# Internal Decoding - Who Cares?



## avaserfi (Jul 5, 2007)

The title pretty much sums it up. Why do so many seem to make so much of a receivers ability to internally decode the new HD formats? 

Personally I don't care what decodes it as long as it is done and I trust my player for that otherwise I wouldn't have put money into it. 

Do people just want to maintain the status quo and do everything the same way it was done in the DVD generation or do you just like your receiver displaying TrueHD?

So why does it or doesn't it matter to you?


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## tonyvdb (Sep 5, 2007)

avaserfi said:


> The title pretty much sums it up. Why do so many seem to make so much of a receivers ability to internally decode the new HD formats?


The main reason that its best to send the uncompressed HD audio signal through to the receiver is because if its done in the DVD player its self you will loose (from what I have read) the back two channels if the HD or DTS HD audio has that information. most DVD players also only have 5.1 analog outputs as well so if you have to use them you have then gone through one unnecessary conversion. Plus if you have a higher end receiver it will do a better job of it anyhow.


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## avaserfi (Jul 5, 2007)

tonyvdb said:


> The main reason that its best to send the uncompressed HD audio signal through to the receiver is because if its done in the DVD player its self you will loose (from what I have read) the back two channels if the HD or DTS HD audio has that information. most DVD players also only have 5.1 analog outputs as well so if you have to use them you have then gone through one unnecessary conversion. Plus if you have a higher end receiver it will do a better job of it anyhow.


If the HD player is capable of decoding full a full 7 channel signal then you don't loose the back two discrete channels via the PCM signal when the receiver gets it if it is capable of handling them of course.

Also, if you have a high end receiver what changes in how the format is decoded? Price does not equal quality. The same algorithms should be used to decode the files no matter the location it takes place.


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## brent_s (Feb 26, 2007)

As long as the player truly does internal decoding to multi-channel PCM, I agree, it shouldn't matter. The s/w is the same for either device and the receiver's DACs will be used in either case. Unfortunately, a few reviews of the latest BD players suggest that internal decoding of TruHD/DTS-HD may actually be getting you a 2-channel downmix. Since they'll still bistream the lossless track, you can get full multi-channel decoding using an appropriate receiver.

From what I've read, the BluRay spec doesn't mandate a losselss decoder onboard compared to HD-DVD's decision to require at least a TrueHD decoder for ceritifcation.

After that, the concern is probably left over from the problems with player decoding of SD-DVD (DD/DTS), DVD-A, and SACD. Very few manufacturers ever gave their players full bass management/delay/level controls which produced inferior results compared to a receiver doing the processing. This fear carries forward without folks realizing that many pre HDMI 1.3 receivers will fully and properly process multi-channel PCM.

IMO, of course. 

-Brent


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## denisincalif (Jan 10, 2008)

> As long as the player truly does internal decoding to multi-channel PCM, I agree, it shouldn't matter. The s/w is the same for either device and the receiver's DACs will be used in either case. Unfortunately, a few reviews of the latest BD players suggest that internal decoding of TruHD/DTS-HD may actually be getting you a 2-channel downmix. Since they'll still bistream the lossless track, you can get full multi-channel decoding using an appropriate receiver.


Excuse my ignorance folks---I am just getting started in home theater. Does the lossless track come via the HDMI output from the player? If so, does every player with an HDMI output always put lossless audio out on HDMI, or do the player manufacturers have a choice as to what goes out that way?


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## avaserfi (Jul 5, 2007)

denisincalif said:


> Excuse my ignorance folks---I am just getting started in home theater. Does the lossless track come via the HDMI output from the player? If so, does every player with an HDMI output always put lossless audio out on HDMI, or do the player manufacturers have a choice as to what goes out that way?


A few things are needed for a lossless track to be used:

1) Your media needs to have it
2) Your player needs to decode it or pass it bistream (this is decided by the manufacturer it might be able to do both, one or neither)
3) If it is decoded by the player your receiver needs to be able to handle Multichannel PCM or if it is sent bistream then your receiver needs to be able to decode it.

PCM signals can be sent via analogue or via HDMI while bistream for HD audio can only be sent via bistream.


