libavfilter/avfilter.c:261: error: Null Dereference
  pointer `ret` last assigned on line 256 could be null and is dereferenced by call to `ff_dprintf_ref()` at line 261, column 109.

libavfilter/avfilter.c:244:1: start of procedure avfilter_get_video_buffer()
242. }
243. 
244. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
245. {
246.     AVFilterBufferRef *ret = NULL;

libavfilter/avfilter.c:246:5: 
244. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
245. {
246.     AVFilterBufferRef *ret = NULL;
         ^
247. 
248.     av_unused char buf[16];

libavfilter/avfilter.c:249:47: 
247. 
248.     av_unused char buf[16];
249.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0);
                                                   ^
250.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
251. 

libavfilter/avfilter.c:233:1: start of procedure ff_dprintf_link()
  231. }
  232. 
  233. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  234. {
  235.     dprintf(ctx,

libavfilter/avfilter.c:242:1: return from a call to ff_dprintf_link
  240.             link->dst ? link->dst->filter->name : "",
  241.             end ? "\n" : "");
  242. }
       ^
  243. 
  244. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)

libavfilter/avfilter.c:252:9: Taking true branch
250.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
251. 
252.     if (link_dpad(link).get_video_buffer)
             ^
253.         ret = link_dpad(link).get_video_buffer(link, perms, w, h);
254. 

libavfilter/avfilter.c:253:9: Skipping __function_pointer__(): unresolved function pointer
251. 
252.     if (link_dpad(link).get_video_buffer)
253.         ret = link_dpad(link).get_video_buffer(link, perms, w, h);
             ^
254. 
255.     if (!ret)

libavfilter/avfilter.c:255:10: Taking true branch
253.         ret = link_dpad(link).get_video_buffer(link, perms, w, h);
254. 
255.     if (!ret)
              ^
256.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
257. 

libavfilter/avfilter.c:256:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
254. 
255.     if (!ret)
256.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
257. 
258.     if (ret)

libavfilter/avfilter.c:258:9: Taking false branch
256.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
257. 
258.     if (ret)
             ^
259.         ret->type = AVMEDIA_TYPE_VIDEO;
260. 

libavfilter/avfilter.c:261:47: 
259.         ret->type = AVMEDIA_TYPE_VIDEO;
260. 
261.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0); dprintf(NULL, " returning "); ff_dprintf_ref(NULL, ret, 1);
                                                   ^
262. 
263.     return ret;

libavfilter/avfilter.c:233:1: start of procedure ff_dprintf_link()
  231. }
  232. 
  233. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  234. {
  235.     dprintf(ctx,

libavfilter/avfilter.c:242:1: return from a call to ff_dprintf_link
  240.             link->dst ? link->dst->filter->name : "",
  241.             end ? "\n" : "");
  242. }
       ^
  243. 
  244. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)

libavfilter/avfilter.c:261:109: 
259.         ret->type = AVMEDIA_TYPE_VIDEO;
260. 
261.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0); dprintf(NULL, " returning "); ff_dprintf_ref(NULL, ret, 1);
                                                                                                                 ^
262. 
263.     return ret;

libavfilter/avfilter.c:205:1: start of procedure ff_dprintf_ref()
  203. }
  204. 
  205. void ff_dprintf_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  206. {
  207.     av_unused char buf[16];

libavfilter/avfilter.c:214:9: Taking false branch
  212.             ref->pts, ref->pos);
  213. 
  214.     if (ref->video) {
               ^
  215.         dprintf(ctx, " a:%d/%d s:%dx%d i:%c",
  216.                 ref->video->pixel_aspect.num, ref->video->pixel_aspect.den,
