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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?