libavfilter/avfilter.c:306: error: Null Dereference
  pointer `ret` last assigned on line 301 could be null and is dereferenced by call to `ff_dlog_ref()` at line 306, column 106.

libavfilter/avfilter.c:289:1: start of procedure avfilter_get_video_buffer()
287. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)
288. 
289. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
     ^
290. {
291.     AVFilterBufferRef *ret = NULL;

libavfilter/avfilter.c:291:5: 
289. AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms, int w, int h)
290. {
291.     AVFilterBufferRef *ret = NULL;
         ^
292. 
293.     av_unused char buf[16];

libavfilter/avfilter.c:294:47: 
292. 
293.     av_unused char buf[16];
294.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0);
                                                   ^
295.     av_dlog(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
296. 

libavfilter/avfilter.c:263:1: start of procedure ff_dlog_link()
  261. }
  262. 
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
       ^
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {

libavfilter/avfilter.c:265:9: Taking false branch
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {
               ^
  266.         av_dlog(ctx,
  267.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:275:9: Skipping av_get_channel_layout_string(): empty list of specs
  273.     } else {
  274.         char buf[128];
  275.         av_get_channel_layout_string(buf, sizeof(buf), -1, link->channel_layout);
               ^
  276. 
  277.         av_dlog(ctx,

libavfilter/avfilter.c:265:5: 
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {
           ^
  266.         av_dlog(ctx,
  267.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:285:1: return from a call to ff_dlog_link
  283.                 end ? "\n" : "");
  284.     }
  285. }
       ^
  286. 
  287. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)

libavfilter/avfilter.c:297:9: Taking true branch
295.     av_dlog(NULL, " perms:%s w:%d h:%d\n", ff_get_ref_perms_string(buf, sizeof(buf), perms), w, h);
296. 
297.     if (link->dstpad->get_video_buffer)
             ^
298.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
299. 

libavfilter/avfilter.c:298:9: Skipping __function_pointer__(): unresolved function pointer
296. 
297.     if (link->dstpad->get_video_buffer)
298.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
             ^
299. 
300.     if (!ret)

libavfilter/avfilter.c:300:10: Taking true branch
298.         ret = link->dstpad->get_video_buffer(link, perms, w, h);
299. 
300.     if (!ret)
              ^
301.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
302. 

libavfilter/avfilter.c:301:9: Skipping avfilter_default_get_video_buffer(): empty list of specs
299. 
300.     if (!ret)
301.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
             ^
302. 
303.     if (ret)

libavfilter/avfilter.c:303:9: Taking false branch
301.         ret = avfilter_default_get_video_buffer(link, perms, w, h);
302. 
303.     if (ret)
             ^
304.         ret->type = AVMEDIA_TYPE_VIDEO;
305. 

libavfilter/avfilter.c:306:47: 
304.         ret->type = AVMEDIA_TYPE_VIDEO;
305. 
306.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);
                                                   ^
307. 
308.     return ret;

libavfilter/avfilter.c:263:1: start of procedure ff_dlog_link()
  261. }
  262. 
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
       ^
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {

libavfilter/avfilter.c:265:9: Taking false branch
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {
               ^
  266.         av_dlog(ctx,
  267.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:275:9: Skipping av_get_channel_layout_string(): empty list of specs
  273.     } else {
  274.         char buf[128];
  275.         av_get_channel_layout_string(buf, sizeof(buf), -1, link->channel_layout);
               ^
  276. 
  277.         av_dlog(ctx,

libavfilter/avfilter.c:265:5: 
  263. static void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
  264. {
  265.     if (link->type == AVMEDIA_TYPE_VIDEO) {
           ^
  266.         av_dlog(ctx,
  267.                 "link[%p s:%dx%d fmt:%-16s %-16s->%-16s]%s",

libavfilter/avfilter.c:285:1: return from a call to ff_dlog_link
  283.                 end ? "\n" : "");
  284.     }
  285. }
       ^
  286. 
  287. #define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)

libavfilter/avfilter.c:306:106: 
304.         ret->type = AVMEDIA_TYPE_VIDEO;
305. 
306.     FF_DPRINTF_START(NULL, get_video_buffer); ff_dlog_link(NULL, link, 0); av_dlog(NULL, " returning "); ff_dlog_ref(NULL, ret, 1);
                                                                                                              ^
307. 
308.     return ret;

libavfilter/avfilter.c:233:1: start of procedure ff_dlog_ref()
  231. #endif
  232. 
  233. static void ff_dlog_ref(void *ctx, AVFilterBufferRef *ref, int end)
       ^
  234. {
  235.     av_unused char buf[16];

libavfilter/avfilter.c:242:9: Taking false branch
  240.             ref->pts, ref->pos);
  241. 
  242.     if (ref->video) {
               ^
  243.         av_dlog(ctx, " a:%d/%d s:%dx%d i:%c iskey:%d type:%c",
  244.                 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}']