AC3 sound over SPDIF - why only stereo? (1 Viewer)

[dale77]

MediaPortal Version: 1.0.2
MediaPortal Skin: bluewide
Windows Version: Vista Premium 32bit SP2
CPU Type: AMD 4850e 2.5Ghz X2
HDD: WD10EARS
Memory: 2Gb DDR800
Motherboard: GA-MA78GPM-UD2H F7
Video Card: Sapphire 4670 1Gb
Video Card Driver: Catalyst 10.5
Sound Card: Realtek ALC889a
Sound Card AC3:
Sound Card Driver: 6.0.1.5780
1. TV Card: Hauppage NOVA-TD-500a
1. TV Card Type: Dual DVB-T
1. TV Card Driver: 3.11.27187
2. TV Card:
2. TV Card Type:
2. TV Card Driver:
3. TV Card:
3. TV Card Type:
3. TV Card Driver:
4. TV Card:
4. TV Card Type:
4. TV Card Driver:
MPEG2 Video Codec: MPC MPEG-2 Gabest
MPEG2 Audio Codec: AC3 Filter
h.264 Video Codec: PCM H.264/AVC Decoder
Satelite/CableTV Provider:
HTPC Case: Antec Fusion 430 v2
Cooling:
Power Supply: Antec 430W
Remote: Logitech Harmony 525
TV: Samsung LA40B530 1080p
TV - HTPC Connection: HDMI

I tried a few things but I couldn't get ac3 (5.1 channel) output over SPDIF playing from a .ts. Audio codec is AC3Filter. The 5.1 channel works fine using 6 speaker analog out, but when I set the renderer to digital out, I only get stereo at the z-5500 receiver.

Any tips?

 

[Andrew H]

WHAT are you rendering? Is the original source one with AC3 audio? How does a DVD play - is it passing the AC3 sound through SPDIF? You should not be using analog anything if you want SPDIF - it's DIGITAL and you need to set AC3Filter to PASSTHROUGH, no rendering, no encoding, simply passthrough. It's a checkbox on the opening tab you need to check, that's it. You could also use SPDIFer which is a passthrough-only version of AC3Filter and set it to pass DD and DTS. Oh, and I use SPDIF for all my sound thus my PC is also set to use SPDIF to pass DD and DTS (inside the realtek configuration) and I set MP to use the default audio renderer.

 

[dale77]

WHAT are you rendering? Is the original source one with AC3 audio? How does a DVD play - is it passing the AC3 sound through SPDIF? You should not be using analog anything if you want SPDIF - it's DIGITAL and you need to set AC3Filter to PASSTHROUGH, no rendering, no encoding, simply passthrough. It's a checkbox on the opening tab you need to check, that's it. You could also use SPDIFer which is a passthrough-only version of AC3Filter and set it to pass DD and DTS. Oh, and I use SPDIF for all my sound thus my PC is also set to use SPDIF to pass DD and DTS (inside the realtek configuration) and I set MP to use the default audio renderer.

The original source is a 1080i + AC3 recording, possibly with an AAC stereo stream as well. I'm just experimenting with SPDIF, I've been using analog out as this is the only way to get close to HD audio out (TrueHD,DTS-Master etc). As I said, with "default audio renderer" (speakers is default in realtek), the .ts plays in full 5.1 glory. I just don't know why AC3Filter would trim the 5.1 stream down to stereo to send it out via SPDIF.

Passthrough is the answer eh? I'll look again at those configs.

Haven't tried a DVD in MP. DVD 5.1 in another player works fine.

 

[dale77]

Worked this time, I ticked the Use SPDIF checkbox in ACFilter config and set the output to Realtek Digital out instead of DirectShow: Realtek Digital out.

One of those seems to have done the trick.

 

[Andrew H]

GLAD to hear of your progress! It's frustrating getting some of this stuff working right.

Now, and not to belabor your initial question, but I looked at the specs on the z-5500 where it states

Experience the full-resolution digital surround sound the studio intended. Featuring both Dolby Digital and DTS decoding, the Z-5500 speaker system puts you in the middle of the action with true 5.1 surround sound

which makes me question why you mention "I've been using analog out as this is the only way to get close to HD audio out (TrueHD,DTS-Master etc)." Both of those formats require higher-end decoding equipment, or for your PC to decode to 8 analog (7.1) outputs, or am I missing the point? I also wonder (because I've not physically gone to listen) whether the average system (in terms of quality/cost) is capable of producing any difference between a DolbyDigital (AC3, 5.1) and a Dolby TruHD (7.1) soundtrack. I'm not dogging you, just wondering. Also, as I understand the player will downsample/strip these soundtracks down to 5.1 if that's how the player is configured. I'm just wondering how you're listening to these HD audio formats on the z-5500?

I'd suggest you should use whichever method (PC decode analog to z-5500 -vs- SPDIF passthrough & z-5500 decode) sounds better to you. It'd be hard to say which component has the better D/A converters. I always advocate using SPDIF in conjunction with the typical A/V receiver but this mini system would be questionable...

 

[kiwijunglist]

btw ac3filter handle 5.1 aac very well, so if it is 5.1 AAC you may find the channels are reversed. also a lot of receivers can't handle 5.1 AAC via passthrough, you may find that ac3filter does 5.1 AAC -> AC3 -> SPDIF rather than 5.1 AAC -> SPDIF.

If it ac3filter does 5.1 AAC -> SPDIF and your receiver doesn't support 5.1 AAC you will only get a stereo image.

If you receiver doesn't do 5.1 AAC and you do 5.1 AAC -> AC3 -> SPDIF using ac3fitler then the channels will be all wrong.
You need to use ffdshow to do the 5.1 AAC conversion because it correctly re-orders the channels. The channel order in AC3 and AAC is different.

Dale77 - What you should be doing is playing the file in MPC-HC then go file -> properties -> details -> copy + paste the data.