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Author Topic: Volume Normalization  (Read 4298 times)

forbigd

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Volume Normalization
« on: December 23, 2015, 07:50:23 am »

Can someone here point me in the right direction for Volume Normalization?

Reading a previous post and researching what was said, I think I may be misusing the DSP and Volume mode.
I have a "jukebox" pc running MC with lots of music and music videos. Some of the music (and videos) are encoded with 5.1 sound.
I have the proper output device set in the Audio panel, the PC talks through an HDMI Video card to a decent receiver that can decode all types of signals.
Naturally with the different material, from older 128 mp3s, to 5.1 FLACS at 8200 kbps, and old wmv videos along with 5.1 Blu Ray rips, I have quite some time keeping the volume relatively the same. We spend way too much time racing for the volume knob when one title is way louder.
I have BitStream set to HDMI, the DSP has both Volume sections on and left at default settings.
From what I read, I should use Internal Volume Mode to get the best sound and have the dsp work, but then I see reference to the dsp not working if it is "passed through".

Does the DSP have any effect on files like 5.1 or DTS where the receiver sees the multichannel signal? Or is this a lightbulb moment where I understand the word "passthrough" :)    Is passthrough used for all multichannel files and the DSP ignores them? What if I leave it on Bitstream? Does that mean the Volume DSP doesn't work at all?
When I run an audio analyze on the 5.1 flacs, volume numbers for each channel are recorded. Are those used, or again, is it all thrown out the window if bitstreaming is on? I guess I don't understand the Volume normalization feature..

If bitstreaming being on removes the dsp, then there is nothing I can do to regulate the volume between DTS, MP3, FLACs, and MKVs (and everything else)?

Another machine runs the same files, but uses Optical connections. To get all the 5.1s to work, I turn on Dolby Digital out in the DSP and all the multichannel files play correctly. Am I negating the DSPs volume section with the DD turned on?

Thanks


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blgentry

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Re: Volume Normalization
« Reply #1 on: December 23, 2015, 08:41:24 am »

With bitstreaming enabled for specific audio types, those types will have NO DSP APPLIED.  That includes volume leveling.  If you turn off bitstreaming, MC will decode those multi-channel formats to PCM and pass them to your receiver, which should be able to handle multi-channel PCM with no issues.  In this case, MC *does* use it's DSP and thus can apply volume leveling.

Setting output format to Dolby Digital should be the last step in the DSP chain.  So in that case, volume leveling should get applied as expected.  Turning it on and off while a song is playing will definitely confirm that for you.  Though you may have to wait 15 seconds or so for the effect to kick in and out.

I hope that helps.

Brian.
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forbigd

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Re: Volume Normalization
« Reply #2 on: December 24, 2015, 05:44:42 am »

Brian:  (Great name, my first son is Brian! :))
You have helped a great deal. I have been using MC for years and never understood Bitstreaming. I am not sure I even do now.
I thought Bitstreaming meant a kind of passthrough, and it needed to be enabled to get multichannel audio. Wrong! It matters not whether it is enabled or not, I still get multichannel output. So what IS bitstreaming? I googled it and most say it means the bits are all in a stream one after another. Isn't that what all audio is? Bits created by the player and rendered by the receiver?
I tried turning it off and back on during playback and I think I can tell that volume normalization works only with bitstreaming off. True?
If so, I have been working hard to get my volumes right, with no chance of the DSP even working. :o

Which volume mode do I use to make sure the full DSP Volume Normalization is used?  Internal? Application?

Thanks!!

Don
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blgentry

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Re: Volume Normalization
« Reply #3 on: December 24, 2015, 09:58:34 am »

So what IS bitstreaming?

Audio in movie files is usually Dolby Digital or DTS.  Those are lossy compressed multi-channel formats.  Sort of like an MP3, but a little different.  So some processor has to decode the DD or DTS audio into uncompressed PCM which can then be played.  With a DVD or BD player, the receiver almost always receives the audio data and decodes it.  The DVD/BD player "bitstreams" the audio data to the receiver.  The DVD/BD player never touches the data.  It just sends it on and lets the receiver handle it.

