Saving AAC audio section from mkv file in ffmpeg

[ShadowEdit]

I would like to cut out and save an audio section from a mkv file in ffmpeg. The audio track is AAC. Would saving the output as AAC decrease the output quality since it's a lossy format?

I tried this command, but it didn't work:

ffmpeg -i input.mkv -vn -c:a -ss 00:01:42:11 -t 00:02:02:19 output.aac

Here is the error description that cmd gave me:

[NULL @ 0000000005629940] Unable to find a suitable output format for '00:01:42:11'
00:01:42:11: Invalid argument

[poisondeathray]

No quality loss if you use "copy"

-c:a copy

ffmpeg -i input.mkv -vn -c:a copy -ss 00:01:42:11 -t 00:02:02:19 output.aac

[ShadowEdit]

Ah, I forgot to add that.

cmd gave me this now:

Invalid duration specification for ss: 00:01:42:11

[ShadowEdit]

Ah, I forgot to add that.

cmd gave me this now:

Invalid duration specification for ss: 00:01:42:11

[poisondeathray]

The notation is hh:mms.ms

-ss 00:01:42.011 -t 00:02:02.019

[ShadowEdit]

This gives me a 01:57 minute long audio clip. I was trying to get a 20 second clip (or 00:00:20:007, to be specific).

[poisondeathray]

-t is duration, not end time

-t 00:00:20.007

If you still can't get it working, you can demux the audio and use mp3directcut (it works on AAC as well)

[ShadowEdit]

I tried that before as well, but it didn't work then. Looks like I used a comma instead of a dot for the microseconds part.
I have gotten a higher quality audio source now, so I'll just have to redo this with an AC3 track.
Thanks!

[autodidact]

This sometimes works better for duration seeking:

ffmpeg -ss 00:01:42.011 -i input.mkv -to 00:00:20.007 -vn -c:a copy output.aac