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helloworld123
Member
Joined: 26 May 2009
Location: Asia
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Ive been using AutoGK for my DVD backups but I'm not contented with its quality. I tried converting my own DVDs using VirtualDubMod with Standalone compatibility (No Custom matrix (AutoGK uses Custom Matrix and its incompatible with standalone players), No QPel, No GMC, VBR 2-pass) - based from http://www.divx-digest.com/articles/xvid_setup_page1.html. I want to use XVID in Codec ID. I adjust my bitrate to 800kbps to compare AutoGK' quality, my own and my other video downloaded from the internet. This is my video's MediaInfo:
Video
Format : MPEG-4 Visual
Format profile : Streaming Video@L1
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : XVID
Codec ID/Hint : XviD
Duration : 36mn
Bit rate : 825 Kbps
Width : 640 pixels
Height : 352 pixels
Display aspect ratio : 16/9
Frame rate : 23.976 fps
Resolution : 24 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.162
Stream size : 222 MiB (86%)
Writing library : XviD 1.2.1 (UTC 2008-12-04)
The video that I downloaded surpasses AutoGK's quality, consequently the video I personally converted didn't even exceeded AutoGK's quality. It has very poor quality and its very blocky while the video I downloaded has crisp and very high quality with the est. same bitrate (800kbps).Where do I start modifying Xvid Settings to surpass AutoGk's quality?
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jagabo
Member
Joined: 09 Dec 2005
Location: none
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Every video is different. No single bitrate is going to be good for all videos:
The higher the resolution -- the more bitrate you need.
The more detail in each frame -- the more bitrate you need.
The more the picture changes from frame to to frame -- the more bitrate you need.
The more noise in the video -- the more bitrate you need (same as previous two, really)
The higher the frame rate -- the more the bitrate you need.
The higher the contrast -- the more the bitrate you need.
AutoGK examines the video and sizes the frame (smaller frame = lower bitrate required) in order to get some kind of balance between resolution and macroblock artifacts. Of course, resolution is a part of quality, otherwise we'd all reduce all our videos to a 1x1 pixel frame size and store them uncompressed. So what AutoGK is really doing is trading one type of quality for another.
Why do you need some arbirtrary bitrate? Just use Target Quantizer encoding. Pick the quality (quantizer) you want and every frame comes out that quality. The file turns out whatever size is necessary. Be sure to use a version of Xvid with Adaptive Quantization.
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manono
Member
Joined: 28 Aug 2003
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| helloworld123 wrote: |
| (AutoGK uses Custom Matrix and its incompatible with standalone players), |
Maybe if you had bothered to read the included tutorial you'd have seen that by installing it with the ESS chipset option, or by turning it on in the Hidden Options, you'd get the standard matrices and other features that ensure full standalone compatibility.
And as mentioned, unless you're comparing the encodes of the same movie, then your comments about the relative merits of the different encoding methods and the AVIs they produce are useless and pointless. That said, if you knew what you were doing you could do a better job than does AutoGK. But you don't, so you can't.
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