Understanding HD: Frame Rates, Color & Compression

Transcription

1 Understanding HD: Frame Rates, Color & Compression

2 HD Format Breakdown An HD Format Describes (in no particular order) Resolution Frame Rate Bit Rate Color Space Bit Depth Color Model / Color Gamut Color Sub-Sampling Compression

3 HD Format Breakdown Examples 1920 x P 10-bit Uncompressed YCbCr 4:2: x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2

4 Resolutions 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Standard HD Resolutions 1920x1080 pixels 1280x720 pixels 2k x 1556 pixels 4k x 2304 pixels

5 Resolution Sub-Sampling Sub-Sampling to Compress Data 1920 x x 1080 (HDCAM, HDV, XDCAM HD) 1280 x 1080 (DVCPRO HD) 1280x x 720 (DVCPRO HD)

6 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 US (NTSC / 60 hz) Frame Rates 59.94i (aka 60i) Interlace Fields per Second 29.97p (aka 30p) Progressive Frames per Second (aka 24p) Progressive Frames per Second 24p - true 24 Progressive Frames per Second

7 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 60i US Standard = 59.94i = 29.97i (Confusing I Know) Odd Field Even Field Odd Field Even Field 60 x Per Second

8 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 30p = 29.97p = PsF First Frame Second Frame Third Frame Fourth Frame 30 fps v v Odd Field Even Field Odd Field Even Field Odd Field Even Field Odd Field Even Field 60 fps

9 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Working with 23.98p 2-3 Pull Down to 59.94i Visually & Broadcast Ready PsF (Progressive Segmented Frames) 48i Interlaced Fields per Second Progress feed to recorders

10 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 24P = p 2:3 Pulldown into 60i First Frame Second Frame Third Frame Fourth Frame 24 fps v v Odd Field Even Field Odd Field Even Field Odd Field Even Field Odd Field Even Field 60 fps

11 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 24PA = p 2:3:3:2 Pulldown into 60i First Frame Second Frame Third Frame 24 fps Odd Field Even Field v Odd Field Even Field Odd Field Even Field Odd Field Even Field 60 fps

12 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2: PsF (Progressive Segment Frame) First Frame Second Frame Third Frame Fourth Frame 24 fps v v Odd Field Even Field Odd Field Even Field Odd Field Even Field Odd Field Even Field 48 fps

13 Frame Rates 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Europe (PAL / 50 hz) Frame Rates 50i Interlaced Fields per Second 25p Progressive Frames per Second That s it!

14 Understanding HD - Frame Rates Questions?

15 Understanding Color How is color made in a digital camera? What is color depth / bit depth? What is a color space? What is a color model? What is a color gamut? What is color sub-sampling?

16 Color: How is it made in camera? All Digital Sensors are Black & White (Luminance Only) Color is made in two different ways: 3 Sensors with a Prism 3 Sensor Imager Single Sensor with a Color Mask Bayer Mask Sensor Both Produce Red, Green, and Blue Images

17 Color: 3 Sensor Color 3 CCD or 3 CMOS Sensors 3 Sensor Imager Color is split by a prism into RGB Images Used in most small sensor cameras HVX200 and HPX170 (1/3 ) Panasonic & Sony ENG (2/3 )

18 Color: 3 Sensor Color

19 Color: Single Sensor Color Single Sensor Color Bayer Mask Sensor Each Pixel is filtered for one color Full RGB images is created by analysis of the color pattern of the sensor Most popular pattern is the Bayer Mask

20 Color: Single Sensor Color Bayer Mask is used on most single sensor cameras RED One & Epic Bayer Mask Sensor Arri Alexa Sony F3 & FS100 Bayer pattern creates color with filtration 2x2 matrix has 2-green, 1-red, 1-blue Invented by Dr. Bryce E. Bayer at Kodak

21 Color: Single Sensor Color Other color patterns are used by different cameras Sony F35 has a stripped sensor Sony F65 has a special design F65 Sensor F35 Sensor

22 Color: The Pixel Image 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Defining Color One Pixel at a Time Each Pixel has its own brightness (luma) and color (chroma) information I m a Pixel

23 Color: The Pixel Image 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Luma - Y - is strictly black and white information Chroma - C - is strictly color information

24 Bit Depth 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Bit Depth AKA Color Depth Defines the amount of color variation available per color channel per pixel 8-bit & 10-bit are very common.

