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/*****************************************************************************
* a52.h
*****************************************************************************
* Copyright (C) 2001-2009 Laurent Aimar
* $Id: 00078d39854297fbde59dbb63c8a08ce7aef78fa $
*
* Authors: Stéphane Borel <stef@via.ecp.fr>
* Christophe Massiot <massiot@via.ecp.fr>
* Gildas Bazin <gbazin@videolan.org>
* Laurent Aimar <fenrir@via.ecp.fr>
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
#ifndef _VLC_A52_H
#define _VLC_A52_H 1
#include <vlc_bits.h>
/**
* Minimum AC3 header size that vlc_a52_header_Parse needs.
*/
#define VLC_A52_HEADER_SIZE (8)
/**
* AC3 header information.
*/
typedef struct
{
bool b_eac3;
unsigned int i_channels;
unsigned int i_channels_conf;
unsigned int i_rate;
unsigned int i_bitrate;
unsigned int i_size;
unsigned int i_samples;
} vlc_a52_header_t;
/**
* It parse AC3 sync info.
*
* This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
* since we don't want to oblige S/PDIF people to use liba52 just to get
* their SyncInfo...
*/
static inline int vlc_a52_header_ParseAc3( vlc_a52_header_t *p_header,
const uint8_t *p_buf,
const uint32_t *p_acmod )
{
static const uint8_t pi_halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
static const unsigned int pi_bitrate[] = { 32, 40, 48, 56, 64, 80, 96, 112,
128, 160, 192, 224, 256, 320, 384, 448,
512, 576, 640 };
static const uint8_t pi_lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
0x04, 0x01, 0x04, 0x01 };
/* */
const unsigned i_rate_shift = pi_halfrate[p_buf[5] >> 3];
/* acmod, dsurmod and lfeon */
const unsigned i_acmod = p_buf[6] >> 5;
if( (p_buf[6] & 0xf8) == 0x50 )
/* Dolby surround = stereo + Dolby */
p_header->i_channels_conf = AOUT_CHANS_STEREO | AOUT_CHAN_DOLBYSTEREO;
else
p_header->i_channels_conf = p_acmod[i_acmod];
if( p_buf[6] & pi_lfeon[i_acmod] )
p_header->i_channels_conf |= AOUT_CHAN_LFE;
p_header->i_channels = popcount(p_header->i_channels_conf
& AOUT_CHAN_PHYSMASK);
const unsigned i_frmsizecod = p_buf[4] & 63;
if( i_frmsizecod >= 38 )
return VLC_EGENERIC;
const unsigned i_bitrate_base = pi_bitrate[i_frmsizecod >> 1];
p_header->i_bitrate = (i_bitrate_base * 1000) >> i_rate_shift;
switch( p_buf[4] & 0xc0 )
{
case 0:
p_header->i_rate = 48000 >> i_rate_shift;
p_header->i_size = 4 * i_bitrate_base;
break;
case 0x40:
p_header->i_rate = 44100 >> i_rate_shift;
p_header->i_size = 2 * (320 * i_bitrate_base / 147 + (i_frmsizecod & 1));
break;
case 0x80:
p_header->i_rate = 32000 >> i_rate_shift;
p_header->i_size = 6 * i_bitrate_base;
break;
default:
return VLC_EGENERIC;
}
p_header->i_samples = 6*256;
p_header->b_eac3 = false;
return VLC_SUCCESS;
}
/**
* It parse E-AC3 sync info
*/
static inline int vlc_a52_header_ParseEac3( vlc_a52_header_t *p_header,
const uint8_t *p_buf,
const uint32_t *p_acmod )
{
static const unsigned pi_samplerate[3] = { 48000, 44100, 32000 };
unsigned i_numblkscod;
bs_t s;
bs_init( &s, (void*)p_buf, VLC_A52_HEADER_SIZE );
bs_skip( &s, 16 + /* start code */
2 + /* stream type */
3 ); /* substream id */
const unsigned i_frame_size = bs_read( &s, 11 );
if( i_frame_size < 2 )
return VLC_EGENERIC;
p_header->i_size = 2 * ( i_frame_size + 1 );
const unsigned i_fscod = bs_read( &s, 2 );
if( i_fscod == 0x03 )
{
const unsigned i_fscod2 = bs_read( &s, 2 );
if( i_fscod2 == 0X03 )
return VLC_EGENERIC;
p_header->i_rate = pi_samplerate[i_fscod2] / 2;
i_numblkscod = 6;
}
else
{
static const int pi_blocks[4] = { 1, 2, 3, 6 };
p_header->i_rate = pi_samplerate[i_fscod];
i_numblkscod = pi_blocks[bs_read( &s, 2 )];
}
const unsigned i_acmod = bs_read( &s, 3 );
const unsigned i_lfeon = bs_read1( &s );
p_header->i_channels_conf = p_acmod[i_acmod];
if( i_lfeon )
p_header->i_channels_conf |= AOUT_CHAN_LFE;
p_header->i_channels = popcount(p_header->i_channels_conf
& AOUT_CHAN_PHYSMASK);
p_header->i_bitrate = 8 * p_header->i_size * (p_header->i_rate)
/ (i_numblkscod * 256);
p_header->i_samples = i_numblkscod * 256;
p_header->b_eac3 = true;
return VLC_SUCCESS;
}
/**
* It will parse the header AC3 frame and fill vlc_a52_header_t* if
* it is valid or return VLC_EGENERIC.
*
* XXX It will only recognize big endian bitstream ie starting with 0x0b, 0x77
*/
static inline int vlc_a52_header_Parse( vlc_a52_header_t *p_header,
const uint8_t *p_buffer, int i_buffer )
{
static const uint32_t p_acmod[8] = {
AOUT_CHANS_2_0 | AOUT_CHAN_DUALMONO,
AOUT_CHAN_CENTER,
AOUT_CHANS_2_0,
AOUT_CHANS_3_0,
AOUT_CHANS_FRONT | AOUT_CHAN_REARCENTER, /* 2F1R */
AOUT_CHANS_FRONT | AOUT_CHANS_CENTER, /* 3F1R */
AOUT_CHANS_4_0,
AOUT_CHANS_5_0,
};
if( i_buffer < VLC_A52_HEADER_SIZE )
return VLC_EGENERIC;
/* Check synword */
if( p_buffer[0] != 0x0b || p_buffer[1] != 0x77 )
return VLC_EGENERIC;
/* Check bsid */
const int bsid = p_buffer[5] >> 3;
if( bsid > 16 )
return VLC_EGENERIC;
if( bsid <= 10 )
{
if( vlc_a52_header_ParseAc3( p_header, p_buffer, p_acmod ) )
return VLC_EGENERIC;
}
else
{
if( vlc_a52_header_ParseEac3( p_header, p_buffer, p_acmod ) )
return VLC_EGENERIC;
}
return VLC_SUCCESS;
}
#endif
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