ipatix / gba-hq-mixer Goto Github PK

The explanation is reversed.

Hello. I hack FE8.
I also making on a tool called FEBuilderGBA.

I'm trying to use your m4a_hq_mixer to achieve DPCM in GBAFE.
I think your DPCM is a great feature because it can halve the wave capacity.
If use this, I think that it is not impossible to use voice data and music in wav.

I have now gotten your routine to work in GBAFE.
The compressed wave is also playing correctly.

However, there are two problems.
The first is the end of the compressed wav.

The first is that it hangs if I play past the end of the compressed wav.
To avoid this, you need to issue an EOT in the score to stop playback before you reach the end.
In vanilla, the sound will automatically stop when it exceeds the tail.

The next issue is that we don't know the data length.
We know the size before compression, but we don't know the size after compression.
DPCM is said to be lossless compression, so although it is possible to guess the data length by calculation, I don't think it is a good method.
We need to write the data length in the header or define the end data.

And if the data length is known, I think it is possible to stop instead of hang.

What are your thoughts on this issue?
I would appreciate your reply.

Environment

Visual Boy Advance-M 2.1.1

Details

I tested this thoroughly using both the old sound engine (2.1) and the current engine (4.0). The following crash only happens with v4.0 both with and without the changes suggested here (the following video example is using the original code in the repo).

The disassembler shows an infinite increase now:

Additional Details

If it helps, the hq_buffer_ptr constant was set to 0x30028E0.

I was trying to document the code (and convert to unified syntax so it can compile with Clang's built-in assembler), and noticed this:
https://github.com/ipatix/gba-hq-mixer/blob/main/m4a_hq_mixer.s#L890-910
L891 and L900 both refer to R6 in the comment, but actually operate on R0. It seems like the rest of the code expects it to be in R6 like the comment.

As per our discussion on Discord, the current version of the mixer produces more background noise than the previous version (2.1).

Here is an example of what certain samples sounded like on 2.1:
https://cdn.discordapp.com/attachments/684056505812516902/846141309948526602/Sound_Test.mp4

Here is an example of what the same samples sound like now:
https://cdn.discordapp.com/attachments/684056505812516902/846141453612744704/Sound_Test.mp4

I have also attached the code used for the video taken with the previous version in use:
High Quality Music v2.1

Changing the DMA buffer's size shouldn't be so painful.

To be fixed by replacing ORR R1, R1, R1, LSL#16 with ORR R2, R2, R2, LSL#16 in line 1020.