ffmpeg.c:1287: error: Null Dereference
  pointer `vstats_file` last assigned on line 1277 could be null and is dereferenced by call to `fprintf()` at line 1287, column 9.

ffmpeg.c:1268:1: start of procedure do_video_stats()
1266. }
1267. 
1268. static void do_video_stats(AVFormatContext *os, AVOutputStream *ost,
      ^
1269.                            int frame_size)
1270. {

ffmpeg.c:1276:10: Taking true branch
1274. 
1275.     /* this is executed just the first time do_video_stats is called */
1276.     if (!vstats_file) {
               ^
1277.         vstats_file = fopen(vstats_filename, "w");
1278.         if (!vstats_file) {

ffmpeg.c:1277:9: 
1275.     /* this is executed just the first time do_video_stats is called */
1276.     if (!vstats_file) {
1277.         vstats_file = fopen(vstats_filename, "w");
              ^
1278.         if (!vstats_file) {
1279.             perror("fopen");

ffmpeg.c:1278:14: Taking true branch
1276.     if (!vstats_file) {
1277.         vstats_file = fopen(vstats_filename, "w");
1278.         if (!vstats_file) {
                   ^
1279.             perror("fopen");
1280.             ffmpeg_exit(1);

ffmpeg.c:1279:13: 
1277.         vstats_file = fopen(vstats_filename, "w");
1278.         if (!vstats_file) {
1279.             perror("fopen");
                  ^
1280.             ffmpeg_exit(1);
1281.         }

ffmpeg.c:1280:13: Skipping ffmpeg_exit(): empty list of specs
1278.         if (!vstats_file) {
1279.             perror("fopen");
1280.             ffmpeg_exit(1);
                  ^
1281.         }
1282.     }

ffmpeg.c:1284:5: 
1282.     }
1283. 
1284.     enc = ost->st->codec;
          ^
1285.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1286.         frame_number = ost->frame_number;

ffmpeg.c:1285:9: Taking true branch
1283. 
1284.     enc = ost->st->codec;
1285.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
              ^
1286.         frame_number = ost->frame_number;
1287.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);

ffmpeg.c:1286:9: 
1284.     enc = ost->st->codec;
1285.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1286.         frame_number = ost->frame_number;
              ^
1287.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
1288.         if (enc->flags&CODEC_FLAG_PSNR)

ffmpeg.c:1287:9: 
1285.     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
1286.         frame_number = ost->frame_number;
1287.         fprintf(vstats_file, "frame= %5d q= %2.1f ", frame_number, enc->coded_frame->quality/(float)FF_QP2LAMBDA);
              ^
1288.         if (enc->flags&CODEC_FLAG_PSNR)
1289.             fprintf(vstats_file, "PSNR= %6.2f ", psnr(enc->coded_frame->error[0]/(enc->width*enc->height*255.0*255.0)));
