Could someone please explain HDMI when it comes to Amps.

[AntonioMS]

Hello one and all,
Once upon a time ago, around the era that the Yamaha DSP-A3090 dawned upon us, I was somewhat an avid fan of home cinema.
I still have said amp (although the centre amplification has gone bust) and it has proven quite wonderful over the years.
A series of inputs and monitors have served it.

Now, however, I am looking to upgrade all.

I have taken the plunge and gotten a Playstation 3 and a Panasonic PT-AX100E Projector (due to arrive on Tuesday from Discount Electrical UK).

This brings me onto utter confusion ragarding HDMI inputs/outputs on amplifier/receivers.

Could somebody very kindly take time to actually stipulate what happens:
My root of bewilderment lies in such things as: upscaling/uncompressed pcm/1.3/switcher as opposed to not etc etc.

I am finding that when I look up at the specs they just say how many inputs and outputs they have but then on the forums... they/you state whether it be up to 1080p or not.

I will stop before I confuse myself further.

Kind regards
Antonio

[Oakleyspatz]

Ok...Lets try and make this simple!

HDMI is a digital connection that can carry both sound and images. It has the ability to carry HD images up to and beyond the current maximum available resolution of 1080p and multi-channel uncompressed PCM which is digital audio that uses no or little compression meaning the audio has better dynamics, better seperation and can attain high frequencies than audio passed through optical or co-axial cables.

The problem many av enthusiasts are finding is that their HD plasma, LCD or projector has only 1 HDMI input and they already have multiple sources such as Sky HD, upscaling DVD, HD DVD and Blu-Ray. This is where the cheaper HDMI amps come into play.
They act as a video switcher only, meaning you can plug a couple of HDMI sources into the amp and have just one cable going to your screen. Then you select the input you want to view on your amp's remote...ergo a video switcher.

The better HDMI equipped amps also have the ability to output up to 8 channels (7.1) of uncompressed PCM (read better) audio from HDMI sources as well. The new HD formats can carry new high resolution audio such as Dolby Digital TrueHD and DTS HD. These uncompressed audio formats are too big to go through optical or co-axial cables and can only be transported via HDMI or 5.1/7.1 analogue cables.

Also the very best HDMI amps can upscale to 1080i/1080p from lower resolution inputs much like some upscaling DVD player can do. So if you connected your 576p PAL DVD player to these amps, they will upscale that image to 1080i for example before sending it to your screen.

Others do something which sounds similar but is different and that is upconvert. Upconversion does not increase the resolution of the image, but rather the quality of the method of transport. For example, if you connected a DVD player via S-Video, the amp will upconvert that signal to HDMI and allow you to then send it to your screen. This results in a much better image especially over long cable lengths.

HDMI v1.3 is the latest incarnation of HDMI and whereas previous HDMI versions can only carry LPCM (uncompressed Linear PCM) which means the conversion of the raw Dolby TrueHD or DTS HD bitstream to PCM has to occur in the player, v1.3 can carry that raw bitstream directly to a compatible amp. How much of an advantage this is remains to be seen once compatible amps start to hit the market. The other advantage v1.3 has is in video colour. It can carry many more colour hues than previous HDMI versions again with a compatible screen.

To be honest, I think HDMI v1.3 is more hype than help and with what we have now you can still obtain superb HD audio/images.

So if you wanted to buy a new amp and wanted to hear HD audio, go for one which can output uncompressed PCM, also called LPCM (linear). The cheaper ones can only switch the HDMI images, but cannot output audio from HDMI.
Toshiba's HD DVD players can output 5.1 TrueHD as LPCM through HDMI (even though the format can carry far more channels than 5.1 when required)

The PS3 uses the new HDMI v1.3 but like I said, the benefit of this remains to be seen....

Hope this helps!

Danny

[Chris Moseley]

Hi

See here

HDMI is more about audio than video which makes it important to look for an AV amp with an HDMI repeater rather than an HDMI switch, as explained in the above post. This means amps can accept and process audio via HDMI and as HD players can nearly all decode the new HD audio CODECs and send it to the amp via HDMI as MPCM (Multi Channel Linear PCM data). Some amps can support upto 6 channel MPCM data over HDMI, others up to 8 channel. Amps with HDMI switches can NOT handle HDMI audio at all. HDMI v 1.1 is the minimum requirement for MPCM.

Although HDMI 1.3 will be able to carry HD Audio bitstream signals (before decoding) it is very unlikly that the record labels and studios will allow this to happen. This means most amps will acept HD audio signals as MPCM.


Regards

Chris Moseley
Yamaha UK

[AntonioMS]

Thanks kindly to you both. I believe I kind of understand it now. I shall reread this a couple more times and then... if I may... research some amps and see if I can correctly illustrate your points. I think that that way I could finally understand it.

