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