What is Blu-ray?

I’m sure there’s hardly anyone affiliated with filmmaking who hasn’t heard of Blu-ray. This article explains:

  • What is Blu-ray?
  • Is it worth getting into at this point?
  • What you need to get started
  • How to burn Blu-ray media

Blu-ray Logo

What is Blu-ray?

Blu-ray is an optical disc format that was meant to replace DVD. The fundamental difference between them is that DVDs support standard definition, while Blu-ray supports high-definition (up to 1080p).

There are different types of Blu-ray, because scientists are always finding newer ways to stuff more into one disc. The three most important kinds are Single Layer, Dual Layer, and XL.

How much can they store?

  • Single Layer – 25 GB
  • Dual Layer – 50 GB
  • XL – Greater than 100 GB

Most Hollywood movies are either Single Layer or Dual Layer, and this is what modern consumer Blu-ray players are designed to play. The XL variety hasn’t found that kind of penetration, but is important because Blu-ray is working on a 4K (Ultra-HD) variant. The maximum frame rate supported at 1080p is 30 fps.

There is one other major difference between DVDs and Blu-ray, and that is the compression codec employed. DVD uses MPEG-2, while Blu-ray supports both H.264 and H.262 (MPEG-2). Many DVD players can also playback AVCHD files.

How is it that Blu-ray can store more data in a disc? It uses a laser with a smaller wavelength. 405 nm to be precise. From Driving Miss Digital, you know that 405 nm is at the blue end of the light spectrum. The following image will make it clearer:

DVD vs Blu-ray
Image Courtesy: Cmglee

By employing a smaller wavelength, a Blu-ray disc can store data more closely. In the above image, w and l is the width and length of the spot. The length can be long enough for the laser to understand it isn’t long by mistake (dash and dots represent 1s and 0s). phi represents the spot size, which is slightly larger than the wavelength (If you want to know, it’s because of the airy disk diffraction pattern).

See where the name comes from? Blue wave laser, blu-ray.

Is Blu-ray worth getting into at this point?

I think it is safe to use Blu-ray for at least five years. This is my estimate, and you should study the market and decide for yourself. I would be very surprised if Blu-ray is still around ten years from now.

In today’s market, Blu-ray has some tremendous advantages:

  • 1080p video quality better than broadcast, VOD or DVD.
  • Excellent data rate (36 Mbps)
  • Dependable playback, unlike VOD
  • Reusable playback, unlike television
  • Home-theater compatibility
  • Excellent audio codec support; from LPCM to Dolby to DTS, stereo, 5.1 and 7.1
  • Technology that can stuff 1 TB on a single drive
  • Ability to incorporate 4K with better data rates than other formats
  • The ability to leap tall buildings in a single bound (just checking if you’re still reading)
  • Ability to store subtitles, captions, menus, bonus features, etc.
  • Some kind of penetration (but not as good as DVD) in the market
  • Ability to read/write at 400 Mbps or more
  • Doesn’t (to some extent) have the region-code problem that plagues DVDs
  • Blu-ray players can play back DVDs, and sometimes CDs as well
  • Has support for AVCHD
  • Has support for Stereoscopic 3D

HDTV hasn’t had the penetration that SD has had. Most television is still broadcast in SD, while most Youtube videos are watched at the lower resolution settings due to limits in Internet speeds. For these reasons, DVD still persists as a popular choice among the masses.

Like I said earlier, Blu-ray is a format created to replace DVD. Looks like both will die together.

What you need to get started

To read a Blu-ray disc, you need a Blu-ray Player. The major manufacturers are Sony and LG.

To burn a Blu-ray disc, you need a Blu-ray Writer. My favorite is LG.

There are two kinds of blank Blu-ray Discs you can use:

  • BD-R (You can record only once, works similarly to DVD-R)
  • BD-RE (You can write and erase multiple times, works similarly to DVD-RW)

I prefer Sony discs.

How to burn Blu-ray media

You can do two things to Blu-ray:

  • Use it as a data drive (ignore the Blu-ray spec and treat it like a hard drive), or
  • You can follow the Blu-ray specification

To do the latter, you need software. A good software will allow you to do all of the goodies mentioned earlier and produce great quality. The process of encoding for Blu-ray and organizing content into video, audio, subtitles, menus, etc. is called Authoring.

My favorite application for professional authoring is Adobe Encore, which interfaces perfectly with Adobe Premiere Pro. The steps are as follows:

  • Save your locked project in Premiere Pro
  • Choose File-> Adobe Dynamic Link -> Send to Encore
  • Choose your resolution and frame rate (PAL or NTSC)
  • Choose your maximum data rate (15 Mbps to 40 Mbps)

Once your project is open in Encore you can create:

  • Menus
  • Slideshows of images
  • Subtitle tracks
  • Audio tracks (like the director’s commentary)
  • Additional video tracks
  • Chapter markers and playlists

We’ll let the detailed workflow wait for another article, but the process is not that hard. The simplest way to learn Adobe Encore is by reading the manual. It’s good enough, trust me.

Once your project is ready you can preview how it works from within Encore. When you are satisfied you burn your disc, with just one transcode between your master and your blu-ray. The way to get the best quality is to keep your workflow simple.

This article is only meant to be a brief overview of Blu-ray and how you can start using it. All said and done, I truly believe Blu-ray is still the best standard for watching movies short of cinema, and will remain so for some years to come.


2 replies on “What is Blu-ray?”

Comments are closed.