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Bitperfect Realtek help

post #1 of 11
Thread Starter 
Hi,

Can anyone explain how to achieve bitperfect play with my onboard Realtek ALC889A (MoBo is a Gigabyte P-35-DS3P)? The DTS test failed.

I use Foobar2000 (KS: Realtek HD Audio output, 24 bit output, No active DSP's), optical cable. In the Realtek audio manager (version 5.10.0.5485) 44.1 KHz output sampling rate is selected.

My amplifier and DAC is a Sony STR-DB940 (I'll buy a Beresford soon) and is capable of DTS.

Then one final thing to note is that I have AC3Filter installed on my computer. Settings are: output format AS IS and PCM 24 bit.

Any ideas?

Thanks,
Ruben

------
Computer - Realtek ALC889A - No name optical - Sony STR-DB940 - Xindak AC-01 - Little Dot MK III - AKG K601
post #2 of 11
Not sure how to get DTS working since I don't have a preamp/processor/receiver, but bit-perfect PCM can be obtained using ASIO4ALL. I use it with foobar and its perfect.

As a note, I use Vista, and it has a much nicer audio settings interface than XP and basically makes the realtek audio manager useless.
post #3 of 11
Thread Starter 
I tried ASIO4ALL with Winamp but it wasn't very stable (no sound at all on many occasions). Went for Foobar instead and don't want to go back. Anyway I thought that Kernel Streaming would do the same?

Is bitperfect easier to achieve in Vista than XP?
post #4 of 11
I use ASIO4ALL with foobar as a note. I honestly don't think XP hinders bit-perfect in any way, I only mentioned Vista because it was the only OS I had experience with with my ALC889A.

In vista, for audio settings, when you go to properties of the digital out, theres a tab called "supported formats" and in that you can check mark DTS, Digital Dolby, etc and also select which sample rates your connected receiver/dac can handle. For example, I use a dac that handles sample rates from 32k-96k. So I check mark those options and I can play a test tone to ensure it works. If I tried playing a test tone for the 192k rate, I get a very nasty sound since my DAC cannot handle it. Also, there are lights on my DAC for the various sample rates and which ever rate the DAC is receiving at the moment, the LED for it will light up. Now in foobar with ASIO as my output, with no DSP's, I see 44.1k light up because all my audio is from CD's with that sample rate. Now if I turn on an upsampling DSP like SSRC or SRC and upsample to 96k, I see the 96k light on my DAC light up. In this manner I know that there is not funny resampling happening between foobar's output and my DAC.

I hope this better helps illustrate my point although I don't know if it is of any benefit to you other than letting you know bit-perfect is a trait of the chip, and that theres no specific "bit-perfect" option to select in the settings. Good luck!!
post #5 of 11
Quote:
Originally Posted by verbaan View Post
Then one final thing to note is that I have AC3Filter installed on my computer. Settings are: output format AS IS and PCM 24 bit.
Could AC3Filter be messing with the bitstream? I thought that Windows Media Player played back AC3 and DTS by default... Maybe not.
post #6 of 11
Thread Starter 
I uninstalled AC3Filter and still no succes on the DTS test. My amp says it's getting PCM 44.1 KHz. I'll try ASIO4ALL instead of kern streaming later, but I think the problem lies elsewhere.

Isn't the Realtek chip resampling everything to 48 KHz before it up/downsamples the stream to what ever you specify the output stream should be: 44.1 / 48 / 96 KHz? If so, is there anyway to achieve "bitperfect" on the Realtek ALC889A at all?

I've seen people state they have bitperfect on the Realtek chip but I'm not sure they've done the correct test to verify their claim. If bitperfect is not possible on the Realtek chip than maybe the best solution would be to let Foobar resample the stream to 48 KHz and set output to 48 KHz as well.

Regards,
Ruben
post #7 of 11
its bit perfect with asio. After foobar's DSP (for upsampling) theres nothing else that touches the signal. If I set the output stream to 96k in the windows/audio manager settings, and have my foobar play back a 44.1k file with asio, the dac sees a 44.1k signal. However, if I was using Direct Stream output in foobar, then yes the chip will resample to whatever the setting is in windows/audio manager.
post #8 of 11
Sorry if this is a bit off-topic but how does one test for bitperfect on the output line since I don't have any hardware to test (like DTS decoders)?
post #9 of 11
Thread Starter 
Wauw, it works!! Had to restart my computer, but AISO4ALL with Foobar2000 now works without problems. DTS test passed

Now I don't know if there's any audible difference, but setting up the computer for the best possible stream is the least you can do EDIT: Now let that Beresford come...

As for testing this without a DTS decoder, I don't know. What is your hardware, maybe you can mimic my settings. EDIT: If you do have a DAC that tells you the sample rate its receiving you may try the trick alleyezon_d described earlier in this thread: use a DSP to upsample the signal. It may work.
post #10 of 11
congrats verbaan!
post #11 of 11

Hi guys. So just to confirm, you can achieve 100% bit perfect audio from most of the current RealTek on board chips? If so, how would you compare the sound quality to say, a Sound Blaster card, if [b]both[/b] are running bit perfect?

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