Chiebot-Mirror
/
FFmpeg
8
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

scale: make the filter parametric

Browse Source 
Make the filter accept parametric expressions for the output video
size.

Signed-off-by: Stefano Sabatini <stefano.sabatini-lala@poste.it>
oldabi
Stefano Sabatini 14 years ago
parent 25601bc564
commit d496d33d26
3 changed files with 140 additions and 15 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 60
      doc/filters.texi
  2. 2
      libavfilter/avfilter.h
  3. 93
      libavfilter/vf_scale.c

60
doc/filters.texi
Unescape View File

@ -1004,13 +1004,33 @@ can be used to test the monowhite pixel format descriptor definition.
Scale the input video to @var{width}:@var{height} and/or convert the image format.
For example the command:
The parameters @var{width} and @var{height} are expressions containing
the following constants:
@example
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
@end example
@table @option
@item E, PI, PHI
the corresponding mathematical approximated values for e
(euler number), pi (greek PI), phi (golden ratio)
@item in_w, in_h
the input width and heigth
@item iw, ih
same as @var{in_w} and @var{in_h}
will scale the input video to a size of 200x100.
@item out_w, out_h
the output (cropped) width and heigth
@item ow, oh
same as @var{out_w} and @var{out_h}
@item a
input display aspect ratio, same as @var{iw} / @var{ih}
@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.
@end table
If the input image format is different from the format requested by
the next filter, the scale filter will convert the input to the
@ -1025,6 +1045,36 @@ ratio of the input image.
The default value of @var{width} and @var{height} is 0.
Some examples follow:
@example
# scale the input video to a size of 200x100.
scale=200:100
# scale the input to 2x
scale=2*iw:2*ih
# the above is the same as
scale=2*in_w:2*in_h
# scale the input to half size
scale=iw/2:ih/2
# increase the width, and set the height to the same size
scale=3/2*iw:ow
# seek for Greek harmony
scale=iw:1/PHI*iw
scale=ih*PHI:ih
# increase the height, and set the width to 3/2 of the height
scale=3/2*oh:3/5*ih
# increase the size, but make the size a multiple of the chroma
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
scale='min(500\, iw*3/2):-1'
@end example
@anchor{setdar}
@section setdar

2
libavfilter/avfilter.h
Unescape View File

@ -27,7 +27,7 @@
#define LIBAVFILTER_VERSION_MAJOR 1
#define LIBAVFILTER_VERSION_MINOR 77
#define LIBAVFILTER_VERSION_MICRO 0
#define LIBAVFILTER_VERSION_MICRO 1
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
LIBAVFILTER_VERSION_MINOR, \

93
libavfilter/vf_scale.c
Unescape View File

@ -24,10 +24,40 @@
*/
#include "avfilter.h"
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/pixdesc.h"
#include "libavutil/avassert.h"
#include "libswscale/swscale.h"
static const char *var_names[] = {
"PI",
"PHI",
"E",
"in_w", "iw",
"in_h", "ih",
"out_w", "ow",
"out_h", "oh",
"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_A,
VAR_HSUB,
VAR_VSUB,
VARS_NB
};
typedef struct {
struct SwsContext *sws; ///< software scaler context
struct SwsContext *isws[2]; ///< software scaler context for interlaced material
@ -44,6 +74,9 @@ typedef struct {
int slice_y; ///< top of current output slice
int input_is_pal; ///< set to 1 if the input format is paletted
int interlaced;
char w_expr[256]; ///< width expression string
char h_expr[256]; ///< height expression string
} ScaleContext;
static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
@ -51,9 +84,12 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
ScaleContext *scale = ctx->priv;
const char *p;
av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr));
av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr));
scale->flags = SWS_BILINEAR;
if (args) {
sscanf(args, "%d:%d", &scale->w, &scale->h);
sscanf(args, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr);
p = strstr(args,"flags=");
if (p) scale->flags = strtoul(p+6, NULL, 0);
if(strstr(args,"interl=1")){
@ -62,14 +98,6 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
scale->interlaced=-1;
}
/* sanity check params */
if (scale->w < -1 || scale->h < -1) {
av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
return AVERROR(EINVAL);
}
if (scale->w == -1 && scale->h == -1)
scale->w = scale->h = 0;
return 0;
}
@ -118,6 +146,48 @@ static int config_props(AVFilterLink *outlink)
AVFilterLink *inlink = outlink->src->inputs[0];
ScaleContext *scale = ctx->priv;
int64_t w, h;
double var_values[VARS_NB], res;
char *expr;
int ret;
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] = 2<<av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
var_values[VAR_VSUB] = 2<<av_pix_fmt_descriptors[inlink->format].log2_chroma_h;
/* evaluate width and height */
av_expr_parse_and_eval(&res, (expr = scale->w_expr),
var_names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, ctx);
scale->w = var_values[VAR_OW] = res;
if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr),
var_names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
goto fail;
scale->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 = scale->w_expr),
var_names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
goto fail;
scale->w = res;
w = scale->w;
h = scale->h;
/* sanity check params */
if (w < -1 || h < -1) {
av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
return AVERROR(EINVAL);
}
if (w == -1 && h == -1)
scale->w = scale->h = 0;
if (!(w = scale->w))
w = inlink->w;
@ -159,6 +229,11 @@ static int config_props(AVFilterLink *outlink)
return AVERROR(EINVAL);
return 0;
fail:
av_log(NULL, AV_LOG_ERROR,
"Error when evaluating the expression '%s'\n", expr);
return ret;
}
static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)

Write Preview
Loading…
Cancel
Save