Sorry. Its been a year since you have posted this thread lol, I can try to download the resource pack to see if it will work, did either of you find a solution?

I don't think you can do custom music discs, but you could make an item that plays a sound whenever you use it. You'd do this by adding a custom item with a use time set at an arbitrarily large number in a behavior pack. You'd also add an animation controller in the behavior pack, which goes into a state if you're using an item & holding the custom item. In the on_entry section, you'd need to use a playsound command, playing a custom sound(I'll get into on how to add that later). Here's an example of what it would look like with multiple custom sound items:
"controller.animation.player.music_disk":{
"initial_state":"none",
"states":{
"none":{
"transitions":[
{ "use":"query.is_using_item==1.0"}
]
},
"use":{
"transitions":[
{
"none":"query.is_using_item==0.0"
},
{
"disk_1":"query.get_equipped_item_name=='new_song_1'"
},
{
disk_2":"query.get_equipped_item_name=='new_song_2'"
}
]
},
"disk_1":{
"on_entry":[
"/playsound custom.sound1 @a ~~~ 1 1 1"
],
"transitions":[
{
"none":"query.get_equipped_item_name!='new_song_1'"
}
]
},
"disk_2":{
"on_entry":[
"/playsound custom.sound2 @a ~~~ 1 1 1"
],
"transitions":[
{
"none":"query.get_equipped_item_name!='new_song_2'"
}
]
}
}
},You'd have to define it in the player.json file in the description, and put it under animate."description": {
"identifier": "minecraft:player",
"is_spawnable": false,
"is_summonable": false,
"is_experimental": false,
"animations": {
"music": "controller.animation.player.music_disk"
},
"scripts": {
"initialize": [],
"pre_animation": [],
"animate": [ "music"]
}
},That's all you need to do for the behavior pack. Now you'll need to make a resource pack for the rest of this.</p><p>The first thing to do would be to add a sound file. Then, you'd need to define it in sound_definitions.json. Here's an example for one sound, assuming the file is in the folder custom."custom.sound1" : {
"__use_legacy_max_distance" : "true",
"category" : "neutral",
"sounds" : [
            "sounds/custom/sound1"
            ]
      },Next, you'd have to go into the .lang file for your language(in the texts folder, look at languages.json to see the file name). Assuming you made the item identifier custom:sound_item1, you'd put the following line into the language file to make it show up as Custom Disc 1 when held:item.custom:sound_item1.name=Custom Disc 1After this, create a folder in the root of the resource pack called items, and create a .json file(name should be similar to the items identifier). This is to make it so you can define a texture for it. Here's an example for custom:sound_item1:"format_version": "1.14.0",
"minecraft:item": {
"description": {
"identifier": "custom:sound_item1",
"category": "food"<
},
"components": {
"minecraft:icon": "sound_item1"
}
}</code>The last thing to do would be to add a texture to the items folder inside of the textures folder, and add the following code to item_texture.json(assuming the file name is custom_disc1) "sound_item1": {
"textures": "textures/items/custom_disc1"
}