[FFmpeg-devel] [PATCH] pad: make the filter parametric
Stefano Sabatini
stefano.sabatini-lala at poste.it
Sun Apr 17 17:28:09 CEST 2011
Also related to trac issue #61.
Signed-off-by: Stefano Sabatini <stefano.sabatini-lala at poste.it>
---
doc/filters.texi | 57 +++++++++++++++++++++++++-
libavfilter/vf_pad.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 160 insertions(+), 9 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index b36ae07..b38abf3 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -985,6 +985,39 @@ given coordinates @var{x}, @var{y}.
It accepts the following parameters:
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
+The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
+expressions containing the following constants:
+
+ at table @option
+ at item E, PI, PHI
+the corresponding mathematical approximated values for e
+(euler number), pi (greek PI), phi (golden ratio)
+
+ at item in_w, in_h
+the input video width and heigth
+
+ at item iw, ih
+same as @var{in_w} and @var{in_h}
+
+ at item out_w, out_h
+the output width and heigth, that is the size of the padded area as
+specified by the @var{width} and @var{height} expressions
+
+ at item ow, oh
+same as @var{out_w} and @var{out_h}
+
+ at item x, y
+x and y offsets as specified by the @var{x} and @var{y}
+expressions, or NAN if not yet specified
+
+ at item a
+input display aspect ratio, same as @var{iw} / @var{ih}
+
+ at item hsub, vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+ at end table
+
Follows the description of the accepted parameters.
@table @option
@@ -994,6 +1027,9 @@ Specify the size of the output image with the paddings added. If the
value for @var{width} or @var{height} is 0, the corresponding input size
is used for the output.
+The @var{width} expression can reference the value set by the
+ at var{height} expression, and viceversa.
+
The default value of @var{width} and @var{height} is 0.
@item x, y
@@ -1001,6 +1037,9 @@ The default value of @var{width} and @var{height} is 0.
Specify the offsets where to place the input image in the padded area
with respect to the top/left border of the output image.
+The @var{x} expression can reference the value set by the @var{y}
+expression, and viceversa.
+
The default value of @var{x} and @var{y} is 0.
@item color
@@ -1012,13 +1051,29 @@ The default value of @var{color} is "black".
@end table
-For example:
+Some examples follow:
@example
# Add paddings with color "violet" to the input video. Output video
# size is 640x480, the top-left corner of the input video is placed at
# column 0, row 40.
pad=640:480:0:40:violet
+
+# pad the input to get an output with dimensions increased bt 3/2,
+# and put the input video at the center of the padded area
+pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+
+# pad the input to get a squared output with size equal to the maximum
+# value between the input width and height, and put the input video at
+# the center of the padded area
+pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
+
+# pad the input to get a final w/h ratio of 16:9
+pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+
+# double output size and put the input video in the bottom-right
+# corner of the output padded area
+pad="2*iw:2*ih:ow-iw:oh-ih"
@end example
@section pixdesctest
diff --git a/libavfilter/vf_pad.c b/libavfilter/vf_pad.c
index 492b08e..f6b6010 100644
--- a/libavfilter/vf_pad.c
+++ b/libavfilter/vf_pad.c
@@ -25,6 +25,8 @@
*/
#include "avfilter.h"
+#include "libavutil/avstring.h"
+#include "libavutil/eval.h"
#include "libavutil/pixdesc.h"
#include "libavutil/colorspace.h"
#include "libavutil/avassert.h"
@@ -32,6 +34,36 @@
#include "libavutil/parseutils.h"
#include "drawutils.h"
+static const char *var_names[] = {
+ "PI",
+ "PHI",
+ "E",
+ "in_w", "iw",
+ "in_h", "ih",
+ "out_w", "ow",
+ "out_h", "oh",
+ "x", "y",
+ "a",
+ "hsub",
+ "vsub",
+ NULL
+};
+
+enum var_name {
+ VAR_PI,
+ VAR_PHI,
+ VAR_E,
+ VAR_IN_W, VAR_IW,
+ VAR_IN_H, VAR_IH,
+ VAR_OUT_W, VAR_OW,
+ VAR_OUT_H, VAR_OH,
+ VAR_X, VAR_Y,
+ VAR_A,
+ VAR_HSUB,
+ VAR_VSUB,
+ VARS_NB
+};
+