25 Bit Depth - 8 Bit 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Bit Depth Variations 8-Bit Color 2 8 = 256 per channel (RGB) 3 Channels x 8 bits = 24 Bits total 16,777,216 colors available

26 Bit Depth - 10 Bit 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Bit Depth Variations 10-Bit Color 2 10 = 1024 per channel (RGB) 3 Channels x 10 bits = 30 Bits total 1,073,741,824 colors available

27 Bit Depth - 12 Bit 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Bit Depth Variations 12-Bit Color 2 12 = 4096 per channel (RGB) 3 Channels x 12 bits = 36 Bits total 68,719,476,736 colors available

28 Bit Depth - Banding 10 bit Image 8-bit Image (no dither)

29 Bit Depth - Dither 8-bit Image (no dither) 8-bit Image (with dither)

30 What is Color Space? Color Space is defined by two parameters: Color Model Color Gamut (footprint) Popular Color Spaces REC 709 / DCI P3 Adobe RGB srgb

31 Color Model 1920 x P 10-bit Uncompressed YCbCr 4:2:2 A Color Model is a mathematical model describing colors as a set of numerical values (usually in 3 or 4 values) Examples RGB YCbCr / YPbPr CMYK (used in print)

32 Color Model 1920 x P 10-bit Uncompressed YCbCr 4:2:2 RGB - Red / Green / Blue R = Red Chroma & Luminance G = Green Chroma & Luminance B = Blue Chroma & Luminance

33 Color Model 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Y Cb Cr (digital) / Y Pb Pr (analog) Removes redundant Y information Y = Luma only information Cb = Blue-Difference Chroma information Cr = Red-Difference Chroma information

34 Color - The Pixel Image In Y Cb Cr - Each pixel contains 1 Y values and 2 Chroma values In R G B - Each pixel contains 3 Y values & 3 Chroma values

35 What is Color Gamut? Defining Color the way HUMANS see it CIE 1931 Color Space International Commission of Illumination 1931 Study which became CIE RGB Later Modified to CIE XYZ Color Space All Color Gamuts are based on limitations of the CIE XYZ Color Space

36 Color Gamut ITU-R Recommendation BT.709 (REC709) Used in HDTV Universally Defines primaries and limits of what colors can be shown in REC709 video. The full spectrum is CIE XYZ REC709 has limited color options (in triangle) D65 is that white point

37 Color Gamut Other Color Gamuts Video Gamuts Computer Gamuts F65 Print Film F35 (S-Gamut) DCI ITU-709 Visible Color

38 Color Space Color Space is defined by: Color Model - RGB, YCbCr, CMYK Color Gamut - Location of Primaries

39 Color Sub-Sampling 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Color Sub-sampling is a reduction in Color Resolution Reducing color also reduces data rates, and it is not easily visible to our eyes. Works in Y Cb Cr Does not work in RGB

40 Chroma Sub-Sampling - 4:4:4 4 Luminance Samples 4 Color Samples 4 Color Samples Y C Y C Y C Y C Y C Y C Y C Y C Y = Luma C = Chroma

41 Chroma Sub-Sampling - 4:4:4 4 Luminance Samples 4 Color Samples 4 Color Samples Y C Y C Y C Y C Y C Y C Y C Y C Y = Luma C = Chroma

42 Chroma Sub-Sampling - 4:2:2 4 Luminance Samples 2 Color Samples 2 Color Samples Y C Y Y C Y Y C Y Y C Y Y = Luma C = Chroma

