Francois Cartegnie
9 years ago
3 changed files with 300 additions and 282 deletions
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/*****************************************************************************
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* flac.h: fLAC audio headers |
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***************************************************************************** |
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* Copyright (C) 2001-2018 VLC authors, VideoLabs and VideoLAN |
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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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#include <vlc_common.h> |
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#define FLAC_HEADER_SIZE_MAX 16 |
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#define FLAC_STREAMINFO_SIZE 34 |
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#define FLAC_FRAME_SIZE_MIN ((48+(8 + 4 + 1*4)+FLAC_HEADER_SIZE_MAX)/8) |
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struct flac_stream_info |
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{ |
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unsigned min_blocksize, max_blocksize; |
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unsigned min_framesize, max_framesize; |
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unsigned sample_rate; |
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unsigned channels; |
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unsigned bits_per_sample; |
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uint64_t total_samples; |
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}; |
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struct flac_header_info |
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{ |
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mtime_t i_pts; |
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unsigned i_rate; |
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unsigned i_channels; |
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unsigned i_bits_per_sample; |
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unsigned i_frame_length; |
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}; |
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static inline void FLAC_ParseStreamInfo( const uint8_t *p_buf, |
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struct flac_stream_info *stream_info ) |
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{ |
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stream_info->min_blocksize = GetWBE( &p_buf[0] ); |
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stream_info->min_blocksize = VLC_CLIP( stream_info->min_blocksize, 16, 65535 ); |
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stream_info->max_blocksize = GetWBE( &p_buf[2] ); |
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stream_info->max_blocksize = VLC_CLIP( stream_info->max_blocksize, 16, 65535 ); |
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stream_info->min_framesize = GetDWBE( &p_buf[3] ) & 0x00FFFFFF; |
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stream_info->min_framesize = __MAX( stream_info->min_framesize, FLAC_FRAME_SIZE_MIN ); |
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stream_info->max_framesize = GetDWBE( &p_buf[6] ) & 0x00FFFFFF; |
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stream_info->sample_rate = GetDWBE( &p_buf[10] ) >> 12; |
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stream_info->channels = (p_buf[12] & 0x0F >> 1) + 1; |
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stream_info->bits_per_sample = (((p_buf[12] & 0x01) << 4) | p_buf[13] >> 4) + 1; |
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stream_info->total_samples = GetQWBE(&p_buf[4+6]) & ((INT64_C(1)<<36)-1); |
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} |
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/* Will return INT64_MAX for an invalid utf-8 sequence */ |
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static inline int64_t read_utf8(const uint8_t *p_buf, int *pi_read) |
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{ |
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/* Max coding bits is 56 - 8 */ |
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/* Value max precision is 36 bits */ |
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int64_t i_result = 0; |
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unsigned i; |
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if (!(p_buf[0] & 0x80)) { /* 0xxxxxxx */ |
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i_result = p_buf[0]; |
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i = 0; |
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} else if (p_buf[0] & 0xC0 && !(p_buf[0] & 0x20)) { /* 110xxxxx */ |
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i_result = p_buf[0] & 0x1F; |
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i = 1; |
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} else if (p_buf[0] & 0xE0 && !(p_buf[0] & 0x10)) { /* 1110xxxx */ |
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i_result = p_buf[0] & 0x0F; |
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i = 2; |
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} else if (p_buf[0] & 0xF0 && !(p_buf[0] & 0x08)) { /* 11110xxx */ |
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i_result = p_buf[0] & 0x07; |
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i = 3; |
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} else if (p_buf[0] & 0xF8 && !(p_buf[0] & 0x04)) { /* 111110xx */ |
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i_result = p_buf[0] & 0x03; |
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i = 4; |
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} else if (p_buf[0] & 0xFC && !(p_buf[0] & 0x02)) { /* 1111110x */ |
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i_result = p_buf[0] & 0x01; |
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i = 5; |
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} else if (p_buf[0] & 0xFE && !(p_buf[0] & 0x01)) { /* 11111110 */ |
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i_result = 0; |
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i = 6; |
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} else { |
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return INT64_MAX; |
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} |
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for (unsigned j = 1; j <= i; j++) { |
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if (!(p_buf[j] & 0x80) || (p_buf[j] & 0x40)) { /* 10xxxxxx */ |
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return INT64_MAX; |
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} |
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i_result <<= 6; |
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i_result |= (p_buf[j] & 0x3F); |
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} |
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*pi_read = i; |
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return i_result; |
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} |
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/*****************************************************************************
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* FLAC_ParseSyncInfo: parse FLAC sync info |
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* - stream_info can be NULL |
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* - pf_crc8 can be NULL to skip crc check |
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* Returns: 1 on success, 0 on failure, and -1 if could be incorrect |
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*****************************************************************************/ |
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static inline int FLAC_ParseSyncInfo(const uint8_t *p_buf, |
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const struct flac_stream_info *stream_info, |
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uint8_t(*pf_crc8)(const uint8_t *, size_t), |
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struct flac_header_info *h) |
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{ |
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bool b_guessing = false; |
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/* Check syncword */ |
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if (p_buf[0] != 0xFF || (p_buf[1] & 0xFE) != 0xF8) |
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return 0; |
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/* Check there is no emulated sync code in the rest of the header */ |
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if (p_buf[2] == 0xff || p_buf[3] == 0xFF) |
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return 0; |
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/* Find blocksize (framelength) */ |
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int blocksize_hint = 0; |
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unsigned blocksize = p_buf[2] >> 4; |
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if (blocksize >= 8) { |
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blocksize = 256 << (blocksize - 8); |
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} else if (blocksize == 0) { /* value 0 is reserved */ |
