Can x264 keep the attachments from the input file?

[Nozdrum]

Is it possible to force x264 to keep the attachments from the source files? like the subtitles, so that remuxing the output file is not needed anymore. Any idea?

[kypec]

x264 is pure video encoder, it doesn't care about any audio, subtitle or another data tracks but video. You should use MKVToolnix to remux your x264 output to include attachments, audio, subtitles or any other metadata you need.

[Selur]

@Nozdrum: You could use ffmpeg with libx264 instead of the x264 binary. ffmpeg support passing through audio and subtitles while only encoding the video.

[foxyshadis]

It's always better to remux to optimize the indexing (and therefore seeking). If using mkv, mkvtoolnix is also gives slightly smaller files than ffmpeg's muxer, but it's usually a trivial difference.

If you aren't concerned about seeking performance, the ffmpeg route is reasonable.

[Nozdrum]

I think mkv merge is still the best, probably I'll stick with it.