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Discussion Starter · #1 ·
My HTPC setup was going great until I got to the final step of hooking it up to my receiver (HK AVR 254) and TV (I set it up on my PC's monitor).


I have a GIGABYTE MA78GPM-UD2H which has the 780G chipset. I knew that it couldn't do 7.1 over HDMI but I had the understanding it could do 5.1 over HDMI (and optical). However, in the sound settings in Windows 7, I can only select stereo output for the HDMI output. I have the latest ATI drivers as well as the Realtek drivers. When hooked through optical, the "configure" option is grayed out but in the last tab I can choose Dolby Surround and I get 5.1 if the source has it. The HDMI advanced tab also has this option but if you try to select it, it says not supported and goes back to 2 channel.


Another issue, which unfortunately could be my receiver, is that the audio is somewhat stuttered. The audio cuts in slightly when no audio has been playing prior to it. For example, when I start watching a video, the first couple seconds are silent then it starts playing. Small sound clips, like the clicks between menu items in Media Portal, are never even heard. Its as if it takes the receiver a moment to "wake up" when its not already getting an audio signal. I hooked the HDMI straight to my TV and didn't have this problem. I actually found someone else with the same issue here but no real fix was found other than playing something in the background to keep the receiver "always on".


I am hoping that all these things are just drivers issues and Windows 7. I originally went with 7 because I couldn't decide between 7MC and MediaPortal, but I'm going with MP so I can just go with any version of Vista now (64 bit doesn't seem to be worth it either for the extra bit of RAM). I found 7 to be a little buggy while doing other things as well, like renaming and tagging all my video files.


Does anyone have any suggestions on how to get 5.1 HDMI audio and get rid of the delay, or am I best off just switching to Vista 32 (probably Business because its the only legit version I have) and seeing if this problem still exists? Also, if I do go with business, will my Harmony Remote (mapped from a cheap ebay MCE Remote) still work even if there's no MCE on there?


Thanks.
 

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"it could do 5.1 over HDMI": If you mean 5.1 LPCM, then that's wrong. The audio formats supported by 780G HDMI are:


- Stereo 16 bit 48 kHz LPCM

- Dolby Digital (bitstream)

- DTS (bitstream)


You need AMD 785G chipset for 5.1/7.1 LPCM over HDMI.
 

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Discussion Starter · #3 ·
ok, then I am looking to get Dolby Digital or DTS...basically just some sort of surround sound over HDMI. When I go to the Realtek HD Audio Manager, there is the "Dolby Digital Live" button to click (as well as an option in the drop down drop list) but as soon as you choose either, it switches back to just stereo immediately. These options are available for the optical output, except they work.


Also I've confirmed the initial audio cut off is something with my receiver...I hooked the HDMI signal up to my tv then ran my tv's digital audio out to the receiver and the problem was still there. Searching around I've found more cases, but no solutions yet.
 

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Dolby Digital Live (and DTS Live) is mainly for gamers who use S/PDIF (as S/PDIF supports only stereo LPCM/DD/DTS, multichannel LPCM from games must be encoded to Dolby Digital [or DTS] to get surround sounds from games).
 

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Quote:
Originally Posted by Detonation /forum/post/16934164


Well then how is everyone else getting DD/DTS bitstream over HDMI? I know its possible, there are plenty of search results suggesting it, including this active topic from today.

DVD/BD movies have DD/DTS audio tracks. If a movie file does have a DD or DTS audio track, then AC3Filter (and ReClock) is a popular utility to encode multichannel LPCM to DD.
 

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Quote:
Originally Posted by Detonation /forum/post/16934410


I have plenty of material with DD audio tracks. The problem is even if the source is DD/5.1, my HDMI audio output is only stereo and there is no setting that I can change.

Which player/audio decoder are you using? The player has to output DD/DTS bitstreams.
 

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Discussion Starter · #9 ·
This is just straight from Windows Control Panel > Hardware and Sound > Sound settings. If the sound controller is only set to output in 2 channels, then even if the player is outputting 5.1 it will still come out stereo. I'm using the Shark007 Windows 7 Codec pack with x64 add on.
 

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Quote:
Originally Posted by Detonation /forum/post/16934714


This is just straight from Windows Control Panel > Hardware and Sound > Sound settings. If the sound controller is only set to output in 2 channels, then even if the player is outputting 5.1 it will still come out stereo. I'm using the Shark007 Windows 7 Codec pack with x64 add on.

