***updated 10/1/2011***
I've written two guides for Beyonwiz P1 and P2 owners about fixing MKV file playback problems, based on my own experiences and stuff I've learned from others along the way.
This first topic is about audio and video issues, the 2nd guide is about subtitle issues and can also be found in this BW forum.
As you probably already know, MKV is an open source container file format, commonly containing MPEG-4 video and capable of carrying multiple file types and high definition video content. Equally cursed and loved, the format has many benefits but also has glitches and compatibility problems, particularly when being played on something other than a PC or Mac or when being converted to DVD.
Note that on these guides I am specifically referring to MKV files containing:
1. h.264 video (in a variety of SD and HD resolutions, sometimes appearing with an .avc file extension)
2. various audio file formats (including .acc .ac3 .dts .ogg)
3. various subtitle file formats (including .srt)
I'm a Beyonwiz DP-P1 owner - most advice here should apply to other models.
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THE GUIDE PART 1: AUDIO & VIDEO ISSUES
* NOTE: To get a look at what any MKV file contains just open it with MKVmergeGUI or MKVextractGUI, both free programs.
PROBLEM: With some MKV files the BW displays a peculiar distortion of aspect ratio, ie. 16:9 images squashed to about 14:9, or 4:3 images squashed to about 3:3.
COMMENTS: This is my biggest issue with MKV videos in the Anime genre encoded by other parties. Adjusting the AR settings on my BW and my plasma panel does not restore the correct A/R, it just creates other distorted displays of the image. The same file looks fine on my PC media player VLC (not immediately however; you have to force 16:9 aspect ratio), yet it never looks right on Media Player Classic. The MKV video also looks fine when converted to DVD with the program ConvertXtoDVD.
I've tried fixing the offending MKV files by opening them in MKVextractGUI, manually setting the aspect ratio or resolution, and then remuxing, but the new file always displayed the same visual distortion.
Some helpful posters at Videohelp.com offered me this technical explanation: the Beyonwiz is assuming that the h.264 video source in these particular MKV files has "square pixels" when it is really encoded using non-square pixels. The MKV container file does flag this information but some hardware and software players ignore the flag. If this is the case, then only a BW firmware fix would make the PVR treat the offending files any differently.
This is how a 16:9 video looks:
This is how a 16:9 video SHOULD look:
This is how a 4:3 video looks:
This is how a 4:3 video SHOULD look:
SOLUTION #1 (this is if you don't need subtitles): Convert the MKV to.TS file format without re-encoding, using the free program tsMuxerGUI.
Follow these steps:
1. Extract all the MKV contents using MKVextractGUI.
2. Open tsMuxerGUI. Add the separated h.264 video file and the audio file.
3. For output choose "TS muxing", choose a new file name and then start muxing.
4. The resulting .ts file should play in the right aspect ratio on your BW. Props to BW Forums member Tonymy01 for giving me this idea.
* This solution is only appropriate if you don't need to view subtitles from your source MKV file. TS files seem hate subtitle files like.srt and .sub and will display them way out of sync or not at all.
SOLUTION #2: (this is if you do need to view subtitles): Convert the MKV to MP4 file format without re-encoding the video, using the free program GOTsent. You can also use the free Zenon MKV to MP4 Conveter.
For using GOTsent follow these steps:
1. Use MKVextractGUI to extract the subtitle file/s you want to use. You won't need to use this subtitle file during conversion - just put it in the same folder as your destination MP4.
2. Open your MKV file in GOTsent - there's no need to extract video and audio seperately from your MKV file beforehand.
3. Select your destination folder.
4. Select your preferred audio stream if there is more than one.
5. DON'T embed subtitles unless you are prepared to accept quality loss and a long conversion, because your video will be re-encoded if you choose this option. Better you leave a separate subtitle file (extracted from your MKV) sitting in the same directory as your completed MP4 file.
6. "AC3 Filter Options" allows you to mess around with the audio if you want but the best setting for your output format is "AS IS". Note that if your audio source is AC3 it will be converted to .AAC format regardless - the only bummer with this solution.
7. Hit "convert". While the audio may be re-encoded, the video will not be, so you will not lose video quality.
Note: This solution is a good one regardless of whether or not you want subtitles, because MP4 is a subtitle-friendly format, unlike .TS and .M2TS. However if you want to preserve a 5.1 channel AC3 audio source (as found on most DVDs) without re-encoding, you are out of luck. That's because the MP4 container is not compliant with AC3 audio (whether 2.0 channel or 5.1) so GOTsent has to convert this to AAC audio.
PROBLEM: MKV video playback becomes jerky or stuttering and audio drops in and out.
SOLUTION: This often happens with 720p or higher resolution files (HDTV or Bluray rips) especially when streamed from your network connection.
The solution is to remux the MKV file to a .M2TS container file using the program tsMuxerGUI (props to BW Forums member Mankmeister for this solution).
For me this always works for smooth & quick playback and seeking, no matter how big the file.
I used to think this problem was the Sigma processing chip in the Beyonwiz player struggling with the demands of high def h.264 video but that's not the case at all; its the damn MKV container.
Remuxing as a .M2TS file solves nearly all jerky and freeze playback problems with files as big as 10 GB. The exception would be some 1080p HD files which the processor DOES struggle with.
PROBLEM: The "unsupported file format" error message appears onscreen when attempting to play an MKV file (here I mean files of any resolution except 1080p).
SOLUTION: I find this occurs when the MKV file contains audio encoded in.ogg format. While ogg is supported on the BW as a standalone file format for music playback, it appears this is not the case when it is the soundtrack in an MKV container. Try this:
1. Extract the ogg audio file from your MKV file using MKVextractGUI.
2. Convert the ogg file to an aac file with your preferred conversion software.
3. Open both the new acc file and the original MKV file with MKVmergeGUI.
4. Tick the aac file, and untick the ogg file that's inside the MKV container, then remux to a new MKV file under a different file name or to a different directory.
PROBLEM: Audio and video is out of sync (sync prblem type #1: the length of sync delay remains constant during playback from start to the finish).
SOLUTION: Remux the file and introduce your own delay to correct it. The program MKVmergeGUI allows you to view all the individual components in the MKV container (video, audio, subtitles) and introduce a delay in milliseconds to the video or the audio, depending on which steam is in front or lagging behind. You then remux it under a new MKV filename or to a different directory.
PROBLEM: Audio and video is out of sync (sync problem type #2: the audio/video drifts further and further out of sync as playback progresses).
COMMENTS: I've had this happen with MKV files that contain DTS-HD audio, an uncompressed version of regular DTS surround. You may also find it happens with with E-AC3/DD+ audio , a similar uncompressed surround format also found on high-def sources.
SOLUTION: Just remux your MKV to a .M2TS file using the program tsMuxer GUI. Simple!
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And finally, if all else fails with MKV playback on your BW....
Try converting your MKV file to DVD using ConvertXToDVD. There are still subtitle problems with this process but that's another story and I've shared some fixes at the end of my other post: "MKV files on Beyonwiz P1/P2 - part 2: subtitles".
Happy viewing.
PS. if you reply to this post and quote text, save our eyes and pleeeeease don't quote the entire freaking thing. thanks!
