best way to re-encode hd mkv with subs?

[arconreef]

I have a foreign tv series (24min each - 1080p mkv h264) that are about 900mb each. I would like to re-encode the videos to about half their current size. What is the highest quality way to do this? As long as the process does not require writing code/script then I can probably figure it out.

[fritzi93]

It's gonna look like crap if you re-encode to ~450MB and keep the resolution at 1080p. Your bitrate is marginal as it is, IMO.

OTOH, you could use HDConvertToX and resize to 720p, output h264 in MKV container. You can keep the subs, even hardcode them if you want.

[arconreef]

Are you sure that a 24 minute video file (1080p H264) needs to be 900mb? I would expect that a full 40-50 minute standard length TV episode would be around that size, but it seems like that would be way more than needed for such a short video. If what you said is true than a 1080p 50min TV episode would need to be around 1.8gb each? In my past experience, most of the other 1080p 24min videos I have seen are around 500mb each. The largest screen I will be displaying them on is 30" (and it is limited at 1080i so it can't quite display 1080p at full quality anyway).

I'm sorry for doubting your logic, but what you said goes against the fact that these 1080p videos are the first I have ever seen that are above 700mb (per 24 minutes). I am most likely wrong, so please enlighten me. Something I neglected to mention earlier is that the videos are animated, and therefore do not need as much detail as a normal video.

What do you think, Am I completely off? It definitely wouldn't be the first time.

[johns0]

I encode my mkv 40 min 720p episodes to a minimum 1gb file size(around 2900kbp),any less and more artifacts start showing.

[fritzi93]

Try it and see?

I don't think there's a consensus that's widely accepted on how much bitrate is necessary for h264 1080p. Much depends on the source, as you say. However, I've seen the figure of 4,500 kbps quoted as minimum for re-encoding clean high quality 1080p commercial BD video, which accords with my own experience. H264 is very efficient, but don't expect the impossible. My bitrate calculator says that for 24 minutes of h264 in MKV container, 29.97 fps, AC3 at 448 kbps (just to plug in a likely figure), and file size of 900 MB, your video bitrate would be ~4,800 kbps. Cut that file size in half and the bitrate's not enough, even for animation, IMO.

At any rate, a program using the x.264 encoder will produce very high quality output, especially at the slower settings. HDConvertToX is just one of the programs available here that use it; I just happen to like that one.

Not to put too fine a point on it, but if we're talking about downloaded videos, file size is typically the priority, *not* quality. On a 30" display, they may look great, on a ~50", not so good. If you don't intend to display on such a large screen, you won't be able to tell the difference between properly encoded 1080p and 720p anyway, at reasonable viewing distance. But a 1080p video with inadequate bitrate will have ugly banding, posterization, etc.

But again, try it both ways and see.