How to remove closed captions from srt/sub/avi/mkv files

mkvextract from MKVToolnix can extract tracks and attachments from a Matroska container.

Ripping the DVD to an MKV file

I suggest you use Handbrake (free, cross platform, open source) to rip the DVDs to an MKV file which contains everything.

Handbrake will already:

• Create an MKV file if you select MKV from Format under Output Settings
• Create an H.264-encoded video track of the titles you select from the DVD
• Create AAC-encoded audio tracks for all languages you select in the Audio tab
• Create soft-coded subtitles for all tracks you select in the Subtitles tab

Make sure you select Constant Quality for the video, and choose something between 18 and 28 for the quality. Lower means better, but you'll have to experiment on what looks good to you.

After you're done ripping, you can export the various tracks from the MKV file with FFmpeg. You can get a recent version by downloading a static build from the homepage. The static builds are always up-to-date, and if you're on Ubuntu, resist the temptation to use the one that comes with apt-get: It's terribly outdated.

How the extraction works depends on how many audio and subtitle tracks your file has. To get this information later on, you can call ffmpeg -i input.mkv and look at the output.

Here it says:

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, …

That's the video. Look further for audio—here are two audio tracks, one English, one German:

Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, …
Stream #0:2(ger): Audio: aac (mp4a / 0x6134706D), 48000 Hz, …

Finally, you might see subtitles. Here, they're german:

Stream #0:3(ger): Subtitle: text (default)

Now, let's extract them…

Extract video only

First, we'll create an empty video with no audio or subtitles. Here, -an disables the audio, and -sn disables subtitles. Or leave out -sn to keep the subtitles in.

ffmpeg -i input.mkv -c copy -an -sn output.mkv

Your output file will only contain video. You could also change the container here, if you want:

ffmpeg -i input.mkv -c copy -an -sn output.mp4

Extract audio only

This depends on how many audio tracks there are. To create separate audio files, we can do the following, assuming there are two audio tracks. Again, we'll disable video and subtitle output.

ffmpeg -i input.mkv \
-c:a:0 copy -vn -sn output-0.m4a
-c:a:1 copy -vn -sn output-1.m4a

As you can see, the index 0 and 1 specify the first and second audio tracks. If you have more, modify the command as needed and add another line.

Extract subtitles only

To get the subtitles, we'll follow a similar approach—assuming there is one subtitle track:

ffmpeg -i input.mkv -vn -an -c copy output.srt

Or, if there are multiple subtitle tracks:

ffmpeg -i input.mkv \
-c:s:0 copy -vn -an output-0.srt
-c:s:1 copy -vn -an output-1.srt