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Published byStuart McCoy Modified over 8 years ago
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Or, how to make it all fit! DIGITAL VIDEO FILES AND COMPRESSION STANDARDS
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Video Formats Standard Definition: 720 pixels by 480 pixels
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Video Formats Standard Definition: 720 pixels by 480 pixels High Definition: 1280 pixels by 720 pixels
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Video Formats Standard Definition: 720 pixels by 480 pixels High Definition: 1280 pixels by 720 pixels High Definition: 1920 pixels by 1080 pixels
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Video Formats Standard Definition: 720 pixels by 480 pixels High Definition: 1280 pixels by 720 pixels High Definition: 1920 pixels by 1080 pixels 2K Film Definition: 2048 pixels by 1536 pixels
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Video Formats Standard Definition: 720 pixels by 480 pixels High Definition: 1280 pixels by 720 pixels High Definition: 1920 pixels by 1080 pixels 2K Film Definition: 2048 pixels by 1536 pixels 4K Film Definition: 4096 pixels by 3072 pixels
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Video Formats Standard Definition: 720 pixels by 480 pixels High Definition: 1280 pixels by 720 pixels High Definition: 1920 pixels by 1080 pixels 2K Film Definition: 2048 pixels by 1536 pixels 4K Film Definition: 4096 pixels by 3072 pixels 8K Film Definition: 8192 pixels by 6144 pixels
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Pixel Counts: 720 x 480 = 345,600 pixels 1280 x 720 = 921,600 pixels 1920 x 1080 = 2,073,600 pixels 2048 x 1536 = 3,145,728 pixels 4096 x 3072 = 12,582,912 pixels 8192 x 6144 = 50,331,648 pixels
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Bit Depth Each pixel consists of varying amounts of red, blue and green (RGB color) The various amounts of each primary color control the final color of the pixel
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Bit Depth Each pixel consists of varying amounts of red, blue and green (RGB color) The various amounts of each primary color control the final color of the pixel In standard 8 bit color each of the 3 component colors has an 8 bit value, or 256 levels. This gives a total of more than 16 million shades and colors.
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Bit Depth Each pixel consists of varying amounts of red, blue and green (RGB color) The various amounts of each primary color control the final color of the pixel In standard 8 bit color each of the 3 component colors has an 8 bit value, or 256 levels. This gives a total of more than 16 million shades and colors. HD video often has 10 bit color (1024 levels) which provides more than 1 billion shades and levels
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Bit Depth Each pixel consists of varying amounts of red, blue and green (RGB color) The various amounts of each primary color control the final color of the pixel In standard 8 bit color each of the 3 component colors has an 8 bit value, or 256 levels. This gives a total of more than 16 million shades and colors. HD video often has 10 bit color (1024 levels) which provides more than 1 billion shades and levels Some film formats offer 12, or even 16 bit color
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Bit Depth The primary advantage of additional bit depth is not more colors but more dynamic range. (levels of shading from complete black to pure white.)
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Bit Depth The primary advantage of additional bit depth is not more colors but more dynamic range. (levels of shading from complete black to pure white.) Some versions of 2K, 4K, and 8K files use “logarithmic” bit systems to give even more dynamic range.
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Uncompressed File Sizes To determine the theoretical size of a video file you simply have to multiply! Multiply the number of total pixels by the number of colors by the bit depth to find total bits per frame. Multiply the frame rate (frames per second) by the total number of seconds to arrive at a final file size in bits. Divide that number by 8 to get the number of bytes.
