ffmpeg.c:1310: error: Null Dereference
  pointer `vstats_file` last assigned on line 1300 could be null and is dereferenced by call to `fprintf()` at line 1310, column 9.

ffmpeg.c:1291:1: start of procedure do_video_stats()
1289. }
1290. 
1291. static void do_video_stats(AVFormatContext *os, AVOutputStream *ost,
      ^
1292.                            int frame_size)
1293. {

ffmpeg.c:1299:10: Taking true branch
1297. 
1298.     /* this is executed just the first time do_video_stats is called */
1299.     if (!vstats_file) {
               ^
1300.         vstats_file = fopen(vstats_filename, "w");
1301.         if (!vstats_file) {

ffmpeg.c:1300:9: 
1298.     /* this is executed just the first time do_video_stats is called */
1299.     if (!vstats_file) {
1300.         vstats_file = fopen(vstats_filename, "w");
              ^
1301.         if (!vstats_file) {
1302.             perror("fopen");

ffmpeg.c:1301:14: Taking true branch
1299.     if (!vstats_file) {
1300.         vstats_file = fopen(vstats_filename, "w");
1301.         if (!vstats_file) {
                   ^
1302.             perror("fopen");
1303.             ffmpeg_exit(1);

ffmpeg.c:1302:13: 
1300.         vstats_file = fopen(vstats_filename, "w");
1301.         if (!vstats_file) {
1302.             perror("fopen");
                  ^
1303.             ffmpeg_exit(1);
1304.         }

ffmpeg.c:1303:13: Skipping ffmpeg_exit(): empty list of specs
1301.         if (!vstats_file) {
1302.             perror("fopen");
1303.             ffmpeg_exit(1);
                  ^
1304.         }
1305.     }

ffmpeg.c:1307:5: 
1305.     }
1306. 
1307.     enc = ost->st->codec;
          ^
1308.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1309.         frame_number = ost->frame_number;

ffmpeg.c:1308:9: Taking true branch
1306. 
1307.     enc = ost->st->codec;
1308.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
              ^
1309.         frame_number = ost->frame_number;
1310.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);

ffmpeg.c:1309:9: 
1307.     enc = ost->st->codec;
1308.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1309.         frame_number = ost->frame_number;
              ^
1310.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
1311.         if (enc->flags&CODEC_FLAG_PSNR)

ffmpeg.c:1310:9: 
1308.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1309.         frame_number = ost->frame_number;
1310.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
              ^
1311.         if (enc->flags&CODEC_FLAG_PSNR)
1312.             fprintf(vstats_file, "PSNR= %6.2f ", psnr(enc->coded_frame->error[0]/(enc->width*enc->height*255.0*255.0)));
