Trying to understand AUDIO RESOLUTION and how it relates to our disc players

[MDS]

If this is correct, it seems, all other elements being equal, that listening to DVD-video's via the 5.1 ch output would produce relatively higher quality sound, even if on paper.

That is a big 'IF' and one that people have differing opinions about. It comes down to whether the receiver or dvd player has the better DACS. IMO, it is next to impossible to tell the difference between any of the quality dacs, whether they be Burr-Brown, Cirrus, Wolfson, etc.

But the answer to the question 'what does the coax digital output offer that the 5.1 outputs do not' gives some more insight into why digital connections are preferred in general [let's assume the dacs in the player and receiver are identical sounding]:

- Most players do not perform adequate bass management (fixed xover, no delay settings, etc). This is slowly changing and the Denon 3930CI is a relatively 'high end' player that could be the exception to the rule.
- Letting the receiver do the decoding affords you the ability to use bass management, other DSP processing if you so choose (like applying PLII on top of DTS if you wanted to try that), dynamic compression (late night mode), cine filter, etc.

Plus, it's simpler - one cable.

 

[timetohunt]

Right, I would always use 5.1 ch when playing DVDA/SACD, but what I'm wondering is, what does the coax digital audio provide that the 5.1 ch 'direct' does not? I may be able to just remove that coax digital cable. I know one difference would be processing would occur in the AVR vs the player. But the 3930CI has excellent bass management. Just wondering what is keeping that extra noodle in my bowl of spaghetti!

Like you, I would also use 5.1 ch to see how it sounded with DVDA/SACD when offered. But is it not the 2 channel hi-res of those formats that we really want (at times). And again I ask the question, can we get the hi-res 2 channel through the optical or coax connections?

 

[MDS]

And again I ask the question, can we get the hi-res 2 channel through the optical or coax connections?

No, the bandwidth required for 24/192 bitstreams exceeds the limit for the s/pdif specification.

 

[MACCA350]

For example, in my 3930CI player, I've chosen the "digital output" setting as "normal", which is bitstream. In this setting, DVD-video's with Dolby Digital or DTS are output as Dolby Digital bitstream or DTS bitstream. Bitstream are signals that have been compressed and converted to digital.

Just wanted to clarify something here.

Ronnie, the 'Bitstream' is the RAW audio stream in its original form as read off the disc, ie the RAW Dolby Digital or DTS bitsream. With the player set to Bitstream/Normal the data is read off the disc and passed over the digital connection straight to the receiver without any conversion(its as if the receiver is reading the disc directly)

cheers

 

[mr-ben]

No, the bandwidth required for 24/192 bitstreams exceeds the limit for the s/pdif specification.

My understanding of the limits of S/PDIF is that it's based on the capabilities of the devides connected together. In other words, if both devices can handle two channel 24/192, then it will work. The catch is that few devices support this, and the copywrite police may forbid it. If anyone has a link to the actual spec, I'd be interested to read it.

This isn't really critical anyway, since few DVD-Audio discs contain 24/192 audio. Mine top out at 24/96. My receiver can handle up to 24/96, but I use analog connections because of the quality difference in the DACs, and I usually listen to SACD, which I don't really want to be converted to PCM.

timetohunt - it's easy to decide for yourself how to connect your player and receiver. You can't use HDMI, so attach a pair of analog cables and a digital cable, and play something. Switch between them while listening. Whichever sounds best is the one to choose.

 

[tbewick]

My understanding of the limits of S/PDIF is that it's based on the capabilities of the devides connected together. In other words, if both devices can handle two channel 24/192, then it will work. The catch is that few devices support this, and the copywrite police may forbid it. If anyone has a link to the actual spec, I'd be interested to read it.

This isn't really critical anyway, since few DVD-Audio discs contain 24/192 audio. Mine top out at 24/96. My receiver can handle up to 24/96, but I use analog connections because of the quality difference in the DACs, and I usually listen to SACD, which I don't really want to be converted to PCM.

timetohunt - it's easy to decide for yourself how to connect your player and receiver. You can't use HDMI, so attach a pair of analog cables and a digital cable, and play something. Switch between them while listening. Whichever sounds best is the one to choose.

http://www.ebu.ch/CMSimages/en/tec_doc_t3250-2004_tcm6-12767.pdf
SPECIFICATION OF THE DIGITAL AUDIO INTERFACE. (The AES/EBU interface). Tech. 3250-E - Third edition. 2004. EBU.

This is for the professional version but the data is very similar and the physical difference, if I remember correctly, is 110 ohm balanced versus 75 ohm unbalanced.

It might be worth mentioning that getting true 24 bit performance through the S/P-DIF interface would probably be unlikely in practice because of jitter. There probably aren't even any DAC's that get this noisefloor (around -145 dB) regardless.

 

[ronnie 1.8]

Just wanted to clarify something here.

