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/* * Copyright (c) 2011 Stefano Sabatini * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * filter for selecting which frame passes in the filterchain */ #include "libavutil/eval.h"#include "libavutil/fifo.h"#include "libavutil/mathematics.h"#include "avfilter.h"#include "internal.h"#include "video.h" static const char *const var_names[] = {    "E",                 ///< Euler number    "PHI",               ///< golden ratio    "PI",                ///< greek pi     "TB",                ///< timebase     "pts",               ///< original pts in the file of the frame    "start_pts",         ///< first PTS in the stream, expressed in TB units    "prev_pts",          ///< previous frame PTS    "prev_selected_pts", ///< previous selected frame PTS     "t",                 ///< first PTS in seconds    "start_t",           ///< first PTS in the stream, expressed in seconds    "prev_t",            ///< previous frame time    "prev_selected_t",   ///< previously selected time     "pict_type",         ///< the type of picture in the movie    "I",    "P",    "B",    "S",    "SI",    "SP",    "BI",     "interlace_type",    ///< the frame interlace type    "PROGRESSIVE",    "TOPFIRST",    "BOTTOMFIRST",     "n",                 ///< frame number (starting from zero)    "selected_n",        ///< selected frame number (starting from zero)    "prev_selected_n",   ///< number of the last selected frame     "key",               ///< tell if the frame is a key frame    "pos",               ///< original position in the file of the frame     NULL}; enum var_name {    VAR_E,    VAR_PHI,    VAR_PI,     VAR_TB,     VAR_PTS,    VAR_START_PTS,    VAR_PREV_PTS,    VAR_PREV_SELECTED_PTS,     VAR_T,    VAR_START_T,    VAR_PREV_T,    VAR_PREV_SELECTED_T,     VAR_PICT_TYPE,    VAR_PICT_TYPE_I,    VAR_PICT_TYPE_P,    VAR_PICT_TYPE_B,    VAR_PICT_TYPE_S,    VAR_PICT_TYPE_SI,    VAR_PICT_TYPE_SP,    VAR_PICT_TYPE_BI,     VAR_INTERLACE_TYPE,    VAR_INTERLACE_TYPE_P,    VAR_INTERLACE_TYPE_T,    VAR_INTERLACE_TYPE_B,     VAR_N,    VAR_SELECTED_N,    VAR_PREV_SELECTED_N,     VAR_KEY,    VAR_POS,     VAR_VARS_NB}; #define FIFO_SIZE 8 typedef struct {    AVExpr *expr;    double var_values[VAR_VARS_NB];    double select;    int cache_frames;    AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames} SelectContext; static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque){    SelectContext *select = ctx->priv;    int ret;     if ((ret = av_expr_parse(&select->expr, args ? args : "1",                             var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {        av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);        return ret;    }     select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));    if (!select->pending_frames) {        av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");        return AVERROR(ENOMEM);    }    return 0;} #define INTERLACE_TYPE_P 0#define INTERLACE_TYPE_T 1#define INTERLACE_TYPE_B 2 static int config_input(AVFilterLink *inlink){    SelectContext *select = inlink->dst->priv;     select->var_values[VAR_E]   = M_E;    select->var_values[VAR_PHI] = M_PHI;    select->var_values[VAR_PI]  = M_PI;     select->var_values[VAR_N]          = 0.0;    select->var_values[VAR_SELECTED_N] = 0.0;     select->var_values[VAR_TB] = av_q2d(inlink->time_base);     select->var_values[VAR_PREV_PTS]          = NAN;    select->var_values[VAR_PREV_SELECTED_PTS] = NAN;    select->var_values[VAR_PREV_SELECTED_T]   = NAN;    select->var_values[VAR_START_PTS]         = NAN;    select->var_values[VAR_START_T]           = NAN;     select->var_values[VAR_PICT_TYPE_I]  = AV_PICTURE_TYPE_I;    select->var_values[VAR_PICT_TYPE_P]  = AV_PICTURE_TYPE_P;    select->var_values[VAR_PICT_TYPE_B]  = AV_PICTURE_TYPE_B;    select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;    select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;     select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;    select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;    select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;;     return 0;} #define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))#define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)) static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref){    SelectContext *select = ctx->priv;    AVFilterLink *inlink = ctx->inputs[0];    double res;     if (isnan(select->var_values[VAR_START_PTS]))        select->var_values[VAR_START_PTS] = TS2D(picref->pts);    if (isnan(select->var_values[VAR_START_T]))        select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);     select->var_values[VAR_PTS] = TS2D(picref->pts);    select->var_values[VAR_T  ] = TS2D(picref->pts) * av_q2d(inlink->time_base);    select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;    select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);     select->var_values[VAR_INTERLACE_TYPE] =        !picref->video->interlaced     ? INTERLACE_TYPE_P :        picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;    select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;     res = av_expr_eval(select->expr, select->var_values, NULL);    av_log(inlink->dst, AV_LOG_DEBUG,           "n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "           "-> select:%f\n",           (int)select->var_values[VAR_N],           (int)select->var_values[VAR_PTS],           select->var_values[VAR_T],           (int)select->var_values[VAR_POS],           select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :           select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :           select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',           (int)select->var_values[VAR_KEY],           av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),           res);     select->var_values[VAR_N] += 1.0;     if (res) {        select->var_values[VAR_PREV_SELECTED_N]   = select->var_values[VAR_N];        select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];        select->var_values[VAR_PREV_SELECTED_T]   = select->var_values[VAR_T];        select->var_values[VAR_SELECTED_N] += 1.0;    }    return res;} static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref){    SelectContext *select = inlink->dst->priv;     select->select = select_frame(inlink->dst, picref);    if (select->select) {        /* frame was requested through poll_frame */        if (select->cache_frames) {            if (!av_fifo_space(select->pending_frames))                av_log(inlink->dst, AV_LOG_ERROR,                       "Buffering limit reached, cannot cache more frames\n");            else                av_fifo_generic_write(select->pending_frames, &picref,                                      sizeof(picref), NULL);            return;        }        ff_start_frame(inlink->dst->outputs[0], avfilter_ref_buffer(picref, ~0));    }} static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir){    SelectContext *select = inlink->dst->priv;     if (select->select && !select->cache_frames)        ff_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);} static void end_frame(AVFilterLink *inlink){    SelectContext *select = inlink->dst->priv;    AVFilterBufferRef *picref = inlink->cur_buf;     if (select->select) {        if (select->cache_frames)            return;        ff_end_frame(inlink->dst->outputs[0]);    }    avfilter_unref_buffer(picref);} static int request_frame(AVFilterLink *outlink){    AVFilterContext *ctx = outlink->src;    SelectContext *select = ctx->priv;    AVFilterLink *inlink = outlink->src->inputs[0];    select->select = 0;     if (av_fifo_size(select->pending_frames)) {        AVFilterBufferRef *picref;        av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);        ff_start_frame(outlink, avfilter_ref_buffer(picref, ~0));        ff_draw_slice(outlink, 0, outlink->h, 1);        ff_end_frame(outlink);        avfilter_unref_buffer(picref);        return 0;    }     while (!select->select) {        int ret = ff_request_frame(inlink);        if (ret < 0)            return ret;    }     return 0;} static int poll_frame(AVFilterLink *outlink){    SelectContext *select = outlink->src->priv;    AVFilterLink *inlink = outlink->src->inputs[0];    int count, ret;     if (!av_fifo_size(select->pending_frames)) {        if ((count = ff_poll_frame(inlink)) <= 0)            return count;        /* request frame from input, and apply select condition to it */        select->cache_frames = 1;        while (count-- && av_fifo_space(select->pending_frames)) {            ret = ff_request_frame(inlink);            if (ret < 0)                break;        }        select->cache_frames = 0;    }     return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);} static av_cold void uninit(AVFilterContext *ctx){    SelectContext *select = ctx->priv;    AVFilterBufferRef *picref;     av_expr_free(select->expr);    select->expr = NULL;     while (select->pending_frames &&           av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))        avfilter_unref_buffer(picref);    av_fifo_free(select->pending_frames);    select->pending_frames = NULL;} AVFilter avfilter_vf_select = {    .name      = "select",    .description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),    .init      = init,    .uninit    = uninit,     .priv_size = sizeof(SelectContext),     .inputs    = (AVFilterPad[]) {{ .name             = "default",                                    .type             = AVMEDIA_TYPE_VIDEO,                                    .get_video_buffer = ff_null_get_video_buffer,                                    .config_props     = config_input,                                    .start_frame      = start_frame,                                    .draw_slice       = draw_slice,                                    .end_frame        = end_frame },                                  { .name = NULL }},    .outputs   = (AVFilterPad[]) {{ .name             = "default",                                    .type             = AVMEDIA_TYPE_VIDEO,                                    .poll_frame       = poll_frame,                                    .request_frame    = request_frame, },                                  { .name = NULL}},};

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