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View Full Version : Converted MKV to M4V and went from 9.39GB to 3.21GB is this normal?




hankkosovo
Aug 15, 2012, 07:18 PM
I used the ATV3 settings in hand brake and I'm just puzzled how the file size has been reduced so much when the quality seems the same, can anyone shed some light on this?



simsaladimbamba
Aug 15, 2012, 07:19 PM
In order to find out, what is the cause of the file size reduction (it is a lowered bitrate), you can use the following three applications to analyse the source .mkv and resulting .mp4.

VideoSpec (http://laurent.ettouati.free.fr/english/) (free)
MediaInfo (http://mediainfo.sourceforge.net/en) (free)
Media Inspector (http://mediainspector.massanti.com/) (2.99 USD in the Mac App Store (MAS) (http://itunes.apple.com/us/app/media-inspector/id419975242?mt=12))

When done, you can use the "Report" (VideoSpec) and "Export" (Media Inspector) button to export a report,
attachable to your next post via the http://dl.dropbox.com/u/10644330/MR_Image_Hotlinks/MR_screenshots/MR_screenshots_2012_02/2012_02_MR_attachbutton.png button.
In MediaInfo you have to go to the Menu Bar, select View > Text and copy the text via CMD+A > CMD+C and paste it via CMD+V into your next post.

mic j
Aug 15, 2012, 08:26 PM
I used the ATV3 settings in hand brake and I'm just puzzled how the file size has been reduced so much when the quality seems the same, can anyone shed some light on this?

I think that is reasonable. A lot of my dvd are 1GB from 5-6GB. It really varies because of the source, but if I got that I would not even question it.

simsaladimbamba
Aug 15, 2012, 08:33 PM
I think that is reasonable. A lot of my dvd are 1GB from 5-6GB. It really varies because of the source, but if I got that I would not even question it.

Video DVDs use the MPEG-2 codec (old), which is not that space efficient and are from 4 to 8 GB in size, .mp4 files use the H.264 codec (newer MPEG-4 codec), which is quite space efficient, thus the smaller file size. .mkv files typically use H.264 or x264 (also an MPEG-4 codec), thus a file size reduction might also come with a reduction in visible image quality or even resolution reduction.

mic j
Aug 15, 2012, 09:55 PM
Video DVDs use the MPEG-2 codec (old), which is not that space efficient and are from 4 to 8 GB in size, .mp4 files use the H.264 codec (newer MPEG-4 codec), which is quite space efficient, thus the smaller file size. .mkv files typically use H.264 or x264 (also an MPEG-4 codec), thus a file size reduction might also come with a reduction in visible image quality or even resolution reduction.

MPEG2 is not old, it's currently in use on every standard dvd. h.264 is used on BR's as they are compressed from original material. Only torrented mkv's are h.264 which means they have been compressed from a mpeg2 or BR. What's your point?

simsaladimbamba
Aug 15, 2012, 10:02 PM
MPEG2 is not old, it's currently in use on every standard dvd. h.264 is used on BR's as they are compressed from original material. Only torrented mkv's are h.264 which means they have been compressed from a mpeg2 or BR. What's your point?

MPEG-2 is old compared to MPEG-4, for me it is old, since it is a storage space inefficient codec.
As for what my point is, the size reduction is dependent on what resolution, codec and bit-rate the source had and what resolution, codec and bit-rate the target file has.
Another part of my point is, that transcoding MPEG-2 to MPEG-4 almost always results in smaller sizes, as video DVDs use a bit-rate of 5 to 8 Mb/s, while H.264 encoded videos use 1 to 2 Mb/s, often even less. MPEG-4 is more space efficient.

I know .mkv is a container for many codecs, MPEG-4 is the one use most often though, and 9 GB sounds like an HD rip of a Blu-Ray using some MPEG-4 variant as codec.

MacinJosh
Aug 16, 2012, 12:07 AM
Don't forget that there are several profiles within the H.264 spec of varying quality. A High Profile level 4.1 can go down in file size significantly while retaining quality, something Low or Main Profile can't come near to.

And yes, MPEG2 *is* old. Almost 20-years.

hankkosovo
Aug 17, 2012, 07:54 AM
In order to find out, what is the cause of the file size reduction (it is a lowered bitrate), you can use the following three applications to analyse the source .mkv and resulting .mp4.

VideoSpec (http://laurent.ettouati.free.fr/english/) (free)
MediaInfo (http://mediainfo.sourceforge.net/en) (free)
Media Inspector (http://mediainspector.massanti.com/) (2.99 USD in the Mac App Store (MAS) (http://itunes.apple.com/us/app/media-inspector/id419975242?mt=12))

When done, you can use the "Report" (VideoSpec) and "Export" (Media Inspector) button to export a report,
attachable to your next post via the Image (http://dl.dropbox.com/u/10644330/MR_Image_Hotlinks/MR_screenshots/MR_screenshots_2012_02/2012_02_MR_attachbutton.png) button.
In MediaInfo you have to go to the Menu Bar, select View > Text and copy the text via CMD+A > CMD+C and paste it via CMD+V into your next post.

