On Sun, 7 May 2023 at 23:47, Stefano Sabatini wrote:
>
> On date Monday 2023-05-01 22:01:05 +0100, Oleg Afanasyev wrote:
> > I'm using setpts to generate timelapses with slowdowns in the middle.
> > Using setpts filter requires complicated expr to handle intervals. This
> > patch allows commands to change expr and also adds a constant that
> > provides time of last command applications to allow specifying gradual
> > changes using difference between time and cmd time.
> >
> > --
> > with best regards
> > Oleg Afanasyev
>
> > From a714a0957a57c1d392feca0ba675ba5ac7c875ee Mon Sep 17 00:00:00 2001
> > From: Oleg
> > Date: Sat, 29 Apr 2023 19:56:46 +0100
> > Subject: [PATCH] avfilter/setpts: add command support
> >
> > Add support for changing expr on the fly.
> >
> > Signed-off-by: Oleg
> > ---
> > doc/filters.texi | 7 +
> > libavfilter/setpts.c | 68 +---
> > 2 files changed, 58 insertions(+), 17 deletions(-)
> >
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index 50e1682144..fbdb1f8ecf 100644
> > diff --git a/libavfilter/setpts.c b/libavfilter/setpts.c
> > index 5bcc0c2dcf..7b09ce7707 100644
> > --- a/libavfilter/setpts.c
> > +++ b/libavfilter/setpts.c
> [...]
> > +static int process_command(AVFilterContext *ctx, const char *cmd, const
> > char *arg,
> > + char *res, int res_len, int flags)
> > +{
> > +SetPTSContext *setpts = ctx->priv;
> > +int ret;
> > +
> > +ret = ff_filter_process_command(ctx, cmd, arg, res, res_len, flags);
> > +
> > +if (ret < 0)
> > +return ret;
> > +
>
> > +if (!strcmp(cmd, "expr")) {
> > +av_expr_free(setpts->expr);
> > +ret = av_expr_parse(>expr, arg, var_names, NULL, NULL,
> > NULL, NULL, 0, ctx);
> > +if (ret < 0) {
> > +av_log(ctx, AV_LOG_ERROR, "Error while parsing expression
> > '%s'\n", arg);
> > +}
>
> what happens in case setpts->expr is freed and this fails?
>
> probably it should keep a reference to expr and remove it only in case
> the new expression was successfully parsed
Fixed! Didn't realize that encoding continues even if command fails,
so it was crashing with the previous expression still in place.
>
> [...]
>
> Looks good to me otherwise.
>
> ___
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From a50bf9e58a0f90d63aba3c84de40f31dc22ebfce Mon Sep 17 00:00:00 2001
From: Oleg
Date: Sat, 29 Apr 2023 19:56:46 +0100
Subject: [PATCH] avfilter/setpts: add command support
Add support for changing expr on the fly.
Signed-off-by: Oleg
---
doc/filters.texi | 7 +
libavfilter/setpts.c | 73 +---
2 files changed, 63 insertions(+), 17 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 50e1682144..fbdb1f8ecf 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -29384,6 +29384,9 @@ The wallclock (RTC) time at the start of the movie in microseconds.
@item TB
The timebase of the input timestamps.
+@item T_CHANGE
+Time of the first frame after command was applied or time of the first frame if no commands.
+
@end table
@subsection Examples
@@ -29439,6 +29442,10 @@ asetpts=N/SR/TB
@end itemize
+@subsection Commands
+
+Both filters support all above options as @ref{commands}.
+
@section setrange
Force color range for the output video frame.
diff --git a/libavfilter/setpts.c b/libavfilter/setpts.c
index 5bcc0c2dcf..c805a60ee4 100644
--- a/libavfilter/setpts.c
+++ b/libavfilter/setpts.c
@@ -63,6 +63,7 @@ static const char *const var_names[] = {
"S", // Number of samples in the current frame
"SR", // Audio sample rate
"FR", ///< defined only for constant frame-rate video
+"T_CHANGE",///< time of first frame after latest command was applied
NULL
};
@@ -90,7 +91,8 @@ enum var_name {
VAR_S,
VAR_SR,
VAR_FR,
-VAR_VARS_NB
+VAR_T_CHANGE,
+VAR_VARS_NB,
};
typedef struct SetPTSContext {
@@ -120,6 +122,7 @@ static av_cold int init(AVFilterContext *ctx)
setpts->var_values[VAR_PREV_OUTT] = NAN;
setpts->var_values[VAR_STARTPTS]= NAN;
setpts->var_values[VAR_STARTT] = NAN;
+setpts->var_values[VAR_T_CHANGE]= NAN;
return 0;
}
@@ -163,6 +166,9 @@ static double eval_pts(SetPTSContext *setpts, AVFilterLink *inlink, AVFrame *fra
setpts->var_values[VAR_STARTPTS] = TS2D(pts);
setpts->var_values[VAR_STARTT ] = TS2T(pts, inlink->time_base);
}
+if (isnan(setpts->var_values[VAR_T_CHANGE])) {
+setpts->var_values[VAR_T_CHANGE] = TS2T(pts, inlink->time_base);
+}
setpts->var_values[VAR_PTS ] = TS2D(pts);
setpts->var_values[VAR_T ] =
