yading@11: /* yading@11: * Copyright (c) 2011 Smartjog S.A.S, Clément Bœsch yading@11: * yading@11: * This file is part of FFmpeg. yading@11: * yading@11: * FFmpeg is free software; you can redistribute it and/or yading@11: * modify it under the terms of the GNU Lesser General Public yading@11: * License as published by the Free Software Foundation; either yading@11: * version 2.1 of the License, or (at your option) any later version. yading@11: * yading@11: * FFmpeg is distributed in the hope that it will be useful, yading@11: * but WITHOUT ANY WARRANTY; without even the implied warranty of yading@11: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU yading@11: * Lesser General Public License for more details. yading@11: * yading@11: * You should have received a copy of the GNU Lesser General Public yading@11: * License along with FFmpeg; if not, write to the Free Software yading@11: * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA yading@11: */ yading@11: yading@11: /** yading@11: * @file yading@11: * Potential thumbnail lookup filter to reduce the risk of an inappropriate yading@11: * selection (such as a black frame) we could get with an absolute seek. yading@11: * yading@11: * Simplified version of algorithm by Vadim Zaliva . yading@11: * @see http://notbrainsurgery.livejournal.com/29773.html yading@11: */ yading@11: yading@11: #include "libavutil/opt.h" yading@11: #include "avfilter.h" yading@11: #include "internal.h" yading@11: yading@11: #define HIST_SIZE (3*256) yading@11: yading@11: struct thumb_frame { yading@11: AVFrame *buf; ///< cached frame yading@11: int histogram[HIST_SIZE]; ///< RGB color distribution histogram of the frame yading@11: }; yading@11: yading@11: typedef struct { yading@11: const AVClass *class; yading@11: int n; ///< current frame yading@11: int n_frames; ///< number of frames for analysis yading@11: struct thumb_frame *frames; ///< the n_frames frames yading@11: AVRational tb; ///< copy of the input timebase to ease access yading@11: } ThumbContext; yading@11: yading@11: #define OFFSET(x) offsetof(ThumbContext, x) yading@11: #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM yading@11: yading@11: static const AVOption thumbnail_options[] = { yading@11: { "n", "set the frames batch size", OFFSET(n_frames), AV_OPT_TYPE_INT, {.i64=100}, 2, INT_MAX, FLAGS }, yading@11: { NULL } yading@11: }; yading@11: yading@11: AVFILTER_DEFINE_CLASS(thumbnail); yading@11: yading@11: static av_cold int init(AVFilterContext *ctx) yading@11: { yading@11: ThumbContext *thumb = ctx->priv; yading@11: yading@11: thumb->frames = av_calloc(thumb->n_frames, sizeof(*thumb->frames)); yading@11: if (!thumb->frames) { yading@11: av_log(ctx, AV_LOG_ERROR, yading@11: "Allocation failure, try to lower the number of frames\n"); yading@11: return AVERROR(ENOMEM); yading@11: } yading@11: av_log(ctx, AV_LOG_VERBOSE, "batch size: %d frames\n", thumb->n_frames); yading@11: return 0; yading@11: } yading@11: yading@11: /** yading@11: * @brief Compute Sum-square deviation to estimate "closeness". yading@11: * @param hist color distribution histogram yading@11: * @param median average color distribution histogram yading@11: * @return sum of squared errors yading@11: */ yading@11: static double frame_sum_square_err(const int *hist, const double *median) yading@11: { yading@11: int i; yading@11: double err, sum_sq_err = 0; yading@11: yading@11: for (i = 0; i < HIST_SIZE; i++) { yading@11: err = median[i] - (double)hist[i]; yading@11: sum_sq_err += err*err; yading@11: } yading@11: return sum_sq_err; yading@11: } yading@11: yading@11: static AVFrame *get_best_frame(AVFilterContext *ctx) yading@11: { yading@11: AVFrame *picref; yading@11: ThumbContext *thumb = ctx->priv; yading@11: int i, j, best_frame_idx = 0; yading@11: int nb_frames = thumb->n; yading@11: double avg_hist[HIST_SIZE] = {0}, sq_err, min_sq_err = -1; yading@11: yading@11: // average histogram of the N frames yading@11: for (j = 0; j < FF_ARRAY_ELEMS(avg_hist); j++) { yading@11: for (i = 0; i < nb_frames; i++) yading@11: avg_hist[j] += (double)thumb->frames[i].histogram[j]; yading@11: avg_hist[j] /= nb_frames; yading@11: } yading@11: yading@11: // find the frame closer to the average using the sum of squared errors yading@11: for (i = 0; i < nb_frames; i++) { yading@11: sq_err = frame_sum_square_err(thumb->frames[i].histogram, avg_hist); yading@11: if (i == 0 || sq_err < min_sq_err) yading@11: best_frame_idx = i, min_sq_err = sq_err; yading@11: } yading@11: yading@11: // free and reset everything (except the best frame buffer) yading@11: for (i = 0; i < nb_frames; i++) { yading@11: memset(thumb->frames[i].histogram, 0, sizeof(thumb->frames[i].histogram)); yading@11: if (i != best_frame_idx) yading@11: av_frame_free(&thumb->frames[i].buf); yading@11: } yading@11: thumb->n = 0; yading@11: yading@11: // raise the chosen one yading@11: picref = thumb->frames[best_frame_idx].buf; yading@11: av_log(ctx, AV_LOG_INFO, "frame id #%d (pts_time=%f) selected " yading@11: "from a set of %d images\n", best_frame_idx, yading@11: picref->pts * av_q2d(thumb->tb), nb_frames); yading@11: thumb->frames[best_frame_idx].buf = NULL; yading@11: yading@11: return picref; yading@11: } yading@11: yading@11: static int filter_frame(AVFilterLink *inlink, AVFrame *frame) yading@11: { yading@11: int i, j; yading@11: AVFilterContext *ctx = inlink->dst; yading@11: ThumbContext *thumb = ctx->priv; yading@11: AVFilterLink *outlink = ctx->outputs[0]; yading@11: int *hist = thumb->frames[thumb->n].histogram; yading@11: const uint8_t *p = frame->data[0]; yading@11: yading@11: // keep a reference of each frame yading@11: thumb->frames[thumb->n].buf = frame; yading@11: yading@11: // update current frame RGB histogram yading@11: for (j = 0; j < inlink->h; j++) { yading@11: for (i = 0; i < inlink->w; i++) { yading@11: hist[0*256 + p[i*3 ]]++; yading@11: hist[1*256 + p[i*3 + 1]]++; yading@11: hist[2*256 + p[i*3 + 2]]++; yading@11: } yading@11: p += frame->linesize[0]; yading@11: } yading@11: yading@11: // no selection until the buffer of N frames is filled up yading@11: thumb->n++; yading@11: if (thumb->n < thumb->n_frames) yading@11: return 0; yading@11: yading@11: return ff_filter_frame(outlink, get_best_frame(ctx)); yading@11: } yading@11: yading@11: static av_cold void uninit(AVFilterContext *ctx) yading@11: { yading@11: int i; yading@11: ThumbContext *thumb = ctx->priv; yading@11: for (i = 0; i < thumb->n_frames && thumb->frames[i].buf; i++) yading@11: av_frame_free(&thumb->frames[i].buf); yading@11: av_freep(&thumb->frames); yading@11: } yading@11: yading@11: static int request_frame(AVFilterLink *link) yading@11: { yading@11: AVFilterContext *ctx = link->src; yading@11: ThumbContext *thumb = ctx->priv; yading@11: yading@11: /* loop until a frame thumbnail is available (when a frame is queued, yading@11: * thumb->n is reset to zero) */ yading@11: do { yading@11: int ret = ff_request_frame(ctx->inputs[0]); yading@11: if (ret == AVERROR_EOF && thumb->n) { yading@11: ret = ff_filter_frame(link, get_best_frame(ctx)); yading@11: if (ret < 0) yading@11: return ret; yading@11: ret = AVERROR_EOF; yading@11: } yading@11: if (ret < 0) yading@11: return ret; yading@11: } while (thumb->n); yading@11: return 0; yading@11: } yading@11: yading@11: static int config_props(AVFilterLink *inlink) yading@11: { yading@11: AVFilterContext *ctx = inlink->dst; yading@11: ThumbContext *thumb = ctx->priv; yading@11: yading@11: thumb->tb = inlink->time_base; yading@11: return 0; yading@11: } yading@11: yading@11: static int query_formats(AVFilterContext *ctx) yading@11: { yading@11: static const enum AVPixelFormat pix_fmts[] = { yading@11: AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24, yading@11: AV_PIX_FMT_NONE yading@11: }; yading@11: ff_set_common_formats(ctx, ff_make_format_list(pix_fmts)); yading@11: return 0; yading@11: } yading@11: yading@11: static const AVFilterPad thumbnail_inputs[] = { yading@11: { yading@11: .name = "default", yading@11: .type = AVMEDIA_TYPE_VIDEO, yading@11: .config_props = config_props, yading@11: .get_video_buffer = ff_null_get_video_buffer, yading@11: .filter_frame = filter_frame, yading@11: }, yading@11: { NULL } yading@11: }; yading@11: yading@11: static const AVFilterPad thumbnail_outputs[] = { yading@11: { yading@11: .name = "default", yading@11: .type = AVMEDIA_TYPE_VIDEO, yading@11: .request_frame = request_frame, yading@11: }, yading@11: { NULL } yading@11: }; yading@11: yading@11: AVFilter avfilter_vf_thumbnail = { yading@11: .name = "thumbnail", yading@11: .description = NULL_IF_CONFIG_SMALL("Select the most representative frame in a given sequence of consecutive frames."), yading@11: .priv_size = sizeof(ThumbContext), yading@11: .init = init, yading@11: .uninit = uninit, yading@11: .query_formats = query_formats, yading@11: .inputs = thumbnail_inputs, yading@11: .outputs = thumbnail_outputs, yading@11: .priv_class = &thumbnail_class, yading@11: };