ffmpeg.c:4200: error: Null Dereference
  pointer `f` last assigned on line 4195 could be null and is dereferenced by call to `feof()` at line 4200, column 12.

ffmpeg.c:4187:1: start of procedure opt_preset()
4185. }
4186. 
4187. static int opt_preset(const char *opt, const char *arg)
      ^
4188. {
4189.     FILE *f=NULL;

ffmpeg.c:4189:5: 
4187. static int opt_preset(const char *opt, const char *arg)
4188. {
4189.     FILE *f=NULL;
          ^
4190.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4191.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4191:24: Condition is false
4189.     FILE *f=NULL;
4190.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4191.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4192.                        *opt == 'a' ? audio_codec_name :
4193.                                      subtitle_codec_name;

ffmpeg.c:4192:24: Condition is false
4190.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4191.     char *codec_name = *opt == 'v' ? video_codec_name :
4192.                        *opt == 'a' ? audio_codec_name :
                             ^
4193.                                      subtitle_codec_name;
4194. 

ffmpeg.c:4191:24: 
4189.     FILE *f=NULL;
4190.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4191.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4192.                        *opt == 'a' ? audio_codec_name :
4193.                                      subtitle_codec_name;

ffmpeg.c:4191:5: 
4189.     FILE *f=NULL;
4190.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4191.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4192.                        *opt == 'a' ? audio_codec_name :
4193.                                      subtitle_codec_name;

ffmpeg.c:4195:64: Condition is false
4193.                                      subtitle_codec_name;
4194. 
4195.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4196.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4197.         ffmpeg_exit(1);

ffmpeg.c:4195:11: Taking true branch
4193.                                      subtitle_codec_name;
4194. 
4195.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4196.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4197.         ffmpeg_exit(1);

ffmpeg.c:4196:9: 
4194. 
4195.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4196.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4197.         ffmpeg_exit(1);
4198.     }

ffmpeg.c:4197:9: Skipping ffmpeg_exit(): empty list of specs
4195.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4196.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4197.         ffmpeg_exit(1);
              ^
4198.     }
4199. 

ffmpeg.c:4200:12: 
4198.     }
4199. 
4200.     while(!feof(f)){
                 ^
4201.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4202.         if(line[0] == '#' && !e)
