ardour/libs/libltc/decoder.c
2017-07-26 22:58:12 +02:00

335 lines
11 KiB
C

/*
libltc - en+decode linear timecode
Copyright (C) 2005 Maarten de Boer <mdeboer@iua.upf.es>
Copyright (C) 2006-2016 Robin Gareus <robin@gareus.org>
Copyright (C) 2008-2009 Jan <jan@geheimwerk.de>
Binary constant generator macro for endianess conversion
by Tom Torfs - donated to the public domain
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 3 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 library.
If not, see <http://www.gnu.org/licenses/>.
*/
/** turn a numeric literal into a hex constant
* (avoids problems with leading zeroes)
* 8-bit constants max value 0x11111111, always fits in unsigned long
*/
#define HEX__(n) 0x##n##LU
/**
* 8-bit conversion function
*/
#define B8__(x) ((x&0x0000000FLU)?1:0) \
+((x&0x000000F0LU)?2:0) \
+((x&0x00000F00LU)?4:0) \
+((x&0x0000F000LU)?8:0) \
+((x&0x000F0000LU)?16:0) \
+((x&0x00F00000LU)?32:0) \
+((x&0x0F000000LU)?64:0) \
+((x&0xF0000000LU)?128:0)
/** for upto 8-bit binary constants */
#define B8(d) ((unsigned char)B8__(HEX__(d)))
/** for upto 16-bit binary constants, MSB first */
#define B16(dmsb,dlsb) (((unsigned short)B8(dmsb)<<8) + B8(dlsb))
/** turn a numeric literal into a hex constant
*(avoids problems with leading zeroes)
* 8-bit constants max value 0x11111111, always fits in unsigned long
*/
#define HEX__(n) 0x##n##LU
/** 8-bit conversion function */
#define B8__(x) ((x&0x0000000FLU)?1:0) \
+((x&0x000000F0LU)?2:0) \
+((x&0x00000F00LU)?4:0) \
+((x&0x0000F000LU)?8:0) \
+((x&0x000F0000LU)?16:0) \
+((x&0x00F00000LU)?32:0) \
+((x&0x0F000000LU)?64:0) \
+((x&0xF0000000LU)?128:0)
/** for upto 8-bit binary constants */
#define B8(d) ((unsigned char)B8__(HEX__(d)))
/** for upto 16-bit binary constants, MSB first */
#define B16(dmsb,dlsb) (((unsigned short)B8(dmsb)<<8) + B8(dlsb))
/* Example usage:
* B8(01010101) = 85
* B16(10101010,01010101) = 43605
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "ltc/decoder.h"
#define DEBUG_DUMP(msg, f) \
{ \
int _ii; \
printf("%s", msg); \
for (_ii=0; _ii < (LTC_FRAME_BIT_COUNT >> 3); _ii++) { \
const unsigned char _bit = ((unsigned char*)(f))[_ii]; \
printf("%c", (_bit & B8(10000000) ) ? '1' : '0'); \
printf("%c", (_bit & B8(01000000) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00100000) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00010000) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00001000) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00000100) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00000010) ) ? '1' : '0'); \
printf("%c", (_bit & B8(00000001) ) ? '1' : '0'); \
printf(" "); \
}\
printf("\n"); \
}
static double calc_volume_db(LTCDecoder *d) {
if (d->snd_to_biphase_max <= d->snd_to_biphase_min)
return -INFINITY;
return (20.0 * log10((d->snd_to_biphase_max - d->snd_to_biphase_min) / 255.0));
}
static void parse_ltc(LTCDecoder *d, unsigned char bit, ltc_off_t offset, ltc_off_t posinfo) {
int bit_num, bit_set, byte_num;
if (d->bit_cnt == 0) {
memset(&d->ltc_frame, 0, sizeof(LTCFrame));
if (d->frame_start_prev < 0) {
d->frame_start_off = posinfo - d->snd_to_biphase_period;
} else {
d->frame_start_off = d->frame_start_prev;
}
}
d->frame_start_prev = offset + posinfo;
if (d->bit_cnt >= LTC_FRAME_BIT_COUNT) {
/* shift bits backwards */
int k = 0;
const int byte_num_max = LTC_FRAME_BIT_COUNT >> 3;
