ffmpeg.c:4196: error: Null Dereference
  pointer `f` last assigned on line 4191 could be null and is dereferenced by call to `feof()` at line 4196, column 12.

ffmpeg.c:4183:1: start of procedure opt_preset()
4181. }
4182. 
4183. static int opt_preset(const char *opt, const char *arg)
      ^
4184. {
4185.     FILE *f=NULL;

ffmpeg.c:4185:5: 
4183. static int opt_preset(const char *opt, const char *arg)
4184. {
4185.     FILE *f=NULL;
          ^
4186.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4187.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4187:24: Condition is false
4185.     FILE *f=NULL;
4186.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4187.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4188.                        *opt == 'a' ? audio_codec_name :
4189.                                      subtitle_codec_name;

ffmpeg.c:4188:24: Condition is false
4186.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4187.     char *codec_name = *opt == 'v' ? video_codec_name :
4188.                        *opt == 'a' ? audio_codec_name :
                             ^
4189.                                      subtitle_codec_name;
4190. 

ffmpeg.c:4187:24: 
4185.     FILE *f=NULL;
4186.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4187.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4188.                        *opt == 'a' ? audio_codec_name :
4189.                                      subtitle_codec_name;

ffmpeg.c:4187:5: 
4185.     FILE *f=NULL;
4186.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4187.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4188.                        *opt == 'a' ? audio_codec_name :
4189.                                      subtitle_codec_name;

ffmpeg.c:4191:64: Condition is false
4189.                                      subtitle_codec_name;
4190. 
4191.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4192.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4193.         ffmpeg_exit(1);

ffmpeg.c:4191:11: Taking true branch
4189.                                      subtitle_codec_name;
4190. 
4191.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4192.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4193.         ffmpeg_exit(1);

ffmpeg.c:4192:9: 
4190. 
4191.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4192.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4193.         ffmpeg_exit(1);
4194.     }

ffmpeg.c:4193:9: Skipping ffmpeg_exit(): empty list of specs
4191.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4192.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4193.         ffmpeg_exit(1);
              ^
4194.     }
4195. 

ffmpeg.c:4196:12: 
4194.     }
4195. 
4196.     while(!feof(f)){
                 ^
4197.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4198.         if(line[0] == '#' && !e)
