[FFmpeg-user] Add subtitles to trimmed mp4

[adam smith]

> On 13 Feb 2021, at 10:46, adam smith via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
> 
> Thanks Leo. 
> I gave it a try but the same thing happened regarding the subtitle position and the in point of the media appeared less accurate and had black at the start.
> I believe this is because -ss prior to the file path does a quick seek to the closest key frame to the desired timing, whereas -ss after the file path decodes all the data to find the actual specified timing.

Actually I think I may have just been a bit of a donut and you may be spot on.
Now I have had a cup of tea and woken up properly, I will do some more testing on different source formats and get back to you.

Thank you for your help, as always to everyone in the group it is very much appreciated.

Adam