ffmpeg.c:1303: error: Null Dereference
  pointer `vstats_file` last assigned on line 1293 could be null and is dereferenced by call to `fprintf()` at line 1303, column 9.

ffmpeg.c:1284:1: start of procedure do_video_stats()
1282. }
1283. 
1284. static void do_video_stats(AVFormatContext *os, AVOutputStream *ost,
      ^
1285.                            int frame_size)
1286. {

ffmpeg.c:1292:10: Taking true branch
1290. 
1291.     /* this is executed just the first time do_video_stats is called */
1292.     if (!vstats_file) {
               ^
1293.         vstats_file = fopen(vstats_filename, "w");
1294.         if (!vstats_file) {

ffmpeg.c:1293:9: 
1291.     /* this is executed just the first time do_video_stats is called */
1292.     if (!vstats_file) {
1293.         vstats_file = fopen(vstats_filename, "w");
              ^
1294.         if (!vstats_file) {
1295.             perror("fopen");

ffmpeg.c:1294:14: Taking true branch
1292.     if (!vstats_file) {
1293.         vstats_file = fopen(vstats_filename, "w");
1294.         if (!vstats_file) {
                   ^
1295.             perror("fopen");
1296.             ffmpeg_exit(1);

ffmpeg.c:1295:13: 
1293.         vstats_file = fopen(vstats_filename, "w");
1294.         if (!vstats_file) {
1295.             perror("fopen");
                  ^
1296.             ffmpeg_exit(1);
1297.         }

ffmpeg.c:1296:13: Skipping ffmpeg_exit(): empty list of specs
1294.         if (!vstats_file) {
1295.             perror("fopen");
1296.             ffmpeg_exit(1);
                  ^
1297.         }
1298.     }

ffmpeg.c:1300:5: 
1298.     }
1299. 
1300.     enc = ost->st->codec;
          ^
1301.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1302.         frame_number = ost->frame_number;

ffmpeg.c:1301:9: Taking true branch
1299. 
1300.     enc = ost->st->codec;
1301.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
              ^
1302.         frame_number = ost->frame_number;
1303.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);

ffmpeg.c:1302:9: 
1300.     enc = ost->st->codec;
1301.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1302.         frame_number = ost->frame_number;
              ^
1303.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
1304.         if (enc->flags&CODEC_FLAG_PSNR)

ffmpeg.c:1303:9: 
1301.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1302.         frame_number = ost->frame_number;
1303.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
              ^
1304.         if (enc->flags&CODEC_FLAG_PSNR)
1305.             fprintf(vstats_file, "PSNR= %6.2f ", psnr(enc->coded_frame->error[0]/(enc->width*enc->height*255.0*255.0)));
