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279 lines
8.6 KiB
279 lines
8.6 KiB
/*****************************************************************************
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* a52.h
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*****************************************************************************
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* Copyright (C) 2001-2016 Laurent Aimar
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* $Id$
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*
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* Authors: Stéphane Borel <stef@via.ecp.fr>
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* Christophe Massiot <massiot@via.ecp.fr>
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* Gildas Bazin <gbazin@videolan.org>
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* Laurent Aimar <fenrir@via.ecp.fr>
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* Thomas Guillem <thomas@gllm.fr>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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#ifndef VLC_A52_H_
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#define VLC_A52_H_
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#include <vlc_bits.h>
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/**
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* Minimum AC3 header size that vlc_a52_header_Parse needs.
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*/
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#define VLC_A52_HEADER_SIZE (8)
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/**
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* AC3 header information.
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*/
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typedef struct
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{
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bool b_eac3;
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unsigned int i_channels;
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unsigned int i_channels_conf;
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unsigned int i_chan_mode;
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unsigned int i_rate;
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unsigned int i_bitrate;
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unsigned int i_size;
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unsigned int i_samples;
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union {
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struct {
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enum {
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EAC3_STRMTYP_INDEPENDENT = 0,
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EAC3_STRMTYP_DEPENDENT = 1,
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EAC3_STRMTYP_AC3_CONVERT = 2,
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EAC3_STRMTYP_RESERVED,
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} strmtyp;
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uint8_t i_substreamid;
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} eac3;
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};
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uint8_t i_blocks_per_sync_frame;
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} vlc_a52_header_t;
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/**
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* It parse AC3 sync info.
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*
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* cf. AC3 spec
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*/
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static inline int vlc_a52_header_ParseAc3( vlc_a52_header_t *p_header,
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const uint8_t *p_buf,
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const uint32_t *p_acmod,
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const unsigned *pi_fscod_samplerates )
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{
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/* cf. Table 5.18 Frame Size Code Table */
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static const uint16_t ppi_frmsizcod_fscod_sizes[][3] = {
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/* 32K, 44.1K, 48K */
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{ 96, 69, 64 },
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{ 96, 70, 64 },
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{ 120, 87, 80 },
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{ 120, 88, 80 },
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{ 144, 104, 96 },
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{ 144, 105, 96 },
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{ 168, 121, 112 },
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{ 168, 122, 112 },
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{ 192, 139, 128 },
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{ 192, 140, 128 },
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{ 240, 174, 160 },
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{ 240, 175, 160 },
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{ 288, 208, 192 },
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{ 288, 209, 192 },
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{ 336, 243, 224 },
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{ 336, 244, 224 },
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{ 384, 278, 256 },
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{ 384, 279, 256 },
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{ 480, 348, 320 },
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{ 480, 349, 320 },
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{ 576, 417, 384 },
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{ 576, 418, 384 },
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{ 672, 487, 448 },
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{ 672, 488, 448 },
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{ 768, 557, 512 },
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{ 768, 558, 512 },
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{ 960, 696, 640 },
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{ 960, 697, 640 },
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{ 1152, 835, 768 },
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{ 1152, 836, 768 },
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{ 1344, 975, 896 },
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{ 1344, 976, 896 },
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{ 1536, 1114, 1024 },
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{ 1536, 1115, 1024 },
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{ 1728, 1253, 1152 },
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{ 1728, 1254, 1152 },
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{ 1920, 1393, 1280 },
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{ 1920, 1394, 1280 }
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};
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static const uint16_t pi_frmsizcod_bitrates[] = {
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32, 40, 48, 56,
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64, 80, 96, 112,
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128, 160, 192, 224,
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256, 320, 384, 448,
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512, 576, 640
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};
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bs_t s;
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bs_init( &s, (void*)p_buf, VLC_A52_HEADER_SIZE );
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bs_skip( &s, 32 ); /* start code + CRC */
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/* cf. 5.3.2 */
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const uint8_t i_fscod = bs_read( &s, 2 );
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if( i_fscod == 3 )
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return VLC_EGENERIC;
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const uint8_t i_frmsizcod = bs_read( &s, 6 );
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if( i_frmsizcod >= 38 )
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return VLC_EGENERIC;
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const uint8_t i_bsid = bs_read( &s, 5 );
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bs_skip( &s, 3 ); /* i_bsmod */
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const uint8_t i_acmod = bs_read( &s, 3 );
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if( ( i_acmod & 0x1 ) && ( i_acmod != 0x1 ) )
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{
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/* if 3 front channels */
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bs_skip( &s, 2 ); /* i_cmixlev */
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}
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if( i_acmod & 0x4 )
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{
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/* if a surround channel exists */
