Particular 1080p video very slow to show audio waveform

[dg1727]

 - Architecture is x86_64
 - OS is Xubuntu 13.04 (yes, I know Ubuntu no longer support this version, but https://github.com/probonopd/AppImageKit/blob/master/README.md says "Use an old system for building (at least 2-3 years old)" :-)
 - Installation method is AppImage
 - Version of OpenShot is 2.2.0
 - The video plays & seeks fine in both "ffplay" and "melt".
 - melt 0.8.8
 - "ffplay -version" reports "avplay version 0.8.9-6:0.8.9-0ubuntu0.13.04.1"
 - Drag-n-drop video from Project Files windowpane to track display, right-click video in the track display, choose Display > Show Waveform.
 - The full video is a 1080p 24fps MP4, about 581 MB and 38 minutes long. The Show Waveform process on this video takes prohibitively long (several minutes or it locks up forever, I suspect it's the latter).
 - If I slice the video into pieces as big as 200 MB, the Show Waveform process takes a more reasonable length of time.
 - I'm using the following command line to split the video:

MP4Box -splits 200000 video.mp4

 - "MP4Box -version" reports 0.5.1-DEV-rev4065
 - The largest split size that MP4Box will honour on this video is 569000. At this split size, OpenShot still appears to take forever to draw the waveform.
 - OpenShot CPU usage is at 100% of one core. The old-school X wristwatch busy-pointer is shown, and the UI still responds (e.g., opening the Preferences window), but slowly. Exiting OpenShot leaves /bin/bash .bin//openshot-qt.wrapper running @ 100% CPU time (one core).
 - Pitivi old version 0.15.2 takes only seconds to show the waveform of the full 38-minute video.

Due to the size of the video, I haven't attached it to this bug report. If you'd like me to get the full video to you some other way, please tell me.

Many thanks.

[dg1727 (dg1727)]

"avprobe" says:

avprobe version 0.8.9-6:0.8.9-0ubuntu0.13.04.1, Copyright (c) 2007-2013 the Libav developers
  built on Nov 9 2013 19:09:48 with gcc 4.7.3
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  Metadata:
    major_brand : isom
    minor_version : 1
    compatible_brands: isom
    creation_time : 2017-01-05 00:59:37
  Duration: 00:38:09.65, start: 0.000000, bitrate: 2029 kb/s
    Stream #0.0(und): Audio: aac, 44100 Hz, stereo, s16, 125 kb/s
    Metadata:
      creation_time : 2016-03-09 18:47:40
    Stream #0.1(und): Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 1900 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
    Metadata:
      creation_time : 2016-03-09 22:36:52

[Ryszard Goń (scarfmonster)]

I can confirm this. I also noticed that, before I tried to generate a waveform, Openshot was using 187.6 MiB of RAM, after I told it to generate a waveform though it just started increasing forever. The few times I tried it got over 1 GiB before I killed it.

Attached is a log where I opened Openshot, placed just a single 40 minute long audio file on the timeline and told it to display the waveform. I let it run for a few minutes before I killed it.