[VTT writer] Duplicate subtitles when vertical and horizontal subtitle appear on the same screen #450
Description
Hello, team! When I was trying to convert the ttml file to vtt format. Though I added additional logic to handle with vertical situation, the converted time code seems still has some problem and therefore, when the vertical subtitle and horizontal subtitle appear on the same screen. Sometimes the vertical subtitle will be duplicated on the screen. I checked the converted the vtt file and it was caused by the end of vertical subtitle is the same with the start time for next vertical cue. I'm wondering is there any way to differentiate the end time and start time? Thanks a lot! For example, given the converted vtt file, line 192 and 193 will show up on the screen at the same time when it hits 00:25:46.587 and it's same with line 194 and 195 when it hits 00:25:47.880 , is there any way to cut the previous one to 00:25:46.586 maybe?
`192
00:25:46.128 --> 00:25:46.587 align:center line:95%,end
ＴＡじゃないの
193
00:25:46.587 --> 00:25:47.880 align:center line:95%,end
ＴＡじゃないの
194
00:25:46.587 --> 00:25:47.880 vertical:rl align:start line:5% position:5% size:80%
ＴＡ…交通事故
195
00:25:47.880 --> 00:25:48.547 vertical:rl align:start line:5% position:5% size:80%
ＴＡ…交通事故`
