libavfilter/vf_select.c

   1 /*
   2  * Copyright (c) 2011 Stefano Sabatini
   3  *
   4  * This file is part of Libav.
   5  *
   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.
  10  *
  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.
  15  *
  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
  19  */
  20
  21 /**
  22  * @file
  23  * filter for selecting which frame passes in the filterchain
  24  */
  25
  26 #include "libavutil/eval.h"
  27 #include "libavutil/fifo.h"
  28 #include "libavutil/internal.h"
  29 #include "libavutil/mathematics.h"
  30 #include "avfilter.h"
  31 #include "internal.h"
  32 #include "video.h"
  33
  34 static const char *const var_names[] = {
  35     "E",                 ///< Euler number
  36     "PHI",               ///< golden ratio
  37     "PI",                ///< greek pi
  38
  39     "TB",                ///< timebase
  40
  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
  45
  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
  50
  51     "pict_type",         ///< the type of picture in the movie
  52     "I",
  53     "P",
  54     "B",
  55     "S",
  56     "SI",
  57     "SP",
  58     "BI",
  59
  60     "interlace_type",    ///< the frame interlace type
  61     "PROGRESSIVE",
  62     "TOPFIRST",
  63     "BOTTOMFIRST",
  64
  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
  68
  69     "key",               ///< tell if the frame is a key frame
  70     "pos",               ///< original position in the file of the frame
  71
  72     NULL
  73 };
  74
  75 enum var_name {
  76     VAR_E,
  77     VAR_PHI,
  78     VAR_PI,
  79
  80     VAR_TB,
  81
  82     VAR_PTS,
  83     VAR_START_PTS,
  84     VAR_PREV_PTS,
  85     VAR_PREV_SELECTED_PTS,
  86
  87     VAR_T,
  88     VAR_START_T,
  89     VAR_PREV_T,
  90     VAR_PREV_SELECTED_T,
  91
  92     VAR_PICT_TYPE,
  93     VAR_PICT_TYPE_I,
  94     VAR_PICT_TYPE_P,
  95     VAR_PICT_TYPE_B,
  96     VAR_PICT_TYPE_S,
  97     VAR_PICT_TYPE_SI,
  98     VAR_PICT_TYPE_SP,
  99     VAR_PICT_TYPE_BI,
 100
 101     VAR_INTERLACE_TYPE,
 102     VAR_INTERLACE_TYPE_P,
 103     VAR_INTERLACE_TYPE_T,
 104     VAR_INTERLACE_TYPE_B,
 105
 106     VAR_N,
 107     VAR_SELECTED_N,
 108     VAR_PREV_SELECTED_N,
 109
 110     VAR_KEY,
 111
 112     VAR_VARS_NB
 113 };
 114
 115 #define FIFO_SIZE 8
 116
 117 typedef struct {
 118     AVExpr *expr;
 119     double var_values[VAR_VARS_NB];
 120     double select;
 121     int cache_frames;
 122     AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
 123 } SelectContext;
 124
 125 static av_cold int init(AVFilterContext *ctx, const char *args)
 126 {
 127     SelectContext *select = ctx->priv;
 128     int ret;
 129
 130     if ((ret = av_expr_parse(&select->expr, args ? args : "1",
 131                              var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
 132         av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
 133         return ret;
 134     }
 135
 136     select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFrame*));
 137     if (!select->pending_frames) {
 138         av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
 139         return AVERROR(ENOMEM);
 140     }
 141     return 0;
 142 }
 143
 144 #define INTERLACE_TYPE_P 0
 145 #define INTERLACE_TYPE_T 1
 146 #define INTERLACE_TYPE_B 2
 147
 148 static int config_input(AVFilterLink *inlink)
 149 {
 150     SelectContext *select = inlink->dst->priv;
 151
 152     select->var_values[VAR_E]   = M_E;
 153     select->var_values[VAR_PHI] = M_PHI;
 154     select->var_values[VAR_PI]  = M_PI;
 155
 156     select->var_values[VAR_N]          = 0.0;
 157     select->var_values[VAR_SELECTED_N] = 0.0;
 158
 159     select->var_values[VAR_TB] = av_q2d(inlink->time_base);
 160
 161     select->var_values[VAR_PREV_PTS]          = NAN;
 162     select->var_values[VAR_PREV_SELECTED_PTS] = NAN;
 163     select->var_values[VAR_PREV_SELECTED_T]   = NAN;
 164     select->var_values[VAR_START_PTS]         = NAN;
 165     select->var_values[VAR_START_T]           = NAN;
 166
 167     select->var_values[VAR_PICT_TYPE_I]  = AV_PICTURE_TYPE_I;
 168     select->var_values[VAR_PICT_TYPE_P]  = AV_PICTURE_TYPE_P;
 169     select->var_values[VAR_PICT_TYPE_B]  = AV_PICTURE_TYPE_B;
 170     select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;
 171     select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;
 172
 173     select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;
 174     select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;
 175     select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;;
 176
 177     return 0;
 178 }
 179
 180 #define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
 181 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
 182
 183 static int select_frame(AVFilterContext *ctx, AVFrame *frame)
 184 {
 185     SelectContext *select = ctx->priv;
 186     AVFilterLink *inlink = ctx->inputs[0];
 187     double res;
 188
 189     if (isnan(select->var_values[VAR_START_PTS]))
 190         select->var_values[VAR_START_PTS] = TS2D(frame->pts);
 191     if (isnan(select->var_values[VAR_START_T]))
 192         select->var_values[VAR_START_T] = TS2D(frame->pts) * av_q2d(inlink->time_base);
 193
 194     select->var_values[VAR_PTS] = TS2D(frame->pts);
