ffmpeg.c:4174: error: Null Dereference
  pointer `f` last assigned on line 4169 could be null and is dereferenced by call to `feof()` at line 4174, column 12.

ffmpeg.c:4161:1: start of procedure opt_preset()
4159. }
4160. 
4161. static int opt_preset(const char *opt, const char *arg)
      ^
4162. {
4163.     FILE *f=NULL;

ffmpeg.c:4163:5: 
4161. static int opt_preset(const char *opt, const char *arg)
4162. {
4163.     FILE *f=NULL;
          ^
4164.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4165.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4165:24: Condition is false
4163.     FILE *f=NULL;
4164.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4165.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4166.                        *opt == 'a' ? audio_codec_name :
4167.                                      subtitle_codec_name;

ffmpeg.c:4166:24: Condition is false
4164.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4165.     char *codec_name = *opt == 'v' ? video_codec_name :
4166.                        *opt == 'a' ? audio_codec_name :
                             ^
4167.                                      subtitle_codec_name;
4168. 

ffmpeg.c:4165:24: 
4163.     FILE *f=NULL;
4164.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4165.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4166.                        *opt == 'a' ? audio_codec_name :
4167.                                      subtitle_codec_name;

ffmpeg.c:4165:5: 
4163.     FILE *f=NULL;
4164.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4165.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4166.                        *opt == 'a' ? audio_codec_name :
4167.                                      subtitle_codec_name;

ffmpeg.c:4169:64: Condition is false
4167.                                      subtitle_codec_name;
4168. 
4169.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4170.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4171.         ffmpeg_exit(1);

ffmpeg.c:4169:11: Taking true branch
4167.                                      subtitle_codec_name;
4168. 
4169.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4170.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4171.         ffmpeg_exit(1);

ffmpeg.c:4170:9: 
4168. 
4169.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4170.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4171.         ffmpeg_exit(1);
4172.     }

ffmpeg.c:4171:9: Skipping ffmpeg_exit(): empty list of specs
4169.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4170.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4171.         ffmpeg_exit(1);
              ^
4172.     }
4173. 

ffmpeg.c:4174:12: 
4172.     }
4173. 
4174.     while(!feof(f)){
                 ^
4175.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4176.         if(line[0] == '#' && !e)
