Re: mpglib/mpg123 MP3 Decoding

Am Tue, 16 Jan 2007 13:08:21 +0100
schrieb "Robert Leiking" <R-Leikinggmx.de>: 

> > There already was an attempt to make mpglib work
on a SHARC 32bit DSP,
> Maybe you could give me some more information about
this stuff: 

Well, we started working on a branch of mpglib for this dsp.
Including giving the result as 32bit float instead of
converting to integers...
Not too much changes were needed, actually. There were some
bugs that arised from the fact that every data type on this
dsp was 32 bits wide.
Well, you can see what happened there via

http://mpg123.de/cgi-bin/viewvc.cgi/mpglib/sharc_dsp/

> 
> > What do this members of the structure
mp3data_struct in mpglib.h mean:"ssize, dsize, bsize,
bsnum"?
> >
> > In this structure: Does
"framesize","fsizeold" represent the
number of samples within one mp3 frame (1152 for a Mp3 file,
right?) or does it mean the length of a frame in bytes?
> > 

These are for the frame data size. The number of of samples
is normally 1152, but can be 576 or 384 ... that number
should be the same throughout a file.
Frame data size depends on the bitrate and can vary for VBR
files (which consist of frames with differing bitrate
values), short:

fr->framesize  = (long)
tabsel_123[fr->lsf][2][fr->bitrate_index] * 144000;



Alrighty then,

Thomas.

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Hi Thomas,

is there also a fixed point implementation available from
mpglib or mpg123??
Or is this SHARP DSP already in fixed point?

cheers

Robert


-------- Original-Nachricht --------
Datum: Thu, 18 Jan 2007 01:37:45 +0100
Von: Thomas Orgis <thomas-forumorgis.org>
An: mp3encoderminnie.tuhs.org
CC: 
Betreff: Re: [mp3encoder] mpglib/mpg123 MP3 Decoding

> Am Tue, 16 Jan 2007 13:08:21 +0100
> schrieb "Robert Leiking" <R-Leikinggmx.de>: 
> 
> > > There already was an attempt to make mpglib
work on a SHARC 32bit DSP,
> > Maybe you could give me some more information
about this stuff: 
> 
> Well, we started working on a branch of mpglib for this
dsp. Including
> giving the result as 32bit float instead of converting
to integers...
> Not too much changes were needed, actually. There were
some bugs that
> arised from the fact that every data type on this dsp
was 32 bits wide.
> Well, you can see what happened there via
> 
> http://mpg123.de/cgi-bin/viewvc.cgi/mpglib/sharc_dsp/
> 
> > 
> > > What do this members of the structure
mp3data_struct in mpglib.h
> mean:"ssize, dsize, bsize, bsnum"?
> > >
> > > In this structure: Does
"framesize","fsizeold" represent the
number of
> samples within one mp3 frame (1152 for a Mp3 file,
right?) or does it mean
> the length of a frame in bytes?
> > > 
> 
> These are for the frame data size. The number of of
samples is normally
> 1152, but can be 576 or 384 ... that number should be
the same throughout a
> file.
> Frame data size depends on the bitrate and can vary for
VBR files (which
> consist of frames with differing bitrate values),
short:
> 
> fr->framesize  = (long)
tabsel_123[fr->lsf][2][fr->bitrate_index] *
> 144000;
> 
> 
> 
> Alrighty then,
> 
> Thomas.
> 
> -- 
> Thomas Orgis - Source Mage GNU/Linux Developer
> (http://www.sourcemage.org) OrgisNetzOrganisation ---)=-
> http://orgis.org GPG
public key: http://thomas.orgi
s.org/public_key
> _______________________________________________
> mp3encoder mailing list
> mp3encoderminnie.tuhs.org
> h
ttps://minnie.tuhs.org/mailman/listinfo/mp3encoder

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