Problem with avformat_open_input()

I lost too much time because of a misleading error message reported by avformat_open_input function! Using the following code:

AVFormatContext *pFormatCtx = NULL;
...
ret = avformat_open_input(&pFormatCtx, argv[1], NULL, NULL);
if (ret < 0)
   print_error_and_exit(ret, "avformat_open_input()");

print_error_and_exit() is a helper function that uses av_strerror() to give textual representation of the error code stored in ret. Running this code produced the following output:

$ ./a.out infile.wav outfile.wav
avformat_open_input(): No such file or directory

But the infile.wav was there! Using strace I found out that open system call wasn't called and so the error was certainly internal. This was frustrating! I started to write this code was to find out why I'm getting another error in VoIP tool simulator, but I was stuck on something even more basic. Googling around at last I found the following link which finally explained me a real cause of the error, i.e. I forgot to call av_register_all() initialization function.

This again shows how important good error reporting is, in both libraries and application programs!

I had also another problem with the previous code. It was segfaulting within avformat_open_input(). At first, I thought that I found a bug within a library but then it turned out I forgot to initialize pFormatCtx to NULL. Namely, allocating a dynamic variable on stack didn't zero it so it was non-NULL and avformat_open_input() misbehaved. Mea culpa! :)