libavfilter/avfilter.c:266: error: Null Dereference
  pointer `ret` last assigned on line 261 could be null and is dereferenced by call to `ff_dprintf_ref()` at line 266, column 109.

libavfilter/avfilter.c:249:1: start of procedure avfilter_get_video_buffer()
247. }
248. 
249. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
250. {
251.     AVFilterBufferRef *ret = NULL;

libavfilter/avfilter.c:251:5: 
249. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
250. {
251.     AVFilterBufferRef *ret = NULL;
         ^
252. 
253.     av_unused char buf[16];

libavfilter/avfilter.c:254:47: 
252. 
253.     av_unused char buf[16];
254.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0);
                                                   ^
255.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
256. 

libavfilter/avfilter.c:238:1: start of procedure ff_dprintf_link()
  236. }
  237. 
  238. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  239. {
  240.     dprintf(ctx,

libavfilter/avfilter.c:247:1: return from a call to ff_dprintf_link
  245.             link->dst ? link->dst->filter->name : "",
  246.             end ? "\n" : "");
  247. }
       ^
  248. 
  249. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)

libavfilter/avfilter.c:257:9: Taking true branch
255.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
256. 
257.     if (link->dstpad->get_video_buffer)
             ^
258.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
259. 

libavfilter/avfilter.c:258:9: Skipping __function_pointer__(): unresolved function pointer
256. 
257.     if (link->dstpad->get_video_buffer)
258.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
             ^
259. 
260.     if (!ret)

libavfilter/avfilter.c:260:10: Taking true branch
258.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
259. 
260.     if (!ret)
              ^
261.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
262. 

libavfilter/avfilter.c:261:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
259. 
260.     if (!ret)
261.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
262. 
263.     if (ret)

libavfilter/avfilter.c:263:9: Taking false branch
261.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
262. 
263.     if (ret)
             ^
264.         ret->type = AVMEDIA_TYPE_VIDEO;
265. 

libavfilter/avfilter.c:266:47: 
264.         ret->type = AVMEDIA_TYPE_VIDEO;
265. 
266.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0); dprintf(NULL, " returning "); ff_dprintf_ref(NULL, ret, 1);
                                                   ^
267. 
268.     return ret;

libavfilter/avfilter.c:238:1: start of procedure ff_dprintf_link()
  236. }
  237. 
  238. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  239. {
  240.     dprintf(ctx,

libavfilter/avfilter.c:247:1: return from a call to ff_dprintf_link
  245.             link->dst ? link->dst->filter->name : "",
  246.             end ? "\n" : "");
  247. }
       ^
  248. 
  249. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)

libavfilter/avfilter.c:266:109: 
264.         ret->type = AVMEDIA_TYPE_VIDEO;
265. 
266.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0); dprintf(NULL, " returning "); ff_dprintf_ref(NULL, ret, 1);
                                                                                                                 ^
267. 
268.     return ret;

libavfilter/avfilter.c:210:1: start of procedure ff_dprintf_ref()
  208. }
  209. 
  210. void ff_dprintf_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  211. {
  212.     av_unused char buf[16];

libavfilter/avfilter.c:219:9: Taking false branch
  217.             ref->pts, ref->pos);
  218. 
  219.     if (ref->video) {
               ^
  220.         dprintf(ctx, " a:%d/%d s:%dx%d i:%c",
  221.                 ref->video->pixel_aspect.num, ref->video->pixel_aspect.den,
