RF5C68 Sample Extracting

[IG2004]

For a while, I've been wondering what kind of 8-bit PCM (and yes, it's 8-bit PCM according to the VGMRips wiki) the RF5C68 uses in Arcade games like Michael Jackson's Moonwalker, which I want to extract the samples from. I tried importing it to Audacity as a Signed 8-bit PCM, an Unsigned 8-bit PCM, U-Law, and A-Law, but I can't get the samples to sound right. I also tried using GoldWave, but couldn't find the correct setting. Does anyone know what kind of 8-bit PCM the RF5C68 uses?

[ValleyBell]

The chips uses a "sign + magnitude" format. The highest bit specifies the "sign" and the lower 7 bits specify the magnitude.

Here are value mappings for the 8-bit PCM formats:

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RF5C68:
00..7F -> -0..-127
80..FF -> +0..+127

Unsigned 8-bit PCM:
00..7F -> -128..-1
80..FF -> 0..+127

Signed 8-bit PCM:
00..7F -> 0..+127
80..FF -> -128..-1

[lo zaffo]

ValleyBell, I agree with You.

Code: Select all

RF5C68 (e.g. PMB 8-bit PCM):
00..7F -> 0..-127
80..FF -> 0..+127

Signed 8-bit PCM:
00..7F -> 0..127
80..FF -> -128..-1

Unsigned 8-bit PCM:
00..7F -> 0..127
80..FF -> 128..255

Ciao!