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