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Subject: Re: Wma to Mp3 conversion results?
From: Michael O'Quinn (michael_at_oquinn.info)
Date: 2003-10-26


On Sat, 25 Oct 2003, Chris Holt wrote:

> On Sat, 25 Oct 2003 08:07:41 -0700 (PDT), Michael O'Quinn wrote:
>
> > Glad to see I'm not the only one who has found JS on LAME working well.
> >
> >
> > What kinds of problems have you had with VBR, and with what source
> > material? And how did you fix it?
> >
> > Michael
>
> The issues were related to performance on MP3 hardware, so no real fault
> of the VBR scheme, other than some issue with LAME not creating headers.
> No quality concerns at all. LAME is very good at employing VBR for good
> quality/size tradeoffs. I understand that WMA 9's 2 pass VBR is quite
> good too, though I haven't done extensive testing.

O.K. That makes sense.

Getting back to the original question, which I believe was...

On Wed, 22 Oct 2003, LoveLearn wrote:

> I've only found some music I want in Wma format. I've tried a few 30-day
> conversion software versions to use these on my Archos. But conversion
> results were troubling. I expected slight conversion loss when changing
> 128 b/s Wma files to 128 b/s Mp3s, but they were conspicuously degraded.
> What guidelines have you decided upon as the best tradeoff between size
> and sound? For instance, do you convert 128 Wma to 128 Mp3 or convert
> 128 Wma to 160 Mp3? Also, do different conversion software products give
> different quality audible if operated comparably? How do you convert Wma
> files?
> Most Archos users convert formats to Mp3s. Please share your insights.
> John LoveLearn

I would say convert to a WAV, then re-encode as an MP-3 using the latest
LAME encoder with JS and VBR, with no min or max restrictions on the
bitrate. I would expect the final file to be larger than the original AAC
or WMA or whatever. Some software can do a direct 1-step conversion, but
I have never bothered to investigate those, since I don't do this all that
often.

If space were a really important concern, I guess would try limiting the
maximum bitrate LAME could use, until I hit some number where I noticed
the degradation. I've never done this since hard disks are relatively
cheap...

I do not think it is possible, as a general rule, to achieve the same
quality at the same bitrate in most cases. MP3 is an older standard, and
some of the others just do a better job at the lower bit rates like 128.
Plus, any time you re-encode -- even with the same (hopefully excellent)
encoder each time -- you lose SOMETHING. That is just the nature of lossy
compression.

I use Exact Audio Copy for all of my encoding, since it can work with WAVs
and with the command line version of LAME (under WinDoze). That gives me
the most control over how LAME operates, for when I am in the mood to pick
nits. Also, EAC adds the ID3 headers back on the finished MP3s after LAME
creates them. Also, I can rip a CD to WAVs, (or get it from wherever in
whatever format, and convert it to WAVs using whatever means) then come
back later and point EAC at the directory containing the WAV files, and it
will find the original CD info in freedb, and then add the correct ID3
tags to the finished MP3s. Voila! LAME's no-header problem is solved.

Michael



Page was last modified "Jan 10 2012" The Rockbox Crew
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