For either over-the-air or cable TV, the same analog demodulation techniques are used, but after that, then the signal is converted to digital data, which must be decompressed using the MPEG codec, and rendered into an image bitmap stored in a frame buffer.
For interlaced video, additional processing is frequently applied to deinterlace the image and make it seem to be clearer or more detailed than it actually is.
Possible culprits are the processing overhead of HDCP, digital rights management (DRM), and also DSP techniques employed to reduce the effects of ghosting – and the cause may vary depending on the model of display.
External devices have also been shown to reduce overall latency by providing faster image-space resizing algorithms than those present in the LCD screen.
Many LCDs also use a technology called "overdrive" which buffers several frames ahead and processes the image to reduce blurring and streaks left by ghosting.
Several approaches to measure display lag have been restarted in slightly changed ways but still reintroduced old problems, that have already been solved by the former mentioned SMTT.
[6] Therefore, it is impossible to use a single stop watch for display lag measurements, nevertheless if it is created by a timecode or a simple stopwatch application, as it will always cause an error of up to 16 ms or even more.
For instance, in World of Warcraft's PvE, a slight input delay is not as critical compared to PvP, or to other games favoring quick reflexes like Counter-Strike.
Rhythm-based games, such as Guitar Hero, also require exact timing; display lag will create a noticeable offset between the music and the on-screen prompts.
Arguably, fighting games such as Street Fighter, Super Smash Bros. Melee and Tekken are the most-affected, since they may require move inputs within extremely tight event windows that sometimes only last 1 frame or 16.67 ms on the screen.
By assuming a Gaussian human response time to a particular in-game event, it becomes possible to discuss the effect of lag in terms of probabilities.
The severity of this impact is a function of the position and variance of a human's response to a visual cue, the amount of lag introduced, and the size of the timing window.
If a home theater receiver with external speakers is used, then the display lag causes the audio to be heard earlier than the picture is seen.
Many televisions, scalers and other consumer-display devices now offer what is often called a "game mode" in which the extensive preprocessing responsible for additional lag is specifically sacrificed to decrease, but not eliminate, latency.
Connection through VGA cable or component should eliminate perceivable input lag on many TVs even if they already have a game mode.
[8] LCD screens with a high response-time value often do not give satisfactory experience when viewing fast-moving images (they often leave streaks or blur; called ghosting).