I need to Convert 4k MKV to 4k MP4 with no loss.

Question

Level 1

31 points

I need to Convert 4k MKV to 4k MP4 with no loss.

As it says.

I want to download a video of my daughter's graduation.

I can download it in 4K, but it downloads it as an MKV, but I need to have it play in QuickTime Player as other family members would like to watch it on their devises who do not have VLC player etc.

I would also like to play it on my TV, which again will only except MP4.

So I need to convert it to MP4 in 4k with no loss.

Can anyone recommend any software that can do this?

I have 'Movavi Video Converter Premium', if anyone knows anything about it, there are so many options for MP4, I'm not sure what to pick to be honest.

Thanks for any help.

MacBook Pro 13″, macOS 14.7

Posted on Jul 8, 2025 09:28 AM

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Answer 1

VikingOSX

Level 10

122,220 points

Jul 8, 2025 02:13 PM in response to DoogyDawg

The free VLC media player is available for Intel and Apple Silicon Macs, Windows, Linux, iOS, Android, and I have it on my M4 iPad Pro with iPadOS 18.5. Even have the VLC app on my Apple TV 4K and it can play just about any format it can sniff on my Synology NAS mounted share including .mkv.

Doesn't the above just about cover what your other family members may have access to without the need to convert the MKV to MP4?

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Answer 2

Jul 8, 2025 10:41 PM in response to DoogyDawg

If the .mkv has QuickTime compatible codecs like H.264/265 video and AAC audio you can rewrap it losslessly (minus possible subtitles) and very fast to .mp4 with:

ffmpeg -i input.mkv -c:v copy -c:a copy output.mp4

If either codec is incompatible like VP9 or Vorbis/Opus, then it is lossy conversion with something like (below are the default quality settings for H.264):

ffmpeg -i input.mkv -c:v libx264 -crf 23 -preset medium -c:a aac_at -b:a 128k output.mp4

Apps like Handbrake and Shutter Encoder have a GUI for that. You can check the codecs with MediaInfo or Invisor.

...or just try to tell the relatives to download IINA or VLC and use it to watch the .mkv movie on the Mac/PC (but with a mobile device that might not be so easy workaround).

https://iina.io/

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Answer 3

DoogyDawg Author

Level 1

31 points

Jul 8, 2025 10:17 PM in response to VikingOSX

No, my wife is really fussy about what she has on her phone...believe it or not, I have tried a few times to get it for her, but it's always a no.

My mother-in-law in her late 70s who lives up the other end of the country, more or less, just hasn't got a clue.

Both only own phones.

We have no other media, I only use my Mac as I don't own a phone, haven't since 2014.

Both my daughters Have Mac's so there's not a problem there.

I could just download it in 1080p mp4 as that will play on almost anything, which I might do.

I would also like to play it on my TV, but it won't play MKV.

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Answer 4

Lemmi1963

Level 2

442 points

Jul 8, 2025 09:49 AM in response to DoogyDawg

mp4 is not a lossless format

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Answer 5

DoogyDawg Author

Level 1

31 points

Jul 8, 2025 10:21 AM in response to Lemmi1963

So these are the options I have....well there are loads more, but these are the main ones.

MP4(mpeg) MP4(HEVC MP4(H264)

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