Do Blu-Rays use Lossless compression

[Linus No Beard]

Because of simple math I know they need to compress it somehow but I want to know it it is lossless or lossy. Because there are lossless audio standards and video standards that allow you to get a 100% similar output after decompression I was wondering if Blu-Rays use this or if they are just using normal lossy compression with a higher bit-rate than streaming.

[tkitch]

lossy

[Linus No Beard]

Just now, tkitch said:

lossy

Oh what type

[tkitch]

https://en.wikipedia.org/wiki/Blu-ray#Media_format

 

mpeg

[Linus No Beard]

3 minutes ago, tkitch said:

https://en.wikipedia.org/wiki/Blu-ray#Media_format

 

mpeg

I though mpeg / mpeg-4 can be made lossless

[Guest]

Yes MPEG-4 SLS is lossless.

 

There's a very good article on Wikipedia, if you want more details.

[Linus No Beard]

9 minutes ago, Thomas4 said:

Yes MPEG-4 SLS is lossless.

 

There's a very good article on Wikipedia, if you want more details.

Do you know of any Blu-Rays that use that type of MPEG?

[BobVonBob]

Just now, Thomas4 said:

Yes MPEG-4 SLS is lossless

MPEG-4 SLS is for lossless audio, not video.

 

12 minutes ago, Linus No Beard said:

I though mpeg / mpeg-4 can be made lossless

I believe MPEG-4 supports a few lossless audio standards (like SLS), but to my knowledge it does not support lossless video. Lossless video is hilariously large, even when using a codec with lossless compression, and it provides no benefit to a media consumer. There's an argument for it if you're going to process or edit the video, but for consumption it's the same situation as audio compression, high quality lossy video compression is multiple times smaller while being visually indistinguishable from lossless video.

[starsmine]

1 hour ago, Linus No Beard said:

Because of simple math I know they need to compress it somehow but I want to know it it is lossless or lossy. Because there are lossless audio standards and video standards that allow you to get a 100% similar output after decompression I was wondering if Blu-Rays use this or if they are just using normal lossy compression with a higher bit-rate than streaming.

Raw video is really the only video files you will ever find that are lossless compressed, and those are only around 3 to 6x smaller then uncompressed video. Its pretty much unusable as a video format for sharing and viewing due to the massive file sizes requiring terabytes of date for short clips. No one really wants buy an episode of a tv show that require shipping on a 50 dollar HDD or 100 dollars of flash. Nor do any studios want to export a master into that form. 

1080p bluray uses h.264 MPEG, 4k Bluray uses h.265 MPEG. and the disks are under a dollar each. 

[Linus No Beard]

2 minutes ago, starsmine said:

Raw video is really the only video files you will ever find that are lossless compressed, and those are only around 3 to 6x smaller then uncompressed video. Its pretty much unusable as a video format for sharing and viewing due to the massive file sizes requiring terabytes of date for short clips. No one really wants buy an episode of a tv show that require shipping on a 50 dollar HDD or 100 dollars of flash. Nor do any studios want to export a master into that form. 

1080p bluray uses h.264 MPEG, 4k Bluray uses h.265 MPEG. and the disks are under a dollar each. 

if there are 8 bits for red, green, and blue then that is 24 bits per pixel for 2073600 pixels at 1080p or 49,766,400 bits per frame then there are 24 frames per second or 1,194,393,600 bits per second then lets say the standard movie is 90 minutes or 5400 seconds so 6,449,725,440,000 bits long or 80,621,568,000,025,698 bytes long or 75.14 GiB so taking your 3 to 6x number and using 6x that make it a cool 12.54 GiB. Wait something seams wrong

  

[starsmine]

27 minutes ago, Linus No Beard said:

if there are 8 bits for red, green, and blue then that is 24 bits per pixel for 2073600 pixels at 1080p or 49,766,400 bits per frame then there are 24 frames per second or 1,194,393,600 bits per second then lets say the standard movie is 90 minutes or 5400 seconds so 6,449,725,440,000 bits long or 80,621,568,000,025,698 bytes long or 75.14 GiB so taking your 3 to 6x number and using 6x that make it a cool 12.54 GiB. Wait something seams wrong

  

Raw is more like 12-16bit, but its not in RGB encoding anyways. 
 

h.265 blurays are 10bit

 

And yea your math is wrong, and there is no need to be that precises. 
3Bytes*2MP = 6MB, per frame

6*24 = 144MB per second
144 * 60 = 13GB per Minute

13*90 = 1.17 TB per 90 min flick
6x would be 200GBs 

200GB per 8bit FHD short movie, with no audio, no menu, no bonus features

[Linus No Beard]

30 minutes ago, starsmine said:

Raw is more like 12-16bit, but its not in RGB encoding anyways. 
 

h.265 blurays are 10bit

 

And yea your math is wrong, and there is no need to be that precises. 
3Bytes*2MP = 6MB, per frame

6*24 = 144MB per second
144 * 60 = 13GB per Minute

13*90 = 1.17 TB per 90 min flick
6x would be 200GBs 

200GB per 8bit FHD short movie, with no audio, no menu, no bonus features

Would something like treating it like a zip give a better ratio than raw?

