[mythtv] [experimental patch] AvFormatDecoder::Reset() fix for ffmpeg

[Jesper Sörensen]

Isn't this something that would be good to get in before 0.18 (if it's 
possible to get it to apply again)? Not a big problem here but IIRC some 
other people were having issues with this.

Daniel Thor Kristjansson wrote:

> When using ffmpeg to play mpeg ts files, AVFD::Reset() does not fully 
> delete streams. When I wrote av_remove_stream I did not intend for it 
> to be called this way, and it does not remove the stream from the mpegts
> state, so if you say switch between two channels that happen to have 
> sound on the same pid's ( and hence the same stream id's, :/ ) you'll 
> lose sound with the current implementation. But I've gone back and 
> made it work by adding a mpegts_remove_stream call which does this, 
> and have modified av_remove_stream to call this if we are decoding an 
> mpegts
> file.
>
> This actually doesn't change avformatdecoder.cpp at all, but just 
> makes the av_remove_stream work like the writer of that rutine 
> expected it too.
>
> This patch works as far as letting me change channels in HDTV, but I 
> haven't tested this very much yet and have left in extra debugging 
> statements, hence it's experimental.
>
> -- Daniel