ffmpeg.c:4192: error: Null Dereference
  pointer `f` last assigned on line 4187 could be null and is dereferenced by call to `feof()` at line 4192, column 12.

ffmpeg.c:4179:1: start of procedure opt_preset()
4177. }
4178. 
4179. static int opt_preset(const char *opt, const char *arg)
      ^
4180. {
4181.     FILE *f=NULL;

ffmpeg.c:4181:5: 
4179. static int opt_preset(const char *opt, const char *arg)
4180. {
4181.     FILE *f=NULL;
          ^
4182.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4183.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4183:24: Condition is false
4181.     FILE *f=NULL;
4182.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4183.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4184.                        *opt == 'a' ? audio_codec_name :
4185.                                      subtitle_codec_name;

ffmpeg.c:4184:24: Condition is false
4182.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4183.     char *codec_name = *opt == 'v' ? video_codec_name :
4184.                        *opt == 'a' ? audio_codec_name :
                             ^
4185.                                      subtitle_codec_name;
4186. 

ffmpeg.c:4183:24: 
4181.     FILE *f=NULL;
4182.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4183.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4184.                        *opt == 'a' ? audio_codec_name :
4185.                                      subtitle_codec_name;

ffmpeg.c:4183:5: 
4181.     FILE *f=NULL;
4182.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4183.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4184.                        *opt == 'a' ? audio_codec_name :
4185.                                      subtitle_codec_name;

ffmpeg.c:4187:64: Condition is false
4185.                                      subtitle_codec_name;
4186. 
4187.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4188.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4189.         ffmpeg_exit(1);

ffmpeg.c:4187:11: Taking true branch
4185.                                      subtitle_codec_name;
4186. 
4187.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4188.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4189.         ffmpeg_exit(1);

ffmpeg.c:4188:9: 
4186. 
4187.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4188.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4189.         ffmpeg_exit(1);
4190.     }

ffmpeg.c:4189:9: Skipping ffmpeg_exit(): empty list of specs
4187.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4188.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4189.         ffmpeg_exit(1);
              ^
4190.     }
4191. 

ffmpeg.c:4192:12: 
4190.     }
4191. 
4192.     while(!feof(f)){
                 ^
4193.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4194.         if(line[0] == '#' && !e)
