2 * Copyright (c) 2011 Stefano Sabatini
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * filter for selecting which frame passes in the filterchain
26 #include "libavutil/eval.h"
27 #include "libavutil/fifo.h"
28 #include "libavcodec/dsputil.h"
29 #include "libavutil/internal.h"
35 static const char *const var_names[] = {
38 "pts", ///< original pts in the file of the frame
39 "start_pts", ///< first PTS in the stream, expressed in TB units
40 "prev_pts", ///< previous frame PTS
41 "prev_selected_pts", ///< previous selected frame PTS
43 "t", ///< first PTS in seconds
44 "start_t", ///< first PTS in the stream, expressed in seconds
45 "prev_t", ///< previous frame time
46 "prev_selected_t", ///< previously selected time
48 "pict_type", ///< the type of picture in the movie
57 "interlace_type", ///< the frame interlace type
62 "n", ///< frame number (starting from zero)
63 "selected_n", ///< selected frame number (starting from zero)
64 "prev_selected_n", ///< number of the last selected frame
66 "key", ///< tell if the frame is a key frame
67 "pos", ///< original position in the file of the frame
80 VAR_PREV_SELECTED_PTS,
117 double var_values[VAR_VARS_NB];
118 int do_scene_detect; ///< 1 if the expression requires scene detection variables, 0 otherwise
119 AVCodecContext *avctx; ///< codec context required for the DSPContext (scene detect only)
120 DSPContext c; ///< context providing optimized SAD methods (scene detect only)
121 double prev_mafd; ///< previous MAFD (scene detect only)
122 AVFilterBufferRef *prev_picref; ///< previous frame (scene detect only)
125 AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
128 static av_cold int init(AVFilterContext *ctx, const char *args)
130 SelectContext *select = ctx->priv;
133 if ((ret = av_expr_parse(&select->expr, args ? args : "1",
134 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
135 av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
139 select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));
140 if (!select->pending_frames) {
141 av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
142 return AVERROR(ENOMEM);
145 select->do_scene_detect = args && strstr(args, "scene");
149 #define INTERLACE_TYPE_P 0
150 #define INTERLACE_TYPE_T 1
151 #define INTERLACE_TYPE_B 2
153 static int config_input(AVFilterLink *inlink)
155 SelectContext *select = inlink->dst->priv;
157 select->var_values[VAR_N] = 0.0;
158 select->var_values[VAR_SELECTED_N] = 0.0;
160 select->var_values[VAR_TB] = av_q2d(inlink->time_base);
162 select->var_values[VAR_PREV_PTS] = NAN;
163 select->var_values[VAR_PREV_SELECTED_PTS] = NAN;
164 select->var_values[VAR_PREV_SELECTED_T] = NAN;
165 select->var_values[VAR_START_PTS] = NAN;
166 select->var_values[VAR_START_T] = NAN;
168 select->var_values[VAR_PICT_TYPE_I] = AV_PICTURE_TYPE_I;
169 select->var_values[VAR_PICT_TYPE_P] = AV_PICTURE_TYPE_P;
170 select->var_values[VAR_PICT_TYPE_B] = AV_PICTURE_TYPE_B;
171 select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;
172 select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;
174 select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;
175 select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;
176 select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;
178 if (select->do_scene_detect) {
179 select->avctx = avcodec_alloc_context3(NULL);
181 return AVERROR(ENOMEM);
182 dsputil_init(&select->c, select->avctx);
187 static double get_scene_score(AVFilterContext *ctx, AVFilterBufferRef *picref)
190 SelectContext *select = ctx->priv;
191 AVFilterBufferRef *prev_picref = select->prev_picref;
194 picref->video->h == prev_picref->video->h &&
195 picref->video->w == prev_picref->video->w &&
196 picref->linesize[0] == prev_picref->linesize[0]) {
200 uint8_t *p1 = picref->data[0];
201 uint8_t *p2 = prev_picref->data[0];
202 const int linesize = picref->linesize[0];
204 for (sad = y = 0; y < picref->video->h; y += 8)
205 for (x = 0; x < linesize; x += 8)
206 sad += select->c.sad[1](select,
207 p1 + y * linesize + x,
208 p2 + y * linesize + x,
211 mafd = sad / (picref->video->h * picref->video->w * 3);
212 diff = fabs(mafd - select->prev_mafd);
213 ret = av_clipf(FFMIN(mafd, diff) / 100., 0, 1);
214 select->prev_mafd = mafd;
215 avfilter_unref_buffer(prev_picref);
217 select->prev_picref = avfilter_ref_buffer(picref, ~0);
221 #define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
222 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
224 static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
226 SelectContext *select = ctx->priv;
227 AVFilterLink *inlink = ctx->inputs[0];
230 if (select->do_scene_detect)
231 select->var_values[VAR_SCENE] = get_scene_score(ctx, picref);
232 if (isnan(select->var_values[VAR_START_PTS]))
233 select->var_values[VAR_START_PTS] = TS2D(picref->pts);
234 if (isnan(select->var_values[VAR_START_T]))
235 select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);
237 select->var_values[VAR_PTS] = TS2D(picref->pts);
