Weird video problem with some MKV files

[carlmart]

This problem I am going to describe is not the rule, but is beginning to happen more often that I would like to.

The movement freezes or jumps from one image to another, like in low quality slow motion. Until now it had mostly happened with some specific kind of images, like moving water, or a strong current of watter, or a waterfall, or even with large explosions. I think it happend on some slow motion sequences too sometime. It looked as if the system was not able to recover the compressed data in the MKV file, if I had to risk an explanation.

In general it happens with 1080p files, and maybe that's why it has been happening more often lately, as I am preferring to download 1080p versions of the same file, if available and not too large. Perhaps I should be paying attention at the kbps rate and reject when it's less than some value?

Today it happened with two sequences (I stopped the film, so there might be more) which didn't have water or fire in them, so I'm starting to get worried.

Are the MKV files changing and the player I'm using can't cope with newer mkv files? Can I re-convert them or should I?

[Baldrick]

What do you play with? On a computer can you try a different player and see if it make any diffference, like potplayer, splash, mpchc or vlc.

[carlmart]

The player I care about is the LG bluray player I use, as many times I burn discs with these MKV files which I want to keep.

OTOS I am getting even worst behaviour sometimes with VLC, even when I tried using my laptop as player and going into my plasma through VGA. Sometimes I had small stop/going situations.

But my concern now, as I said, is the bluray player. There are not that many mkv external players around, except for media centers, and my expectation that more and more BD players would come around is not fulfilling.

[redwudz]

Not that many laptops will play HD MKVs smoothly. VLC, while a great player, does take a bit more CPU power for decoding MKV. MPC-HC is a better choice. If you have a DXVA compatible video card/chipset, that helps playback a lot.

You could drop one of the problem videos into MediaInfo, tree view, and check the bitrate compared to a MKV that plays back OK. I suspect the problem ones are encoded with variable bitrate and the bitrate spikes higher where you get the stuttering.

If the problem is to high a bitrate for your set top player, you may have to re-encode them.

[carlmart]

Your suggestions still don't answer my questions about the LG player, which is the principal player I'm interested in. I'm not too much interested in using a laptop or an HTPC in the future for playing the mkv files. I just mentioned the laptop, which I'm just by chance using these days until I get my desktop back on.

Now, how do I know if a file was encoded with variable bitrate and what can I do to solve the potential problems?

I just did have the stuttering problems with another file, and it might be interesting to see how can I deal with them.

Mediainfo just tells me the rate is 9271kbps. If it's important I can put here the whole data listed by Mediainfo.

[jagabo]

It sounds like bitrate peaks are too high for the player. Use Bitrate Viewer to view a graph of the bitrate to see if the peaks coincide with the jerky playback. The only way to deal with this problem is get a different player or reencode the videos.

[carlmart]

Reencode means just remuxing the file again or what?

[aedipuss]

re-encode would mean to re-encode as in with an encoder like handbrake, mediacoder, xvid4psp, etc. re-muxing would be with mkvmerge which might be a good idea if the videos were made with mkv header stripping.

mediainfo in text mode of a bad file might help if you pasted it here.

is the lg receiving the video through a wired or wireless network? or played off a hard drive?

i wouldn't bother with any 1080 material with a bitrate under 9-10mbps

[carlmart]

To start with, here's the Mediainfo data:

General
Unique ID                                : 197752313436983289314702047888821874204 (0x94C5B5CFCC9629AC945E75DA0ED26E1C)
Complete name                            : C:\file.mkv
Format                                   : Matroska
Format version                           : Version 1
File size                                : 8.42 GiB
Duration                                 : 1h 45mn
Overall bit rate                         : 11.4 Mbps
Encoded date                             : UTC 2011-07-03 01:29:47
Writing application                      : mkvmerge v2.3.0 ('Freak U') built on Sep  8 2008 18:32:16
Writing library                          : libebml v0.7.7 + libmatroska v0.8.1

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 5 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 1h 45mn
Bit rate                                 : 9 271 Kbps
Width                                    : 1 920 pixels
Height                                   : 800 pixels
Display aspect ratio                     : 2.40:1
Frame rate                               : 23.976 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.252
Stream size                              : 6.67 GiB (79%)
Writing library                          : x264 core 115 r2008 4c552d8
Encoding settings                        : cabac=1 / ref=5 /  deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=7 / psy=1 /  psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 /  8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-2 /  threads=12 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 /  bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 /  b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 /  keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 /  rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=9271 / ratetol=1.0 /  qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 /  ip_ratio=1.40 / aq=1:1.00
Language                                 : English

