Señor Ventura escribió:¿Es posible que las melodías del sonic cd estén reproducidas por los canales de audio pcm, y no por audio cd?:
https://www.youtube.com/watch?v=p-A45d_ocHMAquí hay unos juegos de ejmplo en los que se utilizan samples mediante los pertinentes canales pcm:
https://www.youtube.com/watch?v=pdJEh3onkHcCD PCM:
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Eight 8 bit PCM channels with 8 bit volume control and 8 bit pan control (4 bit left & 4 bits right). Waveforms are stored in PCM RAM, you have very good timing up to 32 kHz, and the ability to loop waveforms.
Pros: Eight channels with volume and panning, and a decent sample rate (for the time). Samples can be looped. The samples are fetched by the PCM chip, so very little CPU time is consumed to play the samples.
Cons: A bit more work to use. You have to load the sample into the PCM RAM, of which you have 64 KB. The small size of the RAM limits the size and number of samples you can play without needing to reload the RAM. The samples themselves are a little odd: they are 8 bit sign/magnitude samples. The msb is the sign (positive or negative), and the other seven bits are the magnitude (amplitude) of the sample. That's not a very widespread format, so all your samples will need to be converted. Also, 255 is reserved as the loop marker. When 255 is fetched from the sample RAM, the sample address is set to the loop address and sampling begins at that new location. That means if a sample DOESN'T loop, you need to store an extra zero sample and set the loop address to it.
So the CD PCM is a bit more complicated, but worth the extra effort as you get the ability to play samples at almost any rate with no jitter, and with very little CPU usage. The main limitation is the amount of sample RAM.
Sacado de aquí:
https://www.sega-16.com/forum/archive/i ... -7203.html