ffmpeg.c:1133: error: Null Dereference
  pointer `vstats_file` last assigned on line 1123 could be null and is dereferenced by call to `fprintf()` at line 1133, column 9.

ffmpeg.c:1114:1: start of procedure do_video_stats()
1112. }
1113. 
1114. static void do_video_stats(AVFormatContext *os, AVOutputStream *ost,
      ^
1115.                            int frame_size)
1116. {

ffmpeg.c:1122:10: Taking true branch
1120. 
1121.     /* this is executed just the first time do_video_stats is called */
1122.     if (!vstats_file) {
               ^
1123.         vstats_file = fopen(vstats_filename, "w");
1124.         if (!vstats_file) {

ffmpeg.c:1123:9: 
1121.     /* this is executed just the first time do_video_stats is called */
1122.     if (!vstats_file) {
1123.         vstats_file = fopen(vstats_filename, "w");
              ^
1124.         if (!vstats_file) {
1125.             perror("fopen");

ffmpeg.c:1124:14: Taking true branch
1122.     if (!vstats_file) {
1123.         vstats_file = fopen(vstats_filename, "w");
1124.         if (!vstats_file) {
                   ^
1125.             perror("fopen");
1126.             av_exit(1);

ffmpeg.c:1125:13: 
1123.         vstats_file = fopen(vstats_filename, "w");
1124.         if (!vstats_file) {
1125.             perror("fopen");
                  ^
1126.             av_exit(1);
1127.         }

ffmpeg.c:1126:13: Skipping av_exit(): empty list of specs
1124.         if (!vstats_file) {
1125.             perror("fopen");
1126.             av_exit(1);
                  ^
1127.         }
1128.     }

ffmpeg.c:1130:5: 
1128.     }
1129. 
1130.     enc = ost->st->codec;
          ^
1131.     if (enc->codec_type == CODEC_TYPE_VIDEO) {
1132.         frame_number = ost->frame_number;

ffmpeg.c:1131:9: Taking true branch
1129. 
1130.     enc = ost->st->codec;
1131.     if (enc->codec_type == CODEC_TYPE_VIDEO) {
              ^
1132.         frame_number = ost->frame_number;
1133.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);

ffmpeg.c:1132:9: 
1130.     enc = ost->st->codec;
1131.     if (enc->codec_type == CODEC_TYPE_VIDEO) {
1132.         frame_number = ost->frame_number;
              ^
1133.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
1134.         if (enc->flags&CODEC_FLAG_PSNR)

ffmpeg.c:1133:9: 
1131.     if (enc->codec_type == CODEC_TYPE_VIDEO) {
1132.         frame_number = ost->frame_number;
1133.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
              ^
1134.         if (enc->flags&CODEC_FLAG_PSNR)
1135.             fprintf(vstats_file, "PSNR= %6.2f ", psnr(enc->coded_frame->error[0]/(enc->width*enc->height*255.0*255.0)));
