ffmpeg.c:4228: error: Null Dereference
  pointer `f` last assigned on line 4223 could be null and is dereferenced by call to `feof()` at line 4228, column 12.

ffmpeg.c:4215:1: start of procedure opt_preset()
4213. }
4214. 
4215. static int opt_preset(const char *opt, const char *arg)
      ^
4216. {
4217.     FILE *f=NULL;

ffmpeg.c:4217:5: 
4215. static int opt_preset(const char *opt, const char *arg)
4216. {
4217.     FILE *f=NULL;
          ^
4218.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4219.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4219:24: Condition is false
4217.     FILE *f=NULL;
4218.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4219.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4220.                        *opt == 'a' ? audio_codec_name :
4221.                                      subtitle_codec_name;

ffmpeg.c:4220:24: Condition is false
4218.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4219.     char *codec_name = *opt == 'v' ? video_codec_name :
4220.                        *opt == 'a' ? audio_codec_name :
                             ^
4221.                                      subtitle_codec_name;
4222. 

ffmpeg.c:4219:24: 
4217.     FILE *f=NULL;
4218.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4219.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4220.                        *opt == 'a' ? audio_codec_name :
4221.                                      subtitle_codec_name;

ffmpeg.c:4219:5: 
4217.     FILE *f=NULL;
4218.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4219.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4220.                        *opt == 'a' ? audio_codec_name :
4221.                                      subtitle_codec_name;

ffmpeg.c:4223:64: Condition is false
4221.                                      subtitle_codec_name;
4222. 
4223.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4224.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4225.         ffmpeg_exit(1);

ffmpeg.c:4223:11: Taking true branch
4221.                                      subtitle_codec_name;
4222. 
4223.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4224.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4225.         ffmpeg_exit(1);

ffmpeg.c:4224:9: 
4222. 
4223.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4224.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4225.         ffmpeg_exit(1);
4226.     }

ffmpeg.c:4225:9: Skipping ffmpeg_exit(): empty list of specs
4223.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4224.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4225.         ffmpeg_exit(1);
              ^
4226.     }
4227. 

ffmpeg.c:4228:12: 
4226.     }
4227. 
4228.     while(!feof(f)){
                 ^
4229.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4230.         if(line[0] == '#' && !e)
