ffmpeg.c:4161: error: Null Dereference
  pointer `f` last assigned on line 4156 could be null and is dereferenced by call to `feof()` at line 4161, column 12.

ffmpeg.c:4148:1: start of procedure opt_preset()
4146. }
4147. 
4148. static int opt_preset(const char *opt, const char *arg)
      ^
4149. {
4150.     FILE *f=NULL;

ffmpeg.c:4150:5: 
4148. static int opt_preset(const char *opt, const char *arg)
4149. {
4150.     FILE *f=NULL;
          ^
4151.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4152.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4152:24: Condition is false
4150.     FILE *f=NULL;
4151.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4152.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4153.                        *opt == 'a' ? audio_codec_name :
4154.                                      subtitle_codec_name;

ffmpeg.c:4153:24: Condition is false
4151.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4152.     char *codec_name = *opt == 'v' ? video_codec_name :
4153.                        *opt == 'a' ? audio_codec_name :
                             ^
4154.                                      subtitle_codec_name;
4155. 

ffmpeg.c:4152:24: 
4150.     FILE *f=NULL;
4151.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4152.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4153.                        *opt == 'a' ? audio_codec_name :
4154.                                      subtitle_codec_name;

ffmpeg.c:4152:5: 
4150.     FILE *f=NULL;
4151.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4152.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4153.                        *opt == 'a' ? audio_codec_name :
4154.                                      subtitle_codec_name;

ffmpeg.c:4156:64: Condition is false
4154.                                      subtitle_codec_name;
4155. 
4156.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4157.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4158.         ffmpeg_exit(1);

ffmpeg.c:4156:11: Taking true branch
4154.                                      subtitle_codec_name;
4155. 
4156.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4157.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4158.         ffmpeg_exit(1);

ffmpeg.c:4157:9: 
4155. 
4156.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4157.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4158.         ffmpeg_exit(1);
4159.     }

ffmpeg.c:4158:9: Skipping ffmpeg_exit(): empty list of specs
4156.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4157.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4158.         ffmpeg_exit(1);
              ^
4159.     }
4160. 

ffmpeg.c:4161:12: 
4159.     }
4160. 
4161.     while(!feof(f)){
                 ^
4162.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4163.         if(line[0] == '#' && !e)
