Info: m2ts to mkv

I have a technical issue (not much): I have synchronized a french srt file on Q2’s hybrid ROTJ, which is a m2ts file (20.1 Go and 20 973 kbits/s); I want to mux it in order to get a single video file, so I use mkvtoolnix. The strange thing is that I end up with a mkv file (which is normal) of a lesser weight (18.9 Go and 19 726 kbits/s), so I assume there has been a quality loss during the muxing, although I chose the “no compression” option. Is there a way to prevent the (slight) quality loss ?

Thanks in advance to anyone who’s got an answer !

M2ts files have more “overhead” space wasted than MKVs. I dont’ know if mkvtoolnix is capable of re-encoding (I only use the mkvmerge GUI), but I think it’s likely that you’re okay. Especially if the mux operation took seconds or minutes instead of hours.

Make sure you’ve got all your audio tracks, though.

Ok you confirm what I was thinking, because even with the “loss” the video quality seems the same between both formats, and demuxing the m2ts file through avidemux gives a h264 video file of the exact same weight as the mkv video file only… don’t know if I’m clear but it kinda proves the “overhead” space wasted you’ve mentioned.

Thanks for your answer !

… just now something I don’t get: aren’t mkvmerge and mkvtoolnix the exact same tools ?

MalàStrana said:

… just now something I don’t get: aren’t mkvmerge and mkvtoolnix the exact same tools ?

I think mkvmerge is just a front end for mkvtoolnix. I just meant that I’ve never used the command line app, so if it has re-encoding options that aren’t in the GUI, I haven’t seen them.

It’s a pain going in the other direction, from MKV to m2ts for burning a blu-ray. You think you’ve got a file that’s small enough to fit on a disc, but it inflates as m2ts and goes above the limit for a disc.

Since I still don’t have a bluray burner I’m not yet confronted to this issue, but I’ll keep that in mind !

I’ve made a small change to the ac3 audio file thanks to audacity (Chewie’s “Tarzan scream” was fun when I was 6, now I really don’t like it); is there a way to make a lossless export without ending up with a 3 times larger file ? It’s not a real issue but I was wondering (a quick google search leaves me to believe there is no other way, but I try anyway to ask 😃).

edit: hum… since the original file isn’t native lossless I think it’s not possible.

Thanks for the advise, I would eventually burn it on a bluray disc when I have the tools for. Meanwhile I use a kodi system which can basically read anything. You both confirm the intel I was looking for: MKVToolNix does not compress video files (except when asked for), so I can mux subs without any quality loss. Which is cool !

MalàStrana said:

Thanks for the advise, I would eventually burn it on a bluray disc when I have the tools for. Meanwhile I use a kodi system which can basically read anything. You both confirm the intel I was looking for: MKVToolNix does not compress video files (except when asked for), so I can mux subs without any quality loss. Which is cool !

Hey, I’ve been looking into getting a Kodi system lately. Any recommendations? I’d much prefer to have things on a local harddrive as opposed to any kind of network streaming, so I’m thinking about the KDlinks A300.

I’m must confess I don’t know much in hardware/software (no kidding 😃), but I’ve asked my bro, who’s made my installation, his reply is : “I don’t know the A300 model, but after a quick search it seems it’s largely good enough for a kodi system”. So you wouldn’t make an error buying this model I guess; try to look for a user community of this model in order to know what might be the little issues (and eventually how to fix the issues when fixable).

Thanks. I’ve been doing a bit of research. So you don’t have a set top type box but just a computer media server running windows/linux/whatever?

Yes, it’s like a mini-computer you can access on your tv and which is logged to another main computer.

(edit: to be sure i’ll send a mail to my bro so I don’t say anything stupid…)

edit2: ok, that’s what I said: NUC (Intel) running on Windows 10; data (i.e. movies files) streamed through the NAS system (NAS which is logged to a main computer). So you’re right !

Does someone know how to encode a dts file in the exact same quality (ie lossless) with audacity ? Thanks in advance !

A few things: By editing the AC3 audio in AUdacity, AUdacity can only reencode, so you’ll take a quality hit. For lossless editing, you can try mkvtoolnix or delaycut to add silence & cut etc.

AUdacity cannot make DTS. try Surcode or DTS master audio suite.

ED:2le

junh1024 said:

A few things: By editing the AC3 audio in AUdacity, AUdacity can only reencode, so you’ll take a quality hit. For lossless editing, you can try mkvtoolnix or delaycut to add silence & cut etc.

AUdacity cannot make DTS. try Surcode or DTS master audio suite.

Thanks, i’ll try the other softwares. With audacity and already compressed files used it’s not an issue (well… I might be wrong about that): for instance, a 448kbps file can be saved with the same quality.