When playing video files with MC, you have choices.  If you select "bitstream DD/DTS", then it works just like a DVD/BD player.  It sends the audio data and the receiver handles it.  Because MC is just passing it along (bitstreaming), MC never has the opportunity to apply any DSP functions.  So it can't do volume normalization because it doesn't process the audio data at all.  It just bitstreams it.

If you turn bitstreaming OFF, then MC can use all of it's DSP functions on the audio data.  What happens is, MC sees the Dolby Digital or DTS audio, and DECODES it, into PCM; just like your receiver normally would.  Then MC can apply Volume Leveling, equalization, etc with it's DSP.  Finally, once it's processed the audio, it sends the PCM multi-channel data down the HDMI cable to the receiver.  The receiver now has one less thing to do, because it doesn't have to decode the DD or DTS.  MC already did that.  So the receiver now plays the PCM audio directly.

Quote
I tried turning it off and back on during playback and I think I can tell that volume normalization works only with bitstreaming off. True?

True!  I hope my explanation above makes it clear why that's true.

Quote
Which volume mode do I use to make sure the full DSP Volume Normalization is used?  Internal? Application?

Volume Normalization and the DSP in general don't really depend much on the Volume Mode.  Internal Volume is the safest bet in my opinion, as long as you aren't also feeding audio from other programs directly to the computer.  As long as you are only using MC for audio, I would choose Internal Volume.

Brian.
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forbigd

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Re: Volume Normalization
« Reply #4 on: December 24, 2015, 10:46:54 am »

Thanks so much!
I have always equated Bitstream as enabling DTS or other multichannel, like you needed to "bitstream" anything over stereo.
The receiver now says it is receiving PCM. It is still multichannel and sounds great. I am resampling my collection (Analyze Audio) in anticipation of much better control over differing volume levels. Very exciting!
I also thought it made a difference in Normalization if you picked Application or Internal Volume. I have read the wiki on it and understand what works best, but falsely again I thought Internal Volume meant no MC processes.
Internal will work much better for all of our machines.

Can I ask one more?
I understand Volume Protection (cool)
And Maximum and Starting Volume, but can you tell me how "Internal Volume Reference Level" works?

Thanks!

Don
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blgentry

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Re: Volume Normalization
« Reply #5 on: December 24, 2015, 11:11:43 am »

Volume Reference Level is used for two things:

1.  Playing back movies at a specific average level.  Movies are designed (in theory) to be heard at a specific volume level.  Setting reference lets you set your volume to "zero" and know that the average level should be the proper level that the movie was designed for.  In theory.  More information:

https://wiki.jriver.com/index.php/Volume#Reference_Level_Calibration

2.  Loudness compensation.  This is similar to the loudness feature found on most receivers.  It boosts the low frequencies and the high frequencies at low volume levels.  This is designed to compensate for the fact that human hearing is less sensitive to highs and lows at low volume levels.  MC's implementation is volume dependent.  It uses the volume reference level to determine how much loudness compensation to apply.  Loudness can be turned on and off in the audio setup section.  It is OFF by default.

https://wiki.jriver.com/index.php/Volume#Loudness

Brian.
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ferday

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Re: Volume Normalization
« Reply #6 on: December 24, 2015, 11:22:21 am »

Just to add; reference is not just for loudness features. Room EQ/correction should be done at reference as well

If you and your friend watch the same movie in your likely very different rooms, it should sound nearly identical (making some general assumptions but you get the idea).  Audessy and other auto-EQ features also use reference although audessy uses 75dB as the target

Plus it's handy to know that if you subtract 20dB in MC volume and you've calibrated reference, you will in fact receive an average of 63dB with the highest peak possible of 83dB (+10 for the LFE channel)
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mattkhan

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Re: Re: Volume Normalization
« Reply #7 on: December 24, 2015, 11:25:25 am »

Just to add; reference is not just for loudness features. Room EQ/correction should be done at reference as well

Eq/room correction and reference are two different things. You can measure your system at any level you like (or any level at which your system is within operating range) then calibrate to reference after.
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