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"
31 static const char *const var_names[] = {
34 "pts", ///< original pts in the file of the frame
35 "start_pts", ///< first PTS in the stream, expressed in TB units
36 "prev_pts", ///< previous frame PTS
37 "prev_selected_pts", ///< previous selected frame PTS
39 "t", ///< first PTS in seconds
40 "start_t", ///< first PTS in the stream, expressed in seconds
41 "prev_t", ///< previous frame time
42 "prev_selected_t", ///< previously selected time
44 "pict_type", ///< the type of picture in the movie
53 "interlace_type", ///< the frame interlace type
58 "n", ///< frame number (starting from zero)
59 "selected_n", ///< selected frame number (starting from zero)
60 "prev_selected_n", ///< number of the last selected frame
62 "key", ///< tell if the frame is a key frame
63 "pos", ///< original position in the file of the frame
74 VAR_PREV_SELECTED_PTS,
109 double var_values[VAR_VARS_NB];
112 AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
115 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
117 SelectContext *select = ctx->priv;
120 if ((ret = av_expr_parse(&select->expr, args ? args : "1",
121 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
122 av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
126 select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));
127 if (!select->pending_frames) {
128 av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
129 return AVERROR(ENOMEM);
134 #define INTERLACE_TYPE_P 0
135 #define INTERLACE_TYPE_T 1
136 #define INTERLACE_TYPE_B 2
138 static int config_input(AVFilterLink *inlink)
140 SelectContext *select = inlink->dst->priv;
142 select->var_values[VAR_N] = 0.0;
143 select->var_values[VAR_SELECTED_N] = 0.0;
145 select->var_values[VAR_TB] = av_q2d(inlink->time_base);
147 select->var_values[VAR_PREV_PTS] = NAN;
148 select->var_values[VAR_PREV_SELECTED_PTS] = NAN;
149 select->var_values[VAR_PREV_SELECTED_T] = NAN;
150 select->var_values[VAR_START_PTS] = NAN;
151 select->var_values[VAR_START_T] = NAN;
153 select->var_values[VAR_PICT_TYPE_I] = AV_PICTURE_TYPE_I;
154 select->var_values[VAR_PICT_TYPE_P] = AV_PICTURE_TYPE_P;
155 select->var_values[VAR_PICT_TYPE_B] = AV_PICTURE_TYPE_B;
156 select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;
157 select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;
159 select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;
160 select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;
161 select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;
166 #define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
167 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
169 static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
171 SelectContext *select = ctx->priv;
172 AVFilterLink *inlink = ctx->inputs[0];
175 if (isnan(select->var_values[VAR_START_PTS]))
176 select->var_values[VAR_START_PTS] = TS2D(picref->pts);
177 if (isnan(select->var_values[VAR_START_T]))
178 select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);
180 select->var_values[VAR_PTS] = TS2D(picref->pts);
181 select->var_values[VAR_T ] = TS2D(picref->pts) * av_q2d(inlink->time_base);
182 select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
183 select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);
185 select->var_values[VAR_INTERLACE_TYPE] =
186 !picref->video->interlaced ? INTERLACE_TYPE_P :
187 picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
188 select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;
190 res = av_expr_eval(select->expr, select->var_values, NULL);
191 av_log(inlink->dst, AV_LOG_DEBUG,
192 "n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "
194 (int)select->var_values[VAR_N],
195 (int)select->var_values[VAR_PTS],
196 select->var_values[VAR_T],
197 (int)select->var_values[VAR_POS],
198 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
199 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
200 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
201 (int)select->var_values[VAR_KEY],
202 av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
205 select->var_values[VAR_N] += 1.0;
208 select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
209 select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
210 select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
211 select->var_values[VAR_SELECTED_N] += 1.0;
216 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
218 SelectContext *select = inlink->dst->priv;
220 select->select = select_frame(inlink->dst, picref);
221 if (select->select) {
222 /* frame was requested through poll_frame */
223 if (select->cache_frames) {
224 if (!av_fifo_space(select->pending_frames))
225 av_log(inlink->dst, AV_LOG_ERROR,
226 "Buffering limit reached, cannot cache more frames\n");
228 av_fifo_generic_write(select->pending_frames, &picref,
229 sizeof(picref), NULL);
232 avfilter_start_frame(inlink->dst->outputs[0], avfilter_ref_buffer(picref, ~0));
236 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
238 SelectContext *select = inlink->dst->priv;
240 if (select->select && !select->cache_frames)
241 avfilter_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
244 static void end_frame(AVFilterLink *inlink)
246 SelectContext *select = inlink->dst->priv;
247 AVFilterBufferRef *picref = inlink->cur_buf;
249 if (select->select) {
250 if (select->cache_frames)
252 avfilter_end_frame(inlink->dst->outputs[0]);
254 avfilter_unref_buffer(picref);
257 static int request_frame(AVFilterLink *outlink)
259 AVFilterContext *ctx = outlink->src;
260 SelectContext *select = ctx->priv;
261 AVFilterLink *inlink = outlink->src->inputs[0];
264 if (av_fifo_size(select->pending_frames)) {
265 AVFilterBufferRef *picref;
266 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
267 avfilter_start_frame(outlink, avfilter_ref_buffer(picref, ~0));
268 avfilter_draw_slice(outlink, 0, outlink->h, 1);
269 avfilter_end_frame(outlink);
270 avfilter_unref_buffer(picref);
274 while (!select->select) {
275 int ret = avfilter_request_frame(inlink);
283 static int poll_frame(AVFilterLink *outlink)
285 SelectContext *select = outlink->src->priv;
286 AVFilterLink *inlink = outlink->src->inputs[0];
289 if (!av_fifo_size(select->pending_frames)) {
290 if ((count = avfilter_poll_frame(inlink)) <= 0)
292 /* request frame from input, and apply select condition to it */
293 select->cache_frames = 1;
294 while (count-- && av_fifo_space(select->pending_frames)) {
295 ret = avfilter_request_frame(inlink);
299 select->cache_frames = 0;
302 return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
305 static av_cold void uninit(AVFilterContext *ctx)
307 SelectContext *select = ctx->priv;
308 AVFilterBufferRef *picref;
310 av_expr_free(select->expr);
313 while (select->pending_frames &&
314 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))
315 avfilter_unref_buffer(picref);
316 av_fifo_free(select->pending_frames);
317 select->pending_frames = NULL;
320 AVFilter avfilter_vf_select = {
322 .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
326 .priv_size = sizeof(SelectContext),
328 .inputs = (const AVFilterPad[]) {{ .name = "default",
329 .type = AVMEDIA_TYPE_VIDEO,
330 .get_video_buffer = ff_null_get_video_buffer,
331 .config_props = config_input,
332 .start_frame = start_frame,
333 .draw_slice = draw_slice,
334 .end_frame = end_frame },
336 .outputs = (const AVFilterPad[]) {{ .name = "default",
337 .type = AVMEDIA_TYPE_VIDEO,
338 .poll_frame = poll_frame,
339 .request_frame = request_frame, },