Thanks for the info! Here are the reports:

9.39GB:

***** Analyzed File Results *****

*** General Parameters ***
- Name: fhd-antichrist.1080p.mkv
- Container: Matroska
- Size: 9.395 GB
- Duration: 1h 44mn
- Bitrate: 12.0 Mbps

*** Video Track Parameters ***
- Format: H.264/MPEG-4 AVC
- Bitrate: Max.: Undefined / Average: 9 012 Kbps / Min.: Undefined
- Frame rate (fps): Max.: Undefined / Average: 25.000 / Min.: Undefined
- Encoding profile: High@L4.1
- Image size: 1920*816
- Pixel Aspect Ratio: Undefined
- Display Aspect Ratio: 2.35:1
- Interlacing: Progressive

*** First Audio Track Parameters ***
- Format: DTS Coherent Acoustics
- Bitrate: 1 510 Kbps
- Resolution: 16 bits
- Rate: 48.0 KHz
- Channel(s): 5:1 - 6 channels
- Position: Front: L C R, Side: L R, LFE

*** Miscellaneous ***
- Subtitle(s): #1 : UTF-8 - French / #2 : UTF-8 - French /
- Album: Undefined
- Performer: Undefined
- Genre: Undefined
- Encoded date: UTC 2009-11-04 23:04:58
- Album artist: Undefined


3.21GB

***** Analyzed File Results *****

*** General Parameters ***
- Name: Antichrist 1080p.m4v
- Container: M4V - QuickTime
- Size: 3.21 GB
- Duration: 1h 44mn
- Bitrate: 4 113 Kbps

*** Video Track Parameters ***
- Format: H.264/MPEG-4 AVC
- Bitrate: Max.: Undefined / Average: 3 308 Kbps / Min.: Undefined
- Frame rate (fps): Max.: --- / Average: 25.000 / Min.: ---
- Encoding profile: High@L4.0
- Image size: 1920*816
- Pixel Aspect Ratio: Undefined
- Display Aspect Ratio: 2.35:1
- Interlacing: Progressive

*** First Audio Track Parameters ***
- Format: AAC - MPEG-4 audio
- Bitrate: 160 Kbps
- Resolution: Undefined
- Rate: 48.0 KHz
- Channel(s): 2 (stereo)
- Position: Front: L R

*** Miscellaneous ***
- Subtitle(s): No Subtitle
- Album: Undefined
- Performer: Undefined
- Genre: Undefined
- Encoded date: UTC 2012-08-06 15:05:15
- Album artist: Undefined


It looks like the bit rate has been reduced, is there anyway to stop this in handbrake?

J@ffa
Aug 17, 2012, 08:13 AM
You don't need to convert that file — the Apple TV can play it natively. It's a common problem both here and elsewhere because this process is a bit confusing, but I'll try to explain it as simply as I can.

MKV files are containers, which can hold a variety of video and audio formats. In your case, the file you've… acquired (ahem :p) has H.264 video in it and DTS audio. In terms of containers, the Apple TV only supports the .m4v and .mp4 containers. These are essentially identical, but the .m4v extension is better for either chapters or subtitles (can't remember which, but this is a minor detail). In theory, you can use a software tool to drop the H.264 video and DTS audio into an .m4v/.mp4 container, which would take you the time it takes to copy those files, plus a little extra time to do some special stuff that makes the file play nicely with the Apple TV. The bit where you move the files into a different container is called muxing (or, more accurately, 'remuxing').

However, the Apple TV doesn't support DTS audio. So what you need to do is use a tool that can convert that DTS 5.1 audio into Dolby 5.1, which the Apple TV does support — and, while you're there, add a 2.0 stereo downmix so the file you've got can be played via iTunes/QuickTime on your Mac and any iOS devices you may have. This bit is optional, but the better tools will do it by default, since audio encoding doesn't take particularly long and it doesn't hurt to futureproof your files.

There are dozens of ways to do what I've described, and I've tried most of them. The one I'd recommend most highly is iFlicks (http://www.iflicksapp.com/), which is a drag and drop affair. Drop the Antichrist MKV onto the window, select the 'iTunes compatible' preset, and wait (usually this process takes 10-20 minutes in all, depending). The resultant file will be the same size as the original, give or take a few hundred megabytes (which'll account for the extra audio track). You'll also have no video quality loss, since the H.264 video track will be exactly the same as it is in the .mkv.

Good luck!