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313 lines
10 KiB
313 lines
10 KiB
/*****************************************************************************
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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_MIN 9
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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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vlc_tick_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 UINT64_MAX for an invalid utf-8 sequence */
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static inline uint64_t read_utf8(const uint8_t *p_buf, unsigned i_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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uint64_t i_result = 0;
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unsigned i;
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if(i_buf < 1)
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return UINT64_MAX;
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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 UINT64_MAX;
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}
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if(i_buf < i + 1)
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return UINT64_MAX;
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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 UINT64_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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static inline int FLAC_CheckFrameInfo(const struct flac_stream_info *stream_info,
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const struct flac_header_info *h)
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{
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/* Sanity check using stream info header when possible */
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if (stream_info)
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{
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if ((stream_info->min_blocksize != stream_info->max_blocksize &&
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h->i_frame_length < stream_info->min_blocksize) ||
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h->i_frame_length > stream_info->max_blocksize)
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return 0;
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if(stream_info->max_framesize &&
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stream_info->min_framesize > stream_info->max_framesize)
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return 0;
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if (h->i_bits_per_sample != stream_info->bits_per_sample)
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return 0;
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if (h->i_rate != stream_info->sample_rate)
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return 0;
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}
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return 1;
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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, unsigned i_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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if(unlikely(i_buf < FLAC_HEADER_SIZE_MIN))
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return 0;
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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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unsigned i_header = 4;
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/* > FLAC_HEADER_SIZE_MIN checks start here */
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/* Check Sample/Frame number */
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int i_read;
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uint64_t i_fsnumber = read_utf8(&p_buf[i_header++], i_buf - 4, &i_read);
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/* Invalid UTF-8 */
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if (i_fsnumber == UINT64_MAX)
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return 0;
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/* Invalid Sample/Frame number */
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if (stream_info && stream_info->total_samples != 0 && i_fsnumber > stream_info->total_samples)
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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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if(i_header == i_buf)
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return 0;
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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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if(i_header == i_buf)
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return 0;
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samplerate = p_buf[i_header++];
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if (samplerate_hint != 12) { /* 16 bits */
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if(i_header == i_buf)
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return 0;
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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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if(i_header == i_buf) /* no crc space */
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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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/* Compute from frame absolute time */
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if ( (p_buf[1] & 0x01) == 0 ) /* Fixed blocksize stream / Frames */
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{
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const unsigned fixedblocksize = stream_info ? stream_info->min_blocksize : blocksize;
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h->i_pts = VLC_TICK_0 + vlc_tick_from_samples(fixedblocksize * i_fsnumber, samplerate);
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}
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else /* Variable blocksize stream / Samples */
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h->i_pts = VLC_TICK_0 + vlc_tick_from_samples(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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