@@ -45,6 +45,7 @@ version 10:

 - raw HEVC, HEVC in MOV/MP4, HEVC in Matroska, HEVC in MPEG-TS demuxing

 - remove avplay -vismv option, which has not worked for a long time

 - Live HDS muxer

+- setsar/setdar filters now support variables in ratio expressions

 version 9:

@@ -2049,10 +2049,35 @@ This filter accepts the following options:

 @table @option

 @item dar

-Output display aspect ratio, as a rational or a decimal number.

+Output display aspect ratio.

 @end table

+The parameter @var{dar} is an expression containing

+the following constants:

+

+@table @option

+@item E, PI, PHI

+the corresponding mathematical approximated values for e

+(euler number), pi (greek PI), phi (golden ratio)

+

+@item w, h

+the input width and height

+

+@item a

+same as @var{w} / @var{h}

+

+@item sar

+input sample aspect ratio

+

+@item dar

+input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}

+

+@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

+

 For example to change the display aspect ratio to 16:9, specify:

 @example

 setdar=dar=16/9

@@ -2158,10 +2183,35 @@ This filter accepts the following options:

 @table @option

 @item sar

-Output sample aspect ratio, as a rational or decimal number.

+Output sample aspect ratio.

 @end table

+The parameter @var{sar} is an expression containing

+the following constants:

+

+@table @option

+@item E, PI, PHI

+the corresponding mathematical approximated values for e

+(euler number), pi (greek PI), phi (golden ratio)

+

+@item w, h

+the input width and height

+

+@item a

+same as @var{w} / @var{h}

+

+@item sar

+input sample aspect ratio

+

+@item dar

+input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}

+

+@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

+

 For example to change the sample aspect ratio to 10:11, specify:

 @example

 setsar=sar=10/11

@@ -26,13 +26,42 @@

 #include <float.h>

 #include "libavutil/common.h"

+#include "libavutil/eval.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/opt.h"

+#include "libavutil/parseutils.h"

+#include "libavutil/pixdesc.h"

 #include "avfilter.h"

 #include "internal.h"

 #include "video.h"

+static const char *const var_names[] = {

+    "PI",

+    "PHI",

+    "E",

+    "w",

+    "h",

+    "a", "dar",

+    "sar",

+    "hsub",

+    "vsub",

+    NULL

+};

+

+enum var_name {

+    VAR_PI,

+    VAR_PHI,

+    VAR_E,

+    VAR_W,

+    VAR_H,

+    VAR_A, VAR_DAR,

+    VAR_SAR,

+    VAR_HSUB,

+    VAR_VSUB,

+    VARS_NB

+};

+

 typedef struct {

     const AVClass *class;

     AVRational dar;

@@ -40,6 +69,7 @@ typedef struct {

 #if FF_API_OLD_FILTER_OPTS

     float aspect_num, aspect_den;

 #endif

+    char *ratio_expr;

 } AspectContext;

 #if FF_API_OLD_FILTER_OPTS

@@ -68,12 +98,54 @@ static int filter_frame(AVFilterLink *link, AVFrame *frame)

 #define OFFSET(x) offsetof(AspectContext, x)

 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM

+static int get_aspect_ratio(AVFilterLink *inlink, AVRational *aspect_ratio)

+{

+    AVFilterContext *ctx = inlink->dst;

+    AspectContext *s = inlink->dst->priv;

+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

+    double var_values[VARS_NB], res;

+    int ret;

+

+    var_values[VAR_PI]    = M_PI;

+    var_values[VAR_PHI]   = M_PHI;

+    var_values[VAR_E]     = M_E;

+    var_values[VAR_W]     = inlink->w;

+    var_values[VAR_H]     = inlink->h;

+    var_values[VAR_A]     = (double) inlink->w / inlink->h;

+    var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?

+        (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;

+    var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];

+    var_values[VAR_HSUB]  = 1 << desc->log2_chroma_w;

+    var_values[VAR_VSUB]  = 1 << desc->log2_chroma_h;

+

+    /* evaluate new aspect ratio*/

+    if ((ret = av_expr_parse_and_eval(&res, s->ratio_expr,

+                                      var_names, var_values,

+                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {

+        av_log(NULL, AV_LOG_ERROR,

+               "Error when evaluating the expression '%s'\n", s->ratio_expr);

+        return ret;

+    }

+    *aspect_ratio = av_d2q(res, INT_MAX);

+    return 0;

+}

+

 #if CONFIG_SETDAR_FILTER

 /* for setdar filter, convert from frame aspect ratio to pixel aspect ratio */

 static int setdar_config_props(AVFilterLink *inlink)

 {

     AspectContext *s = inlink->dst->priv;

     AVRational dar;

+    int ret;

+

+#if FF_API_OLD_FILTER_OPTS

+    if (!(s->aspect_num > 0 && s->aspect_den > 0)) {

+#endif

+    if ((ret = get_aspect_ratio(inlink, &s->dar)))

+        return ret;

+#if FF_API_OLD_FILTER_OPTS

+    }

+#endif

     if (s->dar.num && s->dar.den) {

         av_reduce(&s->sar.num, &s->sar.den,

@@ -98,7 +170,7 @@ static const AVOption setdar_options[] = {

     { "dar_num", NULL, OFFSET(aspect_num), AV_OPT_TYPE_FLOAT, { .dbl = 0 }, 0, FLT_MAX, FLAGS },

     { "dar_den", NULL, OFFSET(aspect_den), AV_OPT_TYPE_FLOAT, { .dbl = 0 }, 0, FLT_MAX, FLAGS },

 #endif

-    { "dar", "display aspect ratio", OFFSET(dar), AV_OPT_TYPE_RATIONAL, { .dbl = 0 }, 0, INT_MAX, FLAGS },

+    { "dar", "display aspect ratio", OFFSET(ratio_expr), AV_OPT_TYPE_STRING, { .str = "1" }, .flags = FLAGS },

     { NULL },

 };

@@ -150,6 +222,16 @@ AVFilter ff_vf_setdar = {

 static int setsar_config_props(AVFilterLink *inlink)

 {

     AspectContext *s = inlink->dst->priv;

+    int ret;

+

+#if FF_API_OLD_FILTER_OPTS

+    if (!(s->aspect_num > 0 && s->aspect_den > 0)) {

+#endif

+    if ((ret = get_aspect_ratio(inlink, &s->sar)))

+        return ret;

+#if FF_API_OLD_FILTER_OPTS

+    }

+#endif

     inlink->sample_aspect_ratio = s->sar;

@@ -161,7 +243,7 @@ static const AVOption setsar_options[] = {

     { "sar_num", NULL, OFFSET(aspect_num), AV_OPT_TYPE_FLOAT, { .dbl = 0 }, 0, FLT_MAX, FLAGS },

     { "sar_den", NULL, OFFSET(aspect_den), AV_OPT_TYPE_FLOAT, { .dbl = 0 }, 0, FLT_MAX, FLAGS },

 #endif

-    { "sar", "sample (pixel) aspect ratio", OFFSET(sar), AV_OPT_TYPE_RATIONAL, { .dbl = 1 }, 0, INT_MAX, FLAGS },

+    { "sar", "sample (pixel) aspect ratio", OFFSET(ratio_expr), AV_OPT_TYPE_STRING, { .str = "1" }, .flags = FLAGS },

     { NULL },

 };