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"
30 static const char *var_names[] = {
33 "pts", ///< original pts in the file of the frame
34 "start_pts", ///< first PTS in the stream, expressed in TB units
35 "prev_pts", ///< previous frame PTS
36 "prev_selected_pts", ///< previous selected frame PTS
38 "t", ///< first PTS in seconds
39 "start_t", ///< first PTS in the stream, expressed in seconds
40 "prev_t", ///< previous frame time
41 "prev_selected_t", ///< previously selected time
43 "pict_type", ///< the type of picture in the movie
52 "interlace_type", ///< the frame interlace type
57 "n", ///< frame number (starting from zero)
58 "selected_n", ///< selected frame number (starting from zero)
59 "prev_selected_n", ///< number of the last selected frame
61 "key", ///< tell if the frame is a key frame
62 "pos", ///< original position in the file of the frame
73 VAR_PREV_SELECTED_PTS,
108 double var_values[VAR_VARS_NB];
111 AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
114 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
116 SelectContext *select = ctx->priv;
119 if ((ret = av_expr_parse(&select->expr, args ? args : "1",
120 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
121 av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
125 select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));
126 if (!select->pending_frames) {
127 av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
128 return AVERROR(ENOMEM);
133 #define INTERLACE_TYPE_P 0
134 #define INTERLACE_TYPE_T 1
135 #define INTERLACE_TYPE_B 2
137 static int config_input(AVFilterLink *inlink)
139 SelectContext *select = inlink->dst->priv;
141 select->var_values[VAR_N] = 0.0;
142 select->var_values[VAR_SELECTED_N] = 0.0;
144 select->var_values[VAR_TB] = av_q2d(inlink->time_base);
146 select->var_values[VAR_PREV_PTS] = NAN;
147 select->var_values[VAR_PREV_SELECTED_PTS] = NAN;
148 select->var_values[VAR_PREV_SELECTED_T] = NAN;
149 select->var_values[VAR_START_PTS] = NAN;
150 select->var_values[VAR_START_T] = NAN;
152 select->var_values[VAR_PICT_TYPE_I] = AV_PICTURE_TYPE_I;
153 select->var_values[VAR_PICT_TYPE_P] = AV_PICTURE_TYPE_P;
154 select->var_values[VAR_PICT_TYPE_B] = AV_PICTURE_TYPE_B;
155 select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;
156 select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;
158 select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;
159 select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;
160 select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;;
165 #define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
166 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
168 static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
170 SelectContext *select = ctx->priv;
171 AVFilterLink *inlink = ctx->inputs[0];
174 if (isnan(select->var_values[VAR_START_PTS]))
175 select->var_values[VAR_START_PTS] = TS2D(picref->pts);
176 if (isnan(select->var_values[VAR_START_T]))
177 select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);
179 select->var_values[VAR_PTS] = TS2D(picref->pts);
180 select->var_values[VAR_T ] = TS2D(picref->pts) * av_q2d(inlink->time_base);
181 select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
182 select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);
184 select->var_values[VAR_INTERLACE_TYPE] =
185 !picref->video->interlaced ? INTERLACE_TYPE_P :
186 picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
187 select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;
189 res = av_expr_eval(select->expr, select->var_values, NULL);
190 av_log(inlink->dst, AV_LOG_DEBUG,
191 "n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "
193 (int)select->var_values[VAR_N],
194 (int)select->var_values[VAR_PTS],
195 select->var_values[VAR_T],
196 (int)select->var_values[VAR_POS],
197 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
198 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
199 select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
200 (int)select->var_values[VAR_KEY],
201 av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
204 select->var_values[VAR_N] += 1.0;
207 select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
208 select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
209 select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
210 select->var_values[VAR_SELECTED_N] += 1.0;
215 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
217 SelectContext *select = inlink->dst->priv;
219 select->select = select_frame(inlink->dst, picref);
220 if (select->select) {
221 /* frame was requested through poll_frame */
222 if (select->cache_frames) {
223 if (!av_fifo_space(select->pending_frames))
224 av_log(inlink->dst, AV_LOG_ERROR,
225 "Buffering limit reached, cannot cache more frames\n");
227 av_fifo_generic_write(select->pending_frames, &picref,
228 sizeof(picref), NULL);
231 avfilter_start_frame(inlink->dst->outputs[0], avfilter_ref_buffer(picref, ~0));
235 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
237 SelectContext *select = inlink->dst->priv;
239 if (select->select && !select->cache_frames)
240 avfilter_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
243 static void end_frame(AVFilterLink *inlink)
245 SelectContext *select = inlink->dst->priv;
246 AVFilterBufferRef *picref = inlink->cur_buf;
248 if (select->select) {
249 if (select->cache_frames)
251 avfilter_end_frame(inlink->dst->outputs[0]);
253 avfilter_unref_buffer(picref);
256 static int request_frame(AVFilterLink *outlink)
258 AVFilterContext *ctx = outlink->src;
259 SelectContext *select = ctx->priv;
260 AVFilterLink *inlink = outlink->src->inputs[0];
263 if (av_fifo_size(select->pending_frames)) {
264 AVFilterBufferRef *picref;
265 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
266 avfilter_start_frame(outlink, avfilter_ref_buffer(picref, ~0));
267 avfilter_draw_slice(outlink, 0, outlink->h, 1);
268 avfilter_end_frame(outlink);
269 avfilter_unref_buffer(picref);
273 while (!select->select) {
274 int ret = avfilter_request_frame(inlink);
282 static int poll_frame(AVFilterLink *outlink)
284 SelectContext *select = outlink->src->priv;
285 AVFilterLink *inlink = outlink->src->inputs[0];
288 if (!av_fifo_size(select->pending_frames)) {
289 if ((count = avfilter_poll_frame(inlink)) <= 0)
291 /* request frame from input, and apply select condition to it */
292 select->cache_frames = 1;
293 while (count-- && av_fifo_space(select->pending_frames)) {
294 ret = avfilter_request_frame(inlink);
298 select->cache_frames = 0;
301 return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
304 static av_cold void uninit(AVFilterContext *ctx)
306 SelectContext *select = ctx->priv;
307 AVFilterBufferRef *picref;
309 av_expr_free(select->expr);
312 while (select->pending_frames &&
313 av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))
314 avfilter_unref_buffer(picref);
315 av_fifo_free(select->pending_frames);
316 select->pending_frames = NULL;
319 AVFilter avfilter_vf_select = {
321 .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
325 .priv_size = sizeof(SelectContext),
327 .inputs = (AVFilterPad[]) {{ .name = "default",
328 .type = AVMEDIA_TYPE_VIDEO,
329 .get_video_buffer = avfilter_null_get_video_buffer,
330 .config_props = config_input,
331 .start_frame = start_frame,
332 .draw_slice = draw_slice,
333 .end_frame = end_frame },
335 .outputs = (AVFilterPad[]) {{ .name = "default",
336 .type = AVMEDIA_TYPE_VIDEO,
337 .poll_frame = poll_frame,
338 .request_frame = request_frame, },