Digital Video Forums

Go Back   Digital Video Forums > Disc Formats > FAQ and Guides

Closed Thread
 
LinkBack Thread Tools Rate Thread Display Modes
Old 7 Jan 2005, 07:43 AM   #1
Not a god of digital video
 
blutach's Avatar
 
Join Date: Oct 2004
Location: is everything!
Posts: 24,628
Question FAQ: Compression percentage explained

Compression percentage explained

Many people are asking about the compression percentage and what results in a good quality burn.

Put simply, it is not the compression percentage which matters but the bitrate which is devoted to the video encoding.

For example, if a movie was originally encoded with a "high" bit rate (say 6 Mbps - "mega bits per second") and compressed by a lot, (say to 50%), on average, this would result in a bitrate of 3 MBps.

But if the movie was originally encoded with a "low" bitrate (say 3.5 Mbps) and was compressed only by 20% (to 80%), the resulting average bitrate would be 2.8 Mbps -- worse than the 50% compression!!!

(There are more technical aspects regarding quality that involve I, P, and B frames, and variable vs fixed encoding and transcoding, but these are beyond this FAQ.)

Now, what you can detect as "bad quality" will most likely depend on the final bitrate and the size of your screen. If your are projecting onto a huge screen, the higher numbers are probably necessary (say over 3.5 and preferably 4.5+). But on a regular TV, you can probably get away with the 3 Mbps range (and even lower).

IfoEdit has a neat bitrate calculator in its Tools menu. First, take the total amount of space devoted to your title - DVD Shrink will tell you this in its main screen (it may be 4,464MB for a reauthored DVD). Then, simply enter in the number of audio streams and subtitle streams. If you have a DTS stream add one to the number for audio. IfoEdit will calculate the average bitrate based on this data.

Videocalc has an even better freeware bitrate calculator, which allows you to calcuate, very accurately, the average bitrate of your DVD. Try it out!

Regards
__________________
Les

Essential progs - [PgcEdit] [VobBlanker] [MenuShrink] [IfoEdit] [Muxman] [DVD Remake Pro] [DVD Rebuilder] [BeSweet] [Media Player Classic] [DVDSubEdit] [ImgBurn]

Media and Burning - [Golden Rules of Burning] [Media quality] [Fix your DMA] [Update your Firmware] [What's my Media ID Code?] [How to test your disc]
[What's bitsetting?] [Burn dual layer disks safely] [Why not to burn with Ner0] [Interpret Ner0's burn errors] [Got bad playback?] [Burner/Media compatibility]

Cool Techniques - [2COOL's guides] [Clean your DVD] [Join a flipper] [Split into 2 DVDs] [Save heaps of Mb] [How to mock strip] [Cool Insert Clips]

Real useful info - [FAQ INDEX] [Compression explained] [Logical Remapping of Enabled Streams] [DVD-Replica] [Fantastic info on DVDs]


You should only use genuine Verbatim or Taiyo Yuden media. Many thanks to www.pcx.com.au for their supply and great service.

Explore the sites and the programs - there's a gold mine of information in them

Don't forget to play the Digital Digest Quiz!!! (Click here)


Last edited by blutach; 9 Dec 2007 at 06:26 PM
blutach is offline  
Old 22 Feb 2005, 04:05 PM   #2
Super Moderator
 
jmet's Avatar
 
Join Date: Nov 2002
Location: East, TX
Posts: 8,696
Default

This thread has been closed/locked, as it is for information purposes only. If you have a question regarding this thread. Please start a new thread in the DVD Shrink - General Discussions sub-forum.

Thanks,
Moderators of the FAQ/Knowledgebase forum
jmet is offline  
Closed Thread

Bookmarks

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT +10. The time now is 07:29 AM.

Kirsch designed by Andrew & Austin


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
Copyright © 1999 - 2011 Digital Digest

Visit DivXLand   Visit dvdloc8.com