Thanks for being so generous with your time.

[karl-ireland]

Hi guys,what do you think of the following amp?is it up-to-date with all the hdmi inputs etc??

what do you think?

http://www.pixmania.co.uk/uk/uk/4019...audio-vid.html

Its a pioneer vsx-2016av-s

[AntonioMS]

Have downloaded that pdf file which was linked through a previous thread which adds to the explanation and help you have provided.

Based on what I am learning...

a Question regarding ver 1.3:

Let us say we have a 1.3 amp along with the PS3 which is 1.3.
Let us say for argument's sake that the PJ is 1.2.

Therefore if I plug the PS3 into amp with HDMI and then HDMI to projector but have optical running also from PS3 to amp, would this enable 1.3 for audio but keeping 1.2 for picture or would the PJ cancel all out and relegate all to 1.2 thereby negating any need to wait for 1.3?

further to:

So, if I only have one output source of HDMI (i.e. the PS3) and connect it to the PJ for Hi Def image.

Would there be no difference in terms of sound if that is fed into the Amp via an Optical rather than HDMI?

Therefore if with only one HDMI source and the current absence of ver 1.3 I wouldn't get any difference in sound with either an amp that had HDMI sockets and one that didn't.

Would I still get uncompressed PCM via an optical cable or is that where the catch is? You have to have an amp with HDMI in order to hear that soundtrack... and hence why there is an argument that uncompressed PCM is so good, what difference is version 1.3 going to bring with HD audio when it is pretty amazing with this new enhancement. Is that it?

Am I learning correctly here?

[zerolight]

Antonio,

I think you can get two channel uncompressed PCM over optical, but need HDMI to get 5.1 channels and up.

[Chris Moseley]

Originally Posted by AntonioMS

Have downloaded that pdf file which was linked through a previous thread which adds to the explanation and help you have provided.

Based on what I am learning...

a Question regarding ver 1.3:

Let us say we have a 1.3 amp along with the PS3 which is 1.3.
Let us say for argument's sake that the PJ is 1.2.

Therefore if I plug the PS3 into amp with HDMI and then HDMI to projector but have optical running also from PS3 to amp, would this enable 1.3 for audio but keeping 1.2 for picture or would the PJ cancel all out and relegate all to 1.2 thereby negating any need to wait for 1.3?

further to:

So, if I only have one output source of HDMI (i.e. the PS3) and connect it to the PJ for Hi Def image.

Would there be no difference in terms of sound if that is fed into the Amp via an Optical rather than HDMI?

Therefore if with only one HDMI source and the current absence of ver 1.3 I wouldn't get any difference in sound with either an amp that had HDMI sockets and one that didn't.

Would I still get uncompressed PCM via an optical cable or is that where the catch is? You have to have an amp with HDMI in order to hear that soundtrack... and hence why there is an argument that uncompressed PCM is so good, what difference is version 1.3 going to bring with HD audio when it is pretty amazing with this new enhancement. Is that it?

Am I learning correctly here?

Hi

Zerolight is correct.

Many members on this forum refer incorrectly to MPCM over HDMI as LPCM, which leads to confusion.

PCM is just a transfer method used for carrying digital audio. Several methods exist to carry PCM signals, including optical, coaxial, iLink and HDMI. However, PCM signals do differ. Whilst optical and coaxial can carry a two channel PCM signal (ie stereo), they can not handle multi channel PCM as HDMI can. Some HDMI repeaters can cope with 6 channel PCM, others 8 channel.

As for your question regarding having a 1.3 source, a 1.3 repeater and a 1.2 display. The audio repeater (if set to handle the audio) would not be affected by the display. However, if set to pass the audio on further (to the HDMI output) then as the screen would be connected to this output the HDMI connection between source and audio decoder would now be between the source and the screen and would therfore revert to v 1.2. This setting is usually selected in the menu of the product equipped with the HDMI repeater.

Regards

Chris Moseley
Yamaha UK

[Dann'sTheMan]

Originally Posted by Chris Moseley

Hi

Many members on this forum refer incorrectly to MPCM over HDMI as LPCM, which leads to confusion.

Regards

Chris Moseley
Yamaha UK

Hello Chris,

Linear Pulse-code Modulation is the de-facto and long-established technique used for A-to-D conversion of audio signals and refers to the quantization of the amplitude being "linear". This technique is used in CDs, DVDs, WAV files etc. and has no bearing on what the sampling frequency is; or what the bit depth is; or how many channels are encoded with the technique. The term can, and is, correctly used to describe the formats employing this technique, including multi-channel LPCM.

The more generic term, PCM is often used to describe data encoded as LPCM - but not all PCM data is quantised linearly. Consequently, all of the standards, including BD and HDMI, clearly and precisely refer to LPCM (aka L-PCM and linear PCM), even when referring to multi-channel LPCM. Do a search on this HDMI document to see what I mean...

