[FFmpeg-cvslog] lavc/dvdsubenc: only check canvas size when it is actually set

ffmpeg | branch: release/6.0 | Anton Khirnov | Thu Nov 30 11:21:24 2023 +0100| [133069b4340961a1b3e8562a0dabfc61b35af84c] | committer: Anton Khirnov lavc/dvdsubenc: only check canvas size when it is actually set Fixes #10650 (cherry picked from commit 5230257ea18e1d3761ee6b0549d56a3ca817f301)

[FFmpeg-cvslog] lavc/dvdsubenc: only check canvas size when it is actually set

ffmpeg | branch: release/6.1 | Anton Khirnov | Thu Nov 30 11:21:24 2023 +0100| [111035ccae52b448ccee889546a54594cd3fca5e] | committer: Anton Khirnov lavc/dvdsubenc: only check canvas size when it is actually set Fixes #10650 (cherry picked from commit 5230257ea18e1d3761ee6b0549d56a3ca817f301)

[FFmpeg-cvslog] lavc/dvdsubenc: only check canvas size when it is actually set

ffmpeg | branch: master | Anton Khirnov | Thu Nov 30 11:21:24 2023 +0100| [5230257ea18e1d3761ee6b0549d56a3ca817f301] | committer: Anton Khirnov lavc/dvdsubenc: only check canvas size when it is actually set Fixes #10650 > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5230257ea18e1