ffmpeg.c:4104: error: Null Dereference
  pointer `f` last assigned on line 4099 could be null and is dereferenced by call to `feof()` at line 4104, column 12.

ffmpeg.c:4091:1: start of procedure opt_preset()
4089. }
4090. 
4091. static int opt_preset(const char *opt, const char *arg)
      ^
4092. {
4093.     FILE *f=NULL;

ffmpeg.c:4093:5: 
4091. static int opt_preset(const char *opt, const char *arg)
4092. {
4093.     FILE *f=NULL;
          ^
4094.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4095.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4095:24: Condition is false
4093.     FILE *f=NULL;
4094.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4095.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4096.                        *opt == 'a' ? audio_codec_name :
4097.                                      subtitle_codec_name;

ffmpeg.c:4096:24: Condition is false
4094.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4095.     char *codec_name = *opt == 'v' ? video_codec_name :
4096.                        *opt == 'a' ? audio_codec_name :
                             ^
4097.                                      subtitle_codec_name;
4098. 

ffmpeg.c:4095:24: 
4093.     FILE *f=NULL;
4094.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4095.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4096.                        *opt == 'a' ? audio_codec_name :
4097.                                      subtitle_codec_name;

ffmpeg.c:4095:5: 
4093.     FILE *f=NULL;
4094.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4095.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4096.                        *opt == 'a' ? audio_codec_name :
4097.                                      subtitle_codec_name;

ffmpeg.c:4099:64: Condition is false
4097.                                      subtitle_codec_name;
4098. 
4099.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4100.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4101.         ffmpeg_exit(1);

ffmpeg.c:4099:11: Taking true branch
4097.                                      subtitle_codec_name;
4098. 
4099.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4100.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4101.         ffmpeg_exit(1);

ffmpeg.c:4100:9: 
4098. 
4099.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4100.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4101.         ffmpeg_exit(1);
4102.     }

ffmpeg.c:4101:9: Skipping ffmpeg_exit(): empty list of specs
4099.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4100.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4101.         ffmpeg_exit(1);
              ^
4102.     }
4103. 

ffmpeg.c:4104:12: 
4102.     }
4103. 
4104.     while(!feof(f)){
                 ^
4105.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4106.         if(line[0] == '#' && !e)
