ffmpeg.c:3720: error: Null Dereference
  pointer `oc` last assigned on line 3698 could be null and is dereferenced at line 3720, column 5.

ffmpeg.c:3686:1: start of procedure opt_output_file()
3684. }
3685. 
3686. static void opt_output_file(const char *filename)
      ^
3687. {
3688.     AVFormatContext *oc;

ffmpeg.c:3691:5: 
3689.     int err, use_video, use_audio, use_subtitle;
3690.     int input_has_video, input_has_audio, input_has_subtitle;
3691.     AVFormatParameters params, *ap = &params;
          ^
3692.     AVOutputFormat *file_oformat;
3693.     AVMetadataTag *tag = NULL;

ffmpeg.c:3693:5: 
3691.     AVFormatParameters params, *ap = &params;
3692.     AVOutputFormat *file_oformat;
3693.     AVMetadataTag *tag = NULL;
          ^
3694. 
3695.     if (!strcmp(filename, "-"))

ffmpeg.c:3695:10: Taking false branch
3693.     AVMetadataTag *tag = NULL;
3694. 
3695.     if (!strcmp(filename, "-"))
               ^
3696.         filename = "pipe:";
3697. 

ffmpeg.c:3698:5: 
3696.         filename = "pipe:";
3697. 
3698.     oc = avformat_alloc_context();
          ^
3699.     if (!oc) {
3700.         print_error(filename, AVERROR(ENOMEM));

libavformat/options.c:82:1: start of procedure avformat_alloc_context()
  80. }
  81. 
  82. AVFormatContext *avformat_alloc_context(void)
      ^
  83. {
  84.     AVFormatContext *ic;

libavformat/options.c:85:5: 
  83. {
  84.     AVFormatContext *ic;
  85.     ic = av_malloc(sizeof(AVFormatContext));
          ^
  86.     if (!ic) return ic;
  87.     avformat_get_context_defaults(ic);

libavutil/mem.c:64:1: start of procedure av_malloc()
    62.    linker will do it automatically. */
    63. 
    64. void *av_malloc(FF_INTERNAL_MEM_TYPE size)
        ^
    65. {
    66.     void *ptr = NULL;

libavutil/mem.c:66:5: 
    64. void *av_malloc(FF_INTERNAL_MEM_TYPE size)
    65. {
    66.     void *ptr = NULL;
            ^
    67. #if CONFIG_MEMALIGN_HACK
    68.     long diff;

libavutil/mem.c:72:8: Taking false branch
    70. 
    71.     /* let's disallow possible ambiguous cases */
    72.     if(size > (INT_MAX-16) )
               ^
    73.         return NULL;
    74. 

libavutil/mem.c:83:9: Taking false branch
    81.     ((char*)ptr)[-1]= diff;
    82. #elif HAVE_POSIX_MEMALIGN
    83.     if (posix_memalign(&ptr,16,size))
                ^
    84.         ptr = NULL;
    85. #elif HAVE_MEMALIGN

libavutil/mem.c:116:5: 
    114.     ptr = malloc(size);
    115. #endif
    116.     return ptr;
             ^
    117. }
    118. 

libavutil/mem.c:117:1: return from a call to av_malloc
    115. #endif
    116.     return ptr;
    117. }
         ^
    118. 
    119. void *av_realloc(void *ptr, FF_INTERNAL_MEM_TYPE size)

libavformat/options.c:86:10: Taking true branch
  84.     AVFormatContext *ic;
  85.     ic = av_malloc(sizeof(AVFormatContext));
  86.     if (!ic) return ic;
               ^
  87.     avformat_get_context_defaults(ic);
  88.     ic->av_class = &av_format_context_class;

libavformat/options.c:86:14: 
  84.     AVFormatContext *ic;
  85.     ic = av_malloc(sizeof(AVFormatContext));
  86.     if (!ic) return ic;
                   ^
  87.     avformat_get_context_defaults(ic);
  88.     ic->av_class = &av_format_context_class;

libavformat/options.c:90:1: return from a call to avformat_alloc_context
  88.     ic->av_class = &av_format_context_class;
  89.     return ic;
  90. }
      ^
  91. 
  92. #if FF_API_ALLOC_FORMAT_CONTEXT

