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avfilter/f_sendcmd: implement expr flag

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Make possible to parse expressions and store results as arguments
for target filters.
This commit is contained in:
Paul B Mahol 2020-02-28 23:11:32 +01:00
parent 3117f47f19
commit 70209000fd
2 changed files with 74 additions and 3 deletions
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23
doc/filters.texi
View File

@ -23666,6 +23666,29 @@ The command is sent when the current frame timestamp leaves the
specified interval. In other words, the command is sent when the
previous frame timestamp was in the given interval, and the
current is not.
@item expr
The command @var{ARG} is interpreted as expression and result of
expression is passed as @var{ARG}.
The expression is evaluated through the eval API and can contain the following
constants:
@table @option
@item POS
Original position in the file of the frame, or undefined if undefined
for the current frame.
@item PTS
The presentation timestamp in input.
@item N
The count of the input frame for video or audio, starting from 0.
@item T
The time in seconds of the current frame.
@end table
@end table
If @var{FLAGS} is not specified, a default value of @code{[enter]} is

54
libavfilter/f_sendcmd.c
View File

@ -25,6 +25,7 @@
#include "libavutil/avstring.h"
#include "libavutil/bprint.h"
#include "libavutil/eval.h"
#include "libavutil/file.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
@ -35,10 +36,27 @@
#define COMMAND_FLAG_ENTER 1
#define COMMAND_FLAG_LEAVE 2
#define COMMAND_FLAG_EXPR 4
static const char *const var_names[] = {
"N", /* frame number */
"T", /* frame time in seconds */
"POS", /* original position in the file of the frame */
"PTS", /* frame pts */
NULL
};
enum var_name {
VAR_N,
VAR_T,
VAR_POS,
VAR_PTS,
VAR_VARS_NB
};
static inline char *make_command_flags_str(AVBPrint *pbuf, int flags)
{
static const char * const flag_strings[] = { "enter", "leave" };
static const char * const flag_strings[] = { "enter", "leave", "expr" };
int i, is_first = 1;
av_bprint_init(pbuf, 0, AV_BPRINT_SIZE_AUTOMATIC);
@ -129,6 +147,7 @@ static int parse_command(Command *cmd, int cmd_count, int interval_count,
if (!strncmp(*buf, "enter", strlen("enter"))) cmd->flags |= COMMAND_FLAG_ENTER;
else if (!strncmp(*buf, "leave", strlen("leave"))) cmd->flags |= COMMAND_FLAG_LEAVE;
else if (!strncmp(*buf, "expr", strlen("expr"))) cmd->flags |= COMMAND_FLAG_EXPR;
else {
char flag_buf[64];
av_strlcpy(flag_buf, *buf, sizeof(flag_buf));
@ -450,6 +469,9 @@ static av_cold void uninit(AVFilterContext *ctx)
av_freep(&s->intervals);
}
#define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
#define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)*av_q2d(tb))
static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
{
AVFilterContext *ctx = inlink->dst;
@ -476,6 +498,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
flags += COMMAND_FLAG_LEAVE;
interval->enabled = 0;
}
if (interval->enabled)
flags += COMMAND_FLAG_EXPR;
if (flags) {
AVBPrint pbuf;
@ -487,19 +511,43 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
for (j = 0; flags && j < interval->nb_commands; j++) {
Command *cmd = &interval->commands[j];
char *cmd_arg = cmd->arg;
char buf[1024];
if (cmd->flags & flags) {
if (cmd->flags & COMMAND_FLAG_EXPR) {
double var_values[VAR_VARS_NB], res;
var_values[VAR_N] = inlink->frame_count_in;
var_values[VAR_POS] = ref->pkt_pos == -1 ? NAN : ref->pkt_pos;
var_values[VAR_PTS] = TS2D(ref->pts);
var_values[VAR_T] = TS2T(ref->pts, inlink->time_base);
if ((ret = av_expr_parse_and_eval(&res, cmd->arg, var_names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for command argument.\n", cmd->arg);
av_frame_free(&ref);
return AVERROR(EINVAL);
}
cmd_arg = av_asprintf("%g", res);
if (!cmd_arg) {
av_frame_free(&ref);
return AVERROR(ENOMEM);
}
}
av_log(ctx, AV_LOG_VERBOSE,
"Processing command #%d target:%s command:%s arg:%s\n",
cmd->index, cmd->target, cmd->command, cmd->arg);
cmd->index, cmd->target, cmd->command, cmd_arg);
ret = avfilter_graph_send_command(inlink->graph,
cmd->target, cmd->command, cmd->arg,
cmd->target, cmd->command, cmd_arg,
buf, sizeof(buf),
AVFILTER_CMD_FLAG_ONE);
av_log(ctx, AV_LOG_VERBOSE,
"Command reply for command #%d: ret:%s res:%s\n",
cmd->index, av_err2str(ret), buf);
if (cmd->flags & COMMAND_FLAG_EXPR)
av_freep(&cmd_arg);
}
}
}