43 Chroma Sub-Sampling - 4:1:1 4 Luminance Samples 1 Color Sample 1 Color Sample Y Y Y Y C Y Y Y Y C Y = Luma C = Chroma

44 Chroma Sub-Sampling - 4:2:0 4 Luminance Samples 2 Color Samples 0 Color Sample Y Y Y Y C C Y Y Y Y Y = Luma C = Chroma

45 Understanding HD - Color Questions?

46 Bit Rate 1920 x P 10-bit Uncompressed YCbCr 4:2:2 Bit Rate AKA Data Rate The rate at which video data is transmitted or recorded Uncompressed video = Gb/s (59.94i) = 1.19 Gb/s About 8 Giga Bytes per minute

47 Bit Rate - Compressed Rates Compressed Data Rates ProRes 422 HQ Mb/s AVC-Intra Mb/s DVCPRO HD Mb/s XDCAM Mb/s XDCAM EX - 35 Mb/s AVC HD - 24 Mb/s

48 Bit Rate - Compressed Rates Compressed Data Rates AJA Data Rate Calculator Free Online Calculators Lossless vs Lossy Compression Lossless = Uncompressed Lossy = Compressed Higher Data Rate does not equal Higher Quality

49 Bit Rate - Compressed Rates DCT (Discrete Cosine Transform) Blocks An average of frequencies Used to compress parts of an image Increasing Compression

50 Bit Rate - Compressed Rates DCT Blocks Used in MPEG2 and MPEG4 (small blocks)

51 Compression 1280 x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2 Compression Types MPEG-2 DVCPRO HD HDCAM / HDV XDCAM HD / 422 / EX Digital TV & DVD

52 Compression 1280 x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2 Compression Types MPEG-4 HDCAM SR AVC-Intra 100 / 50 AVC HD / AVCCAM H.264 & Other Web Compressions

53 Compression 1280 x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2 Long GOP and I Frame I-Frame compressions every frame individually Long GOP (Group of Pictures) Compresses over 15 frames GOP I Frames (every 15th frame) are individually compressed B & P Frames are stored as differences

54 Compression Long GOP - 15 Frames I-Frame B-Frame P-Frame

55 Compression 1280 x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2 Compression Types Intermediate Formats ProRess 422 HQ / 422 / LT / Proxy DNX HD / DNX CineForm High bit rate, low compression

56 Compression 1280 x P 8-bit DVCPROHD (100 Mb/s) YCbCr 4:2:2 Compression Types Redcode - Red RAW Compression JPEG2000 (wavelet based) Color Channels compressed individually Four flavors in Red One 28 MB/s (224 mbit/s) 36 MB/s (288 mbit/s), and 42 MB/s (336 mbit/s)

57 Recording Media

58 Codec Comparisons in 1080 HDCAM SR x / 10 bit 4:2:2 / 4:4:4 YCbCr / RGB I-Frame at 440 Mb/s or 880 Mb/s Apple ProRes x / 10 bit 4:4:4 YCbCr / RGB I-Frame at 330 Mb/s Apple ProRes 422 HQ x bit 4:2:2 YCbCr I-Frame at 220 Mb/s

59 Codec Comparisons in 1080 AVC-Intra x bit 4:2:2 YCbCr I-Frame at100 Mb/s XDCAM 422 / Canon XF / NanoFlash x bit 4:2:2 YCbCr Long GOP at 50 Mb/s HDCAM x bit 4:2:2 YCbCr I-Frame at 144 Mb/s

60 Codec Comparisons in 1080 XDCAM EX x bit 4:2:0 YCbCr Long GOP at 35 Mb/s DVCPRO HD x bit 4:2:2 YCbCr I-Frame at 100 Mb/s AVCHD / AVCCAM x bit 4:2:0 YCbCr Long GOP at 24 Mb/s

61 Codec Comparisons in 1080 XDCAM HD x bit 4:2:0 YCbCr Long GOP at 35 Mb/s Canon SLR H x bit 4:2:0 YCbCr Long GOP at Mb/s HDV x bit 4:2:0 YCbCr Long GOP at 25 Mb/s

62 Understanding HD - Compression Questions?