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ffmpeg/libavcodec/setts_bsf.c

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/*
* Copyright (c) 2021 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Change the PTS/DTS timestamps.
*/
#include "libavutil/opt.h"
#include "libavutil/eval.h"
#include "avcodec.h"
#include "bsf.h"
#include "bsf_internal.h"
static const char *const var_names[] = {
"N", ///< frame number (starting at zero)
"TS",
"POS", ///< original position in the file of the frame
"PREV_INPTS", ///< previous input PTS
"PREV_INDTS", ///< previous input DTS
"PREV_OUTPTS", ///< previous output PTS
"PREV_OUTDTS", ///< previous output DTS
"PTS", ///< original PTS in the file of the frame
"DTS", ///< original DTS in the file of the frame
"STARTPTS", ///< PTS at start of movie
"STARTDTS", ///< DTS at start of movie
"TB", ///< timebase of the stream
"SR", ///< sample rate of the stream
NULL
};
enum var_name {
VAR_N,
VAR_TS,
VAR_POS,
VAR_PREV_INPTS,
VAR_PREV_INDTS,
VAR_PREV_OUTPTS,
VAR_PREV_OUTDTS,
VAR_PTS,
VAR_DTS,
VAR_STARTPTS,
VAR_STARTDTS,
VAR_TB,
VAR_SR,
VAR_VARS_NB
};
typedef struct SetTSContext {
const AVClass *class;
char *ts_str;
char *pts_str;
char *dts_str;
int64_t frame_number;
int64_t start_pts;
int64_t start_dts;
int64_t prev_inpts;
int64_t prev_indts;
int64_t prev_outpts;
int64_t prev_outdts;
double var_values[VAR_VARS_NB];
AVExpr *ts_expr;
AVExpr *pts_expr;
AVExpr *dts_expr;
} SetTSContext;
static int setts_init(AVBSFContext *ctx)
{
SetTSContext *s = ctx->priv_data;
int ret;
if ((ret = av_expr_parse(&s->ts_expr, s->ts_str,
var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error while parsing ts expression '%s'\n", s->ts_str);
return ret;
}
if (s->pts_str) {
if ((ret = av_expr_parse(&s->pts_expr, s->pts_str,
var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error while parsing pts expression '%s'\n", s->pts_str);
return ret;
}
}
if (s->dts_str) {
if ((ret = av_expr_parse(&s->dts_expr, s->dts_str,
var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error while parsing dts expression '%s'\n", s->dts_str);
return ret;
}
}
s->frame_number= 0;
s->start_pts = AV_NOPTS_VALUE;
s->start_dts = AV_NOPTS_VALUE;
s->prev_inpts = AV_NOPTS_VALUE;
s->prev_indts = AV_NOPTS_VALUE;
s->prev_outpts = AV_NOPTS_VALUE;
s->prev_outdts = AV_NOPTS_VALUE;
return 0;
}
static int setts_filter(AVBSFContext *ctx, AVPacket *pkt)
{
SetTSContext *s = ctx->priv_data;
int64_t new_ts, new_pts, new_dts;
int ret;
ret = ff_bsf_get_packet_ref(ctx, pkt);
if (ret < 0)
return ret;
if (s->start_pts == AV_NOPTS_VALUE)
s->start_pts = pkt->pts;
if (s->start_dts == AV_NOPTS_VALUE)
s->start_dts = pkt->dts;
s->var_values[VAR_N] = s->frame_number++;
s->var_values[VAR_TS] = pkt->dts;
s->var_values[VAR_POS] = pkt->pos;
s->var_values[VAR_PTS] = pkt->pts;
s->var_values[VAR_DTS] = pkt->dts;
s->var_values[VAR_PREV_INPTS] = s->prev_inpts;
s->var_values[VAR_PREV_INDTS] = s->prev_indts;
s->var_values[VAR_PREV_OUTPTS] = s->prev_outpts;
s->var_values[VAR_PREV_OUTDTS] = s->prev_outdts;
s->var_values[VAR_STARTPTS] = s->start_pts;
s->var_values[VAR_STARTDTS] = s->start_dts;
s->var_values[VAR_TB] = av_q2d(ctx->time_base_out);
s->var_values[VAR_SR] = ctx->par_in->sample_rate;
new_ts = llrint(av_expr_eval(s->ts_expr, s->var_values, NULL));
if (s->pts_str) {
s->var_values[VAR_TS] = pkt->pts;
new_pts = llrint(av_expr_eval(s->pts_expr, s->var_values, NULL));
} else {
new_pts = new_ts;
}
if (s->dts_str) {
s->var_values[VAR_TS] = pkt->dts;
new_dts = llrint(av_expr_eval(s->dts_expr, s->var_values, NULL));
} else {
new_dts = new_ts;
}
s->var_values[VAR_PREV_INPTS] = pkt->pts;
s->var_values[VAR_PREV_INDTS] = pkt->dts;
s->var_values[VAR_PREV_OUTPTS] = new_pts;
s->var_values[VAR_PREV_OUTDTS] = new_dts;
pkt->pts = new_pts;
pkt->dts = new_dts;
return ret;
}
static void setts_close(AVBSFContext *bsf)
{
SetTSContext *s = bsf->priv_data;
av_expr_free(s->ts_expr);
s->ts_expr = NULL;
av_expr_free(s->pts_expr);
s->pts_expr = NULL;
av_expr_free(s->dts_expr);
s->dts_expr = NULL;
}
#define OFFSET(x) offsetof(SetTSContext, x)
#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_BSF_PARAM)
static const AVOption options[] = {
{ "ts", "set expression for packet PTS and DTS", OFFSET(ts_str), AV_OPT_TYPE_STRING, {.str="TS"}, 0, 0, FLAGS },
{ "pts", "set expression for packet PTS", OFFSET(pts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
{ "dts", "set expression for packet DTS", OFFSET(dts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
{ NULL },
};
static const AVClass setts_class = {
.class_name = "setts_bsf",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const AVBitStreamFilter ff_setts_bsf = {
.name = "setts",
.priv_data_size = sizeof(SetTSContext),
.priv_class = &setts_class,
.init = setts_init,
.close = setts_close,
.filter = setts_filter,
};
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