World Library  
Flag as Inappropriate
Email this Article

Smart Bitrate Control

Article Id: WHEBN0001583471
Reproduction Date:

Title: Smart Bitrate Control  
Author: World Heritage Encyclopedia
Language: English
Subject: WAV, ARJ, Blu-code, HDX4, Dolby TrueHD
Collection: Data Compression, Video Codecs
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Smart Bitrate Control

Smart Bitrate Control, commonly referred to as SBC, was a technique for achieving greatly improved ISO MPEG4 video.

Technical details

The DivX 3.11 Alpha codec allowed a user to control three aspects of the encoding process: the average bitrate, keyframe interval, and whether the codec preserved smoother motion or more detailed images. DivX attempted to encode an entire movie at an average bitrate the user specified, varying the quality of the video in order to achieve the target bitrate. This meant that a simple section of video, such as a still image, would look very good, but complex video, such as an action scene, would look very bad. DivX's keyframe placement was also very simplistic, it would place keyframes only on the interval that the user selected, every 300 frames (10 seconds at 30 frame/s) by default.

Nandub's multipass encoding encoded the video twice; in the first pass it would analyze the video (and write informations to a log file), in the second it would actually produce the output file. Instead of varying the image quality to achieve an average bitrate, this allowed SBC to vary the bitrate to achieve an average quality, using higher bitrate for more complex scenes and lower bitrate for simpler scenes. VKI would place keyframes only where needed, such as at scene changes, rather than at a fixed interval. This significantly improved both the compression efficiency and visual quality of the resulting video. A VKI patch (called the DivX Scene Detect Patch) was also available for DivX to allow for VKI functionality without using Nandub, but it offered inferior performance compared to the VKI algorithms included in Nandub.

Nandub was a modification of the Open Source VirtualDub video encoder performed by Nando that incorporated SBC features.

See also

External links

  • Nandub project page at Sourceforge
  • Guide to SBC at Digital-Digest
  • Nandub Options Explained by Koepi, Encoding in Nandub on Doom9.org
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.