[FFmpeg-user] How To Burn Stereo SBS Subtitles Into Video

[郑建峰]

Hi,
I'm trying to burn a stereo SBS subtitles Into video like this:
    $ ffmpeg -i 3dtv.hsbs.mkv -vf "subtitles=test.3d.srt" 3dtv.new.mkv
Rather than layout the subtitles side-by-side in a sigle line as I expect, ffmpeg layout the subtitles into 2 adjacent lines.


The content for "test.3d.srt" is listed as follow:
    line 1: 1
    line 2: 00:00:00,850 --> 01:00:00,430
    line 3: {\pos(98,255)\fscx50}left half view
    line 4: 
    line 5: 2
    line 6: 00:00:00,850 --> 01:00:00,430
    line 7: {\pos(286,255)\fscx50}right half  view


For this "test.3d.srt", what I expect is 
    left half view   right half view
But ffmpeg layout is 
        left half view
       right half view


My Question is 
1. Does ffmpeg currently support stereo side-by-site or above-down subtitles overlay?
2. If yes, what's the canonical operations.
3. If not, is there external tools (which better can be called by or integrated into ffmpeg) can do so?