[mythtv] Need help with frontend seg fault

Jerry Rubinow jerryr at universal-imaging.com
Sun Jul 25 21:30:37 EDT 2004

I've been having segmentation faults in the frontend while trying to play back 1080X1920 and 1280X720 HD content recording using a pcHDTV. 704X480 content appears to play back ok. I'm running the stock 0.15 sources without any deinterlacing or filters.

The seg fault occurs when it tries to call a method of audioOutput, but before it reaches the method it's trying to call. However, the audioOutput pointer has the same value as when it was first allocated, so it seems like something is getting trashed earlier in the execution and only showing up when it tried to use audioOutput. So the debugger backtrace doesn't say anything useful.

It is using the mpeg2video_decoder in mpeg12.c for the playback, and if I comment out a call to mpeg_field_start within mpeg_decode_frame, calls through audioOutput do not get corrupted (when the segfault does occur, it is following the first call to GetFrame/avcodec_decode_video/...). I don't know from mpeg decoding, so I really don't know how to go about narrowing things down any further. Note that if I enter the recorded shows screen but don't start playback, the mini-preview window shows up and displays the recorded show ok, so the data file is ok.

I did determine that if I put mpeg_field_start back in and comment out ff_er_frame_start in error_resilience.c the seg fault also goes away, but I'm not sure what that tells me, since I verified the size of memory it's copying is the same size as the buffer it's copying into.

Can anybody help me out? What other information should I supply? What else can I try? I'm very close to having a running hi-def MythTV system and it's frustrating being able to record shows but not play them back. If anyone wants to try playing the recording, it's about 250MB (2 minutes long).



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