Online desynchronization

It has been suggested that this article should be moved to Online desynchronization. The reason given for the move is: not really a glitch (Discuss)

For information on the Ice Climber technique, see desynching.

A desynch (sometimes spelled as desync, short for desynchronization) is when the perspectives of multiple players competing in one match aren't consistent with each other. The concept is best explained by example:

• Alice is playing as usual, while Bob has a hack that makes his character half their regular size.
• Alice attacks Bob.
  • On Alice's system, the attack connects.
  • On Bob's system, the attack misses due to their character being smaller.
• The match is now desynched.

Overview

Once a match is desynched, the players are essentially playing different matches. Inputs will be sent and acted upon as usual, but the results of the inputs can be wildly different - a control stick input might be a down throw on one system and a fastfall on another. Re-syncing a match is sometimes possible, but requires extensive co-ordination between the players involved, and the cause of the original desynch will likely cause a redisconnection later.

Brawl has a built-in check that triggers every few seconds. When it detects that two or more games are different at a given time, it will send a disconnection signal to all players, and they will be taken back either to the main menu or to the main WFC menu. Following the previous example: Bob's character has 0% damage on his screen, because the attack missed, but 12% damage on Alice's screen. The game can check both players' positions and damage percentages.

Causes

Desynches are generally caused by hacks. Players using identical hacks generally does not cause desynch, but any hack that not all players share carries a risk of desynching. Some categories of hacks, such as textures, carry very little risk of desynching, while things such as model hacks are very likely, and moveset and physics hacks are guaranteed to desynch. Desynching also prevents players playing a proper match online using Brawl mods, such as Balanced Brawl and Brawl-, unless all players use the same mod. The effects of this type of desynching can also be viewed by watching the same saved replays while using different hacks/mods.

Desynchs can also happen if one of the participating players or the server is experiencing connection difficulties. This is normally rare, as most networking devices have built-in safety measures, created for the purpose of avoiding the sending and receiving of incorrect data, but given the amount of data that's sent per match, and given the variety of players and their hardware, as well as the fact that perfect connection conditions can't be met all the time, this type of the desynch is not completely implausible. This happens when, for instance, Alice presses X and A at the same time, but for some reason, one of the bits isn't sent (and, as described above, the hardware doesn't to catch this flaw), her console could end up sending data for only A being pressed. While in her console, she sees her character jumping and performing a neutral aerial attack, other players' Wiis will only receive the A button, and hence, will have that player's character perform a neutral attack.