The right size for the right job

Terms you should know:• Video Compression

• Resolution

• Interlacing vs. Progressive

• Fields vs. Frames

• Lossless vs. Lossy

• VBR vs. CBR

• Intraframe vs. Interframe

Video Compression

• Reducing the quantity of data used to represent digital video images

Resolution

• The number of pixels/lines vertically displayed the screen

• 320x180 (180 lines)• 480x270 (270 lines)• 640x360 (360 lines)• 1280×720 (720 lines)• 1920×1080 (1080 lines)

Interlaced vs. Progressive

• Only HALF the lines are drawn each frame

• A FULL image for each frame

Fields vs. Frames

• Interlaced video is represented by either odd OR even fields per frame

Lossless vs. Lossy

Negligible file size difference from original

NOTE: Lossy compression is most often noticed in scenes with text, transitions and/or lots of movement

1/8th the file size of original with unnoticeable quality

difference to most viewers

VBR vs. CBR

• Complex image sequence that takes advantage of higher bit rate as necessary

VBR: variable bit rate Allows for best compression size based on the needs of the file Will only use the required amount of bits to save frame information

CBR: constant bit rate Maintains the set bit rate throughout the entire video Important for streaming media

• Majority of the screen uses the same background from frame to frame

• File size can decrease greatly without significant quality loss

Intraframe vs. InterframeIntraframe• Records every pixel for every

frame regardless if the pixel information has changed or not• Examples:

• AVC-I• DVC-Pro HD• Apple ProRes

Interframe• Records an I-Frame and then

only records the pixels that change from one frame to the next depending on the GOP structure

• Examples:• HDV• MPEG-2

Evaluating Video for Compression

Evaluating Video for Compression• How was the video shot?

• Is the video image static or in motion?

• Was it shot interlaced or progressive?

• Is the video high or low contrast?

Evaluating Video for Compression• How was the video edited?

• Are there long or short edits?

• Are there mostly cuts or transitions?

• Are there lots of graphics?• If so, are they static or in motion?

• Has the video been stylized in any way?

Evaluating Video for Compression• Who is the intended audience?

• How are the viewers watching? Computer, TV, Mobile, etc…

• Will it be an individual or group viewing?

• How large is the screen?

• How far away are the viewers expected to be?

• Which is more important:

Quality or Speed of Delivery?

Progressive Downloadvs.

Streaming Video

Progressive Download

• Allows the viewer to begin playback before the download is fully complete• Use if:

• Delivering short videos (less than 10min)• Operating a small website with low traffic• Using a higher quality video than a streaming

connection would allow

Streaming Video

• Allows for real time “broadcasting” of live events & the ability to control playback on-demand• Use if:

• Delivering long videos (greater than 10min)• Delivering to many viewers simultaneously• Using bandwidth detection or a quality

monitoring service• Serving live events

Streaming Video

• Must be played back from a separate server programmed for streaming

• Flash Media Server (FLV, SWF)• Apple OS X Server (Quicktime) • Darwin Streaming Server (Quicktime)• Windows Media Services (WMV, Silverlight)

Formats

Formats

• A particular way that information is encoded for storage in a file

• Examples:• AVI, ASF, WMV, FLV, MOV, MPEG-2(TS),

MP4, Ogg, RMV, 3GP

Format vs. Codec

Format vs. Codec

• Wrapper refers to the coding format

• Codec is an acronym for compression/decompression

• Example:• Flash Video (FLV) is a format

• H.264, On2 VP6, Sorenson Spark are codecs for Flash FLVs

Current Popular Codecs

Current Popular Codecs• VC-1 Windows Media

• VP6 FLV

• MPEG-2 Quicktime, DVD

• MPEG-4 part 10 (AVC)

H.264• The most commonly used codec today

Older Common Codecs• MPEG-4 part 2 (DivX, Xvid, FFmpeg, 3ivx)• H.263• Cineform• RealVideo• Sorenson Spark• Sorenson 3• Cinepak• MPEG-1

Compression Software

Adobe Media Encoder CS4 Sorenson Squeeze 5

Apple Compressor 3.5

Telestream Episode 5.2

Microsoft Expression EncoderMac Only Windows Only

Adobe Media Encoder

Adobe Media Encoder

Apple Compressor

Apple Compressor

Sorenson Squeeze

Sorenson Squeeze

Telestream Episode

Your ToolkitPrograms everyone should have:

Examples

YouTubeHD• H.264 codec

• mp4 format

• 1280 x 720

• 6Mbps - 9Mbps

• 24fps

• Audio: AAC 64kbps 44.1 kHz

iPhone• H.264 codec

• m4v format

• 640 x 360

• 1500kbps

• Native frame rate

• Audio: AAC 128kbps 44.1 kHz

DVD-SDVideo Settings:• MPEG-2 codec• m2v format• 720 x 480• 6.2Mbps - 7.7Mbps• 29.97fps• Mode One Pass Best• Motion Estimation: Best

DVD-SDAudio Settings:• Dialog Normalization: -31 dbFS

DVD-SDAudio Settings:• Compression Preset: None

Blu-Ray• H.264 codec

• m4v format

• 1440 x 1080

• 20Mbps - 25Mbps

• 23.98fps

• Audio: PCM 192kbps 48 kHz

Questions?