How to fix a file using ffmpeg so that VLC detects Aspect ratio automatically

Question

I have a video, where the video resolution is 852x480. When I open it up in VLC, "the Video Aspect" ratio defaults to *Default However, all I see is a black screen with a thin line as the video!

If I manually change the Aspect ratio to a something other than Default (e.g. 16:9) the video displays normally.

I've never seen this happen before, why is VLC not detecting the video properly, and why do I have to change the aspect ratio manually?

What command should I use with ffmpeg to fix it ?

Output of ffmpeg:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'SomeLesboMovie (852x480).mp4':   Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    creation_time   : 2015-08-02T16:17:23.000000Z   Duration: 01:36:06.23, start: 0.000000, bitrate: 2163 kb/s   Stream
#0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 852x480 [SAR 1:270 DAR 71:10800], 1996 kb/s,
29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      creation_time   : 2015-08-02T16:17:23.000000Z
      handler_name    : 264#video:fps=29.97:par=1:[email protected]
      vendor_id       : [0][0][0][0]   Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 162 kb/s (default)
    Metadata:
      creation_time   : 2015-08-02T16:05:42.000000Z
      handler_name    : Sound Media Handler
      vendor_id       : [0][0][0][0] At least one output file must be specified

Answer 1

I fixed my video by trying the following command:

ffmpeg -i "MyBadMovie(852x480).mp4" -aspect 852:480 -c copy MyFixedMovie.mp4

NB: user @Gyan has confirmed that my display aspect ratio was 71:10800, and I can see this now in the line below, so credit to him for also sharing his expert knowledge.

#0:00x1: Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 852x480 [SAR 1:270 DAR 71:10800], 1996 kb/s,