Anyone Know Why?

Question

Level 5

5,257 points

Anyone Know Why?

DVD Player's Audio EQ (Window, Audio EQ) won't activate once DVD Player's Audio Output setting is set to Digital Out.

Setting it to Digital Out is the only way I can see to allow DVD Player to pass the 5.1 Dolby Digital signal. Audio can still be heard through the optical output with the DVD Player's Audio Output still set to System Sound Output, and DVD Player's Audio EQ does have affect then, but no surround sound signal is passed through the optical output under the System Sound Output setting.

It seems odd. Apple went through the trouble (and very graciously - thanks Apple) to give us an Audio EQ in DVD Player, but won't allow us to employ it through the optical output, when the DVD Player's Audio Output setting is set to Optical and 5.1 is being passed.

Anyone know why, or better yet know of a way to employ the Audio EQ while a 5.1 Dolby Digital signal is being passed from a 5.1 Dolby Digital source playing through DVD Player?

Posted on Sep 22, 2005 8:54 AM

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Answer 1

hyphen

Level 6

15,505 points

Sep 22, 2005 11:04 AM in response to viper0066

I guess because Apple would expect the 5.1 digital out to be handled by an av amplifier. Just speculation. Digital signals are usually modified at analogue level (after they have been converted).

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Answer 2

AJ

Level 5

7,075 points

Sep 22, 2005 11:06 AM in response to viper0066

I vaguely remember reading somewhere that the EQ functions are actually based on whatver you have set in iTunes *even if you are not using iTunes at the time*

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Answer 3

viper0066 Author

Level 5

5,257 points

Sep 24, 2005 2:05 PM in response to hyphen

A distinct possibility, but for headphone applications (some high-end headphone models are equipped with surround decoders, and I have one that is so-equipped), it seems strange to ever eliminate the EQ's application.

No-doubt, the audio would sound better off a good optical-equipped receiver or amp (with tis sound-coloring controls) than straight from the Mac (EQ or no EQ), but it would be nice to have the EQ flexibility without having to separately buy a receiver or amp just to add audio equalization to 5.1 signals coming through the Mac's optical out from DVD Player. The sound without equalization is SO flat.

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Answer 4

viper0066 Author

Level 5

5,257 points

Sep 24, 2005 2:09 PM in response to AJ

I will try some experimenting with the iTunes EQ, but right now, the iTunes EQ is set to push treble frequencies, and the 5.1 sound is SO flat coming from DVD Player, I wonder how much it could be applying the iTunes EQ setting.

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Answer 5

Sep 24, 2005 10:44 PM in response to viper0066

I think there are three possible reasons for this:

1. The DVD EQ is only a two channel EQ, so when you select the analog outputs.... you have two EQ channels.. one for the left, one for the right. The DVD player can output more than two audio channels so just two EQ channels aren't enough. This would explain why you can use the EQ in iTunes with the digital out... iTunes is always only two channels.

2. Adding EQ to the digital stream can also adversely affect the digital decoding process downstream as well. It's ALWAYS much better to EQ after the stream has been decoded into 5.1 or what ever flavor of digital stream in on the DVD. This is true for both digital and analog audio paths that are encoded.

3. In professional studio environments, when you connect two digital audio devices together, what comes out of one, goes into the other, rendering a perfect digital copy.. (or clone, if you like) The DVD player in this case is acting like a digital output device it's mission is to send to the next digital device via the digital outputs EXACTLY what is on the DVD, with no coloration at all. When you copy a file from your HD to a CD, you don't want anything to be changed in the process... you want the CD to be an EXACT digital duplicate of the file on the HD.

If the digital outputs sound 'flat' then its not the output that is making them so, but rather whatever you are listening to the output with.

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Answer 6

Cary Dean

Level 2

495 points

Sep 30, 2005 12:47 AM in response to viper0066

When the DVD Player is set to Digital out, it is sending the raw SPDIF data to the output device. It does not do any modification to the data at all (and shouldn't). This feature is designed to allow the use of the DVD Player for the video and your 5.1 surround system for the audio.

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Answer 7

viper0066 Author

Level 5

5,257 points

Oct 4, 2005 4:57 PM in response to Cary Dean

Understood, but there are models of surround headphones (and that's what I'm using with the optical output on the Mac), and the decoder on the headphone set has no equalization settings.

Allowing the use of equalization (if only for that much more audio-shaping flexibility), in the absence of an AV receiver or amp - such as with surround headsets - seems reasonable.

