[mythtv] Invalid pointer de-ref in NuppelVideoRecorder.cpp

[Mark Kendall]

Apologies - I've been meaning to follow up on this for a few days:)

My main gripe with the whole nuppel video code is that, for reasons
that were perfectly valid at the time, we backed the betamax of video
codecs:)

15 years or so down the line, we are still actively using it and
producing recordings that aren't exactly portable. Looking at the
smolt stats, it looks like there are 3 tuners using v4l2enc and 13
using v4l - not sure what the difference is, but very low numbers
regardless.

>From my perspective, I'd like to do some refactoring of
avformatdecoder after 0.31 is out. That is currently heavily
complicated by the subclassing for NuppelVideoDecoder. I don't know
whether FFmpeg can decode nuppel files - and I can't find any samples
on line. We now use FFmpeg for everything else - there are currently
no private decoders and I don't really want to add any back:)

>From the recorder perspective, I'd like to think it would be a
relatively straightforward change to use FFmpeg to encode to something
more sensible (FFmpeg even has its own V4L2 input device code).  At
least that way we have broken the chain and even if we can't refactor
the decoding side, we have at least given ourselves an opportunity to
remove it in the future.

Hopefully that makes sense.

Regards
Mark