MKV to MP4 file size question

[CrackerJax]

Hi. I'm trying to convert a video from MKV to MP4 and noticed a pretty large discrepancy between the file sizes. I'm using Xilisoft Video Converter.

The original MKV file is only 448MB and after the conversion to MP4 (using the HD - MPEG4 option) the file is 3.58GB. I don't know what made it essentially 6 times larger, but is there a way to tinker with the options so that I can maintain the quality and make the file closer to the original?

I also tried converting it to non-HD MPEG4, and the file size was still larger than the original (around 650MB) but the quality was terrible.

I don't know anything about video conversion so I'm not sure what accounts for the differing file sizes.

Thanks.

[aedipuss]

you re-encoded it, not converted. you might try the free mkvtomp4 app.

[jagabo]

file size = bitrate * running time

So if you want a smaller file use a lower bitrate.

Do you really need to convert? Maybe a simple remux will do (no loss of quality, about the same file size).

[CrackerJax]

file size = bitrate * running time

So if you want a smaller file use a lower bitrate.

Do you really need to convert? Maybe a simple remux will do (no loss of quality, about the same file size).

Thanks for the replies, everyone.

Well, the main reason I was converting (or re-encoding it turns out) is because when I tried putting the original file onto the Kindle the audio was out of sync all of a sudden. And even though all the MPEG4s were of poor quality the audio was at least in sync on those.

Also, could you explain remuxing?

Edit: Just tried the mkvtomp4 app. It was crazy fast, but unfortunately that still has syncing issues.

[jagabo]

Also, could you explain remuxing?

Take a cake out of one box. Put it in another box. Same cake, different box.

Edit: Just tried the mkvtomp4 app. It was crazy fast, but unfortunately that still has syncing issues.

That program remuxes the video and audio. If necessary it will convert the audio to AAC if necessary.

Since you have sync issues: Does the orginal video have sync problems when played on your computer? Exactly how is the audio out of sync when you play the original file on the Kindle? Is it off from the very beginning and off by the same amount all the way through the video? Or does it start out in sync, then slowly get more and more out of sync?

Post a full MediaInfo report of your source MKV file.

[CrackerJax]

The syncing is fine on the computer. And on the Kindle is gradually gets worse, a couple tenths of a second at first and up to like 3-4 seconds later on.

And what's a MediaInfo report? I searched and downloaded a program, and selected to open the file in it. I can't copy and paste what came up (if I'm even on the right track) so do I take a screenshot of it?

[jagabo]

Put MediaInfo into text mode (View -> Text). Right click on the text and select Select All. Right click again and select Copy. Paste the text into the editor here.

[CrackerJax]

General
Unique ID : 213230852812252047585197348374306910731 (0xA06AC4B920DB21EF8AF8F52DC274720B)
Complete name
Format : Matroska
Format version : Version 1
File size : 448 MiB
Duration : 2h 3mn
Overall bit rate : 506 Kbps
Movie name : The Noteook - YIFY
Encoded date : UTC 2011-03-26 14:00:24
Writing application : mkvmerge v2.2.0 ('Turn It On Again') built on Mar 4 2008 13:20:25
Writing library : libebml v0.7.7 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 2h 3mn
Nominal bit rate : 468 Kbps
Width : 1 280 pixels
Height : 544 pixels
Display aspect ratio : 2.35:1
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.028
Title : The Noteook - YIFY
Writing library : x264 core 98 r1649 c54c47d
Encoding settings : cabac=1 / ref=3 / deblock=1:-2:-1 / analyse=0x3:0x113 / me=umh / subme=5 / psy=1 / psy_rd=0.00:0.00 / mixed_ref=1 / me_range=12 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=16 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=3 / weightb=1 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=468 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=2:1.00
Default : Yes
Forced : No

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : HE-AAC / LC
Codec ID : A_AAC
Duration : 2h 3mn
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz / 24.0 KHz
Compression mode : Lossy
Title : The Noteook - YIFY
Default : Yes
Forced : No

Text
ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Title : The Noteook - YIFY
Language : English
Default : No
Forced : No

Menu
00:00:00.097 : en:00:00:00.097

[enim]

I'm trying to convert a video from MKV to MP4 and noticed a pretty large discrepancy between the file sizes. I'm using Xilisoft Video Converter.

Just for changing container MKV <===> MP4, you can avoid re-encoding, you should not run mkv or mp4 through a video converter.

All you need is de-muxer and muxer. You can de-mux mkv or mp4 into raw streams .h264 and aac and re-mux into mp4 or mkv, vice versa. In later case, you will probably maintain same size except container headers. I do not know how to handle text (subtitle) stream.

[jagabo]

If you can't get a remux to work... I'm not sure which Kindle you're using and what it's limitations are, but try XMediaRecode. It's free, has Kindle presets and works pretty well otherwise.

I suspect the MKV's 16 b-frames is too much for the Kindle. Otherwise the settings don't look too extreme.

[enim]

I never had enough time to dive into a pool of free-stuff. All good converters should have stream pass-through (direct stream copy) feature, for changing containers and valid output.

MKV's 16 b-frames

I missed that part.