ffmpeg.c:4252: error: Null Dereference
  pointer `f` last assigned on line 4247 could be null and is dereferenced by call to `feof()` at line 4252, column 12.

ffmpeg.c:4239:1: start of procedure opt_preset()
4237. }
4238. 
4239. static int opt_preset(const char *opt, const char *arg)
      ^
4240. {
4241.     FILE *f=NULL;

ffmpeg.c:4241:5: 
4239. static int opt_preset(const char *opt, const char *arg)
4240. {
4241.     FILE *f=NULL;
          ^
4242.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4243.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4243:24: Condition is false
4241.     FILE *f=NULL;
4242.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4243.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4244.                        *opt == 'a' ? audio_codec_name :
4245.                                      subtitle_codec_name;

ffmpeg.c:4244:24: Condition is false
4242.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4243.     char *codec_name = *opt == 'v' ? video_codec_name :
4244.                        *opt == 'a' ? audio_codec_name :
                             ^
4245.                                      subtitle_codec_name;
4246. 

ffmpeg.c:4243:24: 
4241.     FILE *f=NULL;
4242.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4243.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4244.                        *opt == 'a' ? audio_codec_name :
4245.                                      subtitle_codec_name;

ffmpeg.c:4243:5: 
4241.     FILE *f=NULL;
4242.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4243.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4244.                        *opt == 'a' ? audio_codec_name :
4245.                                      subtitle_codec_name;

ffmpeg.c:4247:64: Condition is false
4245.                                      subtitle_codec_name;
4246. 
4247.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4248.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4249.         ffmpeg_exit(1);

ffmpeg.c:4247:11: Taking true branch
4245.                                      subtitle_codec_name;
4246. 
4247.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4248.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4249.         ffmpeg_exit(1);

ffmpeg.c:4248:9: 
4246. 
4247.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4248.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4249.         ffmpeg_exit(1);
4250.     }

ffmpeg.c:4249:9: Skipping ffmpeg_exit(): empty list of specs
4247.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4248.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4249.         ffmpeg_exit(1);
              ^
4250.     }
4251. 

ffmpeg.c:4252:12: 
4250.     }
4251. 
4252.     while(!feof(f)){
                 ^
4253.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4254.         if(line[0] == '#' && !e)
