Bluray remux and Bluray re-encode question

[mocqueanh]

I am a noob about Bluray. Just paly some Bluray few days ago.

I have some questions about bakup Bluray. Can you answer me?

- I see somebody backup their Bluray movie in HDD computer, they call "BD Re-encode". They shrink one Bluray disc (about 40-50 GB) into 25GB, and enven 9GB (they call: BD 9). So, will this backup method keep orginal quality of movie? I doubt that, because the size is too small (9GB) to orginal BD disc. If the quality cant be keep, why don't call "Encode" or "Rip" ?

- The other method backup is: "Remux". With this method, they can choose to keep disc menu or not, and remove some unnecessary stuff like some audio streams. And the size of movie after remux isn't too small to orginal disc. They said Remux will keep orginal quality. I think so. But i dont understand: the orginal movie has AVC, or VC-1 video codec. The movie after remux often has H264 video codec. Why ?

I don't intend to backup my Bluray disc in computer, just want to resolve my doubts. Please help me. Thanks

[wulf109]

BDrebuilder can shrink a BR disk to BD25 or BD9 in either full disk or movie only mode. A movie only to BD9 looks very,very good,BD25 better. A program like TSmuxer can remux movie only allowing you to select what streams to keep,it does not re-encode the video,avc would remain avc.

[Baldrick]

1. You might be able to fit the main movie into 25GB. But 9GB would require reencoding/encode/reconverting/reconversion = losing quality.
2. If you change codec it also requires reencoding.

[yoda313]

the orginal movie has AVC, or VC-1 video codec. The movie after remux often has H264 video codec. Why ?

h264 has an excellent compression ratio for high def source material. It has more and more acceptance in playback devices like a ps3 or a wdtv media player - or a bluray player when authored as an avchd.

The original codecs used in bluray are very large and in order to compress to a dvd dual layer for "bd9" discs you need to reencode it - change the quality. They can look very good but won't be the same as the original version.

Bluray backed up to bluray media will be much closer to its original form - compressing to bd25 from bd50 should keep it close to its original form with minimal reduction in quality while maintning features.

Think of converting to h264 from bluray the way you would have converted dvd to divx in years past. The quality can be good but won't be exactly the same as the original. And think of going from bd50 to bd25 the same as shrinking a dvd from dvd9 to dvd5 - transcoding a dual layer to single layer.

[mocqueanh]

Think of converting to h264 from bluray the way you would have converted dvd to divx in years past. The quality can be good but won't be exactly the same as the original. And think of going from bd50 to bd25 the same as shrinking a dvd from dvd9 to dvd5 - transcoding a dual layer to single layer.

Well, they told me that remux is cut unecessary stuff (like Spanish audio in English movie, or commentary audio), so the quality is intact. And i see their BD remux is 30GB (the orginal BD disc is 36GB), isn't too small to orginal. I just confused their Remux video codec is H264.