ffmpeg.c:3699:10: Taking true branch
3697. 
3698.     oc = avformat_alloc_context();
3699.     if (!oc) {
               ^
3700.         print_error(filename, AVERROR(ENOMEM));
3701.         ffmpeg_exit(1);

ffmpeg.c:3700:9: 
3698.     oc = avformat_alloc_context();
3699.     if (!oc) {
3700.         print_error(filename, AVERROR(ENOMEM));
              ^
3701.         ffmpeg_exit(1);
3702.     }

cmdutils.c:360:1: start of procedure print_error()
  358. }
  359. 
  360. void print_error(const char *filename, int err)
       ^
  361. {
  362.     char errbuf[128];

cmdutils.c:363:5: 
  361. {
  362.     char errbuf[128];
  363.     const char *errbuf_ptr = errbuf;
           ^
  364. 
  365.     if (av_strerror(err, errbuf, sizeof(errbuf)) < 0)

cmdutils.c:365:9: Taking true branch
  363.     const char *errbuf_ptr = errbuf;
  364. 
  365.     if (av_strerror(err, errbuf, sizeof(errbuf)) < 0)
               ^
  366.         errbuf_ptr = strerror(AVUNERROR(err));
  367.     fprintf(stderr, "%s: %s\n", filename, errbuf_ptr);

cmdutils.c:366:9: Skipping strerror(): method has no implementation
  364. 
  365.     if (av_strerror(err, errbuf, sizeof(errbuf)) < 0)
  366.         errbuf_ptr = strerror(AVUNERROR(err));
               ^
  367.     fprintf(stderr, "%s: %s\n", filename, errbuf_ptr);
  368. }

cmdutils.c:367:5: 
  365.     if (av_strerror(err, errbuf, sizeof(errbuf)) < 0)
  366.         errbuf_ptr = strerror(AVUNERROR(err));
  367.     fprintf(stderr, "%s: %s\n", filename, errbuf_ptr);
           ^
  368. }
  369. 

cmdutils.c:368:1: return from a call to print_error
  366.         errbuf_ptr = strerror(AVUNERROR(err));
  367.     fprintf(stderr, "%s: %s\n", filename, errbuf_ptr);
  368. }
       ^
  369. 
  370. static int warned_cfg = 0;

ffmpeg.c:3701:9: Skipping ffmpeg_exit(): empty list of specs
3699.     if (!oc) {
3700.         print_error(filename, AVERROR(ENOMEM));
3701.         ffmpeg_exit(1);
              ^
3702.     }
3703. 

ffmpeg.c:3704:9: Taking true branch
3702.     }
3703. 
3704.     if (last_asked_format) {
              ^
3705.         file_oformat = av_guess_format(last_asked_format, NULL, NULL);
3706.         if (!file_oformat) {

ffmpeg.c:3705:9: Skipping av_guess_format(): empty list of specs
3703. 
3704.     if (last_asked_format) {
3705.         file_oformat = av_guess_format(last_asked_format, NULL, NULL);
              ^
3706.         if (!file_oformat) {
3707.             fprintf(stderr, "Requested output format '%s' is not a suitable output format\n", last_asked_format);

ffmpeg.c:3706:14: Taking false branch
3704.     if (last_asked_format) {
3705.         file_oformat = av_guess_format(last_asked_format, NULL, NULL);
3706.         if (!file_oformat) {
                   ^
3707.             fprintf(stderr, "Requested output format '%s' is not a suitable output format\n", last_asked_format);
3708.             ffmpeg_exit(1);

ffmpeg.c:3710:9: 
3708.             ffmpeg_exit(1);
3709.         }
3710.         last_asked_format = NULL;
              ^
3711.     } else {
3712.         file_oformat = av_guess_format(NULL, filename, NULL);

ffmpeg.c:3720:5: 
3718.     }
3719. 
3720.     oc->oformat = file_oformat;
          ^
3721.     av_strlcpy(oc->filename, filename, sizeof(oc->filename));
3722. 
