libavfilter/avfilter.c:265: error: Null Dereference
  pointer `ret` last assigned on line 260 could be null and is dereferenced by call to `ff_dprintf_ref()` at line 265, column 109.

libavfilter/avfilter.c:248:1: start of procedure avfilter_get_video_buffer()
246. }
247. 
248. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
249. {
250.     AVFilterBufferRef *ret = NULL;

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

libavfilter/avfilter.c:253:47: 
251. 
252.     av_unused char buf[16];
253.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0);
                                                   ^
254.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
255. 

libavfilter/avfilter.c:237:1: start of procedure ff_dprintf_link()
  235. }
  236. 
  237. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  238. {
  239.     dprintf(ctx,

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

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

libavfilter/avfilter.c:257:9: Skipping __function_pointer__(): unresolved function pointer
255. 
256.     if (link->dstpad->get_video_buffer)
257.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
             ^
258. 
259.     if (!ret)

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

libavfilter/avfilter.c:260:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
258. 
259.     if (!ret)
260.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
261. 
262.     if (ret)

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

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

libavfilter/avfilter.c:237:1: start of procedure ff_dprintf_link()
  235. }
  236. 
  237. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  238. {
  239.     dprintf(ctx,

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

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

libavfilter/avfilter.c:209:1: start of procedure ff_dprintf_ref()
  207. }
  208. 
  209. void ff_dprintf_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  210. {
  211.     av_unused char buf[16];

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