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View Full Version : Any quality difference between mkv and iso?



debusk
November 15th, 2010, 04:00 PM
I'm having audio sync issues with almost all of my mkv files in Boxee. I rescanned one of the DVDs and created an iso file, which seems to have no audio issues. Anyway, I was just wondering if the iso format looks/works just as good as mkv in Boxee. I didn't notice any major differences, but I didn't have time to watch the whole film.

dan1son
November 15th, 2010, 05:37 PM
ISO and MKV are different containers, not really in any way explaining the video encoding enclosed inside of them.

Now USUALLY an ISO is a disk rip, most of the time a DVD or Blu-Ray disc, but technically can be anything. That is to say it's not usually recompressed and will contain the entire original disk, including menus.

An MKV is a matroska container which can contain just about any video format known to man. It can also contain meta data including chapters, subtitles, audio tracks, etc. It's probably the most versatile container around right now. Now due to the fact that it's been out since H.264 it usually contains H.264 video files and full Dolby Digital or DTS audio, but it doesn't have to. That can be of any bitrate, resolution, etc.

The only way to know is use something like mediainfo (google for it) which tells you what's inside the file.

judgeschambers
November 15th, 2010, 05:39 PM
Also, my understanding is:

ISO is also not encoded to with a codec either. More of a container.

MKV is encoded with a codec.

I can make a dvd ISO in 10 minutes, while an H264 .mkv takes 10 hrs to make.

debusk
November 15th, 2010, 06:09 PM
I downloaded a trial of Clone DVD, which scanned my DVD and allowed me to rip the film alone to an ISO, which seems to play fine in Boxee and doesn't have the audio sync issues I'm running into with mkv. Would there be a reason then not to use ISOs instead? It has subtitles as well.

Also, I noticed my bluray version of the Dark Knight has an m2ts file on the disk that contains just the film, and it also contains subtitles. Would there be a reason not to rip this directly from the disk and use it?

I guess I'm just a bit confused over the need/use of mkv if it's not necessary. Sorry for my lack of understanding. :o

judgeschambers
November 15th, 2010, 06:19 PM
ISO is uncompressed, while MKV is typically. Less hard drive space needed with an MKV.

My mkv's play perfectly on Boxee. Boxee does support many,many codecs but not all or some obscure ones. So, without knowing what your files are encoded with it's hard to say.

See my First Stop link in my sig. I have all things video posted in there.

eldepeche
November 15th, 2010, 08:23 PM
A full DVD ISO file usually runs around 6 GB. Just the main movie title is probably around 4 GB. A rip of the same DVD putting near-DVD quality H.264 video with the original 5.1 Dolby audio can be around 1 GB. If you can make do with compressed stereo audio, you can take 100-200 MB off of that.

That is the reason to compress the video.

On a Blu-Ray, however, I'm pretty sure the video is already H.264 encoded, so you are definitely going to lose some quality if you compress the video stream.

******

How did you get the MKV files that are giving you A/V sync issues? Is the audio off by a constant amount, or does it get worse as the movie plays?

Can you download Mediainfo (http://mediainfo.sourceforge.net/en/Download) and let us know the audio and video information?

dan1son
November 15th, 2010, 10:01 PM
ISO is uncompressed, while MKV is typically. Less hard drive space needed with an MKV.

My mkv's play perfectly on Boxee. Boxee does support many,many codecs but not all or some obscure ones. So, without knowing what your files are encoded with it's hard to say.

See my First Stop link in my sig. I have all things video posted in there.

That's not exactly the case. Even if an ISO is a straight rip of a DVD or BluRay with no modifications, it's still compressed. DVDs are compressed with MPEG2, Blu-Rays are compressed with H.264 or VC-1 depending on what the studio decided to use.

You can take the video and audio streams from a dvd or blu-ray ISO and de/remux them straight into an MKV file as is. Ending up with the exact same media inside a different container. You can put that same media inside of an AVI, MOV, MP4, among a few others.

