libavfilter/vf_aspect.c:100: error: Null Dereference
  pointer `desc` last assigned on line 87 could be null and is dereferenced at line 100, column 34.

libavfilter/vf_aspect.c:83:1: start of procedure get_aspect_ratio()
81. #define FLAGS AV_OPT_FLAG_VIDEO_PARAM
82. 
83. static int get_aspect_ratio(AVFilterLink *inlink, AVRational *aspect_ratio)
    ^
84. {
85.     AVFilterContext *ctx = inlink->dst;

libavfilter/vf_aspect.c:85:5: 
83. static int get_aspect_ratio(AVFilterLink *inlink, AVRational *aspect_ratio)
84. {
85.     AVFilterContext *ctx = inlink->dst;
        ^
86.     AspectContext *s = inlink->dst->priv;
87.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_aspect.c:86:5: 
84. {
85.     AVFilterContext *ctx = inlink->dst;
86.     AspectContext *s = inlink->dst->priv;
        ^
87.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
88.     double var_values[VARS_NB], res;

libavfilter/vf_aspect.c:87:5: 
85.     AVFilterContext *ctx = inlink->dst;
86.     AspectContext *s = inlink->dst->priv;
87.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
        ^
88.     double var_values[VARS_NB], res;
89.     int ret;

libavutil/pixdesc.c:1866:1: start of procedure av_pix_fmt_desc_get()
  1864. }
  1865. 
  1866. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1867. {
  1868.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1868:9: Taking false branch
  1866. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1867. {
  1868.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1869.         return NULL;
  1870.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1868:24: Taking true branch
  1866. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1867. {
  1868.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1869.         return NULL;
  1870.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1869:9: 
  1867. {
  1868.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1869.         return NULL;
                ^
  1870.     return &av_pix_fmt_descriptors[pix_fmt];
  1871. }

libavutil/pixdesc.c:1871:1: return from a call to av_pix_fmt_desc_get
  1869.         return NULL;
  1870.     return &av_pix_fmt_descriptors[pix_fmt];
  1871. }
        ^
  1872. 
  1873. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_aspect.c:91:5: 
89.     int ret;
90. 
91.     var_values[VAR_PI]    = M_PI;
        ^
92.     var_values[VAR_PHI]   = M_PHI;
93.     var_values[VAR_E]     = M_E;

libavfilter/vf_aspect.c:92:5: 
90. 
91.     var_values[VAR_PI]    = M_PI;
92.     var_values[VAR_PHI]   = M_PHI;
        ^
93.     var_values[VAR_E]     = M_E;
94.     var_values[VAR_W]     = inlink->w;

libavfilter/vf_aspect.c:93:5: 
91.     var_values[VAR_PI]    = M_PI;
92.     var_values[VAR_PHI]   = M_PHI;
93.     var_values[VAR_E]     = M_E;
        ^
94.     var_values[VAR_W]     = inlink->w;
95.     var_values[VAR_H]     = inlink->h;

libavfilter/vf_aspect.c:94:5: 
92.     var_values[VAR_PHI]   = M_PHI;
93.     var_values[VAR_E]     = M_E;
94.     var_values[VAR_W]     = inlink->w;
        ^
95.     var_values[VAR_H]     = inlink->h;
96.     var_values[VAR_A]     = (double) inlink->w / inlink->h;

libavfilter/vf_aspect.c:95:5: 
93.     var_values[VAR_E]     = M_E;
94.     var_values[VAR_W]     = inlink->w;
95.     var_values[VAR_H]     = inlink->h;
        ^
96.     var_values[VAR_A]     = (double) inlink->w / inlink->h;
97.     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?

libavfilter/vf_aspect.c:96:5: 
94.     var_values[VAR_W]     = inlink->w;
95.     var_values[VAR_H]     = inlink->h;
96.     var_values[VAR_A]     = (double) inlink->w / inlink->h;
        ^
97.     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
98.         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;

libavfilter/vf_aspect.c:97:29: Condition is true
95.     var_values[VAR_H]     = inlink->h;
96.     var_values[VAR_A]     = (double) inlink->w / inlink->h;
97.     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
                                ^
98.         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
99.     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];

libavfilter/vf_aspect.c:97:5: 
95.     var_values[VAR_H]     = inlink->h;
96.     var_values[VAR_A]     = (double) inlink->w / inlink->h;
97.     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
        ^
98.         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
99.     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];

libavfilter/vf_aspect.c:99:5: 
 97.     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
 98.         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
 99.     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];
         ^
100.     var_values[VAR_HSUB]  = 1 << desc->log2_chroma_w;
101.     var_values[VAR_VSUB]  = 1 << desc->log2_chroma_h;

libavfilter/vf_aspect.c:100:5: 
 98.         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
 99.     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];
100.     var_values[VAR_HSUB]  = 1 << desc->log2_chroma_w;
         ^
101.     var_values[VAR_VSUB]  = 1 << desc->log2_chroma_h;
102. 
