Digital Cinema

[diogen]

A few interesting posts by a Digital Cinema projectionist, starting here
AVS Forum - View Single Post - Industry Insiders Master Q&A thread IV: ONLY Questions to Insiders

Compression is generally done using an advanced codec called JPEG2000...
Paramount's release of Transformers weighed in at a very healthy 263GB for 2hr. and 30mins. or so. And it looks spectacular...

Warner's release of Harry Potter and the Order of the Pheonix weighed in at 61GB with it's 2hr. 10min. runtime.... This film still managed to look amazing!

Disney's release of Pirates of the Caribbean: At World's End looked amazing with a size around 280GB...

Diogen.

 

[John Kotches]

Digital Cinema is different than MPEG-2 / MPEG-4. They are discrete JPGs of each frame using the JPEG-2000 compression algorithm.

Each frame is fully independent with no anything but the picture data.

For Transformers:
263 GB / 150 Minutes ~= 1.75 GB / minute of running time for Transformers. This is a sustained data of about 233 Mbits/second or a hair under 30 MBytes/second.

You might be able to make the film smaller by using more agressive compression but not knowing what the size targets are it's hard to say.

Cheers,

 

[diogen]

...They are discrete JPGs of each frame using the JPEG-2000 compression algorithm.

That was the point: Digital Cinema is using only key frames (I-frames) encoding (just like old QuickTime 6) - compessability down the drain - and can sometimes get away with sub-100GB files (Harry Potter). That means that with the latest batch of sub-$3K 1080/24p projectors and HD/BD movies a very reasonable budget can create at home a movie experience rivaling - if not surpassing - the one in Digital Cinema!

I watched some Blu-ray movies reencoded into 720/24p using x264 (best H.264 encoder according to Stacey Spears) and made fit onto a SL DVD(!). It looks so much better than regular DVD, it is not even funny...

Diogen.

 

[John Kotches]

Are you sure that the HP is not a typo? It's smaller by 200GB (a substantial bit less than the others). If you put the 2 in front it lines up nicely in size.

I disagree with the experience surpassing. Having seen D-Cinema and MPEG-2 / MPEG-4 / VC-1 on the same projector the D-Cinema wins Not that the home HD experience sucks as it stands; but it isn't as good as D-Cinema.

Yes, HD looks better than SD; and a good encoder makes a big difference.

Also, name dropping isn't particularly effective when the other party (me) is personal friends with the name being dropped

Cheers,

 

[diogen]

Are you sure that the HP is not a typo?

Could be.

I disagree with the experience surpassing. Having seen D-Cinema and MPEG-2 / MPEG-4 / VC-1 on the same projector the D-Cinema wins...

To be honest, I haven't seen Digital Cinema. In fact, I watched movies in movie theaters 3 times in the last 5 years: Bourne I, II and III.
But I've seen a few home setups that leave you scratching your head: what can be possible missing here. One of them had Wilson X1 as fronts.

I have some experience in compressing I-frames only video material. In short: it sucks big time.
I would guess modern compression tools would reduce the JPEG2000 file by a factor of ~5 without losing any quality
(even if JPEG2000 uses lossless compression). And this puts a 250GB file at 50GB, same ballpark as HD/BD.

If the Digital Cinema file is better than 4:2:0 and/or 8bit - that could explain the visible difference in quality.

I should also add that I'm not even close to having "golden" eyes or ears...

Diogen.

 

[berck]

If the Digital Cinema file is better than 4:2:0 and/or 8bit - that could explain the visible difference in quality.

It has a 12:12:12 bit depth (36 total) per pixel. It can also do lossless or lossy compression. The audio is LPCM too

Specification (PDF)

 

[mike123abc]

One of the theaters here went all digital (well they have 2 theaters with both digital and film since some small films are still film only). The resolution they are using is only 2k or 2048 vs 1920, but the color depth is 12 bit. The picture shows just how far the home picture needs to improve. The level of detail and color depth is much higher than the home market. When you consider how large the picture is, and you do not see pixelation or other artifacts, you are truely seeing the difference. Also note the decoding hardware has to be 16 bit precision.

The picture in a digital cinema will spoil you. The picture does not degrade, you do not have all the scratches that appear on film after a few showings.

 

[diogen]

...When you consider how large the picture is, and you do not see pixelation or other artifacts...

This can't have anything to do with neither bit depth nor chroma level. Some Panasonic LCD projectors don't exibit any pixel structure either.
But when compared to good DLP projectors, you will notice that Panasonic achieves this by sacrificing sharpness.

Diogen.

 

[mike123abc]

This can't have anything to do with neither bit depth nor chroma level. Some Panasonic LCD projectors don't exibit any pixel structure either.
But when compared to good DLP projectors, you will notice that Panasonic achieves this by sacrificing sharpness.

Diogen.

I think it has more to do with far less compression. They seem to be compressing 1/10 the compression of BD or HDDVD. The ones here are using 3chip DLP projectors.