libavfilter/avfilter.c:260: error: Null Dereference
  pointer `ret` last assigned on line 255 could be null and is dereferenced by call to `ff_dprintf_ref()` at line 260, column 109.

libavfilter/avfilter.c:243:1: start of procedure avfilter_get_video_buffer()
241. }
242. 
243. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
244. {
245.     AVFilterBufferRef *ret = NULL;

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

libavfilter/avfilter.c:248:47: 
246. 
247.     av_unused char buf[16];
248.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dprintf_link(NULL, link, 0);
                                                   ^
249.     dprintf(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
250. 

libavfilter/avfilter.c:232:1: start of procedure ff_dprintf_link()
  230. }
  231. 
  232. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  233. {
  234.     dprintf(ctx,

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

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

libavfilter/avfilter.c:252:9: Skipping __function_pointer__(): unresolved function pointer
250. 
251.     if (link->dstpad->get_video_buffer)
252.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
             ^
253. 
254.     if (!ret)

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

libavfilter/avfilter.c:255:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
253. 
254.     if (!ret)
255.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
256. 
257.     if (ret)

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

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

libavfilter/avfilter.c:232:1: start of procedure ff_dprintf_link()
  230. }
  231. 
  232. void ff_dprintf_link(void *ctx, AVFilterLink *link, int end)
       ^
  233. {
  234.     dprintf(ctx,

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

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

libavfilter/avfilter.c:204:1: start of procedure ff_dprintf_ref()
  202. }
  203. 
  204. void ff_dprintf_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  205. {
  206.     av_unused char buf[16];

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