mkv to mkv

[eajarb]

I already have a mkv file but just want to add an ac3 sound file to it and keep the original mkv's size. Which utility is best for this? Thanks

[Baldrick]

I would use uncropMKV to shrink the mkv and then use mkvtoolnix to add the ac3 file.

Or maybe you could shrink both audio tracks to keep the size or cut the video a bit to avoid reconverting the entire video.

[poisondeathray]

Can't keep the same size. It will increase by the size of the added AC3 file. or You could remove the old audio track

MKVToolNix

[PuzZLeR]

You can only keep the same size if you re-encode the rest of the content within the MKV to a lower bitrate to "match" the old size when adding the AC3 file.

Otherwise the simple addition of the AC3 file, such as with a tool like MKVMerge, increases the overall file size approximately by the size of the AC3 file.