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I want to be able to transcode my music library (lots of nested folders, no space) to a different bitrate. I've been doing this manually with Media Coder, but I've noticed that not every file ends up smaller. Is there a useful batch (preferred) or script that goes through all the folders, converts the file to the specified bitrate, checks the size against the original, and replaces the file assuming it's much smaller?

It would also be helpful if someone could point out an encoder that doesn't change the MP3's tags.

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You do know that every time you transcode mp3s (or other "lossy" formats) that you are losing audio quality don't you? – Mokubai Dec 31 '11 at 8:37
yes :) i'm transcoding >192kpbs files to 192kbps. keeps the library trim – Bananna Dec 31 '11 at 8:51
foobar2000 and/or VLC is very flexible. Have you tried one of those? Also as Mokubai says - remember that this is a lossy format and you will loose quality! – Waxhead Dec 31 '11 at 12:08

Final file size will likely be a result of encoder settings and possibly the bit rate not being correctly reported by some applications for Variable Bit Rate (VBR) and older Average Bit Rate (ABR) files.

In any case, here's how I would do it:

  • Use windows explorer to find high bitrate files by using the following search filter: type:mp3 bitrate:>192kbps (or >224kbps perhaps)

enter image description here

  • Select all file and use a converted that provides a context menu option to convert selected files. Myself, I use dbPowerAmp but it is not free. It will properly overwrite your original files after encoding, if you so desire, and also keeps tags properly. Doesn't Media Coder preserve your tags properly?


Original size: 685 MB
192kbps transcode: 674 MB
V2 transcode: 665 MB (final bitrates 123 to 212kbps)

For this test I used bitrates very close to 192kbps to test your target size problem, but I haven't encountered any final file that was larger than the original, except when using V2.

FWIW, ideally you would want your entire library in V2: total size near 192kbps, but with some files remaining above 192kbps to retain quality where necessary, but you couldn't use the bitrate filter anymore (you would endlessly re-encode those higher bitrate files). DBPowerAmp Batch Convert does provide a "Encoding" column you can sort by to select files and only convert non V2 files, but it's a bit more cumbersome.

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