Suppose I have a video format like this:


    Metadata:
        CREATION_TIME   : 2017-08-04T21:29:42Z
        ENCODER         : Lavf57.7.2
      Duration: 00:24:45.83, start: 0.000000, bitrate: 1130 kb/s
        Chapter #0:0: start 0.000000, end 90.048000
        Metadata:
          title           : Chapter 1
        Chapter #0:1: start 90.048000, end 741.074000
        Metadata:
          title           : Chapter 2
        Chapter #0:2: start 741.074000, end 1391.348000
        Metadata:
          title           : Chapter 3
        Chapter #0:3: start 1391.348000, end 1422.338000
        Metadata:
          title           : Chapter 4
        Chapter #0:4: start 1422.338000, end 1485.693000
        Metadata:
          title           : Chapter 5
        Stream #0:0: Video: h264 (High), yuv420p(tv, bt709, progressive), 960x720 [SAR 1:1 DAR 4:3], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
        Stream #0:1(eng): Audio: aac (LC), 48000 Hz, stereo, fltp (default)
        Metadata:
          title           : Stereo
        Stream #0:2(jpn): Audio: aac (LC), 48000 Hz, stereo, fltp
        Metadata:
          title           : Stereo
        Stream #0:3(eng): Subtitle: ass (default) (forced)
        Stream #0:4: Attachment: ttf
        Metadata:
          filename        : FRAMD.TTF
          mimetype        : application/x-truetype-font
        Stream #0:5: Attachment: ttf
        Metadata:
          filename        : FRAMDCN.TTF
          mimetype        : application/x-truetype-font
        Stream #0:6: Attachment: ttf
        Metadata:
          filename        : FRAMDIT.TTF
          mimetype        : application/x-truetype-font
        Stream #0:7: Attachment: ttf
        Metadata:
          filename        : DEJAVUSERIF.TTF
          mimetype        : application/x-truetype-font
        Stream #0:8: Attachment: ttf
        Metadata:
          filename        : FRADM.TTF
          mimetype        : application/x-truetype-font
        Stream #0:9: Attachment: ttf
        Metadata:
          filename        : FRADMCN.TTF
          mimetype        : application/x-truetype-font
        Stream #0:10: Attachment: ttf
        Metadata:
          filename        : FRADMIT.TTF
          mimetype        : application/x-truetype-font

I want to take every frame of this video and convert it into an image, _but I want to keep the subtitles_.

I tried a command like this:

     ffmpeg -i file.mkv -r 1 -ss 120 -t 350 -map 0:0  images/output_%05d.png

Which gets me the frames from the range I want (`-ss..-t`), but whenever I try to add some variation of `-map 0:3` (the subtitle stream), I get

    Automatic encoder selection failed for output stream #0:1. Default encoder for format image2 (codec none) is probably disabled. Please choose an encoder manually.
Error selecting an encoder for stream 0:1

I have also tried a variation like

    ffmpeg -i file.mkv -r 1 -ss 120 -t 350 -map 0:0 -attach ~/Library/Fonts/DejaVuSans.ttf -metadata:s:0 mimetype=application/x-truetype-font images/output_%05d.png

Which also simply wrote out the PNGs--no subtitles.

What am I missing here?