Re: Convert mp3 to lower-quality mp3?
Re: Convert mp3 to lower-quality mp3?
- Subject: Re: Convert mp3 to lower-quality mp3?
- From: Doug Wyatt <email@hidden>
- Date: Mon, 9 May 2005 10:51:58 -0700
On May 9, 2005, at 10:27, Bill Monk wrote:
I need to batch-convert higher-quality stereo mp3 files to much
lower quality mp3 files. Basically mono, low-bit-rate, low-sample-
rate, and small enough to email; low fidelity is not a problem.
I already had working Quicktime code which exports files into a
variety of formats using ConvertMovieToFile(), using settings
obtained from MovieExportDoUserDialog() and saved/reused via
MovieExportGetSettingsAsAtomContainer() and
MovieExportSetSettingsAsAtomContainer().
My assumption was that converting mp3s would be as trivial as
configuring an mp3 export component and handing it to
ConvertMovieToFile(). Inexplicably, there doesn't seem to *be *such
a component. That's rather surprising, but OK, whatever....
Given the non-existence of an mp3 export component(corrections
gladly accepted), can anyone point me to information on doing this
in CoreAudio?
I've looked at the afconvert tool AudioFileTools CA sample code; it
also doesn't seem to be able to do this conversion -- but maybe I
haven't understood the tool and its options correctly. My attempts
all result in "Error: transcoding not currently supported".
The biggest hurdle is that there is not an MP3 encoder supplied with
QuickTime/CoreAudio.
If there were, you could use afconvert to decode to AIFF and then re-
encode to MP3 in two invocations (granted, with re-encoding artifacts
but there's no avoiding that if you have to start with MP3).
You can probably put something together in AppleScript:
- use afconvert to decode to AIFF
- tell itunes to import it and re-encode to MP3
It'd be worth seeing if this can be done in Automator, which would
save a lot of AppleScripting.
Doug
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