V9-64bit PC playback crashes only on some OTA Channels

[AlbuQuirky]

Originally Posted by wnjj

Another thing you can try: Does the 32-bit version crash the same way? You can install the 32-bit client on the same machine and it should be able to talk to the 64-bit server.

wnjj, I finally managed to play with the 32bit SageTVClient9.2.1.
It crashes in the same manner as the 64bit UI for the server9.2.1.

I also used the 32bit client to connect to my existing 32bit server9.1.9 on the old Window7 platform; it also crashes on livetv and files recorded by the older server;

but, nothing crashes when using the server9.1.9 32bit UI for any type of playback.

Hope that helps.

[SHS]

Originally Posted by wnjj

StreamDemux isn’t used for MPEG2 anyway. It’s using MpegDeMux.ax.

It should be set to 1 any way

[wnjj]

Looking into the debug log for the demux and noticed one difference between the 2 files. In the working one, track 0 is the AC3 audio and track 1 is the Mpeg2 video. In the crashing one, the tracks are swapped. I'm still tracking down where/why it's crashing.

[SHS]

Originally Posted by wnjj

Looking into the debug log for the demux and noticed one difference between the 2 files. In the working one, track 0 is the AC3 audio and track 1 is the Mpeg2 video. In the crashing one, the tracks are swapped. I'm still tracking down where/why it's crashing.

Yup I see that it crashing it make no sense

[trk2]

Have you tried recording the HDHR stream as a transport stream instead of a program stream? I seem to remember this caused less errors in the recording for several users.

[wnjj]

An update on this:

I was able to reproduce the crash with files provided by AlbuQuirky. After many iterations, debug logs and print statements I uncovered the problem. There is an issue in the MpegDeMux.ax filter code when it stores the MPEG2 header info into the DirectShow data structures. The header storage is defined as an array of DWORD (4 bytes long), but was being allocated and loaded with a quantity of data that is not module 4. Then when the downstream filter read that header it would access memory outside the structure.

I found at least one example online where the header was padded to make it modulo 4 which is a simple solution. I’ll submit a pull request when I get some time but in the meantime if anyone else is crashing upon MPEG2 playback on a Windows client I can share the patched filter.

The odd thing is this code was built that way before going open source. I suspect that VS2015 compiles it a bit different which is why it never surfaced on V7 and earlier. It’s funny that it hasn’t been observed on V9 until now but it also takes a certain compression style so may not be prevalent for most OTA streams.

[trk2]

That's interesting. Well done.

[wnjj]

Pull request created: https://github.com/google/sagetv/pull/436

[AlbuQuirky]

Originally Posted by wnjj

Pull request created: https://github.com/google/sagetv/pull/436

I am using wnjj's hack/patch for now and looking forward to the formal resolution.
Many thanks to wnjj and all who have contributed to this finding. Professional, indeed.
If there is any other way that I might assist, please feel free to contact me.

[sacrament055]

Any idea if the changes needed for the format detector mentioned in this thread
https://forums.sagetv.com/forums/showthread.php?t=66352

are also included in this? Hoping to be able to install this fix and keep the updates that came from the format detector.

Is this going to be as easy as replacing a couple files or will it require an updated install of SageTV?

Thanks for your efforts here, greatly appreciated.

[wnjj]

Originally Posted by sacrament055

Any idea if the changes needed for the format detector mentioned in this thread
https://forums.sagetv.com/forums/showthread.php?t=66352

are also included in this? Hoping to be able to install this fix and keep the updates that came from the format detector.

Is this going to be as easy as replacing a couple files or will it require an updated install of SageTV?

Thanks for your efforts here, greatly appreciated.

The changes for the format detector are in Java meaning sage.jar. They are also checked in to the code repository so will get built into the next installer release, whenever that is.

In the meantime, installing a sage.jar per jvl711's instructions (https://github.com/jvl711/MediaForma...ster/README.md) would be equivalent.

[wnjj]

Attached are the patched MpegDeMux.ax filters for 32 and 64 bit. Shut down SageTV, backup the previous version and copy into the SageTV/Common folder.