How to change fps in an MKV 25 down to 23.976 ?

[mahogany]

I'd like to convert an MKV movie from 25 fps down to 23.976 fps and then make of this AVCHD format so after burning out I would be able to watch on my PS3 and my friend on his BD player. For this purpose I used multiAVCHD program and the result was unsuccessfull (audio to video out of sync). I used tsMuxeRGUI and manually set fps to 24000/1001 but during muxing some error comes on:
>Reading buffer overflow. Possible container streams are not syncronized. Please, verify stream fps.<

I removed audio from my movie and put it again thru tsMuxeR. I've got a video with fps to my liking then but there is a problem for me to mux this non-audio AVCHD with an audio. I googled for this for some time and couldn't find anything. Then I'm taking another approach: I want to change fps right in an MKV before any other procedures using MKVMerge but I don't know what I supposed to put in Timecodes field and how to get those timecodes
Can I count for some help/advice, please

Here MediaInfo of the video:

General
Complete name : C:\Users\Mark\Documents\Movies 6\Nordwand.mkv
Format : Matroska
File size : 5.53 GiB
Duration : 2h 1mn
Overall bit rate : 6 537 Kbps
Encoded date : UTC 2010-01-13 07:44:41
Writing application : mkvmerge v2.9.8 ('C'est le bon') built on Aug 13 2009 12:49:06
Writing library : libebml v0.7.7 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Muxing mode : Container profile=Unknown@4.1
Codec ID : V_MPEG4/ISO/AVC
Duration : 2h 1mn
Bit rate : 5 958 Kbps
Nominal bit rate : 5 866 Kbps
Width : 1 280 pixels
Height : 544 pixels
Display aspect ratio : 2.35:1
Frame rate : 25.000 fps
Original frame rate : 24.000 fps
Resolution : 24 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.342
Stream size : 5.04 GiB (91%)
Title : Nordwand (En)
Writing library : x264 core 67 r1130M 8475977
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=7 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=-2 / threads=6 / nr=0 / decimate=1 / mbaff=0 / bframes=3 / b_pyramid=1 / b_adapt=1 / b_bias=0 / direct=1 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc=2pass / bitrate=5866 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
Language : English

Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Codec ID : A_AC3
Duration : 2h 1mn
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Surround: L R, LFE
Sampling rate : 48.0 KHz
Video delay : 6s 999ms
Stream size : 388 MiB (7%)
Title : Nordwand (En)
Language : English

BTW: This part sounds messy, doesn't it
Frame rate : 25.000 fps
Original frame rate : 24.000 fps

[midders]

You can convert between 23.976 and 25 fps using the AssumeFPS command in AVISynth. This changes the framerate without inserting/removing frames so the video will play faster or slower than before; the 4% difference will be overlooked by the viewer. AssumeFPS will also change the audio to match.

If you're new to AVISynth you'll need the following tools: AVISynth (latest version), ffdshow (and possibly Haali Media Splitter). Your script (myfilm.avs) will look something like:

DirectShowSource("myfilm.mkv")
AssumeFPS(2997,125,true)

You can then use the AVS file as input to whatever converter you want to use.

Slainte

midders

[mahogany]

Thanks for the answer. I have to read some about command line now since I've got no clue about it at all.

[johns0]

Try uncropmkv and change fps to 23.976.

[Lawbringer]

Thanks for the answer. I have to read some about command line now since I've got no clue about it at all.

You can load the specified AVS file into Xvid4PSP and convert it to a h264-encoded MKV or MP4.