[FFmpeg-user] how to control quality of subtitles

Moritz Barsnick barsnick at gmx.net
Mon May 25 11:49:05 EEST 2020


On Mon, May 25, 2020 at 10:10:06 +0200, Peter M√ľnster wrote:
> I've tried it with the -palette option, but the rendering of the
> subtitles did not change in any way...

There is a reason for that:

> peter at ws:/tmp/ffmpeg-tests> ffmpeg -i orig-dvbsub.ts -map 0:0 -map 0:1 -map 0:2 -c:v libx264 -c:a copy -c:s dvdsub dvbsub2dvdsub.mkv
> ffmpeg version 3.4.5 Copyright (c) 2000-2018 the FFmpeg developers

This version is quite ancient, in ffmpeg terms.

Please try to build from latest git master, or get such a binary build.
Reason is that such a version will include this change:

https://github.com/FFmpeg/FFmpeg/commit/d4440c7e91b0ef5f6776d98c51dbb6cd66ea0194

which obviously enables the encoder's "palette" option.

You can get binary builds, and be it just for initial testing, from
here for your SuSE platform:
https://johnvansickle.com/ffmpeg/

Please choose a build from the left column "git master".

> [mpeg2video @ 0x5574823a0d80] skipped MB in I-frame at 1 31
> [mpeg2video @ 0x5574823a0d80] Warning MVs not available
> [mpeg2video @ 0x5574823a0d80] concealing 945 DC, 945 AC, 945 MV errors in I frame
> [mpegts @ 0x557482334fc0] PES packet size mismatch
>     Last message repeated 2 times
> [NULL @ 0x55748233b820] Junk in packet
> [dvbsub @ 0x55748235bae0] Invalid object location! 210-720 44-44 11
> [dvbsub @ 0x55748235bae0] Unknown/unsupported pixel block 0x88

You input seems to have some corruption (which should have nothing to
do with your issue).

Have you tried keeping the subs as dvbsubs (instead of dvd)? Does your
TV render them then?

Cheers,
Moritz


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