I am using the following script to overlay a dvdsub stream and a video stream; avconv -i input.mkv -i subtitles.sub -filter_complex "[0:v:0][1:s:0]overlay[vid]" -map "[vid]" -s hd720 -sws_flags lanczos -vcodec libx264 -crf 20 -preset medium ~/Desktop/test.mkv I get the following error ; Stream specifier ':s:0' in filtergraph description [0:v:0][1:s:0]overlay[vid] matches no streams. No matter what I do I just cannot get this to work. Can any one tell me how to 'burn-in' subtitles using avconv (or ffmpeg) ?