FAQ for newbies - Light Alloy Guide

# FAQ for newbies

## Questions

1. Add files dialogs. What's difference?
2. Keyframes. What is it?
3. DXVA. What is it?
4. Video renderers. What's difference?

## Answers

1. Add files dialogs. What's difference?
   Open dialog - standart Windows dialog, everybody knows it.
   Extended open dialog - this is a very functional, media-oriented open dialog (all kinds of disc and devices including network ones, favorites, life time highlight, misc options of files add and so on). But it can me very slow some times (depends on your computer configuration), if directory have a few hundrends or thousands of files.
   You can quickly open file there with mouse left button double click.
   ТВ-oriented dialog - simplified version of extended open dialog. Because of using minimum info about a file, can work in directories with thousands of files a lot faster than previous one. This is a only open dialog where you can set colors and font size (from small to really big), which allows you use it, laying on the sofa, drinking a juice and moving a radiomouse on your cat.
   Fullscreen dialog - designed to be used with TV and remote. Minimum of UI elements. In case of keyboard, everything can be controlled with Tab, Arrow Keys and Enter.
   Folder - standart Windows open folder dialog. Hovewer, its main purpose is more comfortably implemented in Extended and TV-oriented dialogs.
2. Keyframes. What is it?
   Key frames are used to store all the information about the video image. Other frames - only about change the video image with respect to the previous one, which is good to do not waste available space. Key frame features:
   + when referring to key frame you don't need to handle sequence of previous frames. So this is why seek by key frames is a lot faster, and some times - instantaneous.
   - because key frames takes a lot of space, they are rare. So this is why key frame seek have a deviation in +/- 2 seconds (for some very bad encoded movies its about ~10 seconds).
3. DXVA. What is it?
   DXVA (DirectX Video Acceleration) - its a method that allows video decoding to be hardware (videocard) accelarted. Greatly reduces the load on the CPU (processor). Usually videocard makes decoding with less computing resources, which means - less power consumption, less computer heat, less noise from coolers. DXVA is possible only for some specified video encoding methods (for example, h264 - is supported, but XviD - not). DXVA can be activated only when in filters tree between video decoder and video renderer no intermediates (software video processors, subtitles and so on)
4. Video renderers. What's difference?
   Video renderer(VR, for short) — is a kind of software which renders the content on an output device (rendering video content on your monitor, in other words).

   These video renderers are recommended for Windows XP and lower:

   - VMR7 Windowless (VMR7 WL) - default Windows XP VR. Very fast and lite.

     Pros:

     - lite (uses overlay) - recommended for low-end computers;
     - fast - recommended for video with fps more than 50;
     - support DXVA only if no subtitles present in a video (but you can easily disable them in preferences).

     Cons:

     - overlay can be used only for single video; so it needs to be shared with other media players;
     - when pressing PrintScreen saved picture will contain only color-stub.
   - VMR7 Renderless (VMR7 RL) - like previous one, but don't use overlay.

     Pros compared to VMR7 WL:

     - PrintScreen works as intended;
     - allows position subtitles on black bars.

     Cons compared to VMR7 WL:

     - just a little heavier;
     - do not support DXVA;
   - VMR9 Windowless - just like VMR7 Windowless, but uses DirectX 9 for rendering the content.

     Pros compared to VMR7 RL:

     - a little better do image scaling;
     - PrintScreen works as intended.

     Cons compared to VMR7 RL:

     - just a little heavier;
     - do not support DXVA.
   - VMR9 Renderless - just like VMR9 WL, but a little more complicated.

     Pros compared to VMR9 WL:

     - support DXVA even with subtitles;
     - allows position subtitles on black bars;
     - a little better do image scaling;
     - PrintScreen works as intended.

     Cons compared to VMR9 RL:

     - not suitable for high frame rate (> 30fps) video.

   These video renderers are recommended to be used with Windows Vista and higher:

   - EVR - default VR for Windows Vista and up. Most fast and lite (but not for Windows XP!).

     Pros:

     - lite, fast, native;
     - in Windows XP better scale red pictures on Radeon video cards.

     Cons:

     - do not support DXVA with subtitles;
     - in Windows XP requires .NET Framework 3.5.
   - EVR CA - optimized to be used with subtitles.

     Pros compared to EVR:

     - support DXVA with subtitles;
     - allows position subtitles on black bars.

     Cons:

     - required a bit more computing resources.
   - EVR Sync - designed to keep video and monitor (or TV) fps in sync.

     Pros compared to EVR:

     - solution to the videoframes gap.
     - support DXVA with subtitles;
     - allows position subtitles on black bars.

     Cons:

     - most heavier EVR-renderer;
     - requires delicate tuning for specified monitor / tv;
     - sometimes unstable.

   MadVR is a special case.

   - MadVR - its a 3rd party VR. Main purpose of this VR is produce maximum picture quality of a video. MadVR should be installed manully.

     Pros:

     - high quality image scaling;
     - gamut & gamma correction for display calibration;
     - full 16bit processing queue;
     - all work is done via GPU shaders
     - in active development.

     Cons:

     - high graphics card requirements;
     - sometimes unstable;
     - a few nuances which you take in account when using this VR.

   Detailed installation process, settings and nuances about madVR you can read in this section.