Week 3 Structure of the Video Image Containers & Codecs Pixels Aspect Ratio Interlaced/Progressive Containers & Codecs Bitrate & Audio formats Transcoding & Uploading

Structure of the Film Image Each frame is recorded on a strip of film coated with light sensitive emulsion, and exposure yields a LATENT IMAGE Image is produced through a photo-chemical reaction Must be PROCESSED before viewing If REVERSAL, can be viewed after processing if NEGATIVE, it must be printed or transferred cannot be ”rewritten” - additional exposures yield overlapping, brighter images Image constructed from SILVER grains & COLORED DYE

Structure of the Video Image Image is recorded electronically via a VIDEO SENSOR Camera processes recordings and writes to a file or tape Can be viewed instantly after recording Recording medium (tape or file) can be overwritten The screen is constructed from PIXELS, which are arranged in a grid The total number of pixels determines the RESOLUTION (clarity) of the image More pixels = higher resolution

Film & Video Structure projected at 24 FPS format (Super8, 16mm, 35mm, etc) determines size & aspect ratio a series of still photos, individually recorded Tone from density of silver, color from mix of RGB dyes Color adjusted through filters, processing, and printing/transfer processed in a lab, viewable later audio always recorded separately Playback at multiple rates recording format may allow for multiple image sizes and aspect ratios frames recorded as groups and encoded Each pixel can be individually adjusted for tone & color Color adjusted through filters, white balance, and digital processing processed in camera, viewable immediately Audio can be recorded simultaneously

Structure of the Film Image

Modern Color Film emulsion

Processing Machine Schematics

Structure of the Video Image

Structure of the Video Image Usually, the IMAGE SIZE is listed as: width (in pixels) X height (in pixels) 1920x1080 ; 1280 x 720 ; 720 x 480 ; etc Square OR Anamorphic (rectangle) 1440x1080 (anamorphic) = 1920x1080 The ASPECT RATIO depends on the Image Size and the Pixel Shape.

Structure of the Video Image ASPECT RATIO– the ratio of an image’s WIDTH:HEIGHT

Structure of the Video Image Interlaced Frame – When every other (half) line in an image is recorded at a time. During playback this means there are twice as many frames with half as much information each, giving smoother motion without increasing bandwith. Progressive Frame – When all the lines in an image are recorded at once. Provides increased Sharpness and eliminates Artifacts of video, but uses more bandwith and choppier motion.

Structure of the Video Image

Structure of the Video Image FRAME RATE– the number of frames recorded each second (fps). Also known as TEMPORAL RESOLUTION Standard rates in NTSC are 24/24P, 29.97 (30P), and 60i.

Structure of the Video Image SHOOTING FORMAT choices usually indicate Image Size and P/I separately from Frame Rate: Sony NX5U:

Containers & Codecs CONTAINER – a “wrapper” for video, audio, and metadata files .mov, .avi, .mp3, .3gp, .mkv, .ogg Doesn’t determine format, but indicates how it is organized May contain subtitles, multiple streams, or other

Containers & Codecs CODEC – describes the software used to code/decode the media file This may also COMPRESS the file, and may be either LOSELESS or LOSSY In video production, we prefer LOSELESS codecs for shooting & editing: H.264, ProRes422, RAW, 10-Bit Not all editing programs and viewers handle all codecs

Bitrate BITRATE refers to the number of bits/sec that your file contains This could impact the ability for a computer to process your file continuously, or for a viewer to stream your video Higher bitrate means better resolution For streaming video, use 2000 bps or lower

Audio Audio is encoded separately from image in media files The sample rate denotes the partitions per second Use 48 kHz for video Use 44.1 kHz for audio only files You can also adjust the bitrate & codec for audio files AAC, 192bps, 48 kHz - good for video You can use higher bitrate

Transcoding To ensure the best quality, choose the best SEQUENCE settings you can Usually this will be the same as your recording settings When exporting a MASTER FILE, use these same settings for the best quality You can TRANSCODE (ie recompress) your MASTER FILE for various deliveries, such as uploading to the Internet

Transcoding Although you can utilize PREMIERE PRO to export multiple files, the options can be limited A better choice is to export a Master File, then transcode in other programs Adobe Media Encoder (high-end, many options) Compressor (Apple product, high-end, many options) MPEG Streamclip (a good open-source option) Handbrake (limited functions, simple interface)