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I have five GoToMeeting (GTM) .mp4 recordings that I saved and downloaded from a five-day class I was teaching. Each recording represents each day's appx. 8 hour class duration. I am importing them into Camtasia to trim some parts from them and then exporting them back out. It's all going fine until I get to the Day 3 file. Day 1 and Day 2 are 716 MB and 867 MB respectively, and have played back correctly within Camtasia and allowing me to trim and edit just fine.

The Day 3 file is about 5x bigger than the other 4 files (5.7 GB vs ~1 GB). When I import the file into Camtasia it shows that it is 39:13:17 in duration. This I know to be incorrect because I can see the computer's Windows system time in the video in my recording -- the first frame shows a Windows time of 8:00 AM in the recording and the last frame shows a Windows system time of 3:47 PM. So I know the true duration should be 07:47:00.

I suspect that something got messed up when the file downloaded from my GTM account. But I don't know what is messed up or how to fix it. Maybe the framerate is wrong? The bitrate? At any rate, some kind of metadata in the file is obviously wrong and causing Camtasia to load it as a 39 hour file and making it playback at about 5x slower than it should. I'm sure all of the content is there (I see all of the video that I am expecting to see and the audio playback is super slo-mo, but there).

I'm fairly inexperienced with ffmpeg so I'm unsure what settings and/or process I need to go through to fix the file. Can someone kindly walk me through the steps/process? I've been combing through the ffmpeg documentation and Googling from about 3 hours now and am very frustrated.

Edit #1: As requested by @Gyan, output from ffmpeg -i day3.mp4 -report

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\ffmpeg\day3.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp41isom
    creation_time   : 2020-08-29T04:02:38.000000Z
  Duration: 39:13:17.43, start: 0.000000, bitrate: 331 kb/s
  Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 204 kb/s, 30 fps, 30 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2020-08-29T04:02:38.000000Z
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 121 kb/s (default)
    Metadata:
      creation_time   : 2020-08-29T04:02:38.000000Z
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
At least one output file must be specified
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    Run ffmpeg -i day3.mp4 -report. Upload the generated report and link it.
    – Gyan
    Commented Mar 5, 2022 at 8:02
  • @Gyan updated post with output of report. Currently trying ffmpeg -i "C:\ffmpeg\day3.mp4" -r 150 -filter:v "setpts=PTS/5" -an "C:\ffmpeg\out.mp4" to try to shorten the duration by 5x and without dropping frames (hopefully). Beside it taking FOREVER to run, just based on the current file size (it's been running for 5 hours so far) I'm not holding out much hope that the result is going to be correct (07:47:00 duration with 1/5 file size) because it is processing up to 02:36:30 into the file so far and the output file size is 689.921 KB.
    – KurtM
    Commented Mar 5, 2022 at 21:08
  • Try ffmpeg -itsscale 0.2 -an -i day3.mp4 -vn -i day3.mp4 -c copy newday3.mp4
    – Gyan
    Commented Mar 6, 2022 at 4:25

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