259 lines
8.3 KiB
C
259 lines
8.3 KiB
C
/*
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* Copyright (c) 2016 Tobias Rapp
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 GNU
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* 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
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Filter for reading the vertical interval timecode (VITC).
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* See also https://en.wikipedia.org/wiki/Vertical_interval_timecode
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*/
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#include "libavutil/common.h"
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#include "libavutil/internal.h"
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#include "libavutil/opt.h"
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#include "libavutil/pixdesc.h"
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#include "libavutil/timecode.h"
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#include "avfilter.h"
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#include "formats.h"
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#include "internal.h"
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#define LINE_DATA_SIZE 9
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typedef struct ReadVitcContext {
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const AVClass *class;
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int scan_max;
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double thr_b;
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double thr_w;
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int threshold_black;
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int threshold_white;
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int threshold_gray;
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int grp_width;
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uint8_t line_data[LINE_DATA_SIZE];
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char tcbuf[AV_TIMECODE_STR_SIZE];
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} ReadVitcContext;
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#define OFFSET(x) offsetof(ReadVitcContext, x)
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#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
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static const AVOption readvitc_options[] = {
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{ "scan_max", "maximum line numbers to scan for VITC data", OFFSET(scan_max), AV_OPT_TYPE_INT, {.i64 = 45 }, -1, INT_MAX, FLAGS },
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{ "thr_b", "black color threshold", OFFSET(thr_b), AV_OPT_TYPE_DOUBLE, {.dbl = 0.2 }, 0, 1.0, FLAGS },
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{ "thr_w", "white color threshold", OFFSET(thr_w), AV_OPT_TYPE_DOUBLE, {.dbl = 0.6 }, 0, 1.0, FLAGS },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(readvitc);
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static uint8_t get_vitc_crc( uint8_t *line ) {
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uint8_t crc;
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crc = 0x01 | (line[0] << 2);
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crc ^= (line[0] >> 6) | 0x04 | (line[1] << 4);
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crc ^= (line[1] >> 4) | 0x10 | (line[2] << 6);
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crc ^= (line[2] >> 2) | 0x40;
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crc ^= line[3];
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crc ^= 0x01 | (line[4] << 2);
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crc ^= (line[4] >> 6) | 0x04 | (line[5] << 4);
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crc ^= (line[5] >> 4) | 0x10 | (line[6] << 6);
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crc ^= (line[6] >> 2) | 0x40;
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crc ^= line[7];
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crc ^= 0x01;
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crc = (crc >> 2) | (crc << 6); // rotate byte right by two bits
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return crc;
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}
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static inline uint8_t get_pit_avg3( uint8_t *line, int i ) {
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return ((line[i-1] + line[i] + line[i+1]) / 3);
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}
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static int read_vitc_line( ReadVitcContext *ctx, uint8_t *src, int line_size, int width, int height )
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{
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uint8_t *scan_line;
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int grp_index, pit_index;
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int grp_start_pos;
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uint8_t pit_value;
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int x, y, res = 0;
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if (ctx->scan_max >= 0)
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height = FFMIN(height, ctx->scan_max);
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// scan lines for VITC data, starting from the top
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for (y = 0; y < height; y++) {
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scan_line = src;
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memset(ctx->line_data, 0, LINE_DATA_SIZE);
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grp_index = 0;
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x = 0;
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while ((x < width) && (grp_index < 9)) {
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// search next sync pattern
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while ((x < width) && (scan_line[x] < ctx->threshold_white))
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x++;
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while ((x < width) && (scan_line[x] > ctx->threshold_black))
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x++;
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x = FFMAX(x - ((ctx->grp_width+10) / 20), 1); // step back a half pit
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grp_start_pos = x;
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if ((grp_start_pos + ctx->grp_width) > width)
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break; // not enough pixels for reading a whole pit group
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pit_value = get_pit_avg3(scan_line, x);
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if (pit_value < ctx->threshold_white)
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break; // first sync bit mismatch
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x = grp_start_pos + ((ctx->grp_width) / 10);
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pit_value = get_pit_avg3(scan_line, x);
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if (pit_value > ctx->threshold_black )
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break; // second sync bit mismatch
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for (pit_index = 0; pit_index <= 7; pit_index++) {
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x = grp_start_pos + (((pit_index+2)*ctx->grp_width) / 10);
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pit_value = get_pit_avg3(scan_line, x);
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if (pit_value > ctx->threshold_gray)
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ctx->line_data[grp_index] |= (1 << pit_index);
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}
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grp_index++;
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}
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if ((grp_index == 9) && (get_vitc_crc(ctx->line_data) == ctx->line_data[8])) {
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res = 1;
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break;
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}
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src += line_size;
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}
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return res;