[starsmine]

No, zip files dont generally compress already compressed files. at that point its just acting like a wrapper for multiple files. Nor is that going to do much for reading it, it makes sequential reading more difficult, as you have to extract it, place it somewhere then decode sequentially. 

[Linus No Beard]

I mean instead of a raw when you do the first compression compress it like a zip

19 minutes ago, starsmine said:

No, zip files dont generally compress already compressed files. at that point its just acting like a wrapper for multiple files. Nor is that going to do much for reading it, it makes sequential reading more difficult, as you have to extract it, place it somewhere then decode sequentially. 

Or you can use Huffyuv it gets good ratios

[LAwLz]

3 hours ago, Linus No Beard said:

Because of simple math I know they need to compress it somehow but I want to know it it is lossless or lossy. Because there are lossless audio standards and video standards that allow you to get a 100% similar output after decompression I was wondering if Blu-Rays use this or if they are just using normal lossy compression with a higher bit-rate than streaming.

It entirely depends on what you are talking about.

You need to specify exactly what scenario you are talking about.

 

I am going to make an assumption that when you say "Blu-ray" you are actually talking about a professionally made movie saved on a Blu-ray disc. For example the movie Avengers from Marvel.

 

 

The movie itself on the Blu-ray consists of several different data streams. Some of which are compressed, some of which might not be compressed at all, and whether or not they are lossless compressed or lossless also depends on which stream you are talking about. I am going to assume you are talking about the actual video data, which makes up most of the data on the Blu-ray. That data is compressed. It's compressed in the format of H.262, H.264 or VC-1.

 

 

 

 

1 hour ago, Linus No Beard said:

if there are 8 bits for red, green, and blue then that is 24 bits per pixel for 2073600 pixels at 1080p or 49,766,400 bits per frame then there are 24 frames per second or 1,194,393,600 bits per second then lets say the standard movie is 90 minutes or 5400 seconds so 6,449,725,440,000 bits long or 80,621,568,000,025,698 bytes long or 75.14 GiB so taking your 3 to 6x number and using 6x that make it a cool 12.54 GiB. Wait something seams wrong

Your math seems a bit off.

You're correct all the way up to 6,449,725,440,000 there being 6,449,725,440,000 bits of data in a raw 8 bit RGB video if it's 90 minutes long and runs at 24 FPS.

 

6,449,725,440,000 bits is not 80,621,568,000,025,698 bytes however. And 80,621,568,000,025,698 bytes would not be 75GiB (it would be over 80PiB).

In order to convert from bits to bytes we divide by 8.

6449725440000/8 = 806215680000 (I think you mistakenly added a few numbers at the end).

 

In order to convert to Kibibytes, we divide by 1000:

806215680000/1000 = 806215680

806215680KiB

 

In order to get MiB we once again divide by 1000:

806215680/1000 = 806215.68

806215.68MiB

 

In order to get to the final GiB number we once again divide by 1000:

806215.68/1000 = 806.21568

806.21568GiB.

 

The uncompressed 90 minute movie would be slightly over 806GiB large.

 

Just for a sanity check let's test it on Wolfram alpha:

(1920x1080x24x24x5400)/8/1000/1000/1000=608.21568

 

Or we could also do:

6449725440000 bits to gigabytes which results in 806.2GB (Wolfram does not separate between GB and GiB).

 

 

We have nowhere near enough space on a Blu-ray to save uncompressed video. There is also the issue of player support. Even if uncompressed video were to fit on a disc, the players are designed to be cheap to manufacture and mostly backwards compatible. As a result, there are relatively few combinations of video formats and settings allowed to be stored on a Blu-ray disc. Even if an uncompressed video was less than 25GB in size, there is a risk that the Blu-ray players people have at home wouldn't be able to handle decoding and presenting all that data at a fast enough rate.

The read speed of a Blu-ray at x1 is defined as 36Mbps. I think it's safe to say that most consumer devices supports at least 2x speed for playback, but even that is just 72Mbps. That wouldn't even be enough to read 2 uncompressed frames in a second. And that's assuming pretty idea conditions (read speed drops the closer to the center of the disc you are, and some data is required for error correction).

 

 

But it is entirely possible to save uncompressed video on a Blu-ray. You can save any type of data on a Blu-ray if you want. Just don't expect it to be play-able in a Blu-ray player.

[Linus No Beard]

9 hours ago, LAwLz said:

Your math seems a bit off.

You're correct all the way up to 6,449,725,440,000 there being 6,449,725,440,000 bits of data in a raw 8 bit RGB video if it's 90 minutes long and runs at 24 FPS.

 

6,449,725,440,000 bits is not 80,621,568,000,025,698 bytes however. And 80,621,568,000,025,698 bytes would not be 75GiB (it would be over 80PiB).

In order to convert from bits to bytes we divide by 8.

 

I think i might of multiplied by mistake