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b_guessing = true; |
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if (stream_info && |
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stream_info->min_blocksize == stream_info->max_blocksize) |
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blocksize = stream_info->min_blocksize; |
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else |
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return 0; /* We can't do anything with this */ |
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} else if (blocksize == 1) { |
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blocksize = 192; |
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} else if (blocksize == 6 || blocksize == 7) { |
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blocksize_hint = blocksize; |
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blocksize = 0; |
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} else /* 2, 3, 4, 5 */ { |
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blocksize = 576 << (blocksize - 2); |
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} |
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if (stream_info && !blocksize_hint) |
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if (blocksize < stream_info->min_blocksize || |
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blocksize > stream_info->max_blocksize) |
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return 0; |
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/* Find samplerate */ |
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int samplerate_hint = p_buf[2] & 0xf; |
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unsigned int samplerate; |
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if (samplerate_hint == 0) { |
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if (stream_info) |
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samplerate = stream_info->sample_rate; |
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else |
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return 0; /* We can't do anything with this */ |
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} else if (samplerate_hint == 15) { |
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return 0; /* invalid */ |
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} else if (samplerate_hint < 12) { |
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static const int16_t flac_samplerate[12] = { |
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0, 8820, 17640, 19200, |
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800, 1600, 2205, 2400, |
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3200, 4410, 4800, 9600, |
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}; |
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samplerate = flac_samplerate[samplerate_hint] * 10; |
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} else { |
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samplerate = 0; /* at end of header */ |
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} |
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/* Find channels */ |
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unsigned channels = p_buf[3] >> 4; |
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if (channels >= 8) { |
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if (channels >= 11) /* reserved */ |
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return 0; |
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channels = 2; |
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} else |
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channels++; |
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/* Find bits per sample */ |
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static const int8_t flac_bits_per_sample[8] = { |
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0, 8, 12, -1, 16, 20, 24, -1 |
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}; |
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int bits_per_sample = flac_bits_per_sample[(p_buf[3] & 0x0e) >> 1]; |
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if (bits_per_sample == 0) { |
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if (stream_info) |
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bits_per_sample = stream_info->bits_per_sample; |
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else |
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return 0; |
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} else if (bits_per_sample < 0) |
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return 0; |
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/* reserved for future use */ |
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if (p_buf[3] & 0x01) |
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return 0; |
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/* End of fixed size header */ |
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int i_header = 4; |
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/* Check Sample/Frame number */ |
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int i_read; |
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int64_t i_fsnumber = read_utf8(&p_buf[i_header++], &i_read); |
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if ( i_fsnumber == INT64_MAX ) |
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return 0; |
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i_header += i_read; |
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/* Read blocksize */ |
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if (blocksize_hint) { |
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blocksize = p_buf[i_header++]; |
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if (blocksize_hint == 7) { |
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blocksize <<= 8; |
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blocksize |= p_buf[i_header++]; |
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} |
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blocksize++; |
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} |
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/* Read sample rate */ |
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if (samplerate == 0) { |
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samplerate = p_buf[i_header++]; |
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if (samplerate_hint != 12) { /* 16 bits */ |
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samplerate <<= 8; |
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samplerate |= p_buf[i_header++]; |
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} |
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if (samplerate_hint == 12) |
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samplerate *= 1000; |
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else if (samplerate_hint == 14) |
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samplerate *= 10; |
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} |
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if ( !samplerate ) |
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return 0; |
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/* Check the CRC-8 byte */ |
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if (pf_crc8 && |
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pf_crc8(p_buf, i_header) != p_buf[i_header]) |
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return 0; |
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/* Sanity check using stream info header when possible */ |
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if (stream_info) { |
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if (blocksize < stream_info->min_blocksize || |
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blocksize > stream_info->max_blocksize) |
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return 0; |
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if ((unsigned)bits_per_sample != stream_info->bits_per_sample) |
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return 0; |
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if (samplerate != stream_info->sample_rate) |
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return 0; |
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} |
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/* Compute from frame absolute time */ |
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if ( (p_buf[1] & 0x01) == 0 ) /* Fixed blocksize stream / Frames */ |
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h->i_pts = VLC_TS_0 + CLOCK_FREQ * blocksize * i_fsnumber / samplerate; |
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else /* Variable blocksize stream / Samples */ |
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h->i_pts = VLC_TS_0 + CLOCK_FREQ * i_fsnumber / samplerate; |
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h->i_bits_per_sample = bits_per_sample; |
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h->i_rate = samplerate; |
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h->i_channels = channels; |
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h->i_frame_length = blocksize; |
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return b_guessing ? -1 : 1; |
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} |
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