How to crop MKV files without losing quality?

[Chengbin]

I have a movie with black bars, how do I crop that out without losing quality?

[Ranguvar]

You could make an AviSynth script:

DirectShowSource("C:\video.mkv")
Crop(40, 50, -60, -70)

That would crop 40 off the left, 50 off the top, 60 off the right, and 70 off the bottom. You can then play the script in your favorite player.

Some players may also have an option to crop.

These are some of the only lossless choices; I don't believe there is any way of adding a parameter to an MKV so that players automatically crop?

[Snowknight26]

There is, but its something like only from the bottom and right.

[nm]

So you tried to set the cropping values at container level? I seem to get the same effect with VLC, although mkvinfo shows that cropping is set correctly. That leaves two lossless options: fix the bug in the player/demuxer/splitter or set cropping values manually within the player or with AviSynth every time. Some players may also be able to crop black bars automatically.

[bond]

h264info can crop losslessly on h264 video stream level (not container):
http://forum.doom9.org/showthread.php?t=123392

[Atak_Snajpera]

Use mkvmerge GUI and this command line (Muxing -> Add command line options)
--cropping <TID:left,top,right,bottom>
Sets the cropping parameters.

[elguaxo]

thanks for the info Atak_Snajpera!

[nm]

Use mkvmerge GUI and this command line (Muxing -> Add command line options)
--cropping <TID:left,top,right,bottom>
Sets the cropping parameters.
That's what I tried and it doesn't seem to work with VLC and MPlayer. VLC only crops bottom and right parts out and MPlayer does nothing. So bond's suggestion is perhaps a more reliable way for now.

[Atak_Snajpera]

Did you check in MPC-HC?

[nm]

Nope, I don't have Windows around.