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avfilter/zoompan: add in_time variable

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Currently, the zoompan filter exposes a 'time' variable (missing from docs) for use in
the 'zoom', 'x', and 'y' expressions. This variable is perhaps better named
'out_time' as it represents the timestamp in seconds of each output frame
produced by zoompan. This patch adds aliases 'out_time' and 'ot' for 'time'.

This patch also adds an 'in_time' (alias 'it') variable that provides access
to the timestamp in seconds of each input frame to the zoompan filter.
This helps to design zoompan filters that depend on the input video timestamps.
For example, it makes it easy to zoom in instantly for only some portion of a video.
Both the 'out_time' and 'in_time' variables have been added in the documentation
for zoompan.

Example usage of 'in_time' in the zoompan filter to zoom in 2x for the
first second of the input video and 1x for the rest:
    zoompan=z='if(between(in_time,0,1),2,1):d=1'

V2: Fix zoompan filter documentation stating that the time variable
would be NAN if the input timestamp is unknown.

V3: Add 'it' alias for 'in_time. Add 'out_time' and 'ot' aliases for 'time'.
Minor corrections to zoompan docs.

Signed-off-by: exwm <thighsman@protonmail.com>
This commit is contained in:
exwm 2020-06-19 15:58:41 +00:00 committed by Paul B Mahol
parent bd6ae462f8
commit 32d6fe23b6
2 changed files with 24 additions and 5 deletions
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17
doc/filters.texi
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@ -20782,6 +20782,12 @@ Input frame count.
@item on
Output frame count.
@item in_time, it
The input timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
@item out_time, time, ot
The output timestamp expressed in seconds.
@item x
@item y
Last calculated 'x' and 'y' position from 'x' and 'y' expression
@ -20820,13 +20826,13 @@ display aspect ratio
@itemize
@item
Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
Zoom in up to 1.5x and pan at same time to some spot near center of picture:
@example
zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360
@end example
@item
Zoom-in up to 1.5 and pan always at center of picture:
Zoom in up to 1.5x and pan always at center of picture:
@example
zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
@end example
@ -20836,6 +20842,13 @@ Same as above but without pausing:
@example
zoompan=z='min(max(zoom,pzoom)+0.0015,1.5)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
@end example
@item
Zoom in 2x into center of picture only for the first second of the input video:
@example
zoompan=z='if(between(in_time,0,1),2,1)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
@end example
@end itemize
@anchor{zscale}

12
libavfilter/vf_zoompan.c
View File

@ -38,7 +38,8 @@ static const char *const var_names[] = {
"on",
"duration",
"pduration",
"time",
"in_time", "it",
"out_time", "time", "ot",
"frame",
"zoom",
"pzoom",
@ -61,7 +62,8 @@ enum var_name {
VAR_ON,
VAR_DURATION,
VAR_PDURATION,
VAR_TIME,
VAR_IN_TIME, VAR_IT,
VAR_TIME, VAR_OUT_TIME, VAR_OT,
VAR_FRAME,
VAR_ZOOM,
VAR_PZOOM,
@ -155,6 +157,7 @@ static int output_single_frame(AVFilterContext *ctx, AVFrame *in, double *var_va
{
ZPContext *s = ctx->priv;
AVFilterLink *outlink = ctx->outputs[0];
AVFilterLink *inlink = ctx->inputs[0];
int64_t pts = s->frame_count;
int k, x, y, w, h, ret = 0;
uint8_t *input[4];
@ -165,7 +168,10 @@ static int output_single_frame(AVFilterContext *ctx, AVFrame *in, double *var_va
var_values[VAR_PY] = s->y;
var_values[VAR_PZOOM] = s->prev_zoom;
var_values[VAR_PDURATION] = s->prev_nb_frames;
var_values[VAR_TIME] = pts * av_q2d(outlink->time_base);
var_values[VAR_IN_TIME] = var_values[VAR_IT] = in->pts == AV_NOPTS_VALUE ?
NAN : in->pts * av_q2d(inlink->time_base);
var_values[VAR_OUT_TIME] = pts * av_q2d(outlink->time_base);
var_values[VAR_TIME] = var_values[VAR_OT] = var_values[VAR_OUT_TIME];
var_values[VAR_FRAME] = i;
var_values[VAR_ON] = outlink->frame_count_in;