Ronnie, the 'Bitstream' is the RAW audio stream in its original form as read off the disc, ie the RAW Dolby Digital or DTS bitsream. With the player set to Bitstream/Normal the data is read off the disc and passed over the digital connection straight to the receiver without any conversion(its as if the receiver is reading the disc directly)

cheers

Thank you, Macca. So bitstream is raw, uncompressed, straight from the disc, and not compressed. Good ole' Denon manual does it again.

 

[ronnie 1.8]

This isn't really critical anyway, since few DVD-Audio discs contain 24/192 audio. Mine top out at 24/96. My receiver can handle up to 24/96, but I use analog connections because of the quality difference in the DACs, and I usually listen to SACD, which I don't really want to be converted to PCM.

http://www.aixrecords.com/ is an incredible high-res audio experience, and I believe their stereo recordings are 96kHZ/24bit.

 

[MDS]

So bitstream is raw, uncompressed, straight from the disc, and not compressed.

If it is PCM it is uncompressed; if it is DD/DTS it is compressed.

Bitstream quite literally means 'stream of bits'. S/PDIF is a serial communication protocol, which means the bits are sent one after the other. When you set the player to bitstream it means the player should just read the bits of the disc and send ('stream') them to the receiver. The player will not try to interpret the data - it just sends the data to its destination.

All of the compressed formats, even MP3, are actually PCM - just not raw PCM. The bits have been encoded into a slightly different format.

As a simple example to help visualize the difference, consider the super simple compression scheme known as run length encoding (not used for audio). RLE replaces duplicate data with a count of how many times a character occurs:

- Say the data to send is AABBBCCCC. The 'raw' uncompressed data is AABBBCCCC which is 9 bytes of data if we assume each character takes 8 bits to represent. This would be analogous to raw PCM (like a CD).
- RLE encoded the data would be 2A3B4C which is only 6 bytes of data. So the original data has been 'compressed'. This would be (loosely) analogous to DD/DTS.

If the disc contained the raw characters, it would send AABBBCCCC to the receiver. If it contained the rle compressed version, it would send 2A3B4C. It doesn't try to identify the data as rle encoded - it just sends what it read to the receiver and the receiver has the job of identifying the format and decoding it properly.

 

[ronnie 1.8]

If it is PCM it is uncompressed; if it is DD/DTS it is compressed.

Bitstream quite literally means 'stream of bits'. S/PDIF is a serial communication protocol, which means the bits are sent one after the other. When you set the player to bitstream it means the player should just read the bits of the disc and send ('stream') them to the receiver. The player will not try to interpret the data - it just sends the data to its destination.

All of the compressed formats, even MP3, are actually PCM - just not raw PCM. The bits have been encoded into a slightly different format.

As a simple example to help visualize the difference, consider the super simple compression scheme known as run length encoding (not used for audio). RLE replaces duplicate data with a count of how many times a character occurs:

- Say the data to send is AABBBCCCC. The 'raw' uncompressed data is AABBBCCCC which is 9 bytes of data if we assume each character takes 8 bits to represent. This would be analogous to raw PCM (like a CD).
- RLE encoded the data would be 2A3B4C which is only 6 bytes of data. So the original data has been 'compressed'. This would be (loosely) analogous to DD/DTS.

If the disc contained the raw characters, it would send AABBBCCCC to the receiver. If it contained the rle compressed version, it would send 2A3B4C. It doesn't try to identify the data as rle encoded - it just sends what it read to the receiver and the receiver has the job of identifying the format and decoding it properly.

Thanks for taking the time to explain this, MDS. It is most helpful. Are you able to put a "flow chart" of sorts into words, tracking a Dolby Digital 5.1 signal from a disc as it reaches my speakers, via S/PDIF and then again via my player's 5.1 outs? I understand that via S/PDIF, the DD bitstream is passed to my AVR, where it's DACs convert to analogue (not sure exactly how this works, though). Then via 5.1 outs, is the exact same thing happening, except with different DACs? BTW, I listened to chapter 2 of Saving Private Ryan (lots of surround activity), and did not hear an obvious difference w/ S/PDIF vs 5.1 out. I may even have preferred S/PDIF. Bass management of my 3930CI has all settings my AVR2805 has.

 

[Seth=L]

Thanks for taking the time to explain this, MDS. It is most helpful. Are you able to put a "flow chart" of sorts into words, tracking a Dolby Digital 5.1 signal from a disc as it reaches my speakers, via S/PDIF and then again via my player's 5.1 outs? I understand that via S/PDIF, the DD bitstream is passed to my AVR, where it's DACs convert to analogue (not sure exactly how this works, though). Then via 5.1 outs, is the exact same thing happening, except with different DACs? BTW, I listened to chapter 2 of Saving Private Ryan (lots of surround activity), and did not hear an obvious difference w/ S/PDIF vs 5.1 out. I may even have preferred S/PDIF. Bass management of my 3930CI has all settings my AVR2805 has.

Basically you have it.

If I am not mistaken Dolby Digital and/or DTS is processed and then converted to analog. Receivers and AV processors work like computers with RISC (Reduced Instruction Set Computer). Your PC is CISC (Complex Instruction Set Computer) and the processor can do many different types of operations. In a receiver or AV processor, it has a set of instructions that it can do with it's hardware, it cannot be altered and his limited funtionality. This was the case untill more recently, now firmware upgrades can change the functions slightly to add different features.

