[FFmpeg-devel] [PATCH] aea demuxer

Michael Niedermayer michaelni
Tue Aug 11 14:58:42 CEST 2009


On Mon, Aug 10, 2009 at 11:15:05PM +0200, Benjamin Larsson wrote:
> Michael Niedermayer wrote:
> > On Mon, Jun 08, 2009 at 09:32:43PM +0200, Benjamin Larsson wrote:
> >> Simple demuxer for a simple format. Header parsing will be added when I
> >> get the specification. For now it will only be able to decode stereo
> >> streams.
> >>
> >> MvH
> >> Benjamin Larsson
> > 
> >>  Makefile     |    1 
> >>  aea.c        |   89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >>  allformats.c |    1 
> >>  3 files changed, 91 insertions(+)
> >> c331cf1a63bfa21d8ed7ba6cea5d474a12ed48d2  aea_demuxer.diff
> >> Index: libavformat/Makefile
> >> ===================================================================
> >> --- libavformat/Makefile	(revision 18866)
> >> +++ libavformat/Makefile	(working copy)
> >> @@ -12,6 +12,7 @@
> >>  OBJS-$(CONFIG_AC3_DEMUXER)               += raw.o
> >>  OBJS-$(CONFIG_AC3_MUXER)                 += raw.o
> >>  OBJS-$(CONFIG_ADTS_MUXER)                += adtsenc.o
> >> +OBJS-$(CONFIG_AEA_DEMUXER)               += aea.o
> >>  OBJS-$(CONFIG_AIFF_DEMUXER)              += aiff.o riff.o raw.o
> >>  OBJS-$(CONFIG_AIFF_MUXER)                += aiff.o riff.o
> >>  OBJS-$(CONFIG_AMR_DEMUXER)               += amr.o
> >> Index: libavformat/allformats.c
> >> ===================================================================
> >> --- libavformat/allformats.c	(revision 18866)
> >> +++ libavformat/allformats.c	(working copy)
> >> @@ -50,6 +50,7 @@
> >>      REGISTER_DEMUXER  (AAC, aac);
> >>      REGISTER_MUXDEMUX (AC3, ac3);
> >>      REGISTER_MUXER    (ADTS, adts);
> >> +    REGISTER_DEMUXER  (AEA, aea);
> >>      REGISTER_MUXDEMUX (AIFF, aiff);
> >>      REGISTER_MUXDEMUX (AMR, amr);
> >>      REGISTER_DEMUXER  (APC, apc);
> >> Index: libavformat/aea.c
> >> ===================================================================
> >> --- libavformat/aea.c	(revision 0)
> >> +++ libavformat/aea.c	(revision 0)
> >> @@ -0,0 +1,89 @@
> >> +/*
> >> + * MD STUDIO audio demuxer
> >> + *
> >> + * Copyright (c) 2009 Benjamin Larsson
> >> + *
> >> + * This file is part of FFmpeg.
> >> + *
> >> + * FFmpeg is free software; you can redistribute it and/or
> >> + * modify it under the terms of the GNU Lesser General Public
> >> + * License as published by the Free Software Foundation; either
> >> + * version 2.1 of the License, or (at your option) any later version.
> >> + *
> >> + * FFmpeg is distributed in the hope that it will be useful,
> >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >> + * Lesser General Public License for more details.
> >> + *
> >> + * You should have received a copy of the GNU Lesser General Public
> >> + * License along with FFmpeg; if not, write to the Free Software
> >> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> >> + */
> >> +
> >> +/**
> >> + * @file libavformat/aea.c
> >> + */
> >> +
> >> +#include "avformat.h"
> >> +#include "raw.h"
> >> +
> >> +#define AT1_SU_SIZE     212
> >> +
> > 
> >> +static int aea_read_probe(AVProbeData *p)
> > 
> > you dont need the aea prefixes
> > 
> > 
> >> +{
> >> +    /* Magic is '00 08 00 00' */
> >> +    if(*(p->buf) != 0 || *(p->buf+1) != 8 || *(p->buf+2) != 0 || *(p->buf+3) != 0)
> >> +        return 0;
> > 
> > AV_RB32() != ...
> > 
> > and testing more is a good idea if possible
> > 
> 
> Attached is the latest version of the demuxer. It works with the latest
> version of the atrac decoder patch. To do a better match I would need to

> look at 2048+212 bytes before I would be quite sure. Is it ok to use
> that much to identify a file ?

yes


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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