Stage transition Desync

Specifications

Versions: 1.00a
Difficulty: Easy - Normal - Hard - Lunatic - ~~Extra~~
Mode: Main game - ~~Practice mode~~
Shottype: ReimuA - ReimuB - ReimuC - MarisaA - MarisaB - MarisaC

What happens

The replay desyncs when starting from the stage prior to the desync. Sometimes, it is also possible for the replay to desync even when playing the replay from the start of the stage, resulting in a replay that cannot be watched unless a third party tool is used.

How it happens

Bomb before the end of the stage transition occurs.
Furthermore, you must have 2.00 power or more for the desync to work when exiting the stage.

Why it happens

There are two different desyncs that are at play here:

Desync starting from the previous stage
Desync starting from the current stage

Previous stage desync

Replay data is stored at the end of the stage transition.
But some replay data, such as score, power, PIV are loaded at the beginning of the stage transition. (Note that the player position is loaded at the end of the stage transition.) This means if the player changes its power during the stage transition, during the replay the wrong amount of power will be loaded when the new stage is loaded.

Let p be the power the player exits a stage with (for example, if p = 155 then in-game the power is displayed as 1.55 Power). Assume that p >= 200. Then for all p, the following applies:
When causing the desync by playing the game the following happens:

The stage ends. The player is now in the stage transition.
A bomb is used by using the X key. 1.00 power is lost. The player has p-100 power.
Player data is saved to the replay.
The next stage starts.

When viewing the desynced replay, the following happens:

The stage ends. The player is now in the stage transition.
Player data is loaded. The wrong power is loaded, and the Power text is visually incorrect. The player has p-100 power.
A bomb is used by using the X key. 1.00 power is lost. The player has p-200 power.
The next stage starts.

Furthermore, the desync also causes the options to not work properly, resulting in some rather obscure shots.

A game screenshot with a displaced option — Figure 1: MarisaB's option is on the left side, despite her only having 1 power

Though, this only happens in the replay; not during actual runs.

The difference in power alongside the obscure options of the player causes the desync if the player shoots and/or bombs as certain enemies would be killed too early or too late.

Current stage desync

When using a bomb, the player is given i-frames or invincibility frames, making the player invincible for a temporary moment. The i-frames are not saved to the replay, meaning that starting a replay from the current stage does not start off with the correct number of i-frames.

For this desync to happen, the player must bomb at the end of the stage. Then, during the start of the subsequent stage the player has to go through some bullets/enemies and survive using the i-frames. Starting from the stage directly spawns the player with the wrong number of i-frames, meaning that the player will die to the previously-avoided bullets/enemies, causing the desync.