for (k=0; k< byte_num_max; k++) {
const unsigned char bi = ((unsigned char*)&d->ltc_frame)[k];
unsigned char bo = 0;
bo |= (bi & B8(10000000) ) ? B8(01000000) : 0;
bo |= (bi & B8(01000000) ) ? B8(00100000) : 0;
bo |= (bi & B8(00100000) ) ? B8(00010000) : 0;
bo |= (bi & B8(00010000) ) ? B8(00001000) : 0;
bo |= (bi & B8(00001000) ) ? B8(00000100) : 0;
bo |= (bi & B8(00000100) ) ? B8(00000010) : 0;
bo |= (bi & B8(00000010) ) ? B8(00000001) : 0;
if (k+1 < byte_num_max) {
bo |= ( (((unsigned char*)&d->ltc_frame)[k+1]) & B8(00000001) ) ? B8(10000000): B8(00000000);
}
((unsigned char*)&d->ltc_frame)[k] = bo;
}
d->frame_start_off += ceil(d->snd_to_biphase_period);
d->bit_cnt--;
}
d->decoder_sync_word <<= 1;
if (bit) {
d->decoder_sync_word |= B16(00000000,00000001);
if (d->bit_cnt < LTC_FRAME_BIT_COUNT) {
// Isolating the lowest three bits: the location of this bit in the current byte
bit_num = (d->bit_cnt & B8(00000111));
// Using the bit number to define which of the eight bits to set
bit_set = (B8(00000001) << bit_num);
// Isolating the higher bits: the number of the byte/char the target bit is contained in
byte_num = d->bit_cnt >> 3;
(((unsigned char*)&d->ltc_frame)[byte_num]) |= bit_set;
}
}
d->bit_cnt++;
if (d->decoder_sync_word == B16(00111111,11111101) /*LTC Sync Word 0x3ffd*/) {
if (d->bit_cnt == LTC_FRAME_BIT_COUNT) {
int bc;
memcpy( &d->queue[d->queue_write_off].ltc,
&d->ltc_frame,
sizeof(LTCFrame));
for(bc = 0; bc < LTC_FRAME_BIT_COUNT; ++bc) {
const int btc = (d->biphase_tic + bc ) % LTC_FRAME_BIT_COUNT;
d->queue[d->queue_write_off].biphase_tics[bc] = d->biphase_tics[btc];
}
d->queue[d->queue_write_off].off_start = d->frame_start_off;
d->queue[d->queue_write_off].off_end = posinfo + (ltc_off_t) offset - 1LL;
d->queue[d->queue_write_off].reverse = 0;
d->queue[d->queue_write_off].volume = calc_volume_db(d);
d->queue[d->queue_write_off].sample_min = d->snd_to_biphase_min;
d->queue[d->queue_write_off].sample_max = d->snd_to_biphase_max;
d->queue_write_off++;
if (d->queue_write_off == d->queue_len)
d->queue_write_off = 0;
}
d->bit_cnt = 0;
}
if (d->decoder_sync_word == B16(10111111,11111100) /* reverse sync-word*/) {
if (d->bit_cnt == LTC_FRAME_BIT_COUNT) {
/* reverse frame */
int bc;
int k = 0;
int byte_num_max = LTC_FRAME_BIT_COUNT >> 3;
/* swap bits */
for (k=0; k< byte_num_max; k++) {
const unsigned char bi = ((unsigned char*)&d->ltc_frame)[k];
unsigned char bo = 0;
bo |= (bi & B8(10000000) ) ? B8(00000001) : 0;
bo |= (bi & B8(01000000) ) ? B8(00000010) : 0;
bo |= (bi & B8(00100000) ) ? B8(00000100) : 0;
bo |= (bi & B8(00010000) ) ? B8(00001000) : 0;
bo |= (bi & B8(00001000) ) ? B8(00010000) : 0;
bo |= (bi & B8(00000100) ) ? B8(00100000) : 0;
bo |= (bi & B8(00000010) ) ? B8(01000000) : 0;
bo |= (bi & B8(00000001) ) ? B8(10000000) : 0;
((unsigned char*)&d->ltc_frame)[k] = bo;
}
/* swap bytes */
byte_num_max-=2; // skip sync-word
for (k=0; k< (byte_num_max)/2; k++) {
const unsigned char bi = ((unsigned char*)&d->ltc_frame)[k];
((unsigned char*)&d->ltc_frame)[k] = ((unsigned char*)&d->ltc_frame)[byte_num_max-1-k];
((unsigned char*)&d->ltc_frame)[byte_num_max-1-k] = bi;
}
memcpy( &d->queue[d->queue_write_off].ltc,
&d->ltc_frame,
sizeof(LTCFrame));
for(bc = 0; bc < LTC_FRAME_BIT_COUNT; ++bc) {
const int btc = (d->biphase_tic + bc ) % LTC_FRAME_BIT_COUNT;
d->queue[d->queue_write_off].biphase_tics[bc] = d->biphase_tics[btc];
