Get PowerPoint presentation on Web Compression from Rich Roddman.

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Transcript

  • 1. The right size for the right job
  • 2. Terms you should know: • Video Compression • Resolution • Interlacing vs. Progressive • Fields vs. Frames • Lossless vs. Lossy • VBR vs. CBR • Intraframe vs. Interframe
  • 3. Video Compression • Reducing the quantity of data used to represent digital video images
  • 4. 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)
  • 5. Interlaced vs. Progressive • Only HALF the lines are • A FULL image for each drawn each frame frame
  • 6. Fields vs. Frames • Interlaced video is represented by either odd OR even fields per frame
  • 7. Lossless vs. Lossy Negligible file size difference 1/8th the file size of original from original with unnoticeable quality difference to most viewers NOTE: Lossy compression is most often noticed in scenes with text, transitions and/or lots of movement
  • 8. VBR vs. CBR  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 • Complex image sequence that takes • Majority of the screen uses the same advantage of higher bit rate as necessary background from frame to frame • File size can decrease greatly without significant quality loss
  • 9. Intraframe vs. Interframe Intraframe Interframe • Records every pixel for every • Records an I-Frame and then frame regardless if the pixel only records the pixels that information has changed or not change from one frame to the • Examples: next depending on the GOP • AVC-I structure • DVC-Pro HD • Examples: • Apple ProRes • HDV • MPEG-2
  • 10. Evaluating Video for Compression
  • 11. 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?
  • 12. 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?
  • 13. 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?
  • 14. Progressive Download vs. Streaming Video
  • 15. 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
  • 16. 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
  • 17. 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)
  • 18. Formats
  • 19. 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
  • 20. Format vs. Codec
  • 21. 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
  • 22. Current Popular Codecs
  • 23. Current Popular Codecs • VC-1 Windows Media • VP6 FLV • MPEG-2 Quicktime, DVD • MPEG-4 part 10 (AVC)
  • 24. H.264 • The most commonly used codec today
  • 25. Older Common Codecs • MPEG-4 part 2 (DivX, Xvid, FFmpeg, 3ivx) • H.263 • Cineform • RealVideo • Sorenson Spark • Sorenson 3 • Cinepak • MPEG-1
  • 26. Compression Software Adobe Media Encoder CS4 Telestream Episode 5.2 Sorenson Squeeze 5 Apple Compressor 3.5 Microsoft Expression Encoder Mac Only Windows Only
  • 27. Adobe Media Encoder
  • 28. Adobe Media Encoder
  • 29. Apple Compressor
  • 30. Apple Compressor
  • 31. Sorenson Squeeze
  • 32. Sorenson Squeeze
  • 33. Telestream Episode
  • 34. Your Toolkit Programs everyone should have:
  • 35. Examples
  • 36. YouTubeHD • H.264 codec • mp4 format • 1280 x 720 • 6Mbps - 9Mbps • 24fps • Audio: AAC 64kbps 44.1 kHz
  • 37. iPhone • H.264 codec • m4v format • 640 x 360 • 1500kbps • Native frame rate • Audio: AAC 128kbps 44.1 kHz
  • 38. DVD-SD Video Settings: • MPEG-2 codec • m2v format • 720 x 480 • 6.2Mbps - 7.7Mbps • 29.97fps • Mode One Pass Best • Motion Estimation: Best
  • 39. DVD-SD Audio Settings: • Dialog Normalization: -31 dbFS
  • 40. DVD-SD Audio Settings: • Compression Preset: None
  • 41. Blu-Ray • H.264 codec • m4v format • 1440 x 1080 • 20Mbps - 25Mbps • 23.98fps • Audio: PCM 192kbps 48 kHz
  • 42. Questions?