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  1. Member
    Join Date
    Jan 2016
    Location
    Singapore
    Search Comp PM
    Hi guys, I'm using an Android phone as an in-car digital video recorder. The application I'm using also logs data from the car's ECU chip such as engine revs and speed. The resulting files are a .mp4, a .srt file and a .csv file. When I open the video on my computer with MPC-HC, everything works well with the .srt subtitles showing the logged data. However, whenever I attempt to edit the video file in any application, there will be problems with the audio sync. It seems like the problem stems from the video's variable frame rate, as most phones record in.

    I've tried to fix the problem by re-encoding in Handbrake using the Constant framerate option, but no matter what I do the resulting video will have out-of-sync audio. I tried using "ffmpeg -i input.mp4 -c copy -copyts -r 30 -async 30 output.mp4" and it's also out-of-sync. I tried using Adobe Media Encoder with the Frame Blending option and that too fails.

    My aim is to use a program called Dashware to overlay the logged data on top of the above-mentioned video. It does this by reading the .csv file and matching the timecodes to the video but this requires the video to be of a constant framerate, or else it doesn't match up at all.

    Does anyone have any solutions or advice to give me?
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  2. The most reliable tool I've found so far for accurately interpreting and converting variable framerate to constant is TMPGenc Video Mastering works. Everything else (including the ones you mentioned) has fallen short in the sync department.
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  3. Member
    Join Date
    Aug 2010
    Location
    San Francisco, California
    Search PM
    According to FFmpeg, the -async option is deprecated and the aresample filter should be used instead.
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  4. Member racer-x's Avatar
    Join Date
    Mar 2003
    Location
    3rd Rock from the Sun
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    I don't normally edit VFR videos (the only ones I've seen were from my tablet or phone), but Aviutl should handle them easily enough.
    Got my retirement plans all set. Looks like I only have to work another 5 years after I die........
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  5. Member budwzr's Avatar
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    Apr 2007
    Location
    City Of Angels
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    You should decompress all media before editing. Mpeg2/PCM.
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  6. You should use lowest common denominator for frame speed (you can search for lowest delta between two frames (time domain) and later use this delta as framerate. It should be simple frame repeat operation, later you can convert such video to normal speed by using one of typical framerate conversion algorithms.
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  7. Member
    Join Date
    Feb 2004
    Location
    Australia
    Search Comp PM
    converting variable framerate to constant = Ulead Video Studio, it work's for me, nothing else comes close ... download the 30 day trial
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  8. In AviSynth:

    DirectShowSource("filename.ext", fps=x.y, ConvertFPS=true, SeekZero=true)

    Then use an all intra codec like huffyuv or UT Video Codec to create your intermediate file.
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  9. Member
    Join Date
    Jan 2016
    Location
    Singapore
    Search Comp PM
    Hi guys, thanks for all the responses. I've tried TMPGENC and found it to be quite reliable in fixing my problems. I've tried MediaCoder too but it seems to work only when the average frame rate is higher than my encoded frame rate. Is there a freeware program that can fix this though? TMPGEnc is quite expensive. Would appreciate if that program supports QuickSync or NVENC 6.0.
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