2 * Copyright (c) 2011 Stefano Sabatini
4 * This file is part of Libav.
6 * Libav 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 * Libav 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 Libav; 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 "libavutil/internal.h"
29 #include "libavutil/mathematics.h"
34 static const char *const var_names[] = {
35 "E", ///< Euler number
36 "PHI", ///< golden ratio
41 "pts", ///< original pts in the file of the frame
42 "start_pts", ///< first PTS in the stream, expressed in TB units
43 "prev_pts", ///< previous frame PTS
44 "prev_selected_pts", ///< previous selected frame PTS
46 "t", ///< first PTS in seconds
47 "start_t", ///< first PTS in the stream, expressed in seconds
48 "prev_t", ///< previous frame time
49 "prev_selected_t", ///< previously selected time
51 "pict_type", ///< the type of picture in the movie
60 "interlace_type", ///< the frame interlace type
65 "n", ///< frame number (starting from zero)
66 "selected_n", ///< selected frame number (starting from zero)
67 "prev_selected_n", ///< number of the last selected frame
69 "key", ///< tell if the frame is a key frame
70 "pos", ///< original position in the file of the frame
85 VAR_PREV_SELECTED_PTS,
102 VAR_INTERLACE_TYPE_P,
103 VAR_INTERLACE_TYPE_T,
104 VAR_INTERLACE_TYPE_B,
120 double var_values[VAR_VARS_NB];
123 AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
126 static av_cold int init(AVFilterContext *ctx, const char *args)
128 SelectContext *select = ctx->priv;
131 if ((ret = av_expr_parse(&select->expr, args ? args : "1",
132 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
133 av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
137 select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));
138 if (!select->pending_frames) {
139 av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
140 return AVERROR(ENOMEM);
145 #define INTERLACE_TYPE_P 0
146 #define INTERLACE_TYPE_T 1
147 #define INTERLACE_TYPE_B 2
149 static int config_input(AVFilterLink *inlink)
151 SelectContext *select = inlink->dst->priv;
153 select->var_values[VAR_E] = M_E;
154 select->var_values[VAR_PHI] = M_PHI;
155 select->var_values[VAR_PI] = M_PI;
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;;
181 #define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
182 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
184 static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
186 SelectContext *select = ctx->priv;
187 AVFilterLink *inlink = ctx->inputs[0];
190 if (isnan(select->var_values[VAR_START_PTS]))
191 select->var_values[VAR_START_PTS] = TS2D(picref->pts);
192 if (isnan(select->var_values[VAR_START_T]))
193 select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);
195 select->var_values[VAR_PTS] = TS2D(picref->pts);
196 select->var_values[VAR_T ] = TS2D(picref->pts) * av_q2d(inlink->time_base);
197 select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
198 select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);
200 select->var_values[VAR_INTERLACE_TYPE] =
201 !picref->video->interlaced ? INTERLACE_TYPE_P :
202 picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
203 select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;
205 res = av_expr_eval(select->expr, select->var_values, NULL);
206 av_log(inlink->dst, AV_LOG_DEBUG,
207 "n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "
209 (int)select->var_values[VAR_N],
210 (int)select->var_values[VAR_PTS],
211 select->var_values[VAR_T],
212 (int)select->var_values[VAR_POS],
213 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
214 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
215 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
216 (int)select->var_values[VAR_KEY],
217 av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
220 select->var_values[VAR_N] += 1.0;
223 select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
224 select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
225 select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
226 select->var_values[VAR_SELECTED_N] += 1.0;
231 static int start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
233 SelectContext *select = inlink->dst->priv;
235 select->select = select_frame(inlink->dst, picref);
236 if (select->select) {
237 AVFilterBufferRef *buf_out;
238 /* frame was requested through poll_frame */
239 if (select->cache_frames) {
240 if (!av_fifo_space(select->pending_frames))
241 av_log(inlink->dst, AV_LOG_ERROR,
242 "Buffering limit reached, cannot cache more frames\n");
244 av_fifo_generic_write(select->pending_frames, &picref,
245 sizeof(picref), NULL);
248 buf_out = avfilter_ref_buffer(picref, ~0);
250 return AVERROR(ENOMEM);
251 return ff_start_frame(inlink->dst->outputs[0], buf_out);
257 static int draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
259 SelectContext *select = inlink->dst->priv;
261 if (select->select && !select->cache_frames)
262 return ff_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
266 static int end_frame(AVFilterLink *inlink)
268 SelectContext *select = inlink->dst->priv;
270 if (select->select) {
271 if (select->cache_frames)
273 return ff_end_frame(inlink->dst->outputs[0]);
278 static int request_frame(AVFilterLink *outlink)
280 AVFilterContext *ctx = outlink->src;
281 SelectContext *select = ctx->priv;
282 AVFilterLink *inlink = outlink->src->inputs[0];
285 if (av_fifo_size(select->pending_frames)) {
286 AVFilterBufferRef *picref;
289 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
290 if ((ret = ff_start_frame(outlink, picref)) < 0 ||
291 (ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
292 (ret = ff_end_frame(outlink)) < 0);
297 while (!select->select) {
298 int ret = ff_request_frame(inlink);
306 static int poll_frame(AVFilterLink *outlink)
308 SelectContext *select = outlink->src->priv;
309 AVFilterLink *inlink = outlink->src->inputs[0];
312 if (!av_fifo_size(select->pending_frames)) {
313 if ((count = ff_poll_frame(inlink)) <= 0)
315 /* request frame from input, and apply select condition to it */
316 select->cache_frames = 1;
317 while (count-- && av_fifo_space(select->pending_frames)) {
318 ret = ff_request_frame(inlink);
322 select->cache_frames = 0;
325 return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
328 static av_cold void uninit(AVFilterContext *ctx)
330 SelectContext *select = ctx->priv;
331 AVFilterBufferRef *picref;
333 av_expr_free(select->expr);
336 while (select->pending_frames &&
337 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))
338 avfilter_unref_buffer(picref);
339 av_fifo_free(select->pending_frames);
340 select->pending_frames = NULL;
343 AVFilter avfilter_vf_select = {
345 .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
349 .priv_size = sizeof(SelectContext),
351 .inputs = (const AVFilterPad[]) {{ .name = "default",
352 .type = AVMEDIA_TYPE_VIDEO,
353 .get_video_buffer = ff_null_get_video_buffer,
354 .config_props = config_input,
355 .start_frame = start_frame,
356 .draw_slice = draw_slice,
357 .end_frame = end_frame },
359 .outputs = (const AVFilterPad[]) {{ .name = "default",
360 .type = AVMEDIA_TYPE_VIDEO,
361 .poll_frame = poll_frame,
362 .request_frame = request_frame, },