How to make an MP3 player program run on bare metal without an operating system? Please give advice - China DOS Union Forum

How do you access MP3 files?

1. How to access the disk:
Usually the BIOS encapsulates disk operations (INT13h), so it's very simple for us to use.
But now it's bare metal, you have to operate the hard disk controller yourself, send control commands according to the ATA specification, and also set up the DMA chip to achieve batch data transmission.
If you find the disk too complicated and want to use Flash ROM, maybe it can be simplified, but the next problem cannot be avoided.

2. How to access files:
The disk itself can only understand sectors.
The file system is a function provided by the operating system.
You have to analyze the sectors according to the FAT file system format (or other file systems: NTFS, Ext2, Ext3...) to be able to perform file operations.
(Even if you use Flash ROM, generally still need to use the FAT file system format to store MP3 files)

Also, how do you make the speaker sound?
Before 1995, Creative Labs' Sound Blaster cards were very famous, so the sound cards under DOS at that time were compatible with it at the I/O port level. Since Windows 95 came out, because of the concept of drivers, manufacturers can freely design hardware, and there is no longer a specification at the I/O port level. Or you can use AC97, but AC97 involves a lot of content about modern chip sets (such as the PCI architecture). And AC97 was originally designed to reduce costs, and many functions need to be implemented by programming software.

When you are writing an audio playback program, timing control is very important, so you also need to program the 8253 timer chip.

This is almost writing a small operating system

Floor1　wj1987	Posted 2006-08-21 19:44
新手上路　Posts 3　Credits 10
Want to make a program, put it on a virtual machine for experimentation. It can control hardware devices by itself without an operating system. What kind of idea is this? Hope to get an answer

Floor3　electronixtar	Posted 2006-08-22 10:46
铂金会员　Posts 2,672　Credits 7,493
You can connect the iPod to the audio cable and play it without booting up~ haha~~ In fact, there are many Live CDs to choose from for booting the bare machine to play multimedia~ There are too many, mostly Linux kernels

Floor4　wj1987	Posted 2006-08-22 13:16
新手上路　Posts 3　Credits 10
Can you be more specific?/?/?/?What is a Live CD?/?/?/?And I'm making a program, why does it relate to connecting to an IPOD

Floor5　ddctczy	Posted 2006-09-25 14:14
中级用户　Posts 43　Credits 245
Using a bare machine to play MP3 is both wasteful and troublesome!!!!! It's not as good as an MP3 player!!!!!

Floor6　zyl910	Posted 2006-09-25 21:12
中级用户　Posts 126　Credits 282
How do you access MP3 files? 1. How to access the disk: Usually the BIOS encapsulates disk operations (INT13h), so it's very simple for us to use. But now it's bare metal, you have to operate the hard disk controller yourself, send control commands according to the ATA specification, and also set up the DMA chip to achieve batch data transmission. If you find the disk too complicated and want to use Flash ROM, maybe it can be simplified, but the next problem cannot be avoided. 2. How to access files: The disk itself can only understand sectors. The file system is a function provided by the operating system. You have to analyze the sectors according to the FAT file system format (or other file systems: NTFS, Ext2, Ext3...) to be able to perform file operations. (Even if you use Flash ROM, generally still need to use the FAT file system format to store MP3 files) Also, how do you make the speaker sound? Before 1995, Creative Labs' Sound Blaster cards were very famous, so the sound cards under DOS at that time were compatible with it at the I/O port level. Since Windows 95 came out, because of the concept of drivers, manufacturers can freely design hardware, and there is no longer a specification at the I/O port level. Or you can use AC97, but AC97 involves a lot of content about modern chip sets (such as the PCI architecture). And AC97 was originally designed to reduce costs, and many functions need to be implemented by programming software. When you are writing an audio playback program, timing control is very important, so you also need to program the 8253 timer chip. This is almost writing a small operating system

Floor2　wj1987	Posted 2006-08-21 19:46
新手上路　Posts 3　Credits 10

Floor7　zyl910	Posted 2006-09-25 21:16
中级用户　Posts 126　Credits 282
Does anyone understand the compression algorithm of MPEG Audio Layer III? (An MP3 file is a file that only stores compressed data of MPEG Audio Layer III, so it is simply called MP3) I have read quite a few MPEG materials But they are all not detailed enough about audio compression So I haven't understood it yet I want to ask the owner if there is any audio compression material