The only relevant place I've come across this term "MPCM" is from Yamaha - introduced, I suspect, by one of your marketing departments to help differentiate multi-channel LPCM from the 2-channel LPCM used on DVDs etc. However, this is a brand new acronym, and imho, it is more likely to confuse, as LPCM is well established, precise and understood e.g. Wikipedia, or even DTS. The members of the forum who refer to LPCM are doing so quite correctly.

Big smiles,

Andy.

[richimlong]

Hi all,

I just thought I'd point out, for argument's sake, that HD audio doesn't need to be achieved via HDMI. It can also be achieved via 7.1 analogue inputs again with the HD player doing the decoding.

See here for more information:

http://www.dolby.com/consumer/techno...HD_avrs_1.html

Of course this has the obvious disadvantage that you would need up to 4 pairs of analogue cables instead of just one neat HDMI cable...

R

[nevsan]

I also have a PS3 - aswell as a 360.. so I'm looking for a decent (but reasonable price) amp that I can use to output some gorgeous sound. Any recommendations?

[Oakleyspatz]

Originally Posted by richimlong

Hi all,

I just thought I'd point out, for argument's sake, that HD audio doesn't need to be achieved via HDMI. It can also be achieved via 7.1 analogue inputs again with the HD player doing the decoding.

See here for more information:

http://www.dolby.com/consumer/techno...HD_avrs_1.html

Of course this has the obvious disadvantage that you would need up to 4 pairs of analogue cables instead of just one neat HDMI cable...

R

I already mentioned that in post #2

"These uncompressed audio formats are too big to go through optical or co-axial cables and can only be transported via HDMI or 5.1/7.1 analogue cables."

But it's always worth re-mentioning!!

[Chris Moseley]

Originally Posted by Dann'sTheMan

Hello Chris,

or even [. The members of the forum who refer to LPCM are doing so quite correctly.

Andy.

Hi

I fully understand PCM. I was trying to simplify it as, contrary to your post, there are many threads amongst these forums where members do not distinguish the difference between a 2 channel PCM signal and a multi channel PCM signal carried over HDMI. Whilst both are LPCM there is, as I'm sure you'll agree, a difference. Such threads include questions that ask if certain amps equipped with HDMI switches (not repeaters) can support PCM - where the answer is yes but not in the context that the thread talks about. Actually the question in these threads was referring to multi channel PCM over HDMI.

I was only trying to highlight that there was a difference and hopefully ensue people understand that just because an amp supports PCM does NOT mean it will support multi channel PCM over HDMI - sometimes trying to make a fairly technical point simple means making it technically inaccurate at a higher level. If this caused confusion I appologise and thanks for pointing it out.

Regards

Chris Moseley
Yamaha UK

[Oakleyspatz]

Originally Posted by Chris Moseley

Hi

I fully understand PCM. I was trying to simplify it as, contrary to your post, there are many threads amongst these forums where members do not distinguish the difference between a 2 channel PCM signal and a multi channel PCM signal carried over HDMI. Whilst both are LPCM there is, as I'm sure you'll agree, a difference.

Regards

Chris Moseley
Yamaha UK

I must admit, although I do refer to uncompressed multi-channel PCM as LPCM and not MPCM, I do try to also include the words 'multi-channel' or '8 channels' before the 'LPCM' if that is what I am referring to.
But 'MPCM' does remove the chance of mis-interpretation as Chris points out.

[Dann'sTheMan]

Originally Posted by Oakleyspatz

I must admit, although I do refer to uncompressed multi-channel PCM as LPCM and not MPCM, I do try to also include the words 'multi-channel' or '8 channels' before the 'LPCM' if that is what I am referring to.
But 'MPCM' does remove the chance of mis-interpretation as Chris points out.

Multi-channel LPCM is fine, accurate and unambiguous - it's the term the standards use to differentiate from 2-channel LPCM. Incidentally in the HDMI spec, 2-channel LPCM is mandatory for any HDMI source/sink that supports HDMI audio transmission/reception; whereas multi-channel LPCM is only optional.

I'm personally not a fan of the term MPCM - it has no real history or acceptance within the industry - either at the technical level or at the marketing level.

On the flip-side, I agree that there is a lot of confusion out there regarding the capabilities of AVRs that simply switch HDMI, and those that sink HDMI audio and amplify it. However imho this confusion is more to do with whether an AVR amplifies HDMI audio at all rather than being about whether the HDMI audio is multi-channel LPCM or 2-channel LPCM.

I suspect over time, as more and more reference HDMI designs are created, the consumer will not have to be so clued up about the potential pitfalls of being an early adopter. By the time it all shakes out, imho, the term that will be most adopted will simply be LPCM.

Big smiles,

Andy.