thank you for detailed reply.
My file is larger than 5 s (about
There is really a story of multiple of 1152 (or
But if I try to cut the file to do an exact match,
it adds... 1152 silent samples. Most being in the begining, some trailing. (more
exactly there is some white noise in the blank, but this is perhaps artifact of
I tried an exact match minus 1 sample,
and things like that, but it did not worked. It seems that there is
not some "magic number" where the exact length is
I also tried a multiple of 1152 plus 576, it
adds... 576 samples of blank.
So it seems that there is really a problem with the
MP3 length. To give an idea the waw version runs without a hitch (on audacity)
when the MP3 has a very audible blank.
----- Original Message -----
Sent: Monday, September 26, 2005 4:04
Subject: Re: [Audacity-help] Bug with MP3
export: a silence is added at thebeginnig
On Mon, 2005-09-26 at 09:41 +0200, RichardTrigaux
> I used and enjoyed Audacity.
> My file worked fine, I
exported it into wav format, it still worked.
> But when I exported in
MP3, a problem appeared.
> This file is to illustrate a
web page; it is a continuous sound, which
> plays in an infinite
> But in the MP3 export, there is a short silence
added at the
> beginning, of 25 ms, which is harmless if we play the
sound once, but
> which ruins the effect when played in a loop. I tried
to suppress it,
> and re-export in MP3, but the silence is still there.
It is added at
> My Audacity version is 1-2-3 under
windows 2000 and I downloaded the
> version of lame_enc.dll from
There is a known issue with very short files in audacity,
sample rate conversion. If your file is longer than 5 seconds
isn't the problem.
You say that the WAV file works but the
MP3 file doesn't? This is down
the limitations of the MP3 file format,
which is based on encoding
blocks of sound. If there aren't enough audio
samples to make a full
block at the end silence is added on, hence the
length growth you
describe. In theory there will be a length (in samples of
won't need padding. One post I found suggested a multiple of
samples, less 576 for the first frame:
should be possible with the samples selection format in audacity
Set Selection Format).
Whether windows MP3 playing is smart enough to
take advantage of this
and have it work is another question.