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[squeedle]

I'm trying to troubleshoot this issue but would love some advice on where to start. I've ripped my entire library of thousands of DVDs to MKV (H.265), and I don't think I've seen this particular problem before. This file plays fine in VLC but looks all garbled in JRiver (see image below). Any troubleshooting tips?

[squeedle]

Here's roughly the same time in the video grabbed from VLC.

[JimH]

Set MC video to both Red October Standard and HQ.

[squeedle]

Same distortion in both modes.

[wer]

Change the state of the "hardware accelerate video decoding where possible" option.

[squeedle]

Update: I watched the entire 30 minute program in VLC and VLC struggled with it in a few spots too. So there's just something funky with this encoding. I tried re-encoding it with H.265 several times, and same results. For some reason it works fine if I encode it with H.264. Never seen this before. So I'm just gonna use the H.264 encoded file for this program. Super weird. Would be curious to hear if anyone has experienced this before, but whatever it is, it's not JRiver's fault (although VLC does MUCH better with the H.265 file for some reason).

[JimH]

Thanks for posting what you found.  It's possible the machine doesn't have enough power.

[squeedle]

Update: I was able to do some more testing and the issue seems to be related to the "Modulus" setting in Handbrake > Dimensions. The default setting is 2, which causes the issue. If I change it to 4, the issue is resolved. Again, this only seems to be an issue with H.265, not H.264 for some reason.

I don't know what this setting is exactly, the Handbrake tool tip only says:

"Align storage dimensions to multiples of this value. This setting is only necessary for compatibility with some devices. You should use 2 unless you experience compatibility issues."

I realize the mods will say this is a Handbrake issue, and that's fine. I'll try to post in their forums as well. But does anyone here know why MC is unable to correctly interpret these "Modulus 2" files while VLC can? Or if it's possible to alter this setting without re-encoding (is this a setting that lives in the MKV file header or something)?

[Hendrik]

Can you provide a small sample of such a file that doesnt decode properly?

The corruption doesn't look like any typical errors i've seen before.

[squeedle]

Thanks so much for your interest, Hendrik. I have done more testing and found that the problem is actually the dimensions of the file. Perhaps with certain dimensions, MC doesn't know how to correctly determine the aspect ratio? This is what the "Modulus" setting in Handbrake is about: it ensures that the dimensions of the file are cleanly divisible by 2 or 4 or 8, etc. And depending on what value you select, it actually resizes/stretches the dimensions of the file to cleanly fit one of those divisors. It seems MC might need a Modulus of 4 (not 2) in order to work properly in some odd cases? Such as mine...

My file has dimensions of 706x572.

If I select Modulus 4 for this file, 706 does not divide cleanly into 4, so Handbrake resizes it to width of 704. And then MC can play it properly.

But if I select Modulus 2 for this file in Handbrake, 706 does divide cleanly into 2, so the original dimensions are retained. But then MC can't play it properly.

Here are sample files with both dimensions, along with screen grabs from both Handbrake and MC:
http://www.mhat.com/temp/yabb_122225.zip

[Hendrik]

Are you using hardware decoding?

For the record, it seems to be playing fine in MC26, so I would assume the underlying issue was fixed in the decoder we use in the last 2 years since MC23 was made.

[squeedle]

No hardware decoding, that doesn't seem to work well on my system.