@@ -1616,6 +1616,9 @@ static int input_get_buffer(AVCodecContext *codec, AVFrame *pic)

     int i, w, h, stride[4];

     unsigned edge;

+    if (codec->codec->capabilities & CODEC_CAP_NEG_LINESIZES)

+        perms |= AV_PERM_NEG_LINESIZES;

+

     if(pic->buffer_hints & FF_BUFFER_HINTS_VALID) {

         if(pic->buffer_hints & FF_BUFFER_HINTS_READABLE) perms |= AV_PERM_READ;

         if(pic->buffer_hints & FF_BUFFER_HINTS_PRESERVE) perms |= AV_PERM_PRESERVE;

@@ -197,12 +197,13 @@ int avfilter_config_links(AVFilterContext *filter)

 char *ff_get_ref_perms_string(char *buf, size_t buf_size, int perms)

 {

-    snprintf(buf, buf_size, "%s%s%s%s%s",

+    snprintf(buf, buf_size, "%s%s%s%s%s%s",

              perms & AV_PERM_READ      ? "r" : "",

              perms & AV_PERM_WRITE     ? "w" : "",

              perms & AV_PERM_PRESERVE  ? "p" : "",

              perms & AV_PERM_REUSE     ? "u" : "",

-             perms & AV_PERM_REUSE2    ? "U" : "");

+             perms & AV_PERM_REUSE2    ? "U" : "",

+             perms & AV_PERM_NEG_LINESIZES ? "n" : "");

     return buf;

 }

@@ -360,15 +361,17 @@ void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)

 {

     void (*start_frame)(AVFilterLink *, AVFilterBufferRef *);

     AVFilterPad *dst = link->dstpad;

+    int perms = picref->perms;

     FF_DPRINTF_START(NULL, start_frame); ff_dprintf_link(NULL, link, 0); dprintf(NULL, " "); ff_dprintf_ref(NULL, picref, 1);

     if (!(start_frame = dst->start_frame))

         start_frame = avfilter_default_start_frame;

+    if (picref->linesize[0] < 0)

+        perms |= AV_PERM_NEG_LINESIZES;

     /* prepare to copy the picture if it has insufficient permissions */

-    if ((dst->min_perms & picref->perms) != dst->min_perms ||

-         dst->rej_perms & picref->perms) {

+    if ((dst->min_perms & perms) != dst->min_perms || dst->rej_perms & perms) {

         av_log(link->dst, AV_LOG_DEBUG,

                 "frame copy needed (have perms %x, need %x, reject %x)\n",

                 picref->perms,

@@ -87,6 +87,7 @@ typedef struct AVFilterBuffer {

 #define AV_PERM_PRESERVE 0x04   ///< nobody else can overwrite the buffer

 #define AV_PERM_REUSE    0x08   ///< can output the buffer multiple times, with the same contents each time

 #define AV_PERM_REUSE2   0x10   ///< can output the buffer multiple times, modified each time

+#define AV_PERM_NEG_LINESIZES 0x20  ///< the buffer requested can have negative linesizes

 /**

  * Audio specific properties in a reference to an AVFilterBuffer. Since

@@ -43,11 +43,13 @@ static AVFilterBufferRef *get_video_buffer(AVFilterLink *link, int perms,

                                         int w, int h)

 {

     FlipContext *flip = link->dst->priv;

+    AVFilterBufferRef *picref;

     int i;

-    AVFilterBufferRef *picref = avfilter_get_video_buffer(link->dst->outputs[0],

-                                                       perms, w, h);

+    if (!(perms & AV_PERM_NEG_LINESIZES))

+        return avfilter_default_get_video_buffer(link, perms, w, h);

+    picref = avfilter_get_video_buffer(link->dst->outputs[0], perms, w, h);

     for (i = 0; i < 4; i ++) {

         int vsub = i == 1 || i == 2 ? flip->vsub : 0;