MediaInfo reports the avi as being 23.976fps. If I load the file into VirtualDub through an AVISynth script it shows the frame rate as 23.970fps, if I then save that as an avi and try to re-encode the avi with x264, x264 shows the frame rate as 2500000/104297, which comes out to about 23.970008725083175930276038620478fps. My question is, should I even use an audio timecode file? And how do other people do this? How do you get the audio and video in perfect sync? I do not know yet if my new files are in perfect sync, I will post more about it when I watch more transcoded material. Then I left out the audio timecodes file and it worked out fine. mux.sh: line 4: 12944 Aborted mkvmerge -default-language eng -o 'video-muxed.mkv' -language 0:eng -compression 0:none -timecodes 0:'video-timecodes.txt' -d 0 -no-chapters -A -S 'video.h264' -language 0:eng -compression 0:none -timecodes 0:'audio-timecodes.txt' -a 0 -no-chapters -D -S 'audio.m4a' -chapter-language eng -chapters 'chapters.txt' Mkvmerge: /build/buildd/libmatroska-1.4.1/make/linux/././src/KaxCluster.cpp:279: int16 libmatroska::KaxCluster::GetBlockLocalTimecode(uint64) const: Assertion `TimecodeDelay >= int16(0x8000) & TimecodeDelay <= int16(0x7FFF)' failed. The remaining frames of this track might not be timestamped the way you intended them to be. Warning: 'audio.m4a' track 0: The number of external timecodes 945 is smaller than the number of frames in this track. 'video.h264' track 0: Extracted the aspect ratio information from the MPEG-4 layer 10 (AVC) video data and set the display dimensions to 720/405. The file 'video-muxed.mkv' has been opened for writing. 'audio.m4a' track 0: Using the output module for the format 'AAC'. 'video.h264' track 0: Using the output module for the format 'AVC/h.264 (unframed)'.

'audio.m4a': Using the demultiplexer for the format 'QuickTime/MP4'. 'video.h264': Using the demultiplexer for the format 'AVC/h.264'. Code: Select all mkvmerge v6.7.0 ('Back to the Ground') 64bit built on 18:03:17

Mkvtoolnix remux avi to mkv specify fps