[RESOLVED] Can't open MKV with AVC/AC3

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Karyudo
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[RESOLVED] Can't open MKV with AVC/AC3

Post by Karyudo »

I was astonished to find three video files today that wouldn't open in DGIndexNV. All three are WEB-DL MKV files with AC3 audio that play fine in MPC-HC and VLC. Two throw an "MPEG1 not supported" error, and end relatively gracefully. The other looks to have loaded fine until you try to play the file, upon which DGIndexNV says "no video frames found." Click anywhere in the DGIndexNV window, and the whole thing dies and Microsoft starts checking for errors...

I can provide the files, but they're all ~700 MB each (and, without DGIndexNV, I'm not sure how to cut them).

I'm using 2035, 32-bit, on a 64-bit Windows 7 machine.

What am I doing wrong??
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

Looks like a bug in my video type detection.

Demux the video with mkvtoolnix. Load the raw AVC in DGIndexNV and see if it still happens. If so, cut 50MB from the front of the raw file using DGSplit. Upload that to mediafire.com and post the link here. If it doesn't still happen tell me.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

Roger that. I'll get on that this evening. (Thanks!)
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mastrboy
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Re: Can't open MKV with AVC/AC3

Post by mastrboy »

It might be the same thing that has been causing me some trouble in new mkv files:
"Starting with v4.1.0 mkvmerge uses header removal compression for a couple of track types by default. These include AC3, DTS and MP3 audio tracks as well as Dirac and MPEG-4 part 2 (aka. XviD/DivX) video tracks. The user muxing a file may disable it by explicitely selecting 'none' as the compression scheme for such a track. "

There is alot of tools not handling that header compression quite well, try remuxing the files with mkvmerge and set the option none for compression
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

I'll give that a try, as well. I did discover that I myself made an MKV file that also couldn't be parsed correctly, and I did use mkvmerge to mux it, so this certainly bears investigating.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

Well, it looks like mastrboy has correctly identified the problem!

I took one of the files that didn't play nicely with DGIndexNV (the one that crashed it, in fact), re-muxed it in mkvmerge with both video and audio compression explicitly set to 'none', and it then opens fine in DGIndexNV.

admin, Is there any way to add the mkvmerge compression to DGIndexNV's type detection? Or at least identify that it's header compression that's the problem, and suggest to the user that remuxing with uncompressed headers might do the trick?

(Would you still like samples?)
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

Please provide a sample MKV that does not open in DGIndexNV. Thank you.

I cannot see how audio header compression could cause any problem. And you say that video header compression is done only for MPEG4 ASP, so that can't be the problem because DGIndexNV does not open MPEG4 ASP anyway. Maybe it's done for AVC as well?
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

I used mkvmerge to make one, so no need for a sample. It apparently *does* apply to AVC video.

I'll look into what I have to do to support this. I think it is scandalous that this was made the default for mkvmerge.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

OK, I took the file that crashes DGIndexNV, split off a 50 MB chunk with DGSplit 1.2, confirmed the split chunk also crashed DGINV, and have uploaded it to Mediafire. It's here:
http://www.mediafire.com/?gcoxufg1jd769jd

I also tried remuxing the split chunk, as follows:
• no video header compression - file seems to open fine in DGIndexNV
• no audio header compression - file seemed to open, but timeline is not navigable; hitting play brings up 'no video frames found' dialog; can't close DGIndexNV. Immediately re-dragging-and-dropping same file then crashes DGIndexNV (Microsoft dialog box saying "DGIndex has stopped working") as the original did.
• no video or audio header compression - file opened normally
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

Sorry -- missed your post in the process of drafting my own!
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

Anyway, it's not valid to split an MKV with DGSplit so your results are not useful.

I can't find any specs on header removal compression for AVC video, so I wrote to the Matroska guys about it. I've temporarily added an error popup.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

Why isn't it valid to split an MKV with DGSplit? That's not me being argumentative -- I'm truly wondering. Because it worked, and the results in this case were consistent with the hypothesis...
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

The headers still reference parts of the file that no longer exist. It may be OK, if you never try to navigate past the split point.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

I see. Makes sense that it worked fine in this particular case, then, because the main question (that I had, anyway) was if the split file would open at all. Whether or not the file would be robust at the split point was a question that didn't even cross my mind.

Glad to know the disease has been identified. Looking forward to the cure!
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

I have header removal compression working! I still have to regression test it. But it should be in the next release.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

Great news! Nice work. I still find it absolutely remarkable how relentless you are in improving your product. I suspect DGIndexNV users don't really understand how spoiled they are: point out a flaw on Monday -- one not even directly caused by DGIndexNV, even -- and it's basically fixed by Friday. Astonishing.

(Meanwhile, my corporate IT department's "fix it" page sits there, day after day, month after month, with my suggestion to improve how we use the MS Office ribbon gathering dust. Sigh.)
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admin
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Re: Can't open MKV with AVC/AC3

Post by admin »

Thanks for the kind words!

Build 2036 with MKV header removal compression is released.
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Karyudo
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Re: Can't open MKV with AVC/AC3

Post by Karyudo »

You know you're a nerd when your first coherent thought on a Saturday is, "Ooh, look! A new version of DGIndexNV that fixes my problem! Gotta download and try it!"

Downloading and trying...

(Thanks!)
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