static int query_formats(AVFilterContext *ctx)
{
static const enum PixelFormat pix_fmts[] = {
@@ -58,6 +90,11 @@ typedef struct {
int x, y; ///< offsets of the input area with respect to the padded area
int in_w, in_h; ///< width and height for the padded input video, which has to be aligned to the chroma values in order to avoid chroma issues
+ char w_expr[256]; ///< width expression string
+ char h_expr[256]; ///< height expression string
+ char x_expr[256]; ///< width expression string
+ char y_expr[256]; ///< height expression string
+
uint8_t color[4]; ///< color expressed either in YUVA or RGBA colorspace for the padding area
uint8_t *line[4];
int line_step[4];
@@ -70,18 +107,18 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
PadContext *pad = ctx->priv;
char color_string[128] = "black";
+ av_strlcpy(pad->w_expr, "iw", sizeof(pad->w_expr));
+ av_strlcpy(pad->h_expr, "ih", sizeof(pad->h_expr));
+ av_strlcpy(pad->x_expr, "0" , sizeof(pad->w_expr));
+ av_strlcpy(pad->y_expr, "0" , sizeof(pad->h_expr));
+
if (args)
- sscanf(args, "%d:%d:%d:%d:%s", &pad->w, &pad->h, &pad->x, &pad->y, color_string);
+ sscanf(args, "%255[^:]:%255[^:]:%255[^:]:%255[^:]:%255s",
+ pad->w_expr, pad->h_expr, pad->x_expr, pad->y_expr, color_string);
if (av_parse_color(pad->color, color_string, -1, ctx) < 0)
return AVERROR(EINVAL);
- /* sanity check params */
- if (pad->w < 0 || pad->h < 0) {
- av_log(ctx, AV_LOG_ERROR, "Negative size values are not acceptable.\n");
- return AVERROR(EINVAL);
- }
-
return 0;
}
@@ -102,11 +139,64 @@ static int config_input(AVFilterLink *inlink)
PadContext *pad = ctx->priv;
const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[inlink->format];
uint8_t rgba_color[4];
- int is_packed_rgba;
+ int ret, is_packed_rgba;
+ double var_values[VARS_NB], res;
+ char *expr;
pad->hsub = pix_desc->log2_chroma_w;
pad->vsub = pix_desc->log2_chroma_h;
+ var_values[VAR_PI] = M_PI;
+ var_values[VAR_PHI] = M_PHI;
+ var_values[VAR_E] = M_E;
+ var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
+ var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
+ var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
+ var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
+ var_values[VAR_A] = (float) inlink->w / inlink->h;
+ var_values[VAR_HSUB] = 1<<pad->hsub;
+ var_values[VAR_VSUB] = 2<<pad->vsub;
+
+ /* evaluate width and height */
+ av_expr_parse_and_eval(&res, (expr = pad->w_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx);
+ pad->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
+ if ((ret = av_expr_parse_and_eval(&res, (expr = pad->h_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+ goto eval_fail;
+ pad->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
+ /* evaluate again the width, as it may depend on the output height */
+ if ((ret = av_expr_parse_and_eval(&res, (expr = pad->w_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+ goto eval_fail;
+ pad->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
+
+ /* evaluate x and y */
+ av_expr_parse_and_eval(&res, (expr = pad->x_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx);
+ pad->x = var_values[VAR_X] = res;
+ if ((ret = av_expr_parse_and_eval(&res, (expr = pad->y_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+ goto eval_fail;
+ pad->y = var_values[VAR_Y] = res;
+ /* evaluate again x, as it may depend on the y value */
+ if ((ret = av_expr_parse_and_eval(&res, (expr = pad->x_expr),
+ var_names, var_values,
+ NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
+ goto eval_fail;
+ pad->x = var_values[VAR_X] = res;
+
+ /* sanity check params */
+ if (pad->w < 0 || pad->h < 0 || pad->x < 0 || pad->y < 0) {
+ av_log(ctx, AV_LOG_ERROR, "Negative values are not acceptable.\n");
+ return AVERROR(EINVAL);
+ }
+
if (!pad->w)
pad->w = inlink->w;
if (!pad->h)
@@ -140,6 +230,12 @@ static int config_input(AVFilterLink *inlink)
}
return 0;
+
+eval_fail:
+ av_log(NULL, AV_LOG_ERROR,
+ "Error when evaluating the expression '%s'\n", expr);
+ return ret;
+
}
static int config_output(AVFilterLink *outlink)
--
1.7.2.3
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