Does VGM still allow for exorbitant sample rates on PCM capable chips?
I heard a few "homebrewn" 96KHz sample rate VGMs for the MD before, and I wonder, why is this even possible?
I think VGM should focus a bit more on the hardware limitations of the chips it is supporting
Cheers
Oerg866
VGM PCM issues
Technical discussion about the VGM format, and all the software you need to handle VGM files.
Moderator: Staff
- ValleyBell Offline
- Posts: 4785
- Joined: 2011-12-01, 20:20:07
- Location: Germany
Re: VGM PCM issues
There are any? I never heard that someone actually used such high sample rates.Oerg866 wrote:I heard a few "homebrewn" 96KHz sample rate VGMs for the MD before, and I wonder, why is this even possible?
VGM itself has a native sample rate of 44.1 KHz.
The only way to get higher sample rates is to use the DAC Stream Control feature I introduced with v1.60. This way the sample rate is only limited by the emulated sample rate of the chip (which is ~100 KHz for the YM2612).
The highest sample rate I ever used was 44.1 KHz. (I didn't have samples with a higher rate, else I would've used 48 KHz.)
Re: VGM PCM issues
The only time I've seen such a high sample rate was with Tiido's experiments, which reached up to 120 KHz. But of course, the YM2612 caps at around 26 KHz, go higher than that and the chip crashes and needs a hard reset (i.e. power off and on).Oerg866 wrote:I heard a few "homebrewn" 96KHz sample rate VGMs for the MD before, and I wonder, why is this even possible?
YM2612's sample rate is around 53 KHz if I recall correctly.ValleyBell wrote:This way the sample rate is only limited by the emulated sample rate of the chip (which is ~100 KHz for the YM2612).
- ValleyBell Offline
- Posts: 4785
- Joined: 2011-12-01, 20:20:07
- Location: Germany
The output waveform is updated at half that rate though (~53KHz), so that'd be the real sample rate.ValleyBell wrote:The YM2612 itself has a clock divider of 72, so I get a sample rate of 106 534.08 Hz.
Writes to the DAC register can happen at half the output sample rate (so ~26KHz). Writes to other registers usually take longer, and trying to write faster results in first the YM2612 making funny sounds, and if you go very fast you outright make the chip crash and you need to do a hard reset to make it work again.