Difference between revisions of "General advice"

Revision as of 13:38, 6 November 2006

Introduction

This page is for advice / tips / tricks related to everything in the knowledge base.

Expected final results for self-encoded runs

Never use single-pass bitrate mode

When encoding your run, never use single-pass bitrate mode. Two-pass bitrate mode is preferred because the first pass analyzes the video, seeing which parts need more bits to look good and which parts need less while still looking good. The second pass does the actual encoding. So you see, single-pass bitrate mode will produce sub-par quality because it encodes the video blindly.

Do not confuse single-pass bitrate with single-pass quantizer mode. While the former should never be used, the latter is a valid option and is sometimes used by folks at SDA. Don't worry about it though, the guides will always recommend that you use two-pass bitrate mode.

Media players

Running VirtualDub(Mod) in low priority mode (Windows)

One nice feature of MeGUI is that it runs by default in low priority mode. We can do the same with VirtualDub(Mod), but it must be done manually. Setting a task to low priority will allow you to run other things that run at normal priority without computer lag. Basically, you'll be able to browse the internet, play music, etc while encoding your run without any computer lag. Very convenient! There are two ways to accomplish this.

Method 1. The temporary way... With VirtualDub(Mod) running, press ctrl+alt+delete on your keyboard to bring up the Windows Task Manager. Go to the Processes tab and look for the program. Once you find it, right-click on it and set it to low priority.

Method 2. The better way... Create a shortcut to the program if one does not already exist. The following steps assume you don't have one.

• Navigate to the VirtualDub(Mod) folder, should be in "C:\Program Files\".
• Right-click on VirtualDub(Mod).exe and select the Create Shortcut option.
• Move the shortcut somewhere more convenient, the desktop is good.
• Right-click the shortcut and select properties.
• Click on the Shortcut tab.
• In the target box, type the following in:

C:\WINDOWS\system32\cmd.exe /c start "VirtualDubMod" /low "C:\Program Files\VirtualDubMod\VirtualDubMod.exe"

This example is for VirtualDubMod, remove the "Mod" for regular VirtualDub.

Finding frame numbers for the Trim command

VirtualDub(Mod) beats Avisynth in this aspect. To find the range of frames for your cut, open your avs file in VirtualDub(Mod) and look at the frame numbers at the bottom of the screen. Plug those into the Trim() command.

d2v file path

If you're working with DVD source material and have created your DGIndex project file (the d2v), you may get problems if you move your source files around. This is because the d2v file is using an absolute file path. There are two ways to solve this problem.

1. Open DGIndex, go to the Options menu and deselect Use Full Paths. Future d2v files will use relative paths.

2. Open the d2v file in Notepad or any text editor. The third line should have the path to the source file, change it to your liking.

Keep your source files

This rule should be followed especially by people new to encoding. Chances are you will mess up, not following SDA's strict standards and be asked to redo your encodes. Try as hard as possible to backup your source files somewhere, even if you've encoded your run properly and it's already up on SDA. Burning your data to DVD discs is a good idea. Use lossless compression if needed. At the very least, encode your run with a very high bitrate in Xvid/H.264, but beware that these codecs use the YV12 colorspace and could mess up your interlaced source material. The next section explains why.

Never convert to YV12 colorspace before deinterlacing

Compare the following two avisynth scripts in VirtualDub(Mod) to see why. No actual deinterlacing is done, but you can see how the color is messed up in the second script.

color1=Blankclip(pixel_type="yuy2",color=$800000).assumefieldbased() 
color2=Blankclip(pixel_type="yuy2",color=$80FFFF).assumefieldbased() 
interleave(color1,color2).weave

color1=Blankclip(pixel_type="yuy2",color=$800000).assumefieldbased() 
color2=Blankclip(pixel_type="yuy2",color=$80FFFF).assumefieldbased() 
interleave(color1,color2).weave
ConvertToYv12()

Wouldn't want to deinterlace that...

Preview avisynth scripts in Media Player Classic

When creating your avisynth script, it is possible to preview your work by playing the avs file directly in Media Player Classic, instead of encoding it first and then playing it. Of course, whether or not you can play it live without lag depends on how fast your computer is. Don't expect smooth playback if you're deinterlacing your video with mvbob. Though for the purpose of previewing you can try replacing mvbob with the faster leakkernelbob.

Save time with MvBob

MvBob is a very slow deinterlacer. When encoding the HQ and IQ versions, you typically do two-pass encodes for each. This means you'll be mvbob'ing your video four times! It only needs to be done once! You can save time by encoding a new mvbob'ed source file to lossless format (HuffYuV, Lagarith) and loading that into a new script.