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.

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The UDF Standards fall under an ISO Specification.

In many of my postings, I have erroneously described ISO and UDF File Systems as being mutually exclusive. In fact, UDF is also known as ISO-13346, while what I was referring to as ‘Legacy ISO’, is actually known as ISO-9660.

Among other things, this means that software engineers were correct all along, to store UDF File System Images in .ISO-Files.

Only, my own habit of storing them with file-names that end in .UDF, will prevent my desktop-manager from offering to open these, with applications only compatible with ISO-9660.

Dirk

 

UDF-Capable Disk Burning with K3b and Debian / Stretch

According to This earlier posting, I was using a Debian / Jessie laptop, the first part of which is also known as Debian 8, to burn UDF-Capable Blu-ray Disks, given an external Blu-ray burner, and that version of Linux required help. Specifically, I needed to modify the way K3b behaves, by uninstalling the package ‘wodim’, which provides ‘cdrkit’, and by custom-compiling ‘cdrtools’, which is meant to act as a drop-in replacement for ‘cdrkit’, except for the fact that for the moment, ‘cdrtools’ was more powerful than ‘cdrkit’.

Under Debian / Stretch, which is also known as Debian 9, ‘wodim’ is not suggested by ‘K3b’ anymore, but rather a required dependency, for which reason to uninstall ‘wodim’, would also uninstall K3b. And so I needed to know, whether the package-provided version of K3b, and all its dependencies, could still burn Blu-rays via the GUI.

And the short answer is that Indeed, under Debian / Stretch, the packaged software has the required capabilities, so that to try to modify the behavior of K3b ( v2.0.3 ) is not only a bit risky, but totally unnecessary.

I created a Data-DVD Project – which we would also do for Blu-rays, and then burned that onto a DVD+R with 3 sets of options:

  1. File System = “Linux+Windows”, back-end = ‘growsiofs’
  2. File System = “UDF”, back-end = ‘growisofs’
  3. File-System = “UDF”, back-end = ‘cdrecord’

What I next did, was to run the command ‘df -T /dev/sr0′ , after mounting each disk via the GUI, both actions as a regular user. I found that options (2) and (3) both showed up as a “udf” file-system, while option (1) showed up as an “iso9660″ file-system.

This is as much, as custom-compiling ‘cdrtools’ could do for the user. Also, when going into the Programs settings of K3b, the full range of supported back-ends shows up as being available. Using burning-options (3) above, starts out the dialog with “Using Wodim” in the GUI, but all 3 settings still show me in the K3b GUI, “Burning ISO9660 File System”.

(Updated 10/23/2017 :

screenshot_20171023_173754

If this is to be used seriously for burning Blu-rays, then there is something which the user should further know.

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A Note On Playing Back Commercially-Recorded Blu-rays

Just as it was with DVDs, when movies first started to be distributed in that format, commercially-recorded Blu-ray disks today use an encryption system, which is sometimes referred to as ‘content scrambling’, to prevent people from making unauthorized copies. It’s actually named ‘aacs’.

Experts already know about this, but I’m putting this in layman’s terms for anybody who might not.

Basically, Blu-ray playback-devices have a hidden store of public keys, which the users are not allowed to access, and this time, the company is able to update that store of keys via the Internet, because most Blu-ray players today are also online devices.

Unlike how it is with Blu-rays, the content-scrambling system of DVDs was famously hacked. This means that Linux computers are well-able to play back Movie-DVDs. OTOH, the ability to play back commercial Blu-rays, is mainly unsuccessful on Linux computers, or on any other unauthorized devices, because the content-scrambling which gets used – was never hacked. As long as the encryption continues to work, Linux users and pirates will not be able to play back or rip Blu-rays.

As it stands, the company is able to revoke public keys which it was once using.

This is a shame, because some Linux users might only be wanting to view Blu-ray movies which they purchased and paid for. But the main fear of the industry remains, that as a platform, a Linux computer is more susceptible to an unauthorized copy being made of anything, which that Linux computer would also be able to perform authorized playback of.

Therefore, when I gave instructions on how people can record Blu-rays privately, my assumption was that we would not be using any encryption. I don’t see encryption as being important in any way, for home-movies which people might shoot. But, the Blu-ray folder must nevertheless contain a sub-folder named ‘CERTIFICATES’. In the example I wrote about, this sub-folder will simply remain empty.

Further, the mere use of the Blu-ray (single-layer) disk, as a step-up from DVD+Rs, where a Blu-ray can store up to 25GB of pure data instead of 4.7GB, is unfettered for Linux users to use as they wish. All we need is an external Blu-ray burner, and we’re all set to burn pure data. But as soon as we want to burn something using ‘UDF’, which is the approved file-system of Blu-ray players, the level of difficulty already increases, even though no encryption has been used yet.

(Updated 09/19/2017 : )

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