How to reduce video bitrate of a MKV file?

[doronb2]

Hi,
I have a weak gpu but I prefer 1080p movies than 720p so I want to reduce the bitrate of my favorites movies (all of them are x264 MKV files) so I could watch them smoothly.
I'm new to video editing so I'm asking - what program to use? how do I do it?

Thanks

[jagabo]

Spend US$50 on a graphics card with hardware h.264 decoding instead. If your CPU is too weak to play 1080p h.264 it will take you eons to reencode them.

[porfitron]

The new DivX Plus Converter will accept MKV as input and output in the DivX Plus HD (H.264/MKV) profile. Even though it says 15-day trial, that is just for the DivX/AVI output presets... it will continue to make DivX Plus (H.264/MKV) files for free after the trial, so it'll remain completely free for what you're trying to do.

As jagabo points out, if you have a graphics card that supports DXVA, you won't have to re-encode your videos because they can be decoded on the graphics card instead of the CPU, but if upgrading your hardware is not an option, you can try creating lower bit-rate files with DivX Plus Converter:
http://www.divx.com/software/divx-plus/converter

[obewon]

uncropMKV JUST CHANGE THE BIT RATE SETTINGS

[obewon]

uncropMKV JUST ALTER THE BIT RATE SETTINGS

[doronb2]

porfitron, I have a Nvidia 128 mb 8400gs M in my notebook and from what I read in the divx site it supports DXVA.
What are you saying? I'll be able to see these movies if I install the new divx drivers??
I have problems with 1080p movies with 10+ mbps.
Thanks you all for your responses.

[jagabo]

I thought DXVA started with the 8600 GT. But if your 8400GS M supports hardware h.264 decoding: you need a driver that supports DXVA (get the latest drivers from Nvidia), and a player that supports DXVA. Try MPCHC. Enable DXVA decoding of h.264 by selecting View -> Options -> Internal Filters. In the Transform Filter box tick "h.264/AVC (DXVA)". Exit MPCHC and restart it.

[porfitron]

I read in the divx site it supports DXVA.

Yeah, the free DivX Plus Codec Pack supports DXVA, so you just need to go enable it in the settings as described here:
http://labs.divx.com/DivX-H264-Decoder-DXVA

It's free, so why not give it a shot

[guns1inger]

Media Player Classic Home Cinema also supports DXVA and doesn't require an install. I would test playback with it first before installing anything else.

[doronb2]

OK, I'll give it a try.
THANKS!

[doronb2]

Checked again and 8400M GS is suppose to handle DVXA. I tried Media Player Classic Home Cinema but the movie still cripples after few minutes and in the program's menu options -Play->Filters->MPC video Decoder properties it said "Not using DXVA" , so I installed the divx drivers and the latest nvidia driver.
When I used the divx movie player after few minutes the movie starts to cripple again, so no good. Tried again with the Media Player Classic Home Cinema and my regular Media Player Classic but again "Not using DXVA". I also tried using KMplayer with DXVA and a week ago with coreAVC and CUDA but in both cases the movie cripples right from the first second (worse than without the CUDA or coreAVC).
obewon, I installed uncropMKV but the movie went out bad, the video and audio just ruined.
Any ideas why my intel core 2 duo T8300 2.4 ghz with 4 GB RAM and 128 MB 8400M GS can't handle video bitrate of 10-12+ mbps??

[jagabo]

The fact that MPCHC is not using DXVA hints that your video card's drivers don't support it. Update to the latest WHQL certified drivers for your 8400M GS.

Note that DXVA does not support all possible h.264 features. Many people encode with settings that are not DXVA compatible (too many reference frames, too many b-frames, for example).

Normally a 2.4 GHz C2D is fast enough to decode 1920x1080 h.264 in software. Especially with CoreAVC Pro (the regular CoreAVC is single threaded and definitely won't be fast enough) and Divx's latest h.264 decoder. Make sure MPCHC is set to use 2 threads when using its internal h.264 decoder. Double click on the decoder in the same Transform Filters list and set Decoding Thread Number to 2. Also make sure your laptop isn't set to maximum power saving mode. That may limit the clock speed to levels where it can't decode fast enough, even with 2 threads. Run Task Manager to see how much CPU is being used while playing a video.

Try using different output devices in MPCHC. View -> Options -> Playback -> Output. Try especially System Default and Overlay Mixer. In my experience the VMR and Haali output devices are too slow when using integrated graphics.

When playing a video on MPCHC you can right click on the window and hover over Filters to see what filters are in use. You can select any of them to get their options dialog.

[creamyhorror]

After you install the DivX H.264 decoder, you need to make sure it's being used under MPC-HC's Filter submenu. If it is, I'm pretty sure your video will have no problem.

And yes, stick to Overlay Mixer for now, as jagabo said.

[doronb2]

OK, I'll download a heavy video bitrate file and report back in a couple of days.
In the mean time I used Handbrake successfully to re-encode and it worked fine.
Thanks a lot for your help!

[doronb2]

I didn't succeed to view with the DXVA but I just finished view a 1080p movie with 17.5 mbps video bitrate with the regular Media Player Classic, and it went just fine. It used coreAVC and as long as I didn't opened another CPU-demanding program (even a web browser) I was able to see the movie smoothly. Maybe my regular video playing program - KMplayer - don't work well with coreAVC, I don't know, but what it matters - I CAN see high video bitrate movies.
Nevertheless, I tried to re-encode movies to save on disk space and "Handbrake" did it very good.

Thanks you all for all your help!!