Opened 3 years ago

Last modified 3 years ago

#4047 new defect

dvdsub -> dvbsub: color palette and postion do not match

Reported by: Jarod42 Owned by:
Priority: normal Component: undetermined
Version: git-master Keywords: dvdsub
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:
Today I used ffmpeg to remux a VOB file to TS. After remuxing I realized, that the DVB subtitles did not match the original DVD subtitles. The colors did not match and the position was shifted.
I was able to reproduce this with this sample here (http://samples.ffmpeg.org/MPEG-VOB/ClosedCaptions/Starship_Troopers.vob) and got the exact same results.

How to reproduce:

% ffmpeg -fflags +genpts -analyzeduration 100000k -probesize 100000k -i Starship_Troopers.vob -c:v copy  -c:a copy -c:s dvbsub -map 0:0 -map 0:4 -map 0:7 -metadata:s:s:0 language=eng -metadata:s:a:0 language=eng -f mpegts SST.ts

ffmpeg version N-46340-gff68ceb
built on Ubuntu 14.04 x86_64

See attached pics.

Attachments (4)

SST-vob.jpg (221.1 KB) - added by Jarod42 3 years ago.
DVD Subtitles
SST-TS.jpg (219.2 KB) - added by Jarod42 3 years ago.
DVB Subtitles
SST-vob+TS.jpg (190.3 KB) - added by Jarod42 3 years ago.
both subs on one pic
SST-vdr.jpg (232.2 KB) - added by Jarod42 3 years ago.
Screenshot taken from vdr-2.1.6

Download all attachments as: .zip

Change History (14)

Changed 3 years ago by Jarod42

DVD Subtitles

Changed 3 years ago by Jarod42

DVB Subtitles

comment:1 Changed 3 years ago by Jarod42

  • Summary changed from dvdsub -> dvbsub: color palette and postion do not match to dvdsub -> dvbsub: color palette and position do not match

comment:2 Changed 3 years ago by cehoyos

  • Keywords dvdsub added; dvbsub color palette position removed
  • Summary changed from dvdsub -> dvbsub: color palette and position do not match to dvdsub -> dvbsub: color palette and postion do not match

Is encoding to dvbsub really necessary to reproduce the "issue" you see (that vob files do not contain a palette)? Or does using overlay show the same result indicating that this is not related to dvbsub at all?
Use the -palette option if you don't like the default palette:
http://ffmpeg.org/ffmpeg-codecs.html#dvdsub

comment:3 follow-up: Changed 3 years ago by Jarod42

I need to create a TS from the video source, so converting dvdsubs to dvbsubs is required.
After figuring out, that the -palette option needs to be put before the input file, the color "mismatch" problem is solved.
The position of the subs however does not match the original. After a closer look at the converted subs I figured they are shrunk vertically. So I tried to resize them using -s:s:0 720x576 which unfortunately did not have any effect.

Last edited 3 years ago by Jarod42 (previous) (diff)

comment:4 in reply to: ↑ 3 Changed 3 years ago by cehoyos

Replying to Jarod42:

I need to create a TS from the video source, so converting dvdsubs to dvbsubs is required.

I understand that this is your usecase. But a bug report should be as simple as possible and reading your original report makes one believe that there is an issue creating dvbsub subtitles.

The position of the subs however does not match the original. After a closer look at the converted subs I figured they are shrunk vertically. So I tried to resize them using -s:s:0 720x576 which unfortunately did not have any effect.

I cannot reproduce this here and I don't see it looking at your screenshots either. Is the difference very small?

Changed 3 years ago by Jarod42

both subs on one pic

comment:5 Changed 3 years ago by Jarod42

I created a third picture from the two already attached pics where I put the picture with the converted subs (yellow) over the original (white).
It is clear to see that they are not at the same position, nor are they the same size.

comment:6 Changed 3 years ago by cehoyos

I still cannot reproduce: The word three is over Ibanez' right hand here, both on the original (vob) file and for the reencoded transport stream.
Which application did you use for playing the transport stream?

comment:7 Changed 3 years ago by Jarod42

I was using VLC 2.1.5 to replay the TS and that might be the cause. When using ffplay the subs are at the same position, before and after the conversion.

Changed 3 years ago by Jarod42

Screenshot taken from vdr-2.1.6

comment:8 Changed 3 years ago by Jarod42

Today I did another test with VDR 2.1.6. I used it to replay the short sample with re-encoded subs to dvbsubs and a custom palette. The position of the subs do not match the ones from the VOB. So far ffplay seems to be the only program to display the subtititles at their correct position.

comment:9 Changed 3 years ago by er.anshul.maheshwari@gmail.com

When we play Starship_Troopers.vob using ffplay the subtitles are green color, while in vlc they are White with black Shadow, Imo it looks like there is some problem in decoder of dvbsubdec.

comment:10 Changed 3 years ago by cehoyos

A vob file does not contain subtitle colour information, there is no bug regarding the colour of the subtitle that can be fixed within the subtitle decoder when playing this file.

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