Question / Help MKV remux - repair methods

[Beardedbob]

Hi,

So discussions recently mhv or mp4 lead me to think that a post is required on which apps to use / tricks to convert / copy / remux mkv to mp4, i've used the following apps in the past to remux mkv to mp4, but wanted to see if anyone else has got any others which are free and good?

VLC
Xmedia recode
MKV2MP4 (though has audio issues for me)

I've also tried corrupting and mkv with a BSOD, shutting down obs without stopping the record and found that I can still render the mkv useless. So I wanted to understand what methods are available to bring it back from the dead? or is it expected to just carry on being playable in say VLC as I've found I can make it none playable simulating a power cut.

cheers

Bob

 

[Harold]

ffmpeg is very capable of handling remuxing the file, and OBS Studio actually can remux an MKV to an MP4 from the function in the file menu.

It takes a LOT of damage to render an mkv unusable. Using FFMpeg or Avidemux may also allow you to recover the mkv when it's been corrupted in the way you've done.

https://obsproject.com/forum/threads/post-production-tools-you-can-use.34080/

 

[Jack0r]

Generally, unless you want to record more than one audio track, we always recommend to use flv as the container. The file should be playable up to the power cut if its a flv. I havent tested it with mkv, but if the container "completes" the file at the end of writing, a power cut will prevent that from happening.

 

[Beardedbob]

@Harold ffmpeg yep is good haven't used avidemux but will take a look, as for the way it was done it was a simple reset of the OS while obs was running nothing complex or magical :-).

I'm not trying to provide mkv to be corruptible, we know it can be recovered / repaired i'm trying to ensure the process to keep the recording is clear as its useful to know. As we have both shown here there are many different apps / methods to achieve this each serving a different propose e.g. VLC can't do a batch mkv to mp4 remux unless it can be scripted can it? but mkv2mp4 can out of the box.

 

[Harold]

ffmpeg can definitely be scripted with batch files, not sure about vlc.
Using ffmpeg to either remux or re-encode the file will be the most likely to be able to recover one of those corrupted mkvs.
I think we agree that mp4s are a lot more fragile.

I've had mkvs and flvs both be playable after bluescreens that prevented their finalization. The only thing that was screwed up was the length estimate, since that portion of the file didn't get written. Immediately after remuxing that information was corrected.

 

[Beardedbob]

Will give it ago with ffmpeg I'm familiar with it from linux and nginx , the ability to script it for batch load is a benefit.

Yep mp4 is fragile and mp4 likes things to be completed otherwise its toys come out of the pram. As we have said if obs is closed without finalising the recording the mp4 is dead but the mkv will live on. I'm just atm trying to understand how far mkv can be pushed before it can't be brought back or if it can always be.

 

[Harold]

MKVs can be pushed pretty far, but there is still a breaking point for them. Not sure how far it is.

 

[cpdj]

Generally, unless you want to record more than one audio track, we always recommend to use flv as the container. The file should be playable up to the power cut if its a flv. I havent tested it with mkv, but if the container "completes" the file at the end of writing, a power cut will prevent that from happening.

See, the problem I'm having is I need to edit the video after the fact, and the only editing app I have is iMovie9 (I'm using a Mac), which does not support flv, and also Facebook doesn't either, so I need to convert it in order to upload there. Do you know an alternative, FREE editing app that will support flv? All I need to do is cut out dead space at the beginning/end, and, if possible, add some text; nothing too fancy.

Also, I need to understand why you would want to have multiple audio tracks, or why is it more than one, does this mean stereo channels? Or something else? Because also I want to separate the audio from the video, post-production, so that I have just the music part in mp3 for my iPod and mix upload sites (I am doing live DJ mix streams). So Where can I find detailed (dumbed down for newbs) info on these topics? As it is now, I'm uploading raw video to YouTube, then ripping the audio off there using an online site, then editing the audio in Audacity. There has to be an easier way!!! lol Thanks!