Opened 3 years ago

Last modified 2 years ago

#6835 new enhancement

DVBSUB -> DVDSUB "blurring"

Reported by: Sami32 Owned by:
Priority: normal Component: avcodec
Version: git-master Keywords: dvbsub dvdsub
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no


Summary of the bug:
The resulting DVDSUB seem to be "blurred", VLC and PotPlayer? was used, and the subtitle position is different than the DVBSUB default one.

How to reproduce:
Here the source file used:
TS file of around 66 MB, link valid for 7 days.

% ffmpeg -fflags +genpts -i "F:\!MEDIA_TEST_FILES\UMS Video Testing Suite (20150121)\TESTS\INTERNAL SUBTITLES\20130718 2342 - NRK2 HD - Barnearbeid og slaveri.[0].ts" -map 0:v -map 0:a:0 -map 0:a:1 -map 0:s:0 -c:v copy -c:a:0 copy -c:a:1 copy -c:s dvdsub -f matroska testNadahar_dvbsubtitle2.mkv

Attachments (1)

ffmpeg-20171114-154813.log (1.0 MB) - added by Sami32 3 years ago.

Download all attachments as: .zip

Change History (7)

Changed 3 years ago by Sami32


comment:1 Changed 3 years ago by Sami32

  • Summary changed from DVBSUB -> DVDSUB to DVBSUB -> DVDSUB "blurring"

comment:2 Changed 3 years ago by cehoyos

The resolution of the dvb subtitles is (approximately) 720x576, the video resolution is 1280x720. If you neither scale the subtitles nor the video, the subtitles will not correctly fill the screen.

comment:3 Changed 3 years ago by Sami32

Damn !!! i have totally missed that point. Thank you very much for your help :)
I tried -canvas_size 1280x720 and now the subtitle position is fine.

Still this weird DVDSUB blurring main issue though.

EDIT: Apply an aspect ratio correction of 960x720 to the canvas given the correct DVDSUB size. I'm too forgetful ;)

Last edited 3 years ago by Sami32 (previous) (diff)

comment:4 Changed 3 years ago by cehoyos

I don't know if there is a reason why dvdsub subtitles look very ugly while dvbsub subtitles look nice, even after re-encoding (to dvbsub).

comment:5 Changed 3 years ago by Sami32

Could that be related to the color/alpha palette conversion ?

Last edited 2 years ago by Sami32 (previous) (diff)

comment:6 Changed 2 years ago by Sami32

I don't think that it is related to the blurry issue, but when inspecting, comparing the DVBSUB and DVDSUB i saw a frame size difference.
For example in the original DVBSUB, the first frame have a size of 434x46
But in the DVDSUB, it have a size of 439x41

All the others subtitle frames have around the same few pixels difference.

Last edited 2 years ago by Sami32 (previous) (diff)
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