Only show the current controllers being selected.
Given the large amount of options (up to 16 players on up to 16 different controllers), it is best to only show the active controllers.
There are a few things I'd like to focus on.
Give context; tell the user what to do and how many slots have been taken.
Move completed elements out of the way to make ...
Do you feel like precise control speed are needed or nice to have?
Why do you need playback that goes backwards? If it is for navigation trough the media wouldn't progress bar serve better?
[+] You don't have to worry about unreasonable high values
[+] Easy to control on mobile devices
[+] Takes less space
[-] Less control over the playback speed
I think the problem lies with 'where user start on the slot selection screen'.
Taking into account the worst-case scenario where 16 players are using 16 or 8 joystick and enter screen at same time. All the 16 player start on the slot selection screen not knowing where then stand. There is no sense of navigation to slot when any user presses keys on ...
There are 8 slots in the video, and assuming every two slots is occupied by a single controller, i.e two players in a controller. We have 4 controllers and 8 players.
And as you said, if there were to be 16 slots , we will have 8 controllers and 16 players !
Now i am not sure about the nature of the game, but we can safely assume the left and right ...
As mentioned in comments, most speed alteration controls, specify how much the speed is altered. Either by ranges 0.5 (for slower), 1.0 (for normal), and 1.5 (for 50% higher speed). An arbitrary range would cause cognitive load on the user, and negative number range might imply backward play. The range can also be represented by percentage, but a slider ...
(Speaking as a user here)
Having been listening to audiobooks daily for over a decade, I can tell from personal experience that it depends heavily on the speaker. Some are still very clear at x1.8, and others begin to get blurry at 1.3. Of course, depends on the listener as well.
I don't think it's too granular - my favorite audiobook player has the same ...