[mythtv] MythPlayer::DecoderLoop crashes

[George Nassas]

Even with the recent mythtranscode fixes I occasionally see crashes in the codec code. Usually it's while freeing memory for a frame but sometimes it's a bad pointer dereference like what's happening below.

I'm wondering if there's an appetite to hunt down obscure stuff like this and if so should I attach crash reports to an existing ticket or create a new one etc.

- George

Core was generated by `/usr/bin/mythcommflag -j 35221 --noprogress --verbose general,upnp --logpath /v'.
Program terminated with signal 11, Segmentation fault.
#0  0x00007f9d8854c7e7 in av_frame_ref (dst=0x7f9d58023f00, src=0x0)
   at libavutil/frame.c:272
272	    dst->format         = src->format;
#0  0x00007f9d8854c7e7 in av_frame_ref (dst=0x7f9d58023f00, src=0x0) at libavutil/frame.c:272
#1  0x00007f9d875a2b32 in slice_end (avctx=0x7f9d640230e0, pict=0x7f9d58023f00) at libavcodec/mpeg12dec.c:2044
#2  0x00007f9d875a4ac6 in decode_chunks (avctx=0x7f9d640230e0, picture=0x7f9d58023f00, got_output=0x7f9d63ffe798, buf=0x7f9d58146cf0 "", buf_size=73283) at libavcodec/mpeg12dec.c:2564
#3  0x00007f9d875a5b82 in mpeg_decode_frame (avctx=0x7f9d640230e0, data=0x7f9d58023f00, got_output=0x7f9d63ffe798, avpkt=0x7f9d63ffe6d0) at libavcodec/mpeg12dec.c:2916
#4  0x00007f9d8776819c in avcodec_decode_video2 (avctx=0x7f9d640230e0, picture=0x7f9d58023f00, got_picture_ptr=0x7f9d63ffe798, avpkt=0x7f9d58026d00) at libavcodec/utils.c:2286
#5  0x00007f9d868094b1 in AvFormatDecoder::ProcessVideoPacket (this=0x7f9d640165f0, curstream=0x7f9d6401c2a0, pkt=0x7f9d58026d00) at avformatdecoder.cpp:3545
#6  0x00007f9d868118ff in AvFormatDecoder::GetFrame (this=0x7f9d640165f0, decodetype=kDecodeVideo) at avformatdecoder.cpp:5022
#7  0x00007f9d8678719e in MythPlayer::DecoderGetFrame (this=0x2247810, decodetype=kDecodeVideo, unsafe=false) at mythplayer.cpp:3438
#8  0x00007f9d86786b67 in MythPlayer::DecoderLoop (this=0x2247810, pause=false) at mythplayer.cpp:3353
#9  0x00007f9d8676e969 in DecoderThread::run (this=0x7f9d64107a20) at mythplayer.cpp:112
#10 0x00007f9d85bc825d in MThreadInternal::run (this=0x7f9d640240c0) at mthread.cpp:79
#11 0x00007f9d7cab3d0b in QThreadPrivate::start (arg=0x7f9d640240c0) at thread/qthread_unix.cpp:307
#12 0x00007f9d7e5e6b50 in start_thread (arg=<optimized out>) at pthread_create.c:304
#13 0x00007f9d7bfe3e6d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#14 0x0000000000000000 in ?? ()