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}
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static unsigned bcd2uint(uint8_t high, uint8_t low)
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{
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if (high > 9 || low > 9)
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return 0;
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return 10*high + low;
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}
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static char *make_vitc_tc_string(char *buf, uint8_t *line)
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{
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unsigned hh = bcd2uint(line[7] & 0x03, line[6] & 0x0f); // 6-bit hours
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unsigned mm = bcd2uint(line[5] & 0x07, line[4] & 0x0f); // 7-bit minutes
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unsigned ss = bcd2uint(line[3] & 0x07, line[2] & 0x0f); // 7-bit seconds
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unsigned ff = bcd2uint(line[1] & 0x03, line[0] & 0x0f); // 6-bit frames
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unsigned drop = (line[1] & 0x04); // 1-bit drop flag
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snprintf(buf, AV_TIMECODE_STR_SIZE, "%02u:%02u:%02u%c%02u",
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hh, mm, ss, drop ? ';' : ':', ff);
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return buf;
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}
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static av_cold int init(AVFilterContext *ctx)
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{
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ReadVitcContext *s = ctx->priv;
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s->threshold_black = s->thr_b * UINT8_MAX;
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s->threshold_white = s->thr_w * UINT8_MAX;
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if (s->threshold_black > s->threshold_white) {
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av_log(ctx, AV_LOG_WARNING, "Black color threshold is higher than white color threshold (%g > %g)\n",
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s->thr_b, s->thr_w);
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return AVERROR(EINVAL);
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}
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s->threshold_gray = s->threshold_white - ((s->threshold_white - s->threshold_black) / 2);
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av_log(ctx, AV_LOG_DEBUG, "threshold_black:%d threshold_white:%d threshold_gray:%d\n",
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s->threshold_black, s->threshold_white, s->threshold_gray);
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return 0;
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}
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static int config_props(AVFilterLink *inlink)
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{
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AVFilterContext *ctx = inlink->dst;
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ReadVitcContext *s = ctx->priv;
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s->grp_width = inlink->w * 5 / 48;
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av_log(ctx, AV_LOG_DEBUG, "w:%d h:%d grp_width:%d scan_max:%d\n",
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inlink->w, inlink->h, s->grp_width, s->scan_max);
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return 0;
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}
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static int query_formats(AVFilterContext *ctx)
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{
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static const enum AVPixelFormat pixel_fmts[] = {
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AV_PIX_FMT_GRAY8,
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AV_PIX_FMT_NV12,
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AV_PIX_FMT_NV16,
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AV_PIX_FMT_NV21,
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AV_PIX_FMT_YUV410P,
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AV_PIX_FMT_YUV411P,
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AV_PIX_FMT_YUV420P,
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AV_PIX_FMT_YUV422P,
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AV_PIX_FMT_YUV440P,
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AV_PIX_FMT_YUV444P,
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AV_PIX_FMT_YUVA420P,
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AV_PIX_FMT_YUVA422P,
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AV_PIX_FMT_YUVA444P,
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AV_PIX_FMT_YUVJ411P,
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AV_PIX_FMT_YUVJ420P,
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AV_PIX_FMT_YUVJ422P,
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AV_PIX_FMT_YUVJ440P,
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AV_PIX_FMT_YUVJ444P,
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AV_PIX_FMT_NONE
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};
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AVFilterFormats *fmts_list = ff_make_format_list(pixel_fmts);
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if (!fmts_list)
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return AVERROR(ENOMEM);
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return ff_set_common_formats(ctx, fmts_list);
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}
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static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
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{
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AVFilterContext *ctx = inlink->dst;
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AVFilterLink *outlink = ctx->outputs[0];
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ReadVitcContext *s = ctx->priv;
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int found;
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found = read_vitc_line(s, frame->data[0], frame->linesize[0], inlink->w, inlink->h);
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av_dict_set(avpriv_frame_get_metadatap(frame), "lavfi.readvitc.found", (found ? "1" : "0"), 0);
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if (found)
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av_dict_set(avpriv_frame_get_metadatap(frame), "lavfi.readvitc.tc_str", make_vitc_tc_string(s->tcbuf, s->line_data), 0);
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return ff_filter_frame(outlink, frame);
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}
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static const AVFilterPad inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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.filter_frame = filter_frame,
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.config_props = config_props,
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},
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{ NULL }
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};
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static const AVFilterPad outputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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},
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{ NULL }
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};
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AVFilter ff_vf_readvitc = {
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.name = "readvitc",
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.description = NULL_IF_CONFIG_SMALL("Read vertical interval timecode and write it to frame metadata."),
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.priv_size = sizeof(ReadVitcContext),
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.priv_class = &readvitc_class,
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.inputs = inputs,
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.outputs = outputs,
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.init = init,
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.query_formats = query_formats,
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};
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