Would it be (or indeed is it) possible to have GI output a log file if errors and/or warnings are encountered?

I'm thinking scenarios like the current issues with missing segments, where having those warnings/errors in a log would make things easier to trace and deal with. I know the output of GI can be piped to a file, but that I presume would contain everything and you'd then have to filter out the rest.

Being able to set a flag to output just warnings/errors to a separate log file would be simpler I'd say. I'm thinking more of the PVR scenario where GI is running as a scheduled task, rather than as an interactive download where such errors would be more obvious.
 

I couldn't see anything in the wiki guides on doing this though. Is there a way that I've missed, other than pipe and filter?

It's not something that I will implement. Few people would use it, and it doesn't really offer any benefit over current functionality. Just use --quiet and capture stderr (not stdout) in a file when running pvr from a scheduled task.

Fair enough - will give it a go that way and see. You're probably right it's a bit specialised, but some way to keep an eye on the scheduled task's potential problems could be useful (your --quiet and pipe sounds like what I was thinking of in terms of result anyway - I did wonder quite how much quiet would suppress and whether it would help here).

--quiet suppresses the noise from download progress display, and get_iplayer sends its own messages to stderr rather than stdout when --pvr is used. It was designed that way for ease of use with cron, so that the minimal announcements of successful downloads go to stdout (and can thus be captured in an email) and all other output can be captured in a log file. It should work the same with Task Scheduler.