Rockbox mail archive
Subject: Re: is MP3 PRO supported ?
From: Vladimir Pantelic (pan_at_nt.tu-darmstadt.de)
Benoit Midy wrote:
> So You meant that I could play encoded MP3PRO encoded file BUT "but they will
> sound like normal 64kbit/s MP3 files" ???
> I do not understand all ?
Well, MP3Pro is an extension to MP3 for use with low bitrates. A normal
64kbit/s MP3 files sounds quite "bad" because the high frequencies are
missing. MP3Pro tries to cure this be recreating these missing high
frequencies in the decoder. But as the data of the high frequencies is
not compressed (it would then not be able to reach the low bitrate) the
MP3Pro decoder tries to guess the high frequencies from the low ones. To
help it the MP3Pro encoder puts some "hints" about the shape of the high
frequencies into the MP3Pro file (using only a few additional bits).
Now a "normal" MP3 decoder doen't know how to use these "hints" and how
to recreate the high frequencies, so the file will sound like a "normal"
64kbit/s MP3 file.
> Cause i'd like to use MP3PRO to gain in term of space, I want use some 8kb 8Hz Mono
> file (only speech) to gain at 1:2 ratio as I read in some doc about MP3PRO , is this
> possible ?
You can ue a lower bitrate to increase your storage space, but you
cannot use MP3Pro to help you get better sound with low bitrates if the
decoder cannot do MP3Pro
> SO I think the better is to test and see the result myself it still possible to listen to the
> MP3PRO encoded file ? and if the size gain is significant ?
Yes, you can do this, but MP3 at 64kbit/s and MP3Pro at 64kbit/s AND
without an MP3Pro capable decoder will sound more or less the same (=bad)
MP3Pro is a marketing trick, don't fall for it :-)
Page was last modified "Jan 10 2012" The Rockbox Crew