The headphones have their own 5.1 encoder, and it does show and you do hear the difference when it is sent a 5.1 signal from any source, including DVD Player. But, the only way they really sound good is with some audio equalization.

Please consider giving us that flexibility. It would be much more convenient to have the EQ-flexibility right of the Mac, even when coming from the optical output, for at-least headphone applications like mine.

Thank you.

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Answer 8

viper0066 Author

Level 5

5,257 points

Oct 4, 2005 9:41 PM in response to Jeffrey Lee

Referencing your last point, have you ever listened to DVD or CD audio through a receiver/amp with all audio equalization controls flat?

Try it. How's it sound? Now adjust the equalization to your liking. How's it sound now?

I disagree it's solely the output device that makes the sound flat - which seemed to be your suggestion. The sound is flat in any case off the players directly, until we put the signal through an amp through which we color the sound via the audio equalization, and then it sounds good to us.

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Answer 9

Oct 4, 2005 11:19 PM in response to viper0066

I think I understand your position, but surely you realize that your listening environment is most likely not anything at all the environment the CD or DVD was mixed in. I know at home, mine isn't.

I won't disagree about adding EQ.. I do it at home, but sparingly. And I use it with the understanding that I am overcoming the problems of my particular equipment profile and listening area, and not overcoming problems in the mix.

As you know, acoustics is a science, and professional studios spend a lot of time and money to make sure that their listening space is as accurate as possible. The bottom line is that the CD you're listening to now, if played back in the studio in which it was mixed, would sound as close to the original mix as possible, without any EQ.

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Answer 10

Cary Dean

Level 2

495 points

Oct 4, 2005 11:47 PM in response to viper0066

It is not possible to do what you are asking. The audio EQ is done after the audio is decoded. When the data is sent to a digital output device, it is sent as raw data. The digital device then decodes the data to whatever the number of channels it has paid the Dolby licensing for. After the data is decoded, then an Audio EQ can be applied, not before.

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Answer 11

viper0066 Author

Level 5

5,257 points

Oct 5, 2005 9:25 AM in response to Cary Dean

I certainly believe that most if not any AV receiver or amp with an optical output can have sound coloring controls (bass and treble) manipulated, and have such manipulation affect the sound outputted through the optical output - regardless of whether the receiver/amp even has a 5.1 encoder.

It is this case where sound equalization can affect the sound, before 5.1 encoding by my headset is executed. It is also this execution of sound coloring that would improve my experience coming off the Mac.

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Answer 12

viper0066 Author

Level 5

5,257 points

Oct 5, 2005 9:32 AM in response to Jeffrey Lee

Nevertheless, that underscores the point of having EQ flexibility within DVD Player for the optical output.

Even if it's only to compensate for equipment. BTW, of all the pro-level equipment I've ever seen (some in broadcast and other studios), I've never seen one where playback did not have sound coloring, and never seen anyone (that's anyone now) have good sound on any system without audio equalization.

Science, yes, but it's odd to me that the standard set by the producers/encoding engineers doesn't sound good (without sound coloring) on any system I've ever heard. That seems like a lot of misses - maybe.

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Answer 13

Cary Dean

Level 2

495 points

Oct 5, 2005 5:39 PM in response to viper0066

I guess I am not being clear. We are not allowed to change the digital data. We must pass SPDIF out exactly as we receive it. It's a licensing requirement.

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Answer 14

Oct 5, 2005 7:41 PM in response to viper0066

In my 20 + years of professional audio experience, I can think of not ONE device that played back any kind of audio AND had any type of EQ built in. None of the professional CD decks, none of the stand along CD Recorders, none of the professional Digital Audio Tape decks... none of the ISDN audio codecs.. and none of the digital routers..NONE of them had the ability to 'color' the sound.

I would love to know what device that you encountered that did.

As far as studios "coloring" the sound, most studios DO have some type of EQ in the audio chain before it hits the amps for the speakers. However, those EQ's are set based on a very technical analysis of the particular room and equipment. I can think of no studio that makes changes to that EQ at any time.

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Answer 15

viper0066 Author

Level 5

5,257 points

Oct 8, 2005 5:10 PM in response to Jeffrey Lee

SHOUTING at me (which all caps does denote) does not help your argument.

I never said any specific piece has EQ abilities in it, as I do not know or care how they specifically did it.

The fact is, every studio I can recall at this time did in-fact employ sound equalization, so that provided evidence that even at least some studios also employ sound coloring, and do not run the sound flat straight from the source.

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