Automatically correct mp4 video-only dash files

[forthrin]

After downloading a video, there were two problems:

1. VLC thinks the video is twice as long (35 minutes) as it actually is (17 minutes). QuickTime does the same.
2. It is not possible to seek in the video in VLC using the "fast forward" buttons. In QuickTime this works for some reason.

Doing ffmpeg in.mp4 -codec copy out.mp4 fixes the problem, but this should be solved in youtube-dl so that all videos are seekable and show the correct length.

Command executed and verbose output:

$ youtube-dl --verbose -f 160 0zMNK8bqGUk
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'--verbose', u'-f', u'160', u'0zMNK8bqGUk']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2015.10.18
[debug] Python version 2.7.10 - Darwin-15.0.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 2.8.1, ffprobe 2.8.1
[debug] Proxy map: {}
[youtube] 0zMNK8bqGUk: Downloading webpage
[youtube] 0zMNK8bqGUk: Downloading video info webpage
[youtube] 0zMNK8bqGUk: Extracting video information
[youtube] 0zMNK8bqGUk: Downloading DASH manifest
[youtube] 0zMNK8bqGUk: Downloading DASH manifest
[debug] Invoking downloader on 'https://r3---sn-uxaxovg-vnaz.googlevideo.com/videoplayback?id=d3330d2bc6ea1949&itag=160&source=youtube&requiressl=yes&mm=31&mn=sn-uxaxovg-vnaz&pl=17&mv=m&ms=au&ratebypass=yes&mime=video/mp4&gir=yes&clen=14343336&lmt=1417337744686644&dur=1051.984&key=dg_yt0&sver=3&signature=046F31094324D4AE544A2508C025D751985FC6D3.77F975EF6BD1D67353DB0CEBA50C81CDF1D7DE49&upn=a_Sikj5762Q&fexp=9406010,9407155,9408211,9408710,9414702,9414764,9416126,9416729,9416837,9417707,9418184,9418203,9418401,9420482,9422573,9422907&mt=1445603800&ip=88.89.18.85&ipbits=0&expire=1445625504&sparams=ip,ipbits,expire,id,itag,source,requiressl,mm,mn,pl,mv,ms,ratebypass,mime,gir,clen,lmt,dur'
[download] Destination: Luigi's Mansion Dark Moon - Old Clockworks - C-4 Play Catch (Nintendo 3DS Gameplay Walkthrough)-0zMNK8bqGUk.mp4
[download] 100% of 13.68MiB in 00:04

[jaimeMF]

As explained in the bug reporting instructions post the full output you get when running youtube-dl --verbose 0zMNK8bqGUk ADDITIONAL_OPTIONS.

[forthrin]

Updated as requested.

[jaimeMF]

I can reproduce it, but mpv (with ffmpeg compiled from the git repo a few days ago) plays them fine.
Note that the format you selected doesn't contain the audio and running with -f 160+bestaudio will produce a file that both VLC and Quicktime can play.

Doing ffmpeg in.mp4 -codec copy out.mp4 fixes the problem, but this should be solved in youtube-dl so that all videos are seekable and show the correct length.

I guess we can do the same thing we do for m4a files https://github.com/rg3/youtube-dl/blob/8b172c2e10fb38c62c213673304c7e8dcd17b768/youtube_dl/YoutubeDL.py#L1631-L1645

[forthrin]

WFM with 2019.04.30