Converting from MP4/MKV to MTS

[smithb]

Hello, I realize most are going the other way around to shrink files for easier distribution. My situation is that I have 720p 60fps video in MP4 and MKV, but want it in 720p 60fps MTS format for burning on blu-ray. I realize that any conversion that results in re-encoding is going to result in some loss in quality. What I'm interested in is how to minimize the quality loss, as best as possible.

I generally use TMPGEnc Video Mastering to perform conversions.

My question has to do with bitrates. When I open the MP4 or MKV file in the application, the existing bitrate is typically between 2.8 and 3.5. When selecting to convert to MTS, the application defaults to 11, with a resulting file 3 to 4 times larger. I realize MP4 results in a smaller size. However, if the MTS video is also H.264, do I need such a high bitrate for the resulting MTS file?

In other words,
- Assume the application default of 11 for the bitrate and accept the three to four times resulting file, or
- Would it be just as good to use a similar bitrate for the MTS output to match the source MP4 file?

I would think that an MTS and MP4, both based on H.264, would be of similar quality if at the same bitrate, but I'm not versed enough on the subject and could be way off base.

Thanks for your help.

[videobruger]

tsMuxeR. Just muxing.

[smithb]

Thanks for the suggestion. I downloaded and installed the application. I converted a few MKV files easy enough, but when dragged into my Tmpgenc authoring software, it stated the video would require re-encoding due to some of the parameters of the video being outside the blu-ray spec (bummer).

- Profile/Level
- Framerate/Scan Type
- Max bitrate
- Max Number of GOP fields

As for MP4 files, I received an error when trying to add them to tsMuxeR.

Great idea since it supports no re-encoding.

[sneaker]

In other words,
- Assume the application default of 11 for the bitrate and accept the three to four times resulting file, or
- Would it be just as good to use a similar bitrate for the MTS output to match the source MP4 file?

Every conversion by a lossy codec results in a loss of quality. You will lose less quality when choosing e.g. 11 Mbps instead of 3 Mbps even if the source was 3 Mbps. How - if at all - you perceive this loss of quality as a human is hard to predict short of simply testing it and comparing with your own eyes. It is highly dependent on the nature of the content (lots of noise and movement vs some very clean still shots), encoder quality (different encoders mean different results) and settings (e.g. x264 preset veryslow vs preset ultrafast). So it's hard to give a general answer.

[smithb]

Thanks sneaker,

The video is very clean but with lots of motion (HD broadcast basketball games). You are correct, ultimately it comes down to my perception of any quality difference in real viewing. Testing that I will need to do (I watch using a 92" screen projection system).

My hope was to see, based on the experience of those having been more involved in video conversions then myself, if there is a stronger leaning towards a similar bitrate based on both being H.264 encoded, or towards the high end of using the default size of 11 due to other differences between Mp4 to MTS. If for no other reason than having additional guidance to compare with my own findings. But as you mentioned, there may be too many variables involved. I don't mind going high, it just means a difference between 2 games per 25 GB disk vs. 4 to 5 games per disk. Less disks are nice but not required.