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Harsh (clipped?) MP3 results with EAC/LAME
mooch91
post Jun 5 2012, 13:49
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All,

I've been using the standard EAC/LAME process to create some high-quality (320 kbps) MP3s. In the past I've just used iTunes to create them (or downloaded 256 kbps from Amazon) and had been reasonably satisfied, although I still found I preferred lossless or original CDs. I have a high-end stereo system in my car that I use for listening primarily on extended commutes.

With the rips and compression that I've recently been doing with EAC and LAME, I've noticed that the resulting MP3s are sounding very harsh at moderate volumes, primarily in the treble region (vocals and guitars, in particular, are sounding very saturated) - almost painful to listen to. I think, perhaps, the recordings are heavily clipped for some reason. The original CDs, played on the same equipment, sound fantastic. My earlier MP3s sound OK as well.

Not what I expected from what I've read should be a very high quality result.

I'm using the latest builds of EAC and LAME (not exactly sure of the versions, will need to check when I get home). No normalization on either the lossless rip or the lossy compression. LAME command line parameters are "-b 320 -h %source% %dest%". EAC reports 100% peak volume and near 100% accuracy for just about every song I've converted.

Can someone help me out, identify something to check that might be causing this problem? Is there any way to confirm the clipping in the source, resulting WAV, or resulting MP3?

The only thing I can think of is the quality of the CD player on my computer. I'm planning to try the same rip and compression process on my laptop to see if it makes a difference.

Thanks!

This post has been edited by mooch91: Jun 5 2012, 13:50
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greynol
post Jun 5 2012, 14:03
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I don't see any obvious problem from the information you've provided. Unless the disc is damaged it is highly doubtful that a different drive will deliver audibly different results. Even if the disc is damaged, the differences will not be as you've described.

From our Terms of Service:
QUOTE
8. All members that put forth a statement concerning subjective sound quality, must -- to the best of their ability -- provide objective support for their claims. Acceptable means of support are double blind listening tests (ABX or ABC/HR) demonstrating that the member can discern a difference perceptually, together with a test sample to allow others to reproduce their findings. Graphs, non-blind listening tests, waveform difference comparisons, and so on, are not acceptable means of providing support.

I don't see that this criteria has been met.

This post has been edited by greynol: Jun 5 2012, 14:12


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Kohlrabi
post Jun 5 2012, 14:32
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QUOTE (mooch91 @ Jun 5 2012, 14:49) *
Can someone help me out, identify something to check that might be causing this problem? Is there any way to confirm the clipping in the source, resulting WAV, or resulting MP3?

Rip your CD to WAV or FLAC. Convert the resulting files with LAME to MP3, but don't delete the sources. Now you have multiple options to further investigate:
  • Look at the waveforms in Audacity, and use the built-in clipping detector to identify clipping samples. This will show you if the ripped lossless files or the decoded LAME files show any signs of clipping.
  • Do a level-matched(!) ABX test of the LAME encoded files versus the lossless sources. I'd recommend to use foobar2000 and the foo_abx plugin for that. This will show you whether the "harsh" sound is real or just placebo.

FWIW, while your files may be edge cases, it is highly unlikely that you coincidentally tapped into a big problem case of the LAME encoder, especially considering the huge bitrates you use. But that surely can be shown doing the proposed ABX test.

This post has been edited by Kohlrabi: Jun 5 2012, 14:37


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greynol
post Jun 5 2012, 14:52
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QUOTE (Kohlrabi @ Jun 5 2012, 06:32) *
Look at the waveforms in Audacity, and use the built-in clipping detector to identify clipping samples. This will show you if the ripped lossless files or the decoded LAME files show any signs of clipping.

With heavily compressed source material with peak levels at or even a couple dB under full-scale, mp3s and mp4s decoded to integer PCM will clip, so this isn't very interesting. What is of key importance is whether this is audible which can only be addressed by your second bulleted point. The one quoted here will likely only serve to mislead if the other is not given the credence that it deserves. IMO, the former does not deserve to be listed with the latter.

This post has been edited by greynol: Jun 5 2012, 15:01


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benski
post Jun 5 2012, 15:03
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You mention that you listen using a car stereo. There's a possibility that your head unit has some decoding error or other audible error with certain MP3 files.
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pdq
post Jun 5 2012, 15:13
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You mention listening on your car stereo. Have you tried listening with any other equipment and do you hear the same problem?

What model is your car stereo. I would be particularly interested if it has replaygain.
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