Viki old subtitles sync

[shivsah]

Checklist

• I'm reporting a site feature request
• I've verified that I'm running youtube-dl version 2019.08.13
• I've searched the bugtracker for similar site feature requests including closed ones

Description

Some shows of the site viki had updated their subs link sometime back because the original subs weren't synced properly, Some example shows being Dream High and Pinocchio.

For example:-

https://www.viki.com/videos/91001v-dream-high-episode-1 this episode uses subtitle from the link https://api.viki.io/v4/videos/91001v/subtitles/en.vtt?app=100000a&sig=8b1dd0339766408903c35af2f6cd1f4184af187c&stream_id=78495332&t=1566130938&token=kQ_BXDV5TLSHhRI9rKVRQmPru0024185034uti00j8h5lU000_01x

but the one which gets downloaded is the other one.. included in the zip are both the files the one with correct in its name is the proper one.. when comparing you can see the difference in timestamps
Dream High - 1x01 - Episode 1.en.forced.zip

[shivsah]

Forgot the link had a timestamp so it won't be accessible now but you can get both the files in the zip file

[manselmi]

This seems related: https://support.viki.com/hc/en-us/community/posts/360028951053-Issue-Subtitles-out-of-sync

When loading https://www.viki.com/videos/1026409v-my-love-from-the-star-episode-1 (an episode of one of the shows mentioned in the link above) in Firefox, the English subtitle vtt file is synced correctly and begins as follows:

WEBVTT

1
00:00:03.819 --> 00:00:07.819
<i>Annals of the Joseon Dynasty, 1st Year of King Gwang Hae, Volume 20.
 Recorded on September 25th</i>

However when running

youtube-dl \
  --skip-download \
  --sub-format 'vtt' \
  --sub-langs 'en' \
  --write-sub \
  -- \
  https://www.viki.com/videos/1026409v-my-love-from-the-star-episode-1

the English subtitle vtt file is not synced correctly and begins as follows:

WEBVTT

1
00:00:00.360 --> 00:00:04.360
<i>Annals of the Joseon Dynasty, 1st Year of King Gwang Hae, Volume 20.
 Recorded on September 25th</i>

[manselmi]

Update: something else seems to be going on here.

The vtt file loaded by Firefox is synced with the video played by Firefox ( https://www.viki.com/videos/1026409v-my-love-from-the-star-episode-1 ). This is good.

However, when running

youtube-dl \
  --format 'best' \
  --sub-format 'vtt' \
  --sub-langs 'en' \
  --write-sub \
  --output 'My Love From the Star - 01.%(ext)s' \
  -- \
  https://www.viki.com/videos/1026409v-my-love-from-the-star-episode-1

The video downloaded by youtube-dl has a different intro from the video played in Firefox (!), and the vtt file downloaded by youtube-dl doesn't sync up with the video downloaded by youtube-dl. So strange.