238 select->var_values[VAR_T ] = TS2D(picref->pts) * av_q2d(inlink->time_base);
239 select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
240 select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);
242 select->var_values[VAR_INTERLACE_TYPE] =
243 !picref->video->interlaced ? INTERLACE_TYPE_P :
244 picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
245 select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;
247 res = av_expr_eval(select->expr, select->var_values, NULL);
248 av_log(inlink->dst, AV_LOG_DEBUG,
249 "n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "
251 (int)select->var_values[VAR_N],
252 (int)select->var_values[VAR_PTS],
253 select->var_values[VAR_T],
254 (int)select->var_values[VAR_POS],
255 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
256 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
257 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
258 (int)select->var_values[VAR_KEY],
259 av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
262 select->var_values[VAR_N] += 1.0;
265 select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
266 select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
267 select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
268 select->var_values[VAR_SELECTED_N] += 1.0;
273 static int start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
275 SelectContext *select = inlink->dst->priv;
277 select->select = select_frame(inlink->dst, picref);
278 if (select->select) {
279 AVFilterBufferRef *buf_out;
280 /* frame was requested through poll_frame */
281 if (select->cache_frames) {
282 if (!av_fifo_space(select->pending_frames))
283 av_log(inlink->dst, AV_LOG_ERROR,
284 "Buffering limit reached, cannot cache more frames\n");
286 av_fifo_generic_write(select->pending_frames, &picref,
287 sizeof(picref), NULL);
290 buf_out = avfilter_ref_buffer(picref, ~0);
292 return AVERROR(ENOMEM);
293 return ff_start_frame(inlink->dst->outputs[0], buf_out);
299 static int draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
301 SelectContext *select = inlink->dst->priv;
303 if (select->select && !select->cache_frames)
304 return ff_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
308 static int end_frame(AVFilterLink *inlink)
310 SelectContext *select = inlink->dst->priv;
312 if (select->select) {
313 if (select->cache_frames)
315 return ff_end_frame(inlink->dst->outputs[0]);
320 static int request_frame(AVFilterLink *outlink)
322 AVFilterContext *ctx = outlink->src;
323 SelectContext *select = ctx->priv;
324 AVFilterLink *inlink = outlink->src->inputs[0];
327 if (av_fifo_size(select->pending_frames)) {
328 AVFilterBufferRef *picref;
331 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
332 if ((ret = ff_start_frame(outlink, picref)) < 0 ||
333 (ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
334 (ret = ff_end_frame(outlink)) < 0);
339 while (!select->select) {
340 int ret = ff_request_frame(inlink);
348 static int poll_frame(AVFilterLink *outlink)
350 SelectContext *select = outlink->src->priv;
351 AVFilterLink *inlink = outlink->src->inputs[0];
354 if (!av_fifo_size(select->pending_frames)) {
355 if ((count = ff_poll_frame(inlink)) <= 0)
357 /* request frame from input, and apply select condition to it */
358 select->cache_frames = 1;
359 while (count-- && av_fifo_space(select->pending_frames)) {
360 ret = ff_request_frame(inlink);
364 select->cache_frames = 0;
367 return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
370 static av_cold void uninit(AVFilterContext *ctx)
372 SelectContext *select = ctx->priv;
373 AVFilterBufferRef *picref;
375 av_expr_free(select->expr);
378 while (select->pending_frames &&
379 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))
380 avfilter_unref_buffer(picref);
381 av_fifo_free(select->pending_frames);
382 select->pending_frames = NULL;
384 if (select->do_scene_detect) {
385 avfilter_unref_bufferp(&select->prev_picref);
386 avcodec_close(select->avctx);
387 av_freep(&select->avctx);
391 static int query_formats(AVFilterContext *ctx)
393 SelectContext *select = ctx->priv;
395 if (!select->do_scene_detect) {
396 return ff_default_query_formats(ctx);
398 static const enum PixelFormat pix_fmts[] = {
399 PIX_FMT_RGB24, PIX_FMT_BGR24,
402 ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
407 AVFilter avfilter_vf_select = {
409 .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
412 .query_formats = query_formats,
414 .priv_size = sizeof(SelectContext),
416 .inputs = (const AVFilterPad[]) {{ .name = "default",
417 .type = AVMEDIA_TYPE_VIDEO,
418 .get_video_buffer = ff_null_get_video_buffer,
419 .min_perms = AV_PERM_PRESERVE,
420 .config_props = config_input,
421 .start_frame = start_frame,
422 .draw_slice = draw_slice,
423 .end_frame = end_frame },
425 .outputs = (const AVFilterPad[]) {{ .name = "default",
426 .type = AVMEDIA_TYPE_VIDEO,
427 .poll_frame = poll_frame,
428 .request_frame = request_frame, },