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Topic: Pass AC3 directly to X-Fi Dolby Digital decoder? (Read 12159 times) previous topic - next topic
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Pass AC3 directly to X-Fi Dolby Digital decoder?

The Creative X-Fi cards have built-in Dolby Digital and DTS decoders. The issue I'm having is trying to actually use them. So far I can't find a DirectShow filter that can play an AC3 stream without decoding it. They all decode the streams automatically and pass them on to a multi-channel PCM stream. Obviously, this PCM stream already contains the decoder's processing, and not the X-Fi decoder's processing. How can I play a movie's AC3 stream without using a software decoder, and instead allowing the X-Fi to do the decoding?

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #1 –
Found out for myself I believe. PowerDVD's audio decoder did the trick. When configured to output SPDIF, I can still hear sound! So I'm assuming that means X-Fi's decoder is kicking in. Other decoders I tried didn't do this.

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #2 –
To use your soundboard´s built-in decoder you need to send the AC3 thru SPDIF and enable the "Use Built-in Decoder" in the Decoder tab of the soundboard´s configuration panel (instead of "SPDIF Passthrough").
The directshow decoder will feed the sb with the raw stream for the sb to decode it.
AC3filter is a freeware Directshow AC3 and DTS decoder (to me, the best decoder ever) and supports SPDIF output.

Cheers.
"Screw u guys, I´m going home."

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #3 –
With Media Player Classic (the player i prefer), it works as follows:

Options - Internal Filters - doubleclick on AC3 and select "SPDIF". Then the X-Fi decodes it. Note that you can't influence the volume with MPC anymore, you have to do it from the driver now. That's the main reason i don't use SPDIF, even though i have an X-Fi as well. Also, i found no audible quality difference once i matched the volume of the two methods.

P.S. In Vista, the X-Fi won't be able to decode anything in hardware anymore, because the Vista drivers don't allow hardware access for "security reasons". Mind you, this is not for the user's security, this is for the media industry, to make it harder to bypass content protection, DRM and so on.

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #4 –
Quote
P.S. In Vista, the X-Fi won't be able to decode anything in hardware anymore, because the Vista drivers don't allow hardware access for "security reasons". Mind you, this is not for the user's security, this is for the media industry, to make it harder to bypass content protection, DRM and so on.


Where did you read this?
As Creative said anything about it also?

Cheers.
"Screw u guys, I´m going home."

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #5 –
http://www.custompc.co.uk/custompc/news/98...-after-all.html

The german article linked there is a bit more comprehensive.

In brief:

- No direct hardware access with Vista sound drivers, period. X-Fi or not. This affects EAX/DTS/Dolby/AC3/etc.
- Hackfix for EAX by Creative: OpenAL wrapper (2 files to be copied into the game directory), which translates DirectSound3D/EAX instructions into OpenAL instructions. Beta driver coming this month.
- "Fix" for DTS etc.: New buyers get a coupon for PowerDVD software-decoder plugins. Otherwise nada.

Now, this isn't Creative's fault. This was Microsoft, getting sweettalked by the media industry to implement a more secure driver model, so they can DRM/CP us to hell and back and our hands will be tied. The only thing that is secured by this are the paychecks of the music- and movie-industry.

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #6 –
I'm very skeptical of all of this. For Windows Vista to say to Creative and all the on-board audio developers that your audio processing must be done only in software just sounds too radical. In my experience, the industries that support DRM always have a honeymoon period where they can dream up and implement new, radical approaches to screw us when new technologies come to the plate. However, in the end, pressures from other industries level the playing field to a more balanced approach. I don't believe the entire sound card industry is going to buckle under the pressure of Windows Vista after a decade of innovations. Until they can work closer with Microsoft to make their products work as they did before, they're first going to hack their way through, like Creative is doing now. I think Microsoft is too bogged down right now to listen to hardware vendors that they aren't in bed with, but eventually they WILL have to. I for one remain complacent, albeit impatient. I'm keeping XP until Vista is fully matured and supported. No proper X-Fi drivers? Sorry, but that's a deal breaker.
 

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #7 –
Dido. Vista has just died to me cause of this.
I paid for my soundboard almost as much as for the microprocessor, which I choose specifically for the Dolby/DTS decoding features.
And vista is gonna render my sb useless? Screw that!
I´m sticking with XP and that´s final.

Cheers
"Screw u guys, I´m going home."

Pass AC3 directly to X-Fi Dolby Digital decoder?

Reply #8 –
Vista can go to hell.