They don't open in Vegas.

Open source VLC or similar tools - mkv is an open source codec and does not get respect from the establishment boys.

MKV is a wrapper, not a codec. It's format-agnostic, meaning you can put almost anything in it. Probably also why Vegas will never support it.

Use MKVExtractGUI-2 (requires MKVToolnix) to pull your source from the wrapper, then see if that is happy in Vegas, whatever it may be.
A third party conversion tool would be a last resort.

My bad, I said previously .mkv is a codec, but I meant to say wrapper which usually contains a file type that VLC or other open source players will recognize and play. Open source creation or utility software may allow you to manipulate the .mkv wrapper to the extent that it can be many many things. It really helps to know who created the .mkv wrap that you received and what did they start with as the source file.

According to VLC Media Player, the video codec is:

H264 - MPEG-4 AVC (part 10) (avc1)

Video Decoded Format: Planar 4:2:0 YUV

and the audio codec is:

MPEG AAC AAC Audio (mp4a)

I'm not sure why the codec is listed as an mp4, since the file is an .mkv file. Does this info help you guys in finding out a solution to my problem? If you need other info, please let me know. I'm not sure what a wrapper is, I know that a codec is for playing certain types of video files, but that's all I really understand. Is Open Source Creation a program or a terminology?

Any help with this stuff would be greatly appreciated.

Thanks.

Open source means a methodology adopted by computer programmers around the world to open their coded works to others for a universal relative license free tech. What the movement has accomplished is somewhat debatable. Take the .mkv wrapper for example - it can be used by people - but since holders of licenses and patents like Sony do not have a clear interest in this tech, they bypass and ignore it.

Ok, thanks for explaining that to me. I tried using VSO's Video Converter (in Trial mode, so only the 1st 10 minutes are in the converted file) to convert the .mkv file to an .mp4 (regular mp4) and .avi (H264), both files play fine in Windows Media Player and they play fine when I select the Open Media In Player option in DVD Architect, however, I get an error message if I try to add either file to my Blu-ray project (despite it playing fine through the program's media player). I don't see a preview when I just click on the file once, but the video does play if I select the Open Media In Player option (while right-clicking on the file). The error message that I am getting is:

The file is an unsupported format

If I click on Details, it has this error info:

File C:\Users\DraculaX\Documents\VSO Video Converter\Generic video\PS3_Longplay_011_Uncharted_2_-_Among_Thieves\MP4 - Mpeg4\PS3_Longplay_011_Uncharted_2_-_Among_Thieves.mp4 could not be opened.

I'm not sure what the problem is. Do you think DVDAS5 could be partially corrupt or damaged? I can't think of any other reason why it can be opened and viewed, but not added. Should I try uninstalling DVDAS5? I checked for updates, but the website says that the program is up-to-date.

Tools for extracting your AVC/AAC mp4 file from mkv wrapper are listed above. Once you've done that, it should open in Vegas for encoding to compliant BluRay templates. If you have problems with that, post back. But at least get your feet wet, first.

I repeat, third party conversion is not recommended, since you should be able to extract your source video perfectly from the wrapper.

Never install a codec "pack" on your editing machine, and only install a specific codec, it told to do so, from its manufacturer.

If you need help understanding basic video editing terminology and glossary, read here first:
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=866336

Ok, I extracted the .mkv into 3 files (audio, video, and chapters) and I successfully added the audio file to Vegas. How do I add the video file to the project? The video file is named:

PS3_Longplay_011_Uncharted_2_-_Among_Thieves_track1_eng.h264

Am I supposed to change the file extension?

Will your .h264 video open directly in DVD Architect, bypassing the Vegas step?

No, it says:

"The selected file is not of the required type"

Try renaming the extension to .mp4 or .avc
If that doesn't work in Vegas or DVDA, you may need a muxer.
I have a feeling your files are quite large, otherwise I'd ask you to upload them somewhere so I wouldn't have to guess. How big is the mkv itself?

The original .mkv file is 10.4 GBs. MKVGUI has a muxer option, but when I did that with the original .mkv file, it just created a duplicate .mkv file. I'm not sure what muxer does. Am I supposed to mux the audio and video files together into a single file? If so, will that just turn it back into an .mkv file? Any help with this would be greatly appreciated.

Thanks.

Mux the video and audio into an MP4, M2TS, MTS, M2T or TS file, whichever works. I would have thought you could do this in the extraction phase. If you can't do that in the GUI, use TSMuxer instead. Your problem "should" be solved.

Both DVDAS5 and Vegas freeze when I try to add (or preview) the .ts, .m2ts, etc. files. They play fine in WMPlayer, but not in DVDAS5 or Vegas. I couldn't find an option in TSMuxer to make it into an .mp4 file. I also tried making the 2 separated files into a Blu-ray via TSMuxer, but that doesn't play at all on my PC or Blu-ray player (it's just a blank screen). Is there anything else I can try to get this working? Any help would be greatly appreciated.

Thanks.

Sorry, I can't help you further without a short identical MKV as a working example. Understand I'm working totally blind here.
If it started as AVCHD (as it appears), it can be reconstituted as AVCHD.

TSMuxer doesn't make mp4 files.

I thought I might post on this old thread only because I was recently trying to open mkv files in Vegas and DVDA. Almost every Google search result says to recode the file which seems like a very poor choice (as mentioned in this thread). I was successful using a free tool : AviDemux. https://sourceforge.net/projects/avidemux/. The tool allows for direct copy of the audio/video into a wrapper of choice without encoding. It is very fast! I converted to AVI wrapper and the files opened straight away in Vegas. Renaming the AVI to AVC allowed the same file to open in DVDA. Another useful tool for extracting audio to ac3 (or wav) is TAudioConverter. It will extract the audio to a large number of formats and is very simple to use. It is not necessary to demux the audio from the video. Simply drop the multiplexed video file into the program, select the correct track, and convert to ac3. http://taudioconverter.sourceforge.net/ I've had more luck using this tool than Vegas. My ac3 files from Vegas won't open in DVDA.