ffmpeg.c:4113: error: Null Dereference
  pointer `f` last assigned on line 4108 could be null and is dereferenced by call to `feof()` at line 4113, column 12.

ffmpeg.c:4100:1: start of procedure opt_preset()
4098. }
4099. 
4100. static int opt_preset(const char *opt, const char *arg)
      ^
4101. {
4102.     FILE *f=NULL;

ffmpeg.c:4102:5: 
4100. static int opt_preset(const char *opt, const char *arg)
4101. {
4102.     FILE *f=NULL;
          ^
4103.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4104.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4104:24: Condition is false
4102.     FILE *f=NULL;
4103.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4104.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4105.                        *opt == 'a' ? audio_codec_name :
4106.                                      subtitle_codec_name;

ffmpeg.c:4105:24: Condition is false
4103.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4104.     char *codec_name = *opt == 'v' ? video_codec_name :
4105.                        *opt == 'a' ? audio_codec_name :
                             ^
4106.                                      subtitle_codec_name;
4107. 

ffmpeg.c:4104:24: 
4102.     FILE *f=NULL;
4103.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4104.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4105.                        *opt == 'a' ? audio_codec_name :
4106.                                      subtitle_codec_name;

ffmpeg.c:4104:5: 
4102.     FILE *f=NULL;
4103.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4104.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4105.                        *opt == 'a' ? audio_codec_name :
4106.                                      subtitle_codec_name;

ffmpeg.c:4108:64: Condition is false
4106.                                      subtitle_codec_name;
4107. 
4108.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4109.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4110.         ffmpeg_exit(1);

ffmpeg.c:4108:11: Taking true branch
4106.                                      subtitle_codec_name;
4107. 
4108.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4109.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4110.         ffmpeg_exit(1);

ffmpeg.c:4109:9: 
4107. 
4108.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4109.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4110.         ffmpeg_exit(1);
4111.     }

ffmpeg.c:4110:9: Skipping ffmpeg_exit(): empty list of specs
4108.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4109.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4110.         ffmpeg_exit(1);
              ^
4111.     }
4112. 

ffmpeg.c:4113:12: 
4111.     }
4112. 
4113.     while(!feof(f)){
                 ^
4114.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4115.         if(line[0] == '#' && !e)
