Is your feature request related to a problem? Please describe.
At this time, in-car announcements cannot be made without the use of a block.
That is a hassle because you have to go to the location. (I also don't really want to use the teleport command if I can help it, and it's a pain to remember the coordinates every time.)
Also, at the moment, I cannot change the broadcast that comes out immediately after the train departs, so I cannot arrange it in my own way. Furthermore, I can't even broadcast at stations, and I can't even broadcast with music because I can't easily put up audio in mp4 or ogg files.

Describe the solution you'd like
So, we would like to be able to easily add in-train announcements on the train dashboard.
Specifically, I would like to be able to easily play mp3 or ogg imported songs for in-train announcements, and I would like to be able to change the in-train announcements for each and every train line from the train depot settings so that I can change them between each and every station.
I would like to be able to change the broadcasts all at once, or in the advanced settings, for each station, one by one.
Also, currently, the system only broadcasts immediately after departure, but I would like it to be possible to add a song broadcast as many times as necessary.
I would also like to be able to specify how many seconds after departure the announcement will be made.
As an addition, I would like to see the creation of some sort of variable that can be used to create broadcasts. This would allow us to set up all broadcasts at once without having to create them all at once.
For example
Next station = @NextStation"
Previous Station = @PreviousStation"
Current station = @CurrentStation"
System number = @systemnumber"
Inner ring road = @Innerringroad"
Outer ring road = @Outerringroad"
Outer ring road = @Outerringroad, etc.
By adding a trailing delimiter and a preceding @, we can distinguish broadcasts from those that are variable.
Furthermore, the broadcast should be played at the station and where it is designated on the dashboard so that it can be played in the same way at the station.

Additional Information
I would be happy to keep the current broadcast block as it is and develop the features I have written about.
I know some people prefer the old block and have developed trains with it.

It was indeed too long. Sorry.
Also, as for the mp3, I was hoping it would be an added bonus, so the ogg file is fine.

Also, you don't have to put everything in at once, so in order of priority, you can

1. Allow for fine-tuning of broadcasts between all stations.
2. add a useful variable to allow changing the broadcasts at all stations at once from the train dashboard (without this, it would be difficult to change the broadcasts at once).
3. to be able to easily import ogg files so that they can be used for broadcasts.
4. use a block or dashboard to broadcast in the area designated for the station.
   This is a good way to do this.
   It would be difficult to create it all at once, so it would be easier for us to understand if it is created step by step.

By the way, I am a Japanese who is probably one of the few ethnic groups that use it, so I would like to spread the word on youtube and elsewhere.
I hope it will become a more and more wonderful tool in the future.
Also, is it OK if I write in Japanese? (By the way, I used deepl until now.)
Sorry for getting off topic. I don't want you to hurry to create the function, so please do it.

We are very sorry.
This is going to be difficult, so I will delete your post.
Thank you very much.