video_playback_rate_adjuster.js

//YouTube Enhanced
//Author Chad Bailey www.chadbailey.me
//Written 10-6-17

//Initialize global variables
var video_element
var current_speed

//Amount to adjust video playback
var speed_step_fine = 0.5

//Maximim amount to slow down video playback
var min_speed_fine = 0.1
var min_speed_coarse = 0

//Maximim amount to speed up video playback
var max_speed_fine = 4.0
var max_speed_coarse = 128

//Hotkey setup
var hotkey_decrease_fine = '<'
var hotkey_increase_fine = '>'
var hotkey_decrease_coarse = '['
var hotkey_increase_coarse = ']'


function initialize() {
    //Store the object to a variable for easier/cleaner code
    video_element = document.getElementsByTagName("video")[0]
    
    //Get current playback rate and store to a variable
    current_speed = video_element.playbackRate

    //Hotkey events
    $(document).keydown(function(k) {
        if (k.key == hotkey_decrease_fine) {
          decrease_speed_fine()
        }
        if (k.key == hotkey_increase_fine) {
          increase_speed_fine()
        }
        if (k.key == hotkey_decrease_coarse) {
            decrease_speed_coarse()
        }
        if (k.key == hotkey_increase_coarse) {
            increase_speed_coarse()
        }
    });
}

function adjust_playback_rate(element,rate) {
    element.playbackRate = rate
    console.log("current speed: " + current_speed + " new speed: " + video_element.playbackRate)
    current_speed = rate
}

function increase_speed_fine() {
    //Only increase speed if we don't go above max_speed
    if (current_speed + speed_step_fine <= max_speed_fine) {
        //Adjust the playback rate to equal the sum of current_speed + speed_step
        adjust_playback_rate(video_element,current_speed + speed_step_fine)
    }
    //If we are hitting our maximum, set our playback to the maximum speed
    else {
        adjust_playback_rate(video_element,max_speed_fine)
    }
}

function decrease_speed_fine() {
    //Only decrease speed if we don't go below min_speed
    if (current_speed - speed_step_fine >= min_speed_fine) {
        //Adjust the playback rate to equal the sum of current_speed + speed_step
        adjust_playback_rate(video_element,current_speed - speed_step_fine)
    }
    //If we are hitting our maximum, set our playback to the maximum speed
    else {
        adjust_playback_rate(video_element,min_speed_fine)
    }
}

function increase_speed_coarse() {
    if (current_speed <= 0.5) {
        adjust_playback_rate(video_element,1)
    }
    //Only increase speed if we don't go above max_speed
    else if (current_speed *2 <= max_speed_coarse) {
        //Adjust the playback rate to equal the sum of current_speed + speed_step
        adjust_playback_rate(video_element,current_speed *2)
    }
    //If we are hitting our maximum, set our playback to the maximum speed
    else {
        adjust_playback_rate(video_element,max_speed_coarse)
    }
}

function decrease_speed_coarse() {
    //Only decrease speed if we don't go below min_speed
    if (current_speed <= min_speed_coarse + 1) {
        adjust_playback_rate(video_element,min_speed_coarse)
    }
    else {
        //Adjust the playback rate to equal the sum of current_speed + speed_step
        adjust_playback_rate(video_element,current_speed /2)
    }
}
//Timer to add hotkeys once jquery is available
//Note: This is necessary due to the cjs extension
//loading this script and jquery asymmetrically
var checkforjq = setInterval(function(){
    if ($ && document.getElementsByTagName("video")[0].playbackRate) {
        initialize()
        clearInterval(checkforjq); // clear interval
    }
},100); // check every 100ms