Ask questions to Audio insider Sir Terrence

[JasonR]

Originally Posted by lgans316

Please excuse me if the below had already been asked or answered.

I would like to know if there will be any difference between lossless audio bitstreamed to AVR as-is vs lossless audio internally decoded and bitstreamed to AVR as LPCM by the PS3 ? I am sure there will be some kind of manipulations being enforced during the internal decoding but I would like to know if it will impact the overall sound quality ?

Sticky: https://forum.blu-ray.com/showthread.php?t=32961

[lgans316]

Thanks JasonR.

[JamesN]

Sir Terrence,
Could you please explain, in layman's terms, what DTS HD Channel Remapping is and how it works. I have read the high-level "white-paper" on the DTS web-site, but I don't fully understand it. Is it something that a sound engineer encodes into a specific mix, is it something implemented in hardware decoders, or a combination of both?

Thank you in advance.

[Sir Terrence]

Originally Posted by JamesN

Sir Terrence,
Could you please explain, in layman's terms, what DTS HD Channel Remapping is and how it works. I have read the high-level "white-paper" on the DTS web-site, but I don't fully understand it. Is it something that a sound engineer encodes into a specific mix, is it something implemented in hardware decoders, or a combination of both?

Thank you in advance.

Channel remapping allows a audio engineer to re-assign the placement of certain channel when the mix has more than 6 channels. For instance, if the original sources uses the traditional speaker layout, but the end user has their speakers in a slightly different position, remapping allows for that position difference while maintaining the imaging of the original source. If the source uses a 110 degree placement for the surrounds, and the end user 120 degrees, remapping will account for the difference of 10 degrees to maintain the imaging contained from the encoded source. Pretty handy feature.

[JamesN]

Thank you for the reply. Just a few more questions...

Originally Posted by Sir Terrence

Channel remapping allows a audio engineer to re-assign the placement of certain channel when the mix has more than 6 channels...

Does this mean that Channel Remapping cannot be applied to 5.1 mixes?

Originally Posted by Sir Terrence

...remapping allows for that position difference while maintaining the imaging of the original source...

So how does the decoder know what speaker configuration the end user has in order to compensate? I assume there is some manual configuration on the end user's part?

Finally, are there any content discs or decoder units (e.g. receivers) on the market today that make use of this technology?

Again, thank you for your time.

[Sir Terrence]

Originally Posted by JamesN

Thank you for the reply. Just a few more questions...


Does this mean that Channel Remapping cannot be applied to 5.1 mixes?

That is correct. The position of speakers is fixed in 5.1, remapping cannot be applied.

So how does the decoder know what speaker configuration the end user has in order to compensate? I assume there is some manual configuration on the end user's part?

That is correct. There are several different configuration to choose from, both from the encoding and decoding side.

Finally, are there any content discs or decoder units (e.g. receivers) on the market today that make use of this technology?

Again, thank you for your time.

I have kept track of this information from the recording side, but not from the receiver or decoder side. So the answer is I do not know.

[rrios28]

Sir T, I need your help hooking these two units, I have lost my mind and have solution. plz help me. Thx

[Ferris]

SirTerrence, LOVE the avatar! Were you in the Cavaliers? If so, when?

[Sir Terrence]

Originally Posted by rrios28

Sir T, I need your help hooking these two units, I have lost my mind and have solution. plz help me. Thx

This should be really easy. Use a HDMI cable to hook them up.

[Sir Terrence]

Originally Posted by FriedEggs

SirTerrence, LOVE the avatar! Were you in the Cavaliers? If so, when?

Hey thanks, another drum corps fan

I marched in the Cavaliers colorguard from 1979 to 1987

[Robert Siegel]

Sir T, please let me give you this scenario:

Warner has just released the blu-ray of Twister. On it is a Dolby True track running at between 1.7 and 2.9 mbps. Universal owns this movie overseas and is releasing their blu-ray with DTS MA sound, which many times has a bit rate over 4 mbps. Would the addition of 2-3 mbps and using DTS MA rather than Dolby True make any difference?

[savage1984]

Originally Posted by mntwister

Sir T, please let me give you this scenario:

Warner has just released the blu-ray of Twister. On it is a Dolby True track running at between 1.7 and 2.9 mbps. Universal owns this movie overseas and is releasing their blu-ray with DTS MA sound, which many times has a bit rate over 4 mbps. Would the addition of 2-3 mbps and using DTS MA rather than Dolby True make any difference?

I am interested in knowing the answer to this as well....

[WickyWoo]

No

They're both lossless

The DTS core track is 1.5mbps instead of 640, so that's almost 1mbps right there

TrueHD is a multipass system, while DTS HDMA is typically done in singles as I understand it, so THD will come out lower most of the time for those 2 reasons alone. Lossless is lossless.

[Slec]

Originally Posted by WickyWoo

No

They're both lossless

The DTS core track is 1.5mbps instead of 640, so that's almost 1mbps right there

TrueHD is a multipass system, while DTS HDMA is typically done in singles as I understand it, so THD will come out lower most of the time for those 2 reasons alone. Lossless is lossless.

Unless the source material was recorded at a higher bit rate, right? I remember reading something about many sound effects only being 16bit, so a 24 bit track won't do much to increase fidelity on those recordings. As always the answer is much deeper than bit rates numbers eh?

[WickyWoo]

Unless the source material was recorded at a higher bit rate, right? I remember reading something about many sound effects only being 16bit, so a 24 bit track won't do much to increase fidelity on those recordings. As always the answer is much deeper than bit rates numbers eh?

This is true, but it wouldn't affect a final encode, the sound remains the same, it'd just be 24 bit in the data stream but not in terms of quality. Just like you can ripa 128kbps MP3 to 96/24 WAV. Huge file, same sound. So as long as they kept to the 16bit source, that shouldn't be changing the file sizes any

[Sir Terrence]

Originally Posted by Slec

Unless the source material was recorded at a higher bit rate, right? I remember reading something about many sound effects only being 16bit, so a 24 bit track won't do much to increase fidelity on those recordings. As always the answer is much deeper than bit rates numbers eh?

It might not do much for sound effects as a direct source, but other aspects(music and dialog) should benefit from a much lower noise floor and a cleaner more clear sound. Sound effects are usually a compulation of compressed components anyway, so 16bits is enough to capture it without loss.

[savage1984]

thanks for the in depth answers

[MerrickG]

Sir Terrence,

I know this has been answered before in many places, but I am still confused on how to calculate how much disc space is saved using TrueHD vs. PCM vs. DTS-HD MA.

I am curious how much space a 5.1 24-bit/48Khz track would take up on PCM vs. the other two tracks.

Thanks.


If anyone else knows how to answer feel free to share. I suspect WickyWoo would know.

[dialog_gvf]

Originally Posted by merrick97

I know this has been answered before in many places, but I am still confused on how to calculate how much disc space is saved using TrueHD vs. PCM vs. DTS-HD MA.

This white paper, from Dolby, has comparisons for Dolby TrueHD v. LPCM

LPCM bits/sec = Samples per second * bit-depth * channels

e.g. 48,000 * 24 * 6 = 6,912,200

Gary

[MerrickG]

Originally Posted by dialog_gvf

This white paper, from Dolby, has comparisons for Dolby TrueHD v. LPCM

LPCM bits/sec = Samples per second * bit-depth * channels

e.g. 48,000 * 24 * 6 = 6,912,200

Gary

is that in bits or bytes?