 195     select->var_values[VAR_T  ] = TS2D(frame->pts) * av_q2d(inlink->time_base);
 196     select->var_values[VAR_PREV_PTS] = TS2D(frame->pts);
 197
 198     select->var_values[VAR_INTERLACE_TYPE] =
 199         !frame->interlaced_frame     ? INTERLACE_TYPE_P :
 200         frame->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
 201     select->var_values[VAR_PICT_TYPE] = frame->pict_type;
 202
 203     res = av_expr_eval(select->expr, select->var_values, NULL);
 204     av_log(inlink->dst, AV_LOG_DEBUG,
 205            "n:%d pts:%d t:%f interlace_type:%c key:%d pict_type:%c "
 206            "-> select:%f\n",
 207            (int)select->var_values[VAR_N],
 208            (int)select->var_values[VAR_PTS],
 209            select->var_values[VAR_T],
 210            select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
 211            select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
 212            select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
 213            (int)select->var_values[VAR_KEY],
 214            av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
 215            res);
 216
 217     select->var_values[VAR_N] += 1.0;
 218
 219     if (res) {
 220         select->var_values[VAR_PREV_SELECTED_N]   = select->var_values[VAR_N];
 221         select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
 222         select->var_values[VAR_PREV_SELECTED_T]   = select->var_values[VAR_T];
 223         select->var_values[VAR_SELECTED_N] += 1.0;
 224     }
 225     return res;
 226 }
 227
 228 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 229 {
 230     SelectContext *select = inlink->dst->priv;
 231
 232     select->select = select_frame(inlink->dst, frame);
 233     if (select->select) {
 234         /* frame was requested through poll_frame */
 235         if (select->cache_frames) {
 236             if (!av_fifo_space(select->pending_frames)) {
 237                 av_log(inlink->dst, AV_LOG_ERROR,
 238                        "Buffering limit reached, cannot cache more frames\n");
 239                 av_frame_free(&frame);
 240             } else
 241                 av_fifo_generic_write(select->pending_frames, &frame,
 242                                       sizeof(frame), NULL);
 243             return 0;
 244         }
 245         return ff_filter_frame(inlink->dst->outputs[0], frame);
 246     }
 247
 248     av_frame_free(&frame);
 249     return 0;
 250 }
 251
 252 static int request_frame(AVFilterLink *outlink)
 253 {
 254     AVFilterContext *ctx = outlink->src;
 255     SelectContext *select = ctx->priv;
 256     AVFilterLink *inlink = outlink->src->inputs[0];
 257     select->select = 0;
 258
 259     if (av_fifo_size(select->pending_frames)) {
 260         AVFrame *frame;
 261
 262         av_fifo_generic_read(select->pending_frames, &frame, sizeof(frame), NULL);
 263         return ff_filter_frame(outlink, frame);
 264     }
 265
 266     while (!select->select) {
 267         int ret = ff_request_frame(inlink);
 268         if (ret < 0)
 269             return ret;
 270     }
 271
 272     return 0;
 273 }
 274
 275 static int poll_frame(AVFilterLink *outlink)
 276 {
 277     SelectContext *select = outlink->src->priv;
 278     AVFilterLink *inlink = outlink->src->inputs[0];
 279     int count, ret;
 280
 281     if (!av_fifo_size(select->pending_frames)) {
 282         if ((count = ff_poll_frame(inlink)) <= 0)
 283             return count;
 284         /* request frame from input, and apply select condition to it */
 285         select->cache_frames = 1;
 286         while (count-- && av_fifo_space(select->pending_frames)) {
 287             ret = ff_request_frame(inlink);
 288             if (ret < 0)
 289                 break;
 290         }
 291         select->cache_frames = 0;
 292     }
 293
 294     return av_fifo_size(select->pending_frames)/sizeof(AVFrame*);
 295 }
 296
 297 static av_cold void uninit(AVFilterContext *ctx)
 298 {
 299     SelectContext *select = ctx->priv;
 300     AVFrame *frame;
 301
 302     av_expr_free(select->expr);
 303     select->expr = NULL;
 304
 305     while (select->pending_frames &&
 306            av_fifo_generic_read(select->pending_frames, &frame, sizeof(frame), NULL) == sizeof(frame))
 307         av_frame_free(&frame);
 308     av_fifo_free(select->pending_frames);
 309     select->pending_frames = NULL;
 310 }
 311
 312 static const AVFilterPad avfilter_vf_select_inputs[] = {
 313     {
 314         .name             = "default",
 315         .type             = AVMEDIA_TYPE_VIDEO,
 316         .get_video_buffer = ff_null_get_video_buffer,
 317         .config_props     = config_input,
 318         .filter_frame     = filter_frame,
 319     },
 320     { NULL }
 321 };
 322
 323 static const AVFilterPad avfilter_vf_select_outputs[] = {
 324     {
 325         .name          = "default",
 326         .type          = AVMEDIA_TYPE_VIDEO,
 327         .poll_frame    = poll_frame,
 328         .request_frame = request_frame,
 329     },
 330     { NULL }
 331 };
 332
 333 AVFilter avfilter_vf_select = {
 334     .name      = "select",
 335     .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
 336     .init      = init,
 337     .uninit    = uninit,
 338
 339     .priv_size = sizeof(SelectContext),
 340
 341     .inputs    = avfilter_vf_select_inputs,
 342     .outputs   = avfilter_vf_select_outputs,
 343 };