@@ -7,6 +7,7 @@ version <next>:

 - Changed metadata print option to accept general urls

 - Alias muxer for Ogg Video (.ogv)

 - VP8 in Ogg muxing

+- curves filter doesn't automatically insert points at x=0 and x=1 anymore

 version 3.1:

@@ -5710,10 +5710,6 @@ strictly increasing over the x-axis, and their @var{x} and @var{y} values must

 be in the @var{[0;1]} interval.  If the computed curves happened to go outside

 the vector spaces, the values will be clipped accordingly.

-If there is no key point defined in @code{x=0}, the filter will automatically

-insert a @var{(0;0)} point. In the same way, if there is no key point defined

-in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.

-

 The filter accepts the following options:

 @table @option

@@ -5765,13 +5761,13 @@ defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.

 @item

 Increase slightly the middle level of blue:

 @example

-curves=blue='0.5/0.58'

+curves=blue='0/0 0.5/0.58 1/1'

 @end example

 @item

 Vintage effect:

 @example

-curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'

+curves=r='0/0.11 .42/.51 1/0.95':g='0/0 0.50/0.48 1/1':b='0/0.22 .49/.44 1/0.8'

 @end example

 Here we obtain the following coordinates for each components:

 @table @var

@@ -5798,7 +5794,7 @@ curves=vintage

 @item

 Use a Photoshop preset and redefine the points of the green component:

 @example

-curves=psfile='MyCurvesPresets/purple.acv':green='0.45/0.53'

+curves=psfile='MyCurvesPresets/purple.acv':green='0/0 0.45/0.53 1/1'

 @end example

 @end itemize

@@ -110,25 +110,25 @@ static const struct {

     const char *master;

 } curves_presets[] = {

     [PRESET_COLOR_NEGATIVE] = {

-        "0/1 0.129/1 0.466/0.498 0.725/0 1/0",

-        "0/1 0.109/1 0.301/0.498 0.517/0 1/0",

-        "0/1 0.098/1 0.235/0.498 0.423/0 1/0",

+        "0.129/1 0.466/0.498 0.725/0",

+        "0.109/1 0.301/0.498 0.517/0",

+        "0.098/1 0.235/0.498 0.423/0",

     },

     [PRESET_CROSS_PROCESS] = {

-        "0.25/0.156 0.501/0.501 0.686/0.745",

-        "0.25/0.188 0.38/0.501 0.745/0.815 1/0.815",

-        "0.231/0.094 0.709/0.874",

+        "0/0 0.25/0.156 0.501/0.501 0.686/0.745 1/1",

+        "0/0 0.25/0.188 0.38/0.501 0.745/0.815 1/0.815",

+        "0/0 0.231/0.094 0.709/0.874 1/1",

     },

-    [PRESET_DARKER]             = { .master = "0.5/0.4" },

-    [PRESET_INCREASE_CONTRAST]  = { .master = "0.149/0.066 0.831/0.905 0.905/0.98" },

-    [PRESET_LIGHTER]            = { .master = "0.4/0.5" },

-    [PRESET_LINEAR_CONTRAST]    = { .master = "0.305/0.286 0.694/0.713" },

-    [PRESET_MEDIUM_CONTRAST]    = { .master = "0.286/0.219 0.639/0.643" },

+    [PRESET_DARKER]             = { .master = "0/0 0.5/0.4 1/1" },

+    [PRESET_INCREASE_CONTRAST]  = { .master = "0/0 0.149/0.066 0.831/0.905 0.905/0.98 1/1" },

+    [PRESET_LIGHTER]            = { .master = "0/0 0.4/0.5 1/1" },

+    [PRESET_LINEAR_CONTRAST]    = { .master = "0/0 0.305/0.286 0.694/0.713 1/1" },

+    [PRESET_MEDIUM_CONTRAST]    = { .master = "0/0 0.286/0.219 0.639/0.643 1/1" },

     [PRESET_NEGATIVE]           = { .master = "0/1 1/0" },

-    [PRESET_STRONG_CONTRAST]    = { .master = "0.301/0.196 0.592/0.6 0.686/0.737" },

