Check for actual existence of TMPDIR before initiating ffmpeg?

[roschler]

I just had a long head-scratching session that could be solved with a simple addition to audiosprite. On Linux at least, audiosprite uses the directory found in the TMPDIR environment variable for temporary file creation. Because it is the only app on my PC that uses that variable it took me a while to figure out what my root problem was with my audiosprite runs, since they were failing with the dreaded ENOENT error. The problem turned out to be that the directory value assigned to TMPDIR was invalid. That is, the value assigned to TMPDIR did not exist on my disk. Once I figured this out I changed TMPDIR to a valid directory and audiosprite worked fine.

I suggest having audiosprite do a directory existence check for the directory found in TMPDIR, before actually trying to run ffmpeg, and reporting a fatal error if the directory is not found.

Thank you for creating this useful utility.