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Enough power to decode PCM?

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evildragon

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I was curious. If enough disk space is available, could an 8086-8MHz decode full 16-bit 44.1KHz 2 channel PCM?

I know my 286 can do it, but no 8086 utility exists to play a WAV it seems to try this...
 
Dac

Dac

If you have a decent DAC, no reason why it can't. All the software's gotta do is push the data to the DAC. For stereo, you're talking under 200kBytes per second, which the PC can certainly handle for sustained transfer rate.
I have a Quikki AD/DA board that sits in a 8-bit slot and has two Burr-Brown PCM53 DAC's (16-bit designed for Audio parallel input DAC)
patscc
 
well i thought the CPU had to decode the PCM to a format the soundcard would understand. I didn't think the soundcard understood PCM already.
 
Pcm

Pcm

Nope, not really. PCM is just a fancy way of saying you're digitizing a signal sampled at fixed interval. By nature parallel data as well. Raw .wav files are basically uncompressed PCM data, with a bit of overhead telling sample rate, etc. You can take PCM and get lots more complicated by varying the quantization word size, varying the time interval, using just 1 bit to reflect the changes in levels (Delta), or folding a larger word size into a smaller by some sort of non-linear mapping( what phone companies do).
But straight PCM just gets sent to the D/A.
I guess it depends on the soundcard, I think the original Soundblaster could do 8-bit PCM, but the trouble was that it was so much easier to send FM commands to the Yamaha chip then to synchronize PCM audio, which did, after all, require a lot of space, with all the other stuff that was going on in games, who were typically the only programs to really use sound cards on a PC, that it took a while for games to start incorporating PCM.
I think the biggest problem was space, something called ADPCM was supported in hardware to keep space requirements down, but of course it sounded terrible.
I have the datasheet for the PCM-53's (500k), if you want it, by the way.
patscc
 
what i kinda want right now is a wav player for dos that'll run on an 8086... one that supports up to 16-bit sound.
 
Hardware

Hardware

You'd still need the hardware to support it. Of the top of my head, I don't know any soundcards that support 16-bit sound that fit into a 8-bit slot, although I'm not a sound card expert.
patscc
 
While most argue with me about this, and have easily mentioned how to do it, I got an old SB16 that can play 16-bit sounds in an 8-bit slot.

The proof is easy, take a 286 that can run the diagnostic software, put the card in the 8-bit slot, and run it's 16-bit test. Works like a charm.

I think people think that 16-bit sound resolution = 16-bit data, which isn't the case.
 
evildragon said:
I was curious. If enough disk space is available, could an 8086-8MHz decode full 16-bit 44.1KHz 2 channel PCM?

I know my 286 can do it, but no 8086 utility exists to play a WAV it seems to try this...
Click to expand...
Try "ab111.zip" or "sbply254.zip" from this web page:

http://www.oldskool.org/guides/tvdog/sound.html

Most of the programs on that page are for the Tandy DAC chip, but some also support the older 3-voice Tandy chip, the Sound Blaster, or even the plain PC speaker.
 
evildragon said:
I was curious. If enough disk space is available, could an 8086-8MHz decode full 16-bit 44.1KHz 2 channel PCM?

I know my 286 can do it, but no 8086 utility exists to play a WAV it seems to try this...
Click to expand...

The CPU isn't a limiting factor, it's the disk bandwidth. 44KHz 16-bit audio is 176400 bytes a second. If your disk can read data that fast, you can play it.

The more interesting question, which I hope to pursue next year (too many projects this year) is whether or not 44KHz 16-bit ADPCM playback is possible on a 4MHz 8088. It should be.

The tough part about testing any of this is finding a card that does 16-bit playback that uses an 8-bit ISA slot. I thought one of the PAS cards met this requirement but I'm not sure.
 
The default settings that the diagnostic software issued, but on high DMA setting, I set it as the low DMA channel.

The SB16 I have is NOT the PnP model, this model is loaded with filter caps, so it must be an older model.. I can get the exact model number off of the card if I need to.
 
evildragon said:
The SB16 I have is NOT the PnP model, this model is loaded with filter caps, so it must be an older model.. I can get the exact model number off of the card if I need to.
Click to expand...
The original SB16 was the model CT1740, with thumbwheel volume control, optional ASP chip (in what looks like a 387SX coprocessor socket), Panasonic proprietary CD-ROM interface, and pin header for the WaveBlaster daughter board.

The next few models were still based on the CT1740 chipset and were still configured by jumpers, but deleted the thumbwheel, made the ASP chip standard, and added multiple CD-ROM interfaces for Sony and ATAPI as well as Panasonic.

SB16 PnP models based on the real Creative Labs chipset are relatively rare, because shortly thereafter, the SB32 was released and the SBPro was cancelled, so the SB16 became the "budget" model and switched over to the cheapo Vibra chipset (with far fewer capacitors).

The dirty little secret is that CT1740 chipset really only offers 12-bit resolution. If you listen closely at high volume to the ending of a song with a long fade-out, you can hear a "digital hiss" that abruptly cuts off once the sound gets below a certain level. If you listen to the same track played directly from a true 16-bit CD, you won't hear that happen (unless the song was recorded with poor A/D converters in the first place).
 
Mine has no volume knob, but does have the CD-ROM interfaces (of which I do not believe works in the 8-bit slot)..

I honestly don't see the relation between 16-bit sound and a 16-bit bus. If there is a relation, please explain it. I see 16-bit sound as something like resolution, but no relation to the bus interface.
 
vwestlife said:
The dirty little secret is that CT1740 chipset really only offers 12-bit resolution. If you listen closely at high volume to the ending of a song with a long fade-out, you can hear a "digital hiss" that abruptly cuts off once the sound gets below a certain level. If you listen to the same track played directly from a true 16-bit CD, you won't hear that happen (unless the song was recorded with poor A/D converters in the first place).
Click to expand...

And what's sad is that they used "16-bit!!!" as a marketing nail in Adlib Gold's coffin.
 
evildragon said:
I honestly don't see the relation between 16-bit sound and a 16-bit bus. If there is a relation, please explain it. I see 16-bit sound as something like resolution, but no relation to the bus interface.
Click to expand...

You're right; there is no direct correlation between 16-bit sound and a 16-bit bus. It just happens that the overwhelming majority of 16-bit soundcards have required a 16-bit slot, but that's just the timing of the market.
 
Trixter said:
You're right; there is no direct correlation between 16-bit sound and a 16-bit bus. It just happens that the overwhelming majority of 16-bit soundcards have required a 16-bit slot, but that's just the timing of the market.
Click to expand...
A processor with 8-bit external I/O can certainly process 16-bit data; it just has to do it two chunks at a time.

The "32-bit" VESA Local Blus slots on my 486SLC2 motherboard did the same thing. Due to its 386SX base, the 486SLC only has a 16-bit external I/O path (as well as a 16 MB maximum RAM limit), but it can support 32-bit data transfers to and from the VLB cards by doing it two chunks at a time.

Of course, that slows things down to half speed, but it does get done and certainly is possible.
 
bus

bus

So I guess I'll just throw into the fray 16-bit soundcards running on the 32-bit PCI bus, or Bitstream devices.
DAC resolution is a function of the DAC, and has nothing to do with the bus feeding it. All it means is if you have a DAC that uses a larger word than your data bus is that you have to latch data. To 8088 users this shouldn't be anything new.
Folks have been using 12-bit DAC's on 8-bit systems for years, and 12-bit isn't even a common width for a data bus.
patscc
 
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