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bs_skip( &s, 2 ); /* i_surmixlev */
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}
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/* if in 2/0 mode */
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const uint8_t i_dsurmod = i_acmod == 0x2 ? bs_read( &s, 2 ) : 0;
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const uint8_t i_lfeon = bs_read( &s, 1 );
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p_header->i_channels_conf = p_acmod[i_acmod];
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p_header->i_chan_mode = 0;
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if( i_dsurmod == 2 )
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p_header->i_chan_mode |= AOUT_CHANMODE_DOLBYSTEREO;
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if( i_acmod == 0 )
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p_header->i_chan_mode |= AOUT_CHANMODE_DUALMONO;
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if( i_lfeon )
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p_header->i_channels_conf |= AOUT_CHAN_LFE;
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p_header->i_channels = popcount(p_header->i_channels_conf);
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const unsigned i_rate_shift = VLC_CLIP(i_bsid, 8, 11) - 8;
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p_header->i_bitrate = (pi_frmsizcod_bitrates[i_frmsizcod >> 1] * 1000)
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>> i_rate_shift;
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p_header->i_rate = pi_fscod_samplerates[i_fscod] >> i_rate_shift;
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p_header->i_size = ppi_frmsizcod_fscod_sizes[i_frmsizcod][2 - i_fscod] * 2;
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p_header->i_blocks_per_sync_frame = 6;
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p_header->i_samples = p_header->i_blocks_per_sync_frame * 256;
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p_header->b_eac3 = false;
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return VLC_SUCCESS;
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}
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/**
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* It parse E-AC3 sync info
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*/
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static inline int vlc_a52_header_ParseEac3( vlc_a52_header_t *p_header,
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const uint8_t *p_buf,
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const uint32_t *p_acmod,
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const unsigned *pi_fscod_samplerates )
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{
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bs_t s;
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bs_init( &s, (void*)p_buf, VLC_A52_HEADER_SIZE );
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bs_skip( &s, 16 ); /* start code */
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p_header->eac3.strmtyp = bs_read( &s, 2 ); /* Stream Type */
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p_header->eac3.i_substreamid = bs_read( &s, 3 );/* Substream Identification */
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const uint16_t i_frmsiz = bs_read( &s, 11 );
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if( i_frmsiz < 2 )
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return VLC_EGENERIC;
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p_header->i_size = 2 * (i_frmsiz + 1 );
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const uint8_t i_fscod = bs_read( &s, 2 );
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if( i_fscod == 0x03 )
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{
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const uint8_t i_fscod2 = bs_read( &s, 2 );
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if( i_fscod2 == 0x03 )
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return VLC_EGENERIC;
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p_header->i_rate = pi_fscod_samplerates[i_fscod2] / 2;
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p_header->i_blocks_per_sync_frame = 6;
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}
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else
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{
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static const int pi_numblkscod [4] = { 1, 2, 3, 6 };
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p_header->i_rate = pi_fscod_samplerates[i_fscod];
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p_header->i_blocks_per_sync_frame = pi_numblkscod[bs_read( &s, 2 )];
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}
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const unsigned i_acmod = bs_read( &s, 3 );
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const unsigned i_lfeon = bs_read1( &s );
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p_header->i_channels_conf = p_acmod[i_acmod];
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p_header->i_chan_mode = 0;
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if( i_acmod == 0 )
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p_header->i_chan_mode |= AOUT_CHANMODE_DUALMONO;
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if( i_lfeon )
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p_header->i_channels_conf |= AOUT_CHAN_LFE;
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p_header->i_channels = popcount( p_header->i_channels_conf );
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p_header->i_bitrate = 8 * p_header->i_size * p_header->i_rate
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/ (p_header->i_blocks_per_sync_frame * 256);
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p_header->i_samples = p_header->i_blocks_per_sync_frame * 256;
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p_header->b_eac3 = true;
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return VLC_SUCCESS;
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}
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/**
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* It will parse the header AC3 frame and fill vlc_a52_header_t* if
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* it is valid or return VLC_EGENERIC.
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*
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* XXX It will only recognize big endian bitstream ie starting with 0x0b, 0x77
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*/
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static inline int vlc_a52_header_Parse( vlc_a52_header_t *p_header,
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const uint8_t *p_buffer, int i_buffer )
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{
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static const uint32_t p_acmod[8] = {
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AOUT_CHANS_2_0,
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AOUT_CHAN_CENTER,
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AOUT_CHANS_2_0,
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AOUT_CHANS_3_0,
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AOUT_CHANS_FRONT | AOUT_CHAN_REARCENTER, /* 2F1R */
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AOUT_CHANS_FRONT | AOUT_CHANS_CENTER, /* 3F1R */
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AOUT_CHANS_4_0,
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AOUT_CHANS_5_0,
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};
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static const unsigned pi_fscod_samplerates[] = {
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48000, 44100, 32000
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};
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if( i_buffer < VLC_A52_HEADER_SIZE )
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return VLC_EGENERIC;
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/* Check synword */
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if( p_buffer[0] != 0x0b || p_buffer[1] != 0x77 )
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return VLC_EGENERIC;
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/* Check bsid */
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const int bsid = p_buffer[5] >> 3;
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/* cf. Annex E 2.3.1.6 of AC3 spec */
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if( bsid <= 10 )
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return vlc_a52_header_ParseAc3( p_header, p_buffer,
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p_acmod, pi_fscod_samplerates );
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else if( bsid <= 16 )
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return vlc_a52_header_ParseEac3( p_header, p_buffer,
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p_acmod, pi_fscod_samplerates );
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else
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return VLC_EGENERIC;
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}
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#endif
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