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     VAR_POS,
 112
 113     VAR_VARS_NB
 114 };
 115
 116 #define FIFO_SIZE 8
 117
 118 typedef struct {
 119     AVExpr *expr;
 120     double var_values[VAR_VARS_NB];
 121     double select;
 122     int cache_frames;
 123     AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
 124 } SelectContext;
 125
 126 static av_cold int init(AVFilterContext *ctx, const char *args)
 127 {
 128     SelectContext *select = ctx->priv;
 129     int ret;
 130
 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);
 134         return ret;
 135     }
 136
 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);
 141     }
 142     return 0;
 143 }
 144
 145 #define INTERLACE_TYPE_P 0
 146 #define INTERLACE_TYPE_T 1
 147 #define INTERLACE_TYPE_B 2
 148
 149 static int config_input(AVFilterLink *inlink)
 150 {
 151     SelectContext *select = inlink->dst->priv;
 152
 153     select->var_values[VAR_E]   = M_E;
 154     select->var_values[VAR_PHI] = M_PHI;
 155     select->var_values[VAR_PI]  = M_PI;
 156
 157     select->var_values[VAR_N]          = 0.0;
 158     select->var_values[VAR_SELECTED_N] = 0.0;
 159
 160     select->var_values[VAR_TB] = av_q2d(inlink->time_base);
 161
 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;
 167
 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;
 173
 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;;
 177
 178     return 0;
 179 }
 180
 181 #define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
 182 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
 183
 184 static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
 185 {
 186     SelectContext *select = ctx->priv;
 187     AVFilterLink *inlink = ctx->inputs[0];
 188     double res;
 189
 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);
 194
 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);
 199
 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;
 204
 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 "
 208            "-> select:%f\n",
 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]),
 218            res);
 219
 220     select->var_values[VAR_N] += 1.0;
 221
 222     if (res) {
 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;
 227     }
 228     return res;
 229 }
 230
 231 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *frame)
 232 {
 233     SelectContext *select = inlink->dst->priv;
 234
 235     select->select = select_frame(inlink->dst, frame);
 236     if (select->select) {
 237         /* frame was requested through poll_frame */
 238         if (select->cache_frames) {
 239             if (!av_fifo_space(select->pending_frames)) {
 240                 av_log(inlink->dst, AV_LOG_ERROR,
 241                        "Buffering limit reached, cannot cache more frames\n");
 242                 avfilter_unref_bufferp(&frame);
 243             } else
 244                 av_fifo_generic_write(select->pending_frames, &frame,
 245                                       sizeof(frame), NULL);
 246             return 0;
 247         }
 248         return ff_filter_frame(inlink->dst->outputs[0], frame);
 249     }
 250
 251     avfilter_unref_bufferp(&frame);
 252     return 0;
 253 }
 254
 255 static int request_frame(AVFilterLink *outlink)
 256 {
 257     AVFilterContext *ctx = outlink->src;
 258     SelectContext *select = ctx->priv;
 259     AVFilterLink *inlink = outlink->src->inputs[0];
 260     select->select = 0;
 261
 262     if (av_fifo_size(select->pending_frames)) {
 263         AVFilterBufferRef *picref;
 264
 265         av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
 266         return ff_filter_frame(outlink, picref);
 267     }
 268
 269     while (!select->select) {
 270         int ret = ff_request_frame(inlink);
 271         if (ret < 0)
 272             return ret;
 273     }
 274
 275     return 0;
 276 }
 277
 278 static int poll_frame(AVFilterLink *outlink)
 279 {
 280     SelectContext *select = outlink->src->priv;
 281     AVFilterLink *inlink = outlink->src->inputs[0];
 282     int count, ret;
 283
 284     if (!av_fifo_size(select->pending_frames)) {
 285         if ((count = ff_poll_frame(inlink)) <= 0)
 286             return count;
 287         /* request frame from input, and apply select condition to it */
 288         select->cache_frames = 1;
 289         while (count-- && av_fifo_space(select->pending_frames)) {
 290             ret = ff_request_frame(inlink);
 291             if (ret < 0)
 292                 break;
 293         }
 294         select->cache_frames = 0;
 295     }
 296
 297     return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
 298 }
 299
 300 static av_cold void uninit(AVFilterContext *ctx)
 301 {
 302     SelectContext *select = ctx->priv;
 303     AVFilterBufferRef *picref;
 304
 305     av_expr_free(select->expr);
 306     select->expr = NULL;
 307
 308     while (select->pending_frames &&
 309            av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))
 310         avfilter_unref_buffer(picref);
 311     av_fifo_free(select->pending_frames);
 312     select->pending_frames = NULL;
 313 }
 314
 315 static const AVFilterPad avfilter_vf_select_inputs[] = {
 316     {
 317         .name             = "default",
 318         .type             = AVMEDIA_TYPE_VIDEO,
 319         .get_video_buffer = ff_null_get_video_buffer,
 320         .config_props     = config_input,
 321         .filter_frame     = filter_frame,
 322     },
 323     { NULL }
 324 };
 325
 326 static const AVFilterPad avfilter_vf_select_outputs[] = {
 327     {
 328         .name          = "default",
 329         .type          = AVMEDIA_TYPE_VIDEO,
 330         .poll_frame    = poll_frame,
 331         .request_frame = request_frame,
 332     },
 333     { NULL }
 334 };
 335
 336 AVFilter avfilter_vf_select = {
 337     .name      = "select",
 338     .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
 339     .init      = init,
 340     .uninit    = uninit,
 341
 342     .priv_size = sizeof(SelectContext),
 343
 344     .inputs    = avfilter_vf_select_inputs,
 345     .outputs   = avfilter_vf_select_outputs,
 346 };