An Update on how to Create One’s Own Movies, to Play on Home Entertainment Systems.

In a previous posting, I shared information on how it’s possible to burn Blu-ray disks using a Linux computer.

I’d just like to recap, what that posting was meant to provide instructions to do. A Blu-ray Disk essentially has 3 levels of formatting. Actually, the formatting has more than 3 levels, but the following is a simplification:

  1. Low-Level Formatting into blocks,
  2. Formatting of the blocks into a File-System,
  3. A special arrangement of the files, into the format required for Blu-ray players to recognize the content of the disk, as a movie and not just as data.

My posting never suggested, that Linux users wanting to burn their own movies, should use DRM or encryption of any kind.

Nevertheless, this way of doing things has become a bit contentious, and so I’d just like to mention, that I no longer recommend that users do it the way I had first written.

What I now recommend users actually do, is to use their favourite Video Editing application to export a movie as an MP4 File, or as an MTS File, or as an OGV File, or as whatever type of media file they like. And then, users can either burn this file onto a physical Blu-ray, as data, which will then have formatting levels (1) and (2) above but not (3), or that users write this file to a USB Key. That way the decision will be at the discretion of the Blu-ray player, or up to any other component of the Home Entertainment System, whether to accept this format of video for playback on the big screen.

I no longer recommend that users actually imitate the formatting layer (3) above, as if their disk was a commercial Blu-ray Movie Disk. It would be a data disk.

Now, the separate question exists, if users are in fact burning data onto a physical Blu-ray disc, of whether they should choose to use some version of UDF as their file system, which accomplishes formatting level (2) above. And my answer would be ‘Yes!’

The reason why I still recommend this is the fact that when optical disks are made to encode data at very high storage densities, the probability of error-bits – i.e., of bits that were recorded as (1) becoming (0), and of bits that were recorded as (0) becoming (1) when played back, becomes a very strong likelihood. And then, digital storage and compression of video streams degrades nastily, even due to a single corrupted bit.

What the UDF File Systems of various levels accomplish is, to include many redundancy bits with the actual stored data, so that not only 1 bit per block could get corrupted, but so that significantly more than 1 bit per block can become corrupted, and the error can be recognized and corrected during the reading of the data from the disk. These redundancy bits are also referred to as Error Detection and Correction bits.

How high a version of UDF the users should use, can be determined by whatever the Operating System offers them, especially since the goal of the exercise would no longer be, to convince the Blu-ray player that the inserted disk is of the same type, as what we buy in the stores.



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