Changing frame rate using h264

[bernd_b]

I hope I get this clear:

I have a 25 fps mkv and want to do a speed down to 24 fps. I did this already with DVD-sources using mencoder and reencoding audio and(!) video.

With h264-video, something made me think that I only have to reencode the audio (to get it to the proper playing time, using tools like here)
and mux video and reencoded audio to a new file, e.g.

mkvmerge --default-duration 0:24fps video.h264 --compression -1:none audio_reencoded.ac3 -o 24fps.mkv

Xine & Co. seem to play the file right, but my stand alone Blu-Ray-Player seems to use the original frame rate of the video, which leads to a unpleasant slide show.

To my surprise, mediainfo shows, that the information about the original frame rate is still there, e.g.:

24fp.mkv 
General
UniqueID                         : 221286093543339205947632674409668742974 (0xA67A26C10BF5E81D086B8BFF0ED50F3E)
Complete name                    : 24fps.mkv
Format                           : Matroska
File size                        : 2.17 GiB
Duration                         : 1h 36mn
Overall bit rate                 : 3 221 Kbps
Encoded date                     : UTC 2011-02-19 11:29:51
Writing application              : mkvmerge v4.4.0 ('Die Wiederkehr') built on Dec 22 2010 16:05:39
Writing library                  : libebml v1.0.0 + libmatroska v1.0.0

Video
ID                               : 1
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High@L3.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 3 frames
Codec ID                         : V_MPEG4/ISO/AVC
Duration                         : 1h 36mn
Bit rate                         : 2 933 Kbps
Nominal bit rate                 : 3 120 Kbps
Width                            : 1 280 pixels
Height                           : 720 pixels
Display aspect ratio             : 16:9
Frame rate                       : 24.000 fps
Original frame rate              : 25.000 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.133
Stream size                      : 1.98 GiB (91%)
Writing library                  : x264 core 67 r1127M 8d82fec
Encoding settings                : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=6 / psy_rd=1.0:0.0 / mixed_ref=0 / 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=3 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc=2pass / bitrate=3120 / 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

Audio
ID                               : 2
Format                           : MPEG Audio
Format version                   : Version 1
Format profile                   : Layer 3
Mode                             : Joint stereo
Mode extension                   : MS Stereo
Codec ID                         : A_MPEG/L3
Codec ID/Hint                    : MP3
Duration                         : 1h 36mn
Bit rate mode                    : Constant
Bit rate                         : 224 Kbps
Channel(s)                       : 2 channels
Sampling rate                    : 48.0 KHz
Compression mode                 : Lossy
Stream size                      : 155 MiB (7%

So is this all about the question, whether a player uses the frame rate given by the container or the frame rate given by the video stream itself?

Or where does the information of the original frame rate come from? Is there a way to edit these information (maybe being placed in a header ....)?

[nm]

Originally Posted by bernd_b

So is this all about the question, whether a player uses the frame rate given by the container or the frame rate given by the video stream itself?

Yes. With MKV files, the player should use the container framerate, I think.

Is there a way to edit these information (maybe being placed in a header ....)?

Yes, by using roozhou's patched ffmpeg, for example.