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## atledreier (Mar 2, 2007)

I'd like to have my pre/pro do it because of convenience, really. If my player does it I need to set up speaker and bass management both places. Also, my pre/pro has better DACs than most current HD players, so I'd like to use them.


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## denisincalif (Jan 10, 2008)

So lets say I have a snazzy new receiver or pre/pro that handles all existing audio formats very well. And lets say I have a player that also handles these formats. How do I control where the digital signal processing of what I eventually hear takes place? And how does this control differ for cases where the media has a lossless track and cases where it doesn't?


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## avaserfi (Jul 5, 2007)

denisincalif said:


> So lets say I have a snazzy new receiver or pre/pro that handles all existing audio formats very well. And lets say I have a player that also handles these formats. How do I control where the digital signal processing of what I eventually hear takes place? And how does this control differ for cases where the media has a lossless track and cases where it doesn't?


If your player and receiver can do everything then set the player to bitstream if you want the receiver to do the decoding. Most players have options for the older codecs and the newer ones so you can choose bitstream for both the new and old if this is the case.

Alternatively if you wanted everything done by the player just set it to PCM in both cases.


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## denisincalif (Jan 10, 2008)

Thank you. Now I think I am getting closer to understanding. So if I set the player to "bitstream" it puts the least-processed signal it has available out via HDMI and if I set it to "PCM" it will send out fully processed audio also out via HDMI?


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## avaserfi (Jul 5, 2007)

denisincalif said:


> Thank you. Now I think I am getting closer to understanding. So if I set the player to "bitstream" it puts the least-processed signal it has available out via HDMI and if I set it to "PCM" it will send out fully processed audio also out via HDMI?


If you have bitstream set the player just reads and sends it doesn't process. If you have PCM set then the player decodes completely all that is left is for the receiver to point the signal to the right speakers. Both of these options can be done via HDMI.


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## denisincalif (Jan 10, 2008)

Thank you Andrew. You have been a big help. These things are so obvious to people who actually own and use equipment. But for those of us who own virtually nothing but are in the market to buy it is amazing how hard it is to find the really basic information.


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## brent_s (Feb 26, 2007)

atledreier said:


> I'd like to have my pre/pro do it because of convenience, really. If my player does it I need to set up speaker and bass management both places. Also, my pre/pro has better DACs than most current HD players, so I'd like to use them.


You'll have some player configuration to do regardless, like pretty much every device in a HT rig. But, it's usually a set-it-and-forget-it proposition...unless you make a habit of moving your speakers around frequently :bigsmile:

You'll only need to configure bass management/distance delay in the player if you're using the analog outputs (if present). If you're worried about the analog outputs then you don't have an HDMI audio capable receiver/processor so the discussion about which device should do the processing becomes moot. Even then, this would/should still be a one time setup. 

For in player decoding passed via HDMI to the receiver/processor, the only DACs in use will be in the receiver/processor. Very generally, you can think of in player decoding to PCM as simply "unzipping" the TrueHD/DTS-HD track into X.1 PCM data streams. All bass management/delay processing/DAC would still be performed in the receiver/processor on the X.1 PCM data. 

Caveat: As I said in post #4...the player's decoding to PCM has to be true decoding to multi-channel PCM. A number of recent BluRay player reviews have revealed that in giving the consumer bitstream access, the DD+/TrueHD/DTS-HD decoders were stripped down to only downmix to 2.0 via PCM. IIRC, the UltimateAVMag review of the new LG dual format player found it couldn't bitstream or decode properly to multichannel PCM. 

-Brent


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## Magyar (Feb 20, 2007)

The problem with inplayer decoding is really with the implementation of how some machines do it.
Like the Toshiba XA2. The signal will enter through it's DSP processing, and some settings becomes active, like speaker selection, even when you use the HDMI output. This is of course is not ideal, nor how it should work IMO. To me direct bitsreaming is the cleanest possible way to transmit the original soundtrack, with no annoying beeps and sound effects that the secondary mixer will mix the film track with [HD DVD]. If I wan't to watch some of the PIP features I could always switch back to in player decoding, but for watching the movie I like the bitsream option better.


