ffmpeg.c:4255: error: Null Dereference
  pointer `f` last assigned on line 4250 could be null and is dereferenced by call to `feof()` at line 4255, column 12.

ffmpeg.c:4242:1: start of procedure opt_preset()
4240. }
4241. 
4242. static int opt_preset(const char *opt, const char *arg)
      ^
4243. {
4244.     FILE *f=NULL;

ffmpeg.c:4244:5: 
4242. static int opt_preset(const char *opt, const char *arg)
4243. {
4244.     FILE *f=NULL;
          ^
4245.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4246.     char *codec_name = *opt == 'v' ? video_codec_name :

ffmpeg.c:4246:24: Condition is false
4244.     FILE *f=NULL;
4245.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4246.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4247.                        *opt == 'a' ? audio_codec_name :
4248.                                      subtitle_codec_name;

ffmpeg.c:4247:24: Condition is false
4245.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4246.     char *codec_name = *opt == 'v' ? video_codec_name :
4247.                        *opt == 'a' ? audio_codec_name :
                             ^
4248.                                      subtitle_codec_name;
4249. 

ffmpeg.c:4246:24: 
4244.     FILE *f=NULL;
4245.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4246.     char *codec_name = *opt == 'v' ? video_codec_name :
                             ^
4247.                        *opt == 'a' ? audio_codec_name :
4248.                                      subtitle_codec_name;

ffmpeg.c:4246:5: 
4244.     FILE *f=NULL;
4245.     char filename[1000], tmp[1000], tmp2[1000], line[1000];
4246.     char *codec_name = *opt == 'v' ? video_codec_name :
          ^
4247.                        *opt == 'a' ? audio_codec_name :
4248.                                      subtitle_codec_name;

ffmpeg.c:4250:64: Condition is false
4248.                                      subtitle_codec_name;
4249. 
4250.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                                                                     ^
4251.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4252.         ffmpeg_exit(1);

ffmpeg.c:4250:11: Taking true branch
4248.                                      subtitle_codec_name;
4249. 
4250.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
                ^
4251.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4252.         ffmpeg_exit(1);

ffmpeg.c:4251:9: 
4249. 
4250.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4251.         fprintf(stderr, "File for preset '%s' not found\n", arg);
              ^
4252.         ffmpeg_exit(1);
4253.     }

ffmpeg.c:4252:9: Skipping ffmpeg_exit(): empty list of specs
4250.     if (!(f = get_preset_file(filename, sizeof(filename), arg, *opt == 'f', codec_name))) {
4251.         fprintf(stderr, "File for preset '%s' not found\n", arg);
4252.         ffmpeg_exit(1);
              ^
4253.     }
4254. 

ffmpeg.c:4255:12: 
4253.     }
4254. 
4255.     while(!feof(f)){
                 ^
4256.         int e= fscanf(f, "%999[^\n]\n", line) - 1;
4257.         if(line[0] == '#' && !e)