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Uncompressed File Sizes 1 frame of Standard Definition: 1,036,800 bytes (1 MB)
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB 1 frame of 1920 x 1080 HD: 6.2 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB 1 frame of 1920 x 1080 HD: 6.2 MB 1 frame of 1920 x 1080 HD (10 bit): 7.8 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB 1 frame of 1920 x 1080 HD: 6.2 MB 1 frame of 1920 x 1080 HD (10 bit): 7.8 MB 1 frame of 2K Digital Film: 11.8 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB 1 frame of 1920 x 1080 HD: 6.2 MB 1 frame of 1920 x 1080 HD (10 bit): 7.8 MB 1 frame of 2K Digital Film: 11.8 MB 1 Frame of 4K Digital Film: 47.2 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB 1 frame of 1280 x 720 HD: 2.8 MB 1 frame of 1920 x 1080 HD: 6.2 MB 1 frame of 1920 x 1080 HD (10 bit): 7.8 MB 1 frame of 2K Digital Film: 11.8 MB 1 Frame of 4K Digital Film: 47.2 MB 1 frame of 8K Digital Film: 188 MB
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Uncompressed File Sizes 1 frame of Standard Definition: 1 MB = 1.4 GB/min 1 frame of 1280 x 720 HD: 2.8 MB = 4 GB/min 1 frame of 1920 x 1080 HD: 6.2 MB = 9 GB/min 1 frame of 1920 x 1080 HD (10 bit): 7.8 MB = 11 GB/min 1 frame of 2K Digital Film: 11.8 MB = 17 GB/min 1 Frame of 4K Digital Film: 47.2 MB = 68 GB/min 1 frame of 8K Digital Film: 188 MB = 270 GB/min
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Compression In the Computer world compression is the act of taking a large file and making it smaller.
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Compression Advantages: Less storage space needed (saves $$$)
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Compression Advantages: Less storage space needed (saves $$$) Faster processing times
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Compression Advantages: Less storage space needed (saves $$$) Faster processing times Faster transmission speeds (smaller bandwidth requirement)
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Compression Disadvantages Degrades Quality
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Compression Disadvantages Degrades Quality Difficult to do well
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Compression Disadvantages Degrades Quality Difficult to do well Must be de-compressed before using
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Compression Disadvantages Degrades Quality Difficult to do well Must be de-compressed before using Can make some types of processing more difficult
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Types of Compression Lossless: meaning that no data is actually lost An example would be a “zip” file Not effective for audio or video “Lossy”: Meaning that some data is actually lost An example would be an MP-3 file Useful for audio and video files
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Compression Ratio A simple comparison of the size of the file before compression to the size of the file after compression Example: a 10 MB photo file is compressed down to 1 MB. That is a 10-1 compression ratio. It is not unusual for video files to be compressed at a ratio of 10 or 20 to 1. (or even more!)
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Compression Standards A compression algorithm is a mathematical formula used to determine which bits of data can be eliminated. The same standard can then be used at the end to “de-compress” the file for playback.
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Compression Standards JPEG: Originally used for still pictures MPEG-1: First video standard. Supports low bit rates (also the basis for MP-3 audio) MPEG-2: DVD standard MPEG-4: High Quality – Blue Ray standard MPEG-7: Currently under development
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Basic Compression Concepts Intra-frame coding: Each frame stands on its own and is compressed individually. This has advantages: Easier to process Much easier to edit More difficult to corrupt
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Basic Compression Concepts Inter-Frame Coding: Information from one frame is used to help compress surrounding frames. I- frame: Complete on it’s own P-frame: Predictive coded frames B-frame: Bidirectional Predictive coded frames Typically every 15 th frame or so is made into an “I” frame. P-frames and B-frames might follow like this: IBBPBBPBBPBBPBB(I) to form a Group of Pictures (GOP)
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MPEG-2 Currently the standard for video compression
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MPEG-2 Currently the standard for video compression Serves as a general standard. Different institutions can adapt it to their use.
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MPEG-2 Currently the standard for video compression Serves as a general standard. Different institutions can adapt it to their use. Not very good at very low data rates.
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MPEG-2 Applications (formats) include: DVD-Video HDV XDCAM Data (from Sony EX type cameras) DVB (Digital Video Broadcasting) ATSC (US High Definition Broadcasting) Earlier computer compression standards
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MPEG-4 New emerging standard for video compression Still a general standard – adaptable by different institutions Much higher quality than MPEG-2, but requires more computing power. Supports Digital Rights Management
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MPEG-4 Applications (formats) include Quicktime 6 and above DivX H-264 standards Digital AVC Blu-Ray Video Discs Newest versions of WMV files Real Video Files
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