Audio #1
ID                                       : 2
Format                                   : DTS
Format/Info                              : Digital Theater Systems
Codec ID                                 : A_DTS
Duration                                 : 1h 45mn
Bit rate mode                            : Constant
Bit rate                                 : 1 510 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 KHz
Bit depth                                : 24 bits
Compression mode                         : Lossy
Delay relative to video                  : 11ms
Stream size                              : 1.11 GiB (13%)
Title                                    : English DTS 5.1
Language                                 : English

Audio #2
ID                                       : 3
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Mode extension                           : CM (complete main)
Codec ID                                 : A_AC3
Duration                                 : 1h 45mn
Bit rate mode                            : Constant
Bit rate                                 : 640 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Compression mode                         : Lossy
Stream size                              : 483 MiB (6%)
Title                                    : English DD5.1
Language                                 : English

Text
ID                                       : 4
Format                                   : UTF-8
Codec ID                                 : S_TEXT/UTF8
Codec ID/Info                            : UTF-8 Plain Text
Title                                    : Nederlands SRT
Language                                 : Dutch

General
Complete name                            : C:\file
Format                                   : SubRip
File size                                : 93.5 KiB

Text
Format                                   : SubRip
Compression mode                         : Lossless

The LG receiver is wired, of course. Wireless reception of HD files is always stuttered. It should never be used for this purpose.

I haven't tried this file off a data stick on the player.

I will try remuxing and see what happens to the bitrate.

[carlmart]

Just for the record.

I've just tried a memory stick and played the critical parts. The problem happens again: stuttering image, sound mutes, etc.

It seems to be a little bit less than on the network connection though.

I also tried MPC-HT with this files and it certainly plays better than on VLC. But the film audio is slightly out of sync with it, which was not the case on VLC or the LG player.

[jagabo]

Remuxing won't change the bitrate. The usual symptom of "header removal compression" in newer releases of MKVMerge is the player not playing the file at all. I think 5 reference frames could be a problem.

[carlmart]

I guessed so about the bitrate not changing on remuxing.

Now checked on other 1080p files I have on my HDD, and they all have 5 reference frames too. Even the 720p version of the same file I have is also 5 reference frames, and it doesn't seem to affect its flawless playing.

The problem seems to be in the bitrate count. The 1080p version gets to very high rates on the critical play points, but the 720p version even plays fine the medium bitrate points where the 1080p version failed to.

Of course there's no danger of burning a critical play file, as I watch them first complete and burn them later if they are interesting.

Another thing on the 1080p version: when played on the MPC-HC, this file has out of sync audio. This is in common with the other problematic 1080p file. So I just compared another 1080p file I had, and it played fine with MPC-HC, completely in sync.

I don't know what that symptom means, but at least shows me that if I can play a 1080p file with MPC-HC with no problems, then the file is "fine". Not a very profound finding, but at least a seemingly valuable info...

[jagabo]

I don't know what that symptom means, but at least shows me that if I can play a 1080p file with MPC-HC with no problems, then the file is "fine".

I wouldn't count on that.

[carlmart]

Well, that's why I wrote fine between quotation marks.

[aedipuss]

that mkv was created about 3 years ago. x264 and mkvtools were not as good at 1080 material back then as they are now. i'd "make" a new version if possible. it's most likely just a badly rendered video.

[carlmart]

Two comments on that:

1) I don't have access to the original file, so I can't render it again. Only convert it using the programs suggested above.

2) The MKVmerge used may be an older version, but the the encoding date was 03/07/2011. I wonder why they still used that version.

Edit: OK, I think you mean the x264 converter is from 2008, right?

[aedipuss]

i don't know, a remux is always worth a try though, it only takes minutes. get the latest version of mkvtools and make sure to turn off header stripping in the settings then open it with mkvmergegui and set any video things like 23.967fps that it misses then mux.

[jagabo]

get the latest version of mkvtools and make sure to turn off header stripping in the settings

File -> Options:



Turn that feature on for maximum compatibility.

[carlmart]

Talking about MKVmerge, sometimes the "disable header compression" trick is not enough.

What should be done is what I explain here in way 2:

https://forum.videohelp.com/threads/337066-Understanding-MKV-files?p=2110022&viewfull=1#post2110022

That should guarantee compatibility.

[fits79]

Is there any program that i can add it one folder with mkv files with "header removal compression" and remove it from ALL the mkv files there is in that folder and subfolders without writing again the mkv file simply remove that "header removal compression".

A lot of thanks.