control group. Interesting.

So more questions:

What is clipping?

Should I run all my mp3s through mp3gain, or should I just use EAC to "normalize" them as I go? I really don't understand the difference. And what should I set either of these apps to for the best results (if there is a standard).

Sorry for being a complete n00b here! smile.gif
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jarsonic
post Dec 30 2003, 15:37
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Other formats, such as Musepack (MPC), have replaygain built into the format spec, and store the values in a metadata tag within the file. Something you might look into. Foobar2000 has a wonderful built-in replaygain tool that makes it easy to replaygain your files.
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fenterbug
post Dec 30 2003, 15:59
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ReplayGain and normalization are not the same thing. Normalizing a file will adjust the volume based on the raw data. However, not all frequencies sound as loud as each other at the same dB level. ReplayGain compensates for this and attempts to adjust the volume based on the apparent loudness. (I strongly suggest browsing the ReplayGain website.) For your purposes, this is the only difference, though it is an important one.

In order to take advantage of ReplayGain, you'll need a tool that will convert back to wave, applying the ReplayGain info. Foobar2000 does this and is easy to use... highly recommended. My suggestion, and I'm sure many will agree, would be to store your music as MP3 (your requirement) and when you want to burn a music CD, convert to WAV using Foobar2000 and use those WAVs for the CD.


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symbiont7
post Dec 30 2003, 17:15
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QUOTE (fenterbug @ Dec 30 2003, 06:59 AM)
ReplayGain and normalization are not the same thing. Normalizing a file will adjust the volume based on the raw data. However, not all frequencies sound as loud as each other at the same dB level. ReplayGain compensates for this and attempts to adjust the volume based on the apparent loudness. (I strongly suggest browsing the ReplayGain website.) For your purposes, this is the only difference, though it is an important one.

In order to take advantage of ReplayGain, you'll need a tool that will convert back to wave, applying the ReplayGain info. Foobar2000 does this and is easy to use... highly recommended. My suggestion, and I'm sure many will agree, would be to store your music as MP3 (your requirement) and when you want to burn a music CD, convert to WAV using Foobar2000 and use those WAVs for the CD.

Did some reading about normalization and replaygain, I understand a little more now. Thanks.

But why not just run the mp3s through mp3gain (then save) instead of the whole fubar2000 routine? The mp3s would then be at the same volume, and my burning issues would be solved (not to mention the different volume issues of mp3s).

Your foobar2000 procedure implies to me that it doesn't change the mp3s, only the WAV files during decoding.
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fenterbug
post Dec 30 2003, 18:15
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I hadn't read up on MP3Gain until just now. According to the MP3Gain FAQ,
QUOTE
MP3Gain uses David Robinson's Replay Gain algorithm
. I also see in the MP3Gain FAQ on HA that hardware/software support is not required. Now that I know this, it becomes apparent that MP3Gain is the perfect option for you.

As for the FB2K procedure: it changes the file by adding a ReplayGain tag. (Someone correct me if I'm wrong, but I don't think FB2K uses MP3Gain.) So yes, it changes the file, but no, it doesn't change the data. The ReplayGain is added during playback, thus requiring software support. It appears, though, that MP3Gain is applied within the data frames themselves-- lossless but doesn't require software support.

I hope that answered your question.


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symbiont7
post Dec 30 2003, 19:23
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Absolutely. Thanks very much for the help.
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