Handle non-aligned timestamps

[grusell]

Cases where the (start) timestamps of two files are not aligned should be handled better. Possible default strategies could be:

1 Automatically set frameoffset so that the starting frames of both videos align
2 Fast forward to the first timestamp that are present in both files
3 Combination of the above, ie use strategy 2 if possible, otherwise 1

See also #67

[Gloster10]

I use a workaround :
The start timestamps of two ts-files (or other) will be set to = 0, and a new container "mp4" will be used. To minimize the conversion time, only the first 10 min. will be converted, after all, vivictpp will be started with new generated files.

Only two files are in the directory.

The script :
`#!/bin/bash

declare -a new_videos

while IFS= read -r -d $'\0' video
do
filename=$(basename -- "$video")
filename="${filename%.*}"

#ffmpeg grep, s.: https://stackoverflow.com/questions/16931244/checking-if-output-of-a-command-contains-a-certain-string-in-a-shell-script
if ffmpeg -i "$video" null - 2>&1 | grep -q "hevc";
#if ffmpeg -i "$video" null - 2>&1 | grep -q "h264";
then
ffmpeg -y -i "$video" -codec copy -muxpreload 0 -muxdelay 0 -t 00:10:00.000 "${filename}0.mp4" </dev/null
new_video="${filename}0.mp4"
new_videos+=("$new_video")
else
ffmpeg -y -i "$video" -codec copy -muxpreload 0 -muxdelay 0 -t 00:10:00.000 "${filename}O0.mp4" </dev/null
new_video="${filename}O0.mp4"
new_videos+=("$new_video")
fi

done < <(find -iregex ".*.(m2ts|webm|ts|mp4|mkv)" -print0)

vivictpp "${new_videos[0]}" "${new_videos[1]}" `

To leave the videos in a ts-container, did lead to a timestamp offset difference of 40-80ms after conversion.