Try to play the following test files:


- test.ac3

- test.dts


MPC HomeCinema + ffdshow Audio Decoder (latest build) can play them straightforwardly. Make sure to choose AC3/DTS "Pass-through" in ffdshow Audio Decoder output configuration.
 

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I often switch between Reclock outputting AC3 to just using the DTS Live option on the sound control panel. Can't say I notice a difference, even though using reclock = 640 bitrate vs 1.5 Mbit with DTS Live.


For the moment I'm using DTS Live, no drama.
 

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Discussion Starter · #12 ·
Alright so I've made some progress on the issue but its still not solved. Apparently I did not have the latest versions of each driver (they were from June), so I got the most recent Realtek ATI HDMI Driver and the Windows 7 x64 Realtek HD Audio Codec/Manager from the Realtek site. I am now able to choose Dolby Live option and there is also an option I can tick that says "Use AC3/DTS/WMA Surround" or something like that. Well my receiver now shows that it is receiving Dolby Digital and all 5 speakers are activated. However, in the properties for the HDMI Audio device, it still says Maximum Channels Supported: 2 and I can only select two speakers in the config setup. The test files above play the rear channels through their front equivalent still.


So, the HDMI output is sending a DD Surround signal, but Windows is still limiting it to 2 speakers. If I can get it to recognize the device as having 5.1 capabilities, then this problem would be solved, but I don't know what else I can do short of trying Vista and hoping its a Win7 conflict.
 

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Quote:
Originally Posted by Detonation /forum/post/16939004


However, in the properties for the HDMI Audio device, it still says Maximum Channels Supported: 2 and I can only select two speakers in the config setup. The test files above play the rear channels through their front equivalent still.


So, the HDMI output is sending a DD Surround signal, but Windows is still limiting it to 2 speakers. If I can get it to recognize the device as having 5.1 capabilities, then this problem would be solved, but I don't know what else I can do short of trying Vista and hoping its a Win7 conflict.

This is normal. The number of channels in Windows control panel is strictly for LPCM (and HD 3200 HDMI supports stereo LPCM).


You should be able to hear sounds from all five speakers (one by one) if you play test.ac3 and test.dts and DD/DTS indicator in the receiver should light up. If not, something is still wrong, i.e. DD/DTS is decoded to 5.1 LPCM somewhere in PC, then limited to stereo LPCM.


DD/DTS are bitstreams of data; no application or Windows Audio Engine can convert them to "stereo DD/DTS" without first decoding them 5.1 LPCM, then limit to stereo LPCM, then re-encode them to DD/DTS (and there is no application that does this automatically without user's awareness).
 

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I recommend you to play the test files with GraphStudio to see if any other filter intervenes between ffdshow Audio Decoder and DirectSound Device. (Just drug and drop the test file.)

 

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Discussion Starter · #15 ·
Problem solved! Graph Studio verified that only AC3Filter was decoding them, and when I played it through Graph Studio I got all 5 channels (and my sub) separate. But it was still Stereo in MediaPlayer Classic (the program I used the whole time) and I found out that in the output options, the internal AC3/DTS/etc filters were actually set to output stereo. So I just disabled those so it uses the external filters and it was finally 5.1. Thanks for all the help.


But as soon as you fix one problem, another one arises...the audio is somewhat stuttered and out of sync on the file I used, but that was a 4GB split of a 1080p x264 DTS mkv movie, so I think if I just split it up into smaller pieces it won't be a problem.


Also, do you suggest AC3 or ffdshow? They're both in the Shark007 pack. I don't care that much to tweak settings to extreme or use all the advanced settings...as long as it sounds good enough and works, I'm happy. Is either one faster/more efficient?
 

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Some people say AC3Filter is the only audio filter that supports DTS bitstreaming without stuttering. Personally I use madFlac for FLAC (this is for mutlichannel HDMI audio) and ffdshow for everthing else.


BTW you can use GraphStudio to see what filters are used in a media player such as MPC HomeCinema: File > Connect to Remote Graph... You may need to register the file proppage.dll . (Save it in a folder; copy and paste the following command, save it as "install.bat" in the same folder and double click it to register proppage.dll.

Code:
Code:
@%SystemRoot%\\System32\
egsvr32.exe proppage.dll
)
 
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