Which is kind of cool... but makes it rather confusing. :)


As Judges said though, MKVs tend to be recompressed in the attempt to make the files smaller. They're also fully supported in boxee (and simple). ISO files are just disc images with a bunch of files and are really only supported if they follow the strict DVD file structure (AUDIO_TS, VIDEO_TS folders, etc. etc.). You might get lucky and have boxee play some less strict ISO files, but I'd doubt it.

DVDs using MPEG2 are relatively large files for the quality you get so it's possible to compress them into an H.264 encode (then put them in an MKV) with minimal quality loss and shrink the file dramatically. As you said it takes a long freakin time. :) Lots of processing required to do it, but it does amazingly well.

MPEG2 is also the official HDTV compression used over the air. DirecTV recompresses everything down with Mpeg4 (h.264 is a form of that) so they can fit more on the satellites without losing noticeable quality.

It's fun stuff.

Prospero424
November 15th, 2010, 11:19 PM
Also, my understanding is:

ISO is also not encoded to with a codec either. More of a container.

MKV is encoded with a codec.

I can make a dvd ISO in 10 minutes, while an H264 .mkv takes 10 hrs to make.

Incorrect. You can make a DVD ISO in a short period of time because you're not doing any recompression. You're just remuxing (copying) the audio and video streams.

You can do the same thing with an MKV - remux the original streams from the source media into a new container. You can also recompress a video stream for eventual storage in an ISO.

Also, ISO files aren't technically "containers" in the same way that the MKV format is. An ISO is an image of an actual file system (like an optical disc), and it contains media in a folder structure holding A/V containers like VOB or MT2S files. The MKV format is comparable with the VOB or MT2S containers, but not with the ISO format.

I think Dan1son adequately covered the rest of the issues at hand.

As a short answer to the original question: it depends on the quality of the audio and video streams contained within each format. Speaking very, very generally, (what you will most often see "in the wild") a BluRay ISO will look better than an MKV, which will look much better than a DVD ISO, which will still look better than an AVI.

debusk
November 16th, 2010, 03:22 PM
I can make a dvd ISO in 10 minutes, while an H264 .mkv takes 10 hrs to make.

Maybe this is part of my problem. When I create an mkv file, it never seem to take longer than an hour, two at most, even my bluray rips. Are you using MakeMKV? Is there a better program I should be using?

dan1son
November 16th, 2010, 04:43 PM
Maybe this is part of my problem. When I create an mkv file, it never seem to take longer than an hour, two at most, even my bluray rips. Are you using MakeMKV? Is there a better program I should be using?

It just depends on what settings you use. If you use something like handbrake and encode to a pretty decent variable bitrate with 5 or so reference frames it's going to take quite a long time to encode. That depends GREATLY on your processing power. On my 2.4ghz dual core macbook handbrake could encode a dvd into an H.264 MKV or M4V file in about 5 hours at their "Apple TV" preset (which yields near transparent quality IMO).

Prospero424
November 16th, 2010, 09:52 PM
Maybe this is part of my problem. When I create an mkv file, it never seem to take longer than an hour, two at most, even my bluray rips. Are you using MakeMKV? Is there a better program I should be using?

That's because MakeMKV is only a remuxer, not a transcoder. All it's doing is copying the audio and video streams from the BluRay/DVD to a MKV container.

Because of this, there will be no difference in quality between an ISO of your source (BluRAy or DVD) and an MKV. However, you will very, very quickly fill up your drive if you're storing these movies long-term. That's the trade-off you make.

With MakeMKV, you'll get file sizes in the tens of gigabytes. If you reencode the movie to a compressed MKV with something like Handbrake, you'll lose a little bit of quality, but you can achieve file sizes of roughly 1/4 the size! Edit: But I should probably mention that there can be a very steep learning curve, depending on how picky about quality you are.

It all depends on what your needs and preferences are.