}
d->queue[d->queue_write_off].off_start = d->frame_start_off - 16 * d->snd_to_biphase_period;
d->queue[d->queue_write_off].off_end = posinfo + (ltc_off_t) offset - 1LL - 16 * d->snd_to_biphase_period;
d->queue[d->queue_write_off].reverse = (LTC_FRAME_BIT_COUNT >> 3) * 8 * d->snd_to_biphase_period;
d->queue[d->queue_write_off].volume = calc_volume_db(d);
d->queue[d->queue_write_off].sample_min = d->snd_to_biphase_min;
d->queue[d->queue_write_off].sample_max = d->snd_to_biphase_max;
d->queue_write_off++;
if (d->queue_write_off == d->queue_len)
d->queue_write_off = 0;
}
d->bit_cnt = 0;
}
}
static inline void biphase_decode2(LTCDecoder *d, ltc_off_t offset, ltc_off_t pos) {
d->biphase_tics[d->biphase_tic] = d->snd_to_biphase_period;
d->biphase_tic = (d->biphase_tic + 1) % LTC_FRAME_BIT_COUNT;
if (d->snd_to_biphase_cnt <= 2 * d->snd_to_biphase_period) {
pos -= (d->snd_to_biphase_period - d->snd_to_biphase_cnt);
}
if (d->snd_to_biphase_state == d->biphase_prev) {
d->biphase_state = 1;
parse_ltc(d, 0, offset, pos);
} else {
d->biphase_state = 1 - d->biphase_state;
if (d->biphase_state == 1) {
parse_ltc(d, 1, offset, pos);
}
}
d->biphase_prev = d->snd_to_biphase_state;
}
void decode_ltc(LTCDecoder *d, ltcsnd_sample_t *sound, size_t size, ltc_off_t posinfo) {
size_t i;
for (i = 0 ; i < size ; i++) {
ltcsnd_sample_t max_threshold, min_threshold;
/* track minimum and maximum values */
d->snd_to_biphase_min = SAMPLE_CENTER - (((SAMPLE_CENTER - d->snd_to_biphase_min) * 15) / 16);
d->snd_to_biphase_max = SAMPLE_CENTER + (((d->snd_to_biphase_max - SAMPLE_CENTER) * 15) / 16);
if (sound[i] < d->snd_to_biphase_min)
d->snd_to_biphase_min = sound[i];
if (sound[i] > d->snd_to_biphase_max)
d->snd_to_biphase_max = sound[i];
/* set the thresholds for hi/lo state tracking */
min_threshold = SAMPLE_CENTER - (((SAMPLE_CENTER - d->snd_to_biphase_min) * 8) / 16);
max_threshold = SAMPLE_CENTER + (((d->snd_to_biphase_max - SAMPLE_CENTER) * 8) / 16);
if ( /* Check for a biphase state change */
( d->snd_to_biphase_state && (sound[i] > max_threshold) )
|| ( !d->snd_to_biphase_state && (sound[i] < min_threshold) )
) {
/* If the sample count has risen above the biphase length limit */
if (d->snd_to_biphase_cnt > d->snd_to_biphase_lmt) {
/* single state change within a biphase priod. decode to a 0 */
biphase_decode2(d, i, posinfo);
biphase_decode2(d, i, posinfo);
} else {
/* "short" state change covering half a period
* together with the next or previous state change decode to a 1
*/
d->snd_to_biphase_cnt *= 2;
biphase_decode2(d, i, posinfo);
}
if (d->snd_to_biphase_cnt > (d->snd_to_biphase_period * 4)) {
/* "long" silence in between
* -> reset parser, don't use it for phase-tracking
*/
d->bit_cnt = 0;
} else {
/* track speed variations
* As this is only executed at a state change,
* d->snd_to_biphase_cnt is an accurate representation of the current period length.
*/
d->snd_to_biphase_period = (d->snd_to_biphase_period * 3.0 + d->snd_to_biphase_cnt) / 4.0;
/* This limit specifies when a state-change is
* considered biphase-clock or 2*biphase-clock.
* The relation with period has been determined
* empirically through trial-and-error */
d->snd_to_biphase_lmt = (d->snd_to_biphase_period * 3) / 4;
}
d->snd_to_biphase_cnt = 0;
d->snd_to_biphase_state = !d->snd_to_biphase_state;
}
d->snd_to_biphase_cnt++;
}
}