Audio out using HDMI or Optical?

S

sandygws

n00b
Joined
May 30, 2008
Messages
6
Hi,

I’m using the following hardware and software and wanted to ask which would be the best way to set up the audio.

Creative X-Fi Titanium HD
XFX NVIDIA GTX680
Logitech Z-5500
Sony BRAVIA KDL40X3500

Media Player Classic Home Cinema
ffdshow
LAV Splitter
madVR
Reclock
Avisynth


Is it best to connect:

X-Fi Optical SPDIF > Z-5500 for the audio
HDMI from the GTX680 > TV for the video

Or

GTX680 HDMI > TV for audio and video
TV Optical SPDIF out > Z-5500 for the audio


Either method will output DTS-HD MA and DD TrueHD as DTS and DD5.1 respectively, but is there likely to be any qualitative difference between the two methods above?


Thanks
 
If you can use HDMI then do it. SPDIF shoulda been deprecated 20 years ago. No need to worry about Dolby codecs.
 
If you want to get REALLY technical. Optical has the least amount of jitter (variable rate of data transfer) and should only really make a difference on high end systems.
 
My main concern about using HDMI for the audio was that it effectively renders the X-Fi Titanium redundant. Also, if I send the audio via Optical from the TV to the Z5500, is it not effectively being processed twice?
 
you actually want to use analog with those speakers. second best option would be optical with DTS connect.
 
sandygws said:
My main concern about using HDMI for the audio was that it effectively renders the X-Fi Titanium redundant.
Click to expand...

so what, the X-Fi titanium is not a surround sound card. If you dont use headphones, or a 2ch analog stereo, just take it out of the system, honestly.

Also, if I send the audio via Optical from the TV to the Z5500, is it not effectively being processed twice?
Click to expand...

yes, and:
you wont be able to send DTS or 5.1ch PCM to the TV. only Dolby Digital and 2ch PCM. and everything will be 2ch PCM by the time the TV processes it.
 
sandygws said:
My main concern about using HDMI for the audio was that it effectively renders the X-Fi Titanium redundant. Also, if I send the audio via Optical from the TV to the Z5500, is it not effectively being processed twice?
Click to expand...

If you're outputting digital audio from your computer, any fancy stuff your soundcard can do is redundant anyway.

A lot of TVs will only output 5.1 digital audio if you're using the tuner; they won't accept a 5.1 signal in HDMI and pass it through to whatever.
 
When you use digital, the soundcard hardware does NOTHING. It doesn't matter if you use HDMI, Optical, or any other connection. You get the benefit of the options in the soundcard drivers, thats it.

What that means, if you connect to the Z-5500's via optical, the Z-5500's DAC will be doing the audio conversion to analog. Say "goodbye" to whatever audio quality the soundcard could give you.

My advice: Connect the Z5500's directly via analog, so the $200 soundcard you have actually DOES something.
 
gamerk2 said:
When you use digital, the soundcard hardware does NOTHING. It doesn't matter if you use HDMI, Optical, or any other connection. You get the benefit of the options in the soundcard drivers, thats it.

What that means, if you connect to the Z-5500's via optical, the Z-5500's DAC will be doing the audio conversion to analog. Say "goodbye" to whatever audio quality the soundcard could give you.

My advice: Connect the Z5500's directly via analog, so the $200 soundcard you have actually DOES something.
Click to expand...

The only way to connect to the Z5500 with a Titanium HD is through an optical cable. The titanium HD doesn't have 5.1 analog inputs.

1284363959o6zX9y2OLB_2_4_l.jpg
 
HDMI if you are doing surround sound. Optical if you are doing 2-channel. But really, either will be pretty much fine for either scenario.
 
NoTrigger said:
The only way to connect to the Z5500 with a Titanium HD is through an optical cable. The titanium HD doesn't have 5.1 analog inputs.
Click to expand...

Doy, should have known that. Was thinking the first Titanium, not the HD.

In any case, since the Z5500's DAC will be responsable for the conversion to analog, it really won't matter too much which way you go. In theory, the Titanium HD may as well be the device used, simply so you get the benefit from the driver software. Seems like a waste to get a titanium HD and then use SPDIF though...
 
Not sure if the OP reads in the HTPC section of the forum, but I saw this:


SirMaster said:
Normal Dolby Digital uses 448kbit on DVD but can use 640K on BluRay.

Dolby Digital Live! uses 640kbit. Yes, it is the same as normal Dolby Digital.

But here is the problem. 5.1 audio is a 6-channel signal. 6 channels of 16bit/44.1KHz audio uncompressed takes up 4223kbit bitrate. With the best lossless compression algorithms we can reduce this by around 30% on average so that's still about 2963kbit required to send the full 6-channel sound.

Problem is, we cannot send this kind of bit-rate across the S/PDIF interface. So you need to encode it into a compressed and lossy codec. Dolby Digital needs to throw out some audio data to be able to shrink it down to 640kbit. To keep the story short, it starts by throwing out sounds that most humans can't hear anyways, but there is still a lot more that needs to be thrown out to finally reduce it to 640kbit.

You need to compress the original sound that your video game is sending out by 85% to make it fit within a 640kbit stream. That's a lot of compression. Even in the best case, looking at using as much lossless compression as is possible we would still need to further shrink the ~2963kbit compressed lossless stream down by 78% to make it fit in 640kbit.

When you use analog or HDMI none of this compression is needed and you can simply send the full 4223kbits to your amp.
Click to expand...

The topic is worth a read if you're considering optical over HDMI
 
gamerk2 said:
Doy, should have known that. Was thinking the first Titanium, not the HD.

In any case, since the Z5500's DAC will be responsable for the conversion to analog, it really won't matter too much which way you go. In theory, the Titanium HD may as well be the device used, simply so you get the benefit from the driver software. Seems like a waste to get a titanium HD and then use SPDIF though...
Click to expand...

Incorrect assumptions made, post removed.
 
NoTrigger said:
Not sure if the OP reads in the HTPC section of the forum, but I saw this:




The topic is worth a read if you're considering optical over HDMI
Click to expand...


Very true. Only use optical if you are doing it for a 2 channel stereo system (not including subwoofers). PCM over optical is as much as lossless 24bit, 192KHz and is perfectly adequate for everything.

If you use a dolby or dts thing to do surround sound via optical, then you are dealing with lossy compression.HDMI doesn't have this issue. On the other hand, I haven't yet seen a video card that outputs a great stereo signal via HDMI.
 
timestretch said:
Very true. Only use optical if you are doing it for a 2 channel stereo system (not including subwoofers). PCM over optical is as much as lossless 24bit, 192KHz and is perfectly adequate for everything.

If you use a dolby or dts thing to do surround sound via optical, then you are dealing with lossy compression.HDMI doesn't have this issue. On the other hand, I haven't yet seen a video card that outputs a great stereo signal via HDMI.
Click to expand...

Dolby/DTS are both lossy formats, regardless of the transmission mechanism, so if using HDMI, its better to send the uncompressed 5.1 stream rather then bothering with Dolby/DTS encoding at all.
 
timestretch said:
On the other hand, I haven't yet seen a video card that outputs a great stereo signal via HDMI.
Click to expand...

I've heard of this, OTOH it makes little sense. HDMI cannot be a "great stereo signal", it is just PCM ones and zeros like SPDIF PCM. The fault of how it sounds should be on the DAC. But like I said, I've heard of this before using HDMI.
 
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