@@ -27,6 +27,7 @@

 #include "avfilter.h"

 #include "libavutil/pixdesc.h"

 #include "libavutil/colorspace.h"

+#include "libavutil/avassert.h"

 #include "libavcore/imgutils.h"

 #include "libavcore/parseutils.h"

@@ -100,6 +101,24 @@ static void draw_rectangle(AVFilterBufferRef *outpic, uint8_t *line[4], int line

     }

 }

+static void copy_rectangle(AVFilterBufferRef *outpic,uint8_t *line[4], int line_step[4], int linesize[4],

+                           int hsub, int vsub, int x, int y, int y2, int w, int h)

+{

+    int i, plane;

+    uint8_t *p;

+

+    for (plane = 0; plane < 4 && outpic->data[plane]; plane++) {

+        int hsub1 = plane == 1 || plane == 2 ? hsub : 0;

+        int vsub1 = plane == 1 || plane == 2 ? vsub : 0;

+

+        p = outpic->data[plane] + (y >> vsub1) * outpic->linesize[plane];

+        for (i = 0; i < (h >> vsub1); i++) {

+            memcpy(p + (x >> hsub1) * line_step[plane], line[plane] + linesize[plane]*(i+(y2>>vsub1)), (w >> hsub1) * line_step[plane]);

+            p += outpic->linesize[plane];

+        }

+    }

+}

+

 static int query_formats(AVFilterContext *ctx)

 {

     static const enum PixelFormat pix_fmts[] = {

@@ -132,6 +151,7 @@ typedef struct {

     uint8_t *line[4];

     int      line_step[4];

     int hsub, vsub;         ///< chroma subsampling values

+    int needs_copy;

 } PadContext;

 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)

@@ -243,21 +263,65 @@ static AVFilterBufferRef *get_video_buffer(AVFilterLink *inlink, int perms, int

     return picref;

 }

+static int does_clip(PadContext *pad, AVFilterBufferRef *outpicref, int plane, int hsub, int vsub, int x, int y)

+{

+    int64_t x_in_buf, y_in_buf;

+

+    x_in_buf =  outpicref->data[plane] - outpicref->buf->data[plane]

+             +  (x >> hsub) * pad      ->line_step[plane]

+             +  (y >> vsub) * outpicref->linesize [plane];

+

+    if(x_in_buf < 0 || x_in_buf % pad->line_step[plane])

+        return 1;

+    x_in_buf /= pad->line_step[plane];

+

+    av_assert0(outpicref->buf->linesize[plane]>0); //while reference can use negative linesize the main buffer should not

+

+    y_in_buf = x_in_buf / outpicref->buf->linesize[plane];

+    x_in_buf %= outpicref->buf->linesize[plane];

+

+    if(   y_in_buf<<vsub >= outpicref->buf->h

+       || x_in_buf<<hsub >= outpicref->buf->w)

+        return 1;

+    return 0;

+}

+

 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)

 {

     PadContext *pad = inlink->dst->priv;

     AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);

     int plane;

-    inlink->dst->outputs[0]->out_buf = outpicref;

-

     for (plane = 0; plane < 4 && outpicref->data[plane]; plane++) {

         int hsub = (plane == 1 || plane == 2) ? pad->hsub : 0;

         int vsub = (plane == 1 || plane == 2) ? pad->vsub : 0;

-        outpicref->data[plane] -= (pad->x >> hsub) * pad->line_step[plane] +

-            (pad->y >> vsub) * outpicref->linesize[plane];

+        av_assert0(outpicref->buf->w>0 && outpicref->buf->h>0);

+

+        if(outpicref->format != outpicref->buf->format) //unsupported currently

+            break;

+

+        outpicref->data[plane] -=   (pad->x  >> hsub) * pad      ->line_step[plane]

+                                  + (pad->y  >> vsub) * outpicref->linesize [plane];

+

+        if(   does_clip(pad, outpicref, plane, hsub, vsub, 0, 0)

+           || does_clip(pad, outpicref, plane, hsub, vsub, 0, pad->h-1)

+           || does_clip(pad, outpicref, plane, hsub, vsub, pad->w-1, 0)

+           || does_clip(pad, outpicref, plane, hsub, vsub, pad->w-1, pad->h-1)

+          )

+            break;

     }

+    pad->needs_copy= plane < 4 && outpicref->data[plane];

+    if(pad->needs_copy){

+        av_log(inlink->dst, AV_LOG_DEBUG, "Direct padding impossible allocating new frame\n");

+        avfilter_unref_buffer(outpicref);

+        outpicref = avfilter_get_video_buffer(inlink->dst->outputs[0], AV_PERM_WRITE | AV_PERM_NEG_LINESIZES,

+                                                       FFMAX(inlink->w, pad->w),

+                                                       FFMAX(inlink->h, pad->h));

+        avfilter_copy_buffer_ref_props(outpicref, inpicref);

+    }

+

+    inlink->dst->outputs[0]->out_buf = outpicref;

     outpicref->video->w = pad->w;

     outpicref->video->h = pad->h;

@@ -298,6 +362,7 @@ static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)

 {

     PadContext *pad = link->dst->priv;

     AVFilterBufferRef *outpic = link->dst->outputs[0]->out_buf;

+    AVFilterBufferRef *inpic = link->cur_buf;

     y += pad->y;

@@ -311,6 +376,13 @@ static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)

     /* left border */

     draw_rectangle(outpic, pad->line, pad->line_step, pad->hsub, pad->vsub,

                    0, y, pad->x, h);

+

+    if(pad->needs_copy){

+        copy_rectangle(outpic,

+                       inpic->data, pad->line_step, inpic->linesize, pad->hsub, pad->vsub,

+                       pad->x, y, y-pad->y, inpic->video->w, h);

+    }

+

     /* right border */

     draw_rectangle(outpic, pad->line, pad->line_step, pad->hsub, pad->vsub,

                    pad->x + pad->in_w, y, pad->w - pad->x - pad->in_w, h);