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

2. 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

3. 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

4. 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

5. Structure of the Film Image

6. Modern Color Film emulsion

7. Processing Machine Schematics

8. Structure of the Video Image

9. 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.

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

11. 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.

12. Structure of the Video Image

13. 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, (30P), and 60i.

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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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)