HDMI 1.3 vs. S/PDIF?

[FatStrat85]

This is a continuation of the following thread.

http://forums.audioholics.com/forums/showthread.php?t=36221

I've decided on a pair of Polk RTi8's and a HSU STF-2 subwoofer. These will provide sound for my music as well as my HT. My TV is a Toshiba REGZA 47" 1080p LCD, model # 47HL167. Originally I was planning on buying a 7.1 receiver with HDMI 1.3a switching. My HD Cable box and Blu-Ray player would connect through the receiver via HDMI 1.3 and the receiver would connect to my TV via HDMI 1.3.

I was wondering if it would make sense for me to save money by getting a recevier without HDMI switching, since my TV has 3 HDMI inputs anyway. The TV has a digital audio output (I'm assuming that is S/PDIF) that I think I could run to a receiver. So everything would go into the TV and ALL the audio into the TV would automatically go to the reciever with just one wire.

I've hear that S/PDIF can only handle 2 channels of uncompressed audio. After that, it would start to compress it. Is that correct? I've heard that HDMI 1.3 would be able to handle a full 8 channels of uncompressed audio. Is that correct?

My system will be 2.1, so that is all I'm worried about for now. I can get a 7.1 receiver down the road if I upgrade to surround sound. My concern is with the ".1" portion of my 2.1 system. Will the LFE channel of movies not go through the S/PDIF uncompressed? If so, would this affect only movies and not CD music? Would the LFE channel still go through S/PDIF, only compressed, or would it not go through at all? Also, doesn't a receiver that has HDMI switching convert a surround sound signal into 2 channels for you? If I went with the S/PDIF from the TV, would that not happen?

Basically, would I get better sound quality by spending the extra money on a reciever that has HDMI switching and routing everything through the receiver first, or will the S/PDIF be just as good with my setup? Thanks in advance.

 

[MDS]

I've hear that S/PDIF can only handle 2 channels of uncompressed audio. After that, it would start to compress it. Is that correct? I've heard that HDMI 1.3 would be able to handle a full 8 channels of uncompressed audio. Is that correct?

S/PDIF won't compress anything - it's a protocol and data format for sending digital audio. The issue is that s/pdif is limited to 16 bit/48 kHz 2 channel PCM (because PCM is uncompressed). DD/DTS are compressed audio formats so that although there are 5.1 channels of audio the total amount of data that is being sent is less than the max s/pdif can transport. The bandwidth of HDMI is much greater and can carry multi-channel PCM (as well as video at the same time).

Will the LFE channel of movies not go through the S/PDIF uncompressed? If so, would this affect only movies and not CD music? Would the LFE channel still go through S/PDIF, only compressed, or would it not go through at all?

The LFE is just another channel and will be sent along with the other 5 channels over s/pdif just fine.

Would I get better sound quality by spending the extra money on a reciever that has HDMI switching and routing everything through the receiver first? Thanks in advance.

You get a lot more convenience having the receiver handle switching and you get the ability to play multi-channel PCM from an HD-DVD/BD disc. The idea of routing everything to the TV first will not work for anything but 2 channel PCM and DD.

 

[FatStrat85]

Thank you for your quick response.

The LFE is just another channel and will be sent along with the other 5 channels over s/pdif just fine.

When you say "just fine", movie audio will be compressed because of the extra channels, won't it? Compressed is not as good as uncompressed, right? So for a 2.1 setup, I would be better with HDMI switching through the receiver, correct?

You get a lot more convenience having the receiver handle switching and you get the ability to play multi-channel PCM from an HD-DVD/BD disc. The idea of routing everything to the TV first will not work for anything but 2 channel PCM and DD.

I don't think it would be any more convient. Either way, I only have to use one remote to switch one device, and the audio and video with both automatically switch. With the S/PDIF, I just switch the inputs on the TV. With the HDMI switching on the reciever, I just switch the inputs on the reciever. My main concern here is about quality.

 

[no. 5]

When you say "just fine", movie audio will be compressed because of the extra channels, won't it? Compressed is not as good as uncompressed, right? So for a 2.1 setup, I would be better with HDMI switching through the receiver, correct?

'Movie audio' (i.e. Dolby Digital, DTS) is compressed audio, S/PDIF will pass that information unaltered, the connection type will not alter the level of compression that already exists in the recording.

If it's no compression you want from your movie sound tracks (i.e. the multi-channel PCM sound track of a Blu-ray disc), you would need to use a HDMI connection to the receiver to access that audio.

 

[FatStrat85]

'Movie audio' (i.e. Dolby Digital, DTS) is compressed audio, S/PDIF will pass that information unaltered, the connection type will not alter the level of compression that already exists in the recording.

If it's no compression you want from your movie sound tracks (i.e. the multi-channel PCM sound track of a Blu-ray disc), you would need to use a HDMI connection to the receiver to access that audio.

That makes sense. Thank you. It won't pass uncompressed formats like TrueHD though, right? For music (a CD in my Blu-Ray player) going into the TV with HDMI and then to the reciever with the S/PDIF, I will still get full uncompressed audio, correct? There would be no advantage to using a HDMI switching receiver instead for 2 channel music?

Which reciever should I get that can take a Dolby 5.1 signal through S/PDIF and mix it into a 2.1 signal with a crossover control for the subwoofer? I was originally looking at the Denon AVR-1908, the Marantz SR4002, or the Onkyo TX-SR605. If I didn't get HDMI 1.3 switching, what would be some good (cheaper) alternatives to those recievers that would do what I am looking for?

 

[no. 5]

That makes sense. Thank you.

Your welcome.

It won't pass uncompressed formats like TrueHD though, right?

Correct, S/PDIF will not pass TrueHD.

For music (a CD in my Blu-Ray player) going into the TV with HDMI and then to the reciever with the S/PDIF, I will still get full uncompressed audio, correct?

Correct. However, you may need to have the TV on to listen to a CD.

 

[FatStrat85]

Correct. However, you may need to have the TV on to listen to a CD.

Good point. I never thought of that. That might annoy me. Hmmm... Maybe I'll just stick with a HDMI switching receiver then. Does anyone have any opinions about the 3 receivers I mentioned (Denon AVR-1908, Marantz SR4002, or the Onkyo TX-SR605)? They're fairly new, so it's hard to get reviews, let alone comparisons.

 

[mtrycrafts]

That makes sense. Thank you. It won't pass uncompressed formats like TrueHD though, right? For music (a CD in my Blu-Ray player) going into the TV with HDMI and then to the reciever with the S/PDIF, I will still get full uncompressed audio, correct? There would be no advantage to using a HDMI switching receiver instead for 2 channel music?

Which reciever should I get that can take a Dolby 5.1 signal through S/PDIF and mix it into a 2.1 signal with a crossover control for the subwoofer? I was originally looking at the Denon AVR-1908, the Marantz SR4002, or the Onkyo TX-SR605. If I didn't get HDMI 1.3 switching, what would be some good (cheaper) alternatives to those recievers that would do what I am looking for?

One way around all this is if you can output 5.1 channels of analog audio from your hi def DVD player and connect that to the 5.1 analog input on a receiver that you may already have and has this connection available to you, depending on age of receiver, you will get the uncompressed analog audio decoded by the DVD player to your receiver without using HDMI and a possible need for a new receiver.