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## Hakka (Sep 10, 2006)

If you read the manuals of most HD players you will find that they compromise higher res tracks, for example the XA-2 can only do 2 channels at 192khz sampling rate, or all channels at 48khz. Receivers such as the Denon 08 series have a lot more processing power and do not suffer from this limitation. This will not be a factor fro most film tracks at 48khz, but will affect live concerts recorded at the higher resolution.

There seems to be some cinfusion about player DACs vs receiver DACs. When you are connected via HDMI you ALWAYS use the DACs in the receiver, regardless of player decoding or bitstreaming.
The only time the DACs in the player are used is when you connect through the analog outputs.

Another thing to keep in mind when comparing internal decoding vs bitstream is there will be a difference in levels, with the bitstreamed signal being louder than the decoded signal.

Having said all that I currently connect my HD players with 5.1 analog so internal decoding of DTS-MA would be nice.

Hakka.


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## Funkmonkey (Jan 13, 2008)

sorry if this is a total noobie question, but I was wondering if it is possible to run a decoded analog signal from a source (in my case oppo 981HD) directly to an amp ? Does the audio need to run through a pre-amp? If it is not decoding anything, the only thing that a pre-amp would be providing would be volume control, correct? or not?


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## Hakka (Sep 10, 2006)

You need the pre for volume control, if you connected the analog outs of the player directly to the power amp you will get full power from the amp and probably damage your gear/ears or both.

Hakka.


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## brent_s (Feb 26, 2007)

Funkmonkey said:


> sorry if this is a total noobie question, but I was wondering if it is possible to run a decoded analog signal from a source (in my case oppo 981HD) directly to an amp ? Does the audio need to run through a pre-amp? If it is not decoding anything, the only thing that a pre-amp would be providing would be volume control, correct? or not?





Hakka said:


> You need the pre for volume control, if you connected the analog outs of the player directly to the power amp you will get full power from the amp and probably damage your gear/ears or both.
> 
> Hakka.


This is one of those "it depends" questions.

You would only get full output from the amp if the player delivered the signal needed to drive the amp to full power. The output from a player varies with the recorded level of the signal and the pre's volume control can provide attenuation or gain to that signal, as needed, to get the desired output from the amp.

I haven't read the 981HD's manual, but my Oppo 970 does provide a "volume" control for the analog outs, so it should be usable directly with an amp. I've done some brief comparisons between the 970's onboard DD/DTS decoder/BM/delay processing via the analog outs into the 5.1 inputs against bitstream decoding in my now antique Sherwood-Newcastle AVP-9080 and shamefully, couldn't hear any obvious difference. FWIW, I didn't do metered level matching between the 970's decoder and the 9080's decoder...the 970 did its own delay/BM/DAC processing with the 9080 doing the channel level balancing at the analog level (the 9080 is analog from input to output on the 5.1 inputs).

Funk, if you wish to pursue this further, I could move yours, Hakka's, and this post into it's own thread....likely to generate more comment that way. This thread was started to discuss player vs processor decoding of DD+/TrueHD/DTS-HD formats in HD-DVD/BluRay players, not standard DD/DTS.

-Brent


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## Funkmonkey (Jan 13, 2008)

brent_s said:


> Funk, if you wish to pursue this further, I could move yours, Hakka's, and this post into it's own thread....likely to generate more comment that way.
> -Brent


Sure, if you think it would be a topic of interest for anybody else, that would be great. 

Seems to me that every link in the chain is capable of some type of processing these days, and wondered if a dedicated processor was becoming completely redundant. ( i.e. I now have video processors in my TV, cable box, and dvd player, and sound processors in my cd/dvd player, receiver, and TV, ...and I have a very modest system.) 
I'm just trying to comprehend spending a thousand dollars for a volume knob... I know I am over simplifying it, but I theoretically could I just hook up a rheostat/gain knob to an amp to regulate the line level signal and provide the volume control?

Or, I am sure this would work as a minimalist system: use powered speakers and hook them directly into the analog outs of the Oppo, or any other player, and have 5.1 sound?

Just questions/ideas running through my head...


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