+    [PRESET_STRONG_CONTRAST]    = { .master = "0/0 0.301/0.196 0.592/0.6 0.686/0.737 1/1" },

     [PRESET_VINTAGE] = {

         "0/0.11 0.42/0.51 1/0.95",

-        "0.50/0.48",

+        "0/0 0.50/0.48 1/1",

         "0/0.22 0.49/0.44 1/0.8",

     }

 };

@@ -177,28 +177,11 @@ static int parse_points_str(AVFilterContext *ctx, struct keypoint **points, cons

         last = point;

     }

-    /* auto insert first key point if missing at x=0 */

-    if (!*points) {

-        last = make_point(0, 0, NULL);

-        if (!last)

-            return AVERROR(ENOMEM);

-        last->x = last->y = 0;

-        *points = last;

-    } else if ((*points)->x != 0.) {

-        struct keypoint *newfirst = make_point(0, 0, *points);

-        if (!newfirst)

-            return AVERROR(ENOMEM);

-        *points = newfirst;

-    }

-

-    av_assert0(last);

-

-    /* auto insert last key point if missing at x=1 */

-    if (last->x != 1.) {

-        struct keypoint *point = make_point(1, 1, NULL);

-        if (!point)

-            return AVERROR(ENOMEM);

-        last->next = point;

+    if (*points && !(*points)->next) {

+        av_log(ctx, AV_LOG_WARNING, "Only one point (at (%f;%f)) is defined, "

+               "this is unlikely to behave as you expect. You probably want"

+               "at least 2 points.",

+               (*points)->x, (*points)->y);

     }

     return 0;

@@ -222,14 +205,28 @@ static int get_nb_points(const struct keypoint *d)

 static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *points)

 {

     int i, ret = 0;

-    const struct keypoint *point;

+    const struct keypoint *point = points;

     double xprev = 0;

+    double (*matrix)[3];

+    double *h, *r;

     int n = get_nb_points(points); // number of splines

-    double (*matrix)[3] = av_calloc(n, sizeof(*matrix));

-    double *h = av_malloc((n - 1) * sizeof(*h));

-    double *r = av_calloc(n, sizeof(*r));

+    if (n == 0) {

+        for (i = 0; i < 256; i++)

+            y[i] = i;

+        return 0;

+    }

+

+    if (n == 1) {

+        for (i = 0; i < 256; i++)

+            y[i] = av_clip_uint8(point->y * 255);

+        return 0;

+    }

+

+    matrix = av_calloc(n, sizeof(*matrix));

+    h = av_malloc((n - 1) * sizeof(*h));

+    r = av_calloc(n, sizeof(*r));

     if (!matrix || !h || !r) {

         ret = AVERROR(ENOMEM);

@@ -277,9 +274,14 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

     for (i = n - 2; i >= 0; i--)

         r[i] = r[i] - matrix[i][AD] * r[i + 1];

-    /* compute the graph with x=[0..255] */

-    i = 0;

     point = points;

+

+    /* left padding */

+    for (i = 0; i < (int)(point->x * 255); i++)

+        y[i] = av_clip_uint8(point->y * 255);

+

+    /* compute the graph with x=[x0..xN] */

+    i = 0;

     av_assert0(point->next); // always at least 2 key points

     while (point->next) {

         double yc = point->y;

@@ -300,7 +302,7 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

         for (x = x_start; x <= x_end; x++) {

             double xx = (x - x_start) * 1/255.;

             double yy = a + b*xx + c*xx*xx + d*xx*xx*xx;

-            y[x] = av_clipf(yy, 0, 1) * 255;

+            y[x] = av_clip_uint8(yy * 255);

             av_log(ctx, AV_LOG_DEBUG, "f(%f)=%f -> y[%d]=%d\n", xx, yy, x, y[x]);

         }

@@ -308,6 +310,10 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

         i++;

     }

+    /* right padding */

+    for (i = (int)(point->x * 255); i <= 255; i++)

+        y[i] = av_clip_uint8(point->y * 255);

+

 end:

     av_free(matrix);

     av_free(h);