[BUG] or [QUESTION] : Hardsubx didn't extract burn-in subs exactly as expected

[brebetez]

Please prefix your issue with one of the following: [BUG], [QUESTION].

CCExtractor version: 0.94
CCExtractor detailed version info
Git commit: 290e2f1
Compilation date: 2021-12-27
Libraries used by CCExtractor
Tesseract Version: 4.1.1
Leptonica Version: leptonica-1.79.0
libGPAC Version: 1.0.1
zlib: 1.2.11
utf8proc Version: 2.4.0
protobuf-c Version: 1.3.1
libpng Version: 1.6.37
FreeType
libhash
nuklear
libzvbi

In raising this issue, I confirm the following:

• I have read and understood the contributors guide.
• I have checked that the bug-fix I am reporting can be replicated, or that the feature I am suggesting isn't already present.
• I have checked that the issue I'm posting isn't already reported.
• I have checked that the issue I'm porting isn't already solved and no duplicates exist in closed issues and in opened issues
• I have checked the pull requests tab for existing solutions/implementations to my issue/suggestion.
• I have used the latest available version of CCExtractor to verify this issue exists.
• I have ticked all the boxes in this section and to prove it I'm deleting the section completely to remove boilerplate text.

Necessary information

• Is this a regression (i.e. did it work before)? {DON'T KNOW}
• What platform did you use? {Linux}
• What were the used arguments? myVideo.mp4 -ocrlang fra -hardsubx -ocr_mode frame -subcolor white -min_sub_duration 0.01 -detect_italics -whiteness_thresh 97 -conf_thresh 75

Video links

• {you can ask for an exemple if needed, run the tool on 24 videos with some differants look and feel of burn in subs...all the time the same issues.}

Additional information

{I have several issue:

• Subtitle output didn't fit on a time base with the burn in subtitle. Sometimes, the subtitles start a little bit (between 2sec until a few frame) before as the burn in subtitle. I tried to change the parameter of OCR_MODE, but no change on this delay.
• Subtitle duration of the output: All subtitle extracted has a a fix duration of 1 or 2 seconds. But nothing in between, more or less. That means, the subtitle disappears before that the burn in subtitle disappear.
• Burn in subtitle on 2 lines: Inside the output, mostly, only the second line a recognized. Or it create 2 or 3 subtitles with always something more inside the subtitle...but online on a one line, not exactly as it is in burn in subs.

I don't know if it is an issue or if I didn't use correctly the parameters, but as I said, I tried a lot of different ways...with all the time the same result. That is why, I'm opening an Issue.

Thanks for your feedback and help.}

[PunitLodha]

Please share the videos, so that we could look into this issue

[shashwat1002]

On investigating, at least on the files I have there are subtitles extracted with duration less than a second.
So I guess the second point is not entirely general, either it has changed since the issue or it's an artefact of the files used.

@brebetez please consider sharing the file you used

cc: @PunitLodha