Compression Schemes

DVCPRO HD (D-12 by SMPTE recognition) is a dual video format, menu selectable HD tape format that is switchable between 1080i and 720p. The compression scheme is DVCPRO HD, a frame bound, deterministic HD CODEC. The video payload upon recording is 100Mb/s. Audio, METADATA, ECC etc is added to bring the total recorded bit rate to about 175Mb/s.

DVCPRO HD uses the following sampling structures:

DVC PRO HD Varicam at 1280 x720 at 60p, we sub-sample the Y signal to 960 x 720, the R-Y/B-Y is sub sampled to 480 x 720, both at 8 bits.Then compressed 6:1 to achieve 99.038Mb/s on tape. This is for 60 frames per sec. When shooting at 24p the camera adds frames to make up to 60. The Varicam format always records 60 frames.

So each frame of DVCPROHD at 720p is 1.65Mb per frame. Multiply by 24 to get 39.60Mb/s at 24p.

720p 59.94/60.00 ( SMPTE 296M) Input signal is 1280 x 720p 10 bit for Y and 640 x 720 for R-Y/B-Y. On tape

DVCPROHD 1080i 29.97 (SMPTE 274M) Input signal is 1920 x 1080 10 bit for Y and 960 x 1080 for R-Y/B-Y. On recording they sub-sample the Y signal to 1280 x 1080, and the R-Y/B-Y to 640 x 1080, both at 8 bits then compressed approx 6.1 to 1.

DVCPROHD 1080i 25.00 (SMPTE 274M) This format is added in the new AJ-HD1700 VTR and 1200 VTR.

Input signal is 1920 x 1080 10 bit for Y and 960 x 1080 for R-Y/B-Y. On tape they sub-ample the Y signal to 1440 x 1080, and the R-Y/B-Y to 720 x 1080, both at 8 bits then compressed approx 6.1 to 1. The AJ-HD150 and AJ-HD1700 decks have the ability to record 1080i or 720p and convert to the other formats on playout.

1920×1080 at 24p is then subsampled to 1440×1080 and 3:1:1 outputs 497.66 raw. So sub-sampled to Y 1440, R-Y/B-Y 480 at 8 bits. Then compressed 4.3 to 1 achieve 115.62Mb/s on tape. Divide by 24, so each frame equals 4.82Mb

1920×1080 Raw 995.328 Subsampled R-Y/B-Y 960. Compressed 3.5 to achieve 284.379Mb/s.

At 24 frames per second so each frame is 11.85Mb. Frame sizes expressed as Pixels. Cineon systems use the following sizes (pixels across the 35mm frame x lines per picture):

‘4K’ Full app 4096 x 3112 pixels

‘2K’ Full app 2096 x 1556 pixels

‘4K’ scope 3656 x 3112 pixels

‘2K’ scope 1828 x 1556 pixels

‘4K’ Academy 3656 x 2664 pixels

‘2K’ Academy 1828 x 1332 pixels

As ever, best to look at the picture, preferably of subjects similar to those that you are planning to shoot. Be aware of the type of display. If it is a plasma it may only display a limited range of colours.