libavfilter/avfilter.c:303: error: Null Dereference
  pointer `ret` last assigned on line 298 could be null and is dereferenced by call to `ff_dlog_ref()` at line 303, column 106.

libavfilter/avfilter.c:286:1: start of procedure avfilter_get_video_buffer()
284. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)
285. 
286. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
287. {
288.     AVFilterBufferRef *ret = NULL;

libavfilter/avfilter.c:288:5: 
286. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
287. {
288.     AVFilterBufferRef *ret = NULL;
         ^
289. 
290.     av_unused char buf[16];

libavfilter/avfilter.c:291:47: 
289. 
290.     av_unused char buf[16];
291.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0);
                                                   ^
292.     av_dlog(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
293. 

libavfilter/avfilter.c:260:1: start of procedure ff_dlog_link()
  258. }
  259. 
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
       ^
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {

libavfilter/avfilter.c:262:9: Taking false branch
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {
               ^
  263.         av_dlog(ctx,
  264.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:272:9: Skipping av_get_channel_layout_string(): empty list of specs
  270.     } else {
  271.         char buf[128];
  272.         av_get_channel_layout_string(buf, sizeof(buf), -1, link->channel_layout);
               ^
  273. 
  274.         av_dlog(ctx,

libavfilter/avfilter.c:262:5: 
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {
           ^
  263.         av_dlog(ctx,
  264.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:282:1: return from a call to ff_dlog_link
  280.                 end ? "\n" : "");
  281.     }
  282. }
       ^
  283. 
  284. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)

libavfilter/avfilter.c:294:9: Taking true branch
292.     av_dlog(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
293. 
294.     if (link->dstpad->get_video_buffer)
             ^
295.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
296. 

libavfilter/avfilter.c:295:9: Skipping __function_pointer__(): unresolved function pointer
293. 
294.     if (link->dstpad->get_video_buffer)
295.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
             ^
296. 
297.     if (!ret)

libavfilter/avfilter.c:297:10: Taking true branch
295.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
296. 
297.     if (!ret)
              ^
298.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
299. 

libavfilter/avfilter.c:298:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
296. 
297.     if (!ret)
298.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
299. 
300.     if (ret)

libavfilter/avfilter.c:300:9: Taking false branch
298.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
299. 
300.     if (ret)
             ^
301.         ret->type = AVMEDIA_TYPE_VIDEO;
302. 

libavfilter/avfilter.c:303:47: 
301.         ret->type = AVMEDIA_TYPE_VIDEO;
302. 
303.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);
                                                   ^
304. 
305.     return ret;

libavfilter/avfilter.c:260:1: start of procedure ff_dlog_link()
  258. }
  259. 
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
       ^
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {

libavfilter/avfilter.c:262:9: Taking false branch
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {
               ^
  263.         av_dlog(ctx,
  264.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:272:9: Skipping av_get_channel_layout_string(): empty list of specs
  270.     } else {
  271.         char buf[128];
  272.         av_get_channel_layout_string(buf, sizeof(buf), -1, link->channel_layout);
               ^
  273. 
  274.         av_dlog(ctx,

libavfilter/avfilter.c:262:5: 
  260. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  261. {
  262.     if (link->type == AVMEDIA_TYPE_VIDEO) {
           ^
  263.         av_dlog(ctx,
  264.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:282:1: return from a call to ff_dlog_link
  280.                 end ? "\n" : "");
  281.     }
  282. }
       ^
  283. 
  284. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)

libavfilter/avfilter.c:303:106: 
301.         ret->type = AVMEDIA_TYPE_VIDEO;
302. 
303.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);
                                                                                                              ^
304. 
305.     return ret;

libavfilter/avfilter.c:230:1: start of procedure ff_dlog_ref()
  228. }
  229. 
  230. static void ff_dlog_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  231. {
  232.     av_unused char buf[16];

libavfilter/avfilter.c:239:9: Taking false branch
  237.             ref->pts, ref->pos);
  238. 
  239.     if (ref->video) {
               ^
  240.         av_dlog(ctx, " a:%d/%d s:%dx%d i:%c iskey:%d type:%c",
  241.                 ref->video->pixel_aspect.num, ref->video->pixel_aspect.den,

AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
{
    AVFilterBufferRef *ret = NULL;
    av_unused char buf[16];
    FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0);
    av_dlog(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
    if (link->dstpad->get_video_buffer)
        ret = link->dstpad->get_video_buffer(link, perms, w, h);
    if (!ret)
        ret = avfilter_default_get_video_buffer(link, perms, w, h);
    if (ret)
        ret->type = AVMEDIA_TYPE_VIDEO;
    FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);
    return ret;
}
['AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)\n{\n    AVFilterBufferRef *ret = NULL;\n    av_unused char buf[16];\n    FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0);\n    av_dlog(NULL, " perms:%s w:%d h:%d\\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);\n    if (link->dstpad->get_video_buffer)\n        ret = link->dstpad->get_video_buffer(link, perms, w, h);\n    if (!ret)\n        ret = avfilter_default_get_video_buffer(link, perms, w, h);\n    if (ret)\n        ret->type = AVMEDIA_TYPE_VIDEO;\n    FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);\n    return ret;\n}', 'static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)\n{\n    if (link->type == AVMEDIA_TYPE_VIDEO) {\n        av_dlog(ctx,\n                "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",\n                link, link->w, link->h,\n                av_pix_fmt_descriptors[link->format].name,\n                link->src ? link->src->filter->name : "",\n                link->dst ? link->dst->filter->name : "",\n                end ? "\\n" : "");\n    } else {\n        char buf[128];\n        av_get_channel_layout_string(buf, sizeof(buf), -1, link->channel_layout);\n        av_dlog(ctx,\n                "link[%p r:%"PRId64" cl:%s fmt:%-16s %-16s->%-16s]%s",\n                link, link->sample_rate, buf,\n                av_get_sample_fmt_name(link->format),\n                link->src ? link->src->filter->name : "",\n                link->dst ? link->dst->filter->name : "",\n                end ? "\\n" : "");\n    }\n}', 'static void ff_dlog_ref(void *ctx, AVFilterBufferRef *ref, int end)\n{\n    av_unused char buf[16];\n    av_dlog(ctx,\n            "ref[%p buf:%p refcount:%d perms:%s data:%p linesize[%d, %d, %d, %d] pts:%"PRId64" pos:%"PRId64,\n            ref, ref->buf, ref->buf->refcount, ff_get_ref_perms_string(buf, sizeof(buf), ref->perms), ref->data[0],\n            ref->linesize[0], ref->linesize[1], ref->linesize[2], ref->linesize[3],\n            ref->pts, ref->pos);\n    if (ref->video) {\n        av_dlog(ctx, " a:%d/%d s:%dx%d i:%c iskey:%d type:%c",\n                ref->video->pixel_aspect.num, ref->video->pixel_aspect.den,\n                ref->video->w, ref->video->h,\n                !ref->video->interlaced     ? \'P\' :\n                ref->video->top_field_first ? \'T\' : \'B\',\n                ref->video->key_frame,\n                av_get_picture_type_char(ref->video->pict_type));\n    }\n    if (ref->audio) {\n        av_dlog(ctx, " cl:%"PRId64"d sn:%d s:%d sr:%d p:%d",\n                ref->audio->channel_layout,\n                ref->audio->nb_samples,\n                ref->audio->size,\n                ref->audio->sample_rate,\n                ref->audio->planar);\n    }\n    av_dlog(ctx, "]%s", end ? "\\n" : "");\n}']