Using MKVmerge to 'tidy' MakeMKV output

[BlueMagician]

Dear all,

I've noticed that whenever I use MKVmerge to post- process an MKV file produced by MakeMKV, the resultant file is appreciably smaller.

I've read one or two posts that suggest that MKVmerge does not alter quality or lose at data as such; it is simply better/more efficient at muxing. I heard mention that is removes zero/stuffing bits etc?

Is this true?

Is there any harm in running all my MakeMKV output through MKVmerge as an additional final step?

I do not want to do this if it risks the integrity of the file or causes loss of any meaningful data, or introduce any issues with Audio sync etc...

...But the reduction in file size for a typical BR rip is appreciable, so the space saving would be nice if it's safe to do so.

Many thanks,

[Woodstock]

MKVmerge has the advantage that all streams within the MKV file are "complete" when it runs, and there should be no issue with running it as an added pass.

However, please define "appreciably smaller". If all the tracks are left in the MKV file, the only difference should be in overhead for the "connecting bits", that is, header information. Certainly less than 1%. Anything more than that would be something being left out during the merge process.

If you really want smaller, re-encoding the video with a more advanced compression method would be in order. And neither MakeMKV nor MKVmerge do that.

[BlueMagician]

Thank you for your reply.

It's good to know that using MKVmerge as a final stage shouldn't ruin anything.

I wasn't looking to re-encode anything - indeed this is precisely what I want to avoid, as preservation of original source is of utmost importance to me. Hard drive space is cheap, time is precious.

Your comments made me revisit my original beliefs on the space saving to be had.

I was remuxing a few test files the other day, and I'm certain I saw some 10% size drops in the final file from MKVmerge. However, having tried a few different files tonight, I can't reproduce those reductions.

That being the case and the fact that I'm now only seeing 1% saving at most - I don't think I'll bother, which makes my question mostly pointless.

Thank you for your time,

[Woodstock]

Not really pointless, but the reason for doing it may have been. With MKVmerge, you can re-arrange the order of tracks, which can make a big difference in playback.

For example, many players completely ignore the DEFAULT and FORCED flags on subtitles. They play the first track found, which may be the "forced" track, it may be the "default" track, or it may be "all subtitles in Mandarin". MKVmerge will let you make sure the first track is the one you want to display by default.

Same with audio tracks - if your system does not work well with a particular audio encoding, you can make sure the "best" for your system is the first track found.

And if you ripped a disk and found that several of the "English" tracks are mislabeled tracks in another language you don't want to play, you can remove those (which can save some space).

So there are reasons to do it!

[angelgraves13]

I always run my MKVs through mkvmerge before archiving it.

I usually rename and/or remove unwanted tracks from the files and reorder forced subtitles above regular subtitles.

If need be, I also extract pcm to wavs and re-encode to DTS-HD MA and replace the pcm track.

[MrVideo]

If need be, I also extract pcm to wavs and re-encode to DTS-HD MA and replace the pcm track.

There is a DTS-HD-MA encoder out there? Free, I hope.

[angelgraves13]

If need be, I also extract pcm to wavs and re-encode to DTS-HD MA and replace the pcm track.

There is a DTS-HD-MA encoder out there? Free, I hope.

Nope, not free. Very pricey, but I got it for my video editing needs.

[MrVideo]

Thanks for the update.

[maykemtuyet]

Thanks !