So the signal (raw bitstream) comes into the processor of the receiver or AV processor and is decoded with minimal error. Then from there it is converted by the DACs of the receiver or AV processor for amplification.

 

[mr-ben]

I'll give this a shot. Here are some examples, as best as I can do. There are probably infinitely more if anyone wants something else. Please point out any mistakes:

DTS movie, s/pdif link to receiver, raw output from player:
Disc[DTS compressed]->Laser->Output over cable->Into receiver->DTS decode to 6 channel PCM->Bass management/effects->Analog conversion->power amp->speakers.

DTS movie, s/pdif link to receiver, PCM output from player:
Disc[DTS compressed]->Laser->DTS decode to 6 channel PCM->Output over cable->Into receiver->Bass management/effects->Analog conversion->power amp->speakers.

Regular CD, s/pdif link to receiver:
Disc[PCM uncompressed]->Laser->Output over cable->Into receiver->Bass management/effects->Analog conversion->power amp->speakers.

DVDAudio, 2-channel analog link to receiver (that re-digitizes everything):
Disc[MLP compressed]->Laser->MLP Decompression to PCM->Analog conversion->Output over cable->Into receiver->Digital conversion to PCM->Bass management/effects/bleh->Analog conversion->power amp->speakers.

DVDAudio, 6-channel analog link to receiver (that does not re-digitize), no bass management:
Disc[MLP compressed]->Laser->MLP Decompression to PCM->Analog conversion->Output over cables->Into receiver->power amp->speakers.

SACD, HDMI 1.2 digital link to receiver, DSD output, no bass management:
Disc[DST compressed]->Laser->Decompress to DSD->Output over cable->Into receiver->Analog conversion->power amp->speakers.

SACD, HDMI 1.1 digital link to receiver, PCM output:
Disc[DST compressed]->Laser->Decompress to DSD->DSD conversion to PCM->Output over cable->Into receiver->Analog conversion->power amp->speakers.

SACD, HDMI 1.1 digital link to receiver, PCM output, bass management in receiver:
Disc[DST compressed]->Laser->Decompress to DSD->DSD conversion to PCM->Output over cable->Into receiver->Bass management->Analog conversion->power amp->speakers.

SACD, 6-channel Analog link, DSD-native bass management in player:
Disc[DST compressed]->Laser->Decompress to DSD->Bass management->Analog conversion->Output over cable->Into receiver->power amp->speakers.

SACD, 6-channel Analog link, PCM-native bass management in player:
Disc[DST compressed]->Laser->Decompress to DSD->Convert to PCM->Bass management->Analog conversion->Output over cable->Into receiver->power amp->speakers.

Any of the points that are in PCM form can be anywhere from 12/44k up to 24/192k, depending on the source and/or the converters in the components.

 

[MDS]

Any of the points that are in PCM form can be anywhere from 12/44k up to 24/192k, depending on the source and/or the converters in the components.

The flowchart looks accurate to me, but the above quote isn't quite true. The most that s/pdif can do is 16bit/48 kHz. S/PDIF is based on aes/ebu and the data format allows 20 bits for each sample with the remaining 4 bits being used for control information. S/PDIF doesn't use those 4 bits so it theoretically could allow up to 20/48 kHz.

DTS 96/24 can be transported over s/pdif and would seem to violate the bandwidth limitation but it is a compressed format and the bandwidth required is much less than a raw 24/96 bitstream would require.

 

[mr-ben]

The flowchart looks accurate to me, but the above quote isn't quite true. The most that s/pdif can do is 16bit/48 kHz. S/PDIF is based on aes/ebu and the data format allows 20 bits for each sample with the remaining 4 bits being used for control information. S/PDIF doesn't use those 4 bits so it theoretically could allow up to 20/48 kHz.

DTS 96/24 can be transported over s/pdif and would seem to violate the bandwidth limitation but it is a compressed format and the bandwidth required is much less than a raw 24/96 bitstream would require.

I think we partially agree. I was mainly thinking of the analog->digital->analog that is internal to the receiver, which can be a full 24/192k. You're right in that DTS 24/96 is not transmitted in PCM form. It's transmitted in compressed form (kinda like streamed MP3) and uses the same bandwith as regular DTS when transmitted as a raw bitstream. I think the DTS 24/96 is a big sham anyway - it's like eating a fancy steak dinner that was dehydrated and rehydrated - it's just not the same. My receiver documentation does say that it can accept 2-channel 24/96 PCM over s/pdif though. I'll refer to this document again, page 3: http://usa.denon.com/avr3300_technotes.pdf The AVR-5800 appears to support 2-channel 24/192k over s/pdif http://usa.denon.com/AVR5800_productsheet.pdf

This may be just because 2-channel 24/96k uses less bandwith than 6-channel 16/48k. You're probably correct about the limit for 6 channels.

 

[MACCA350]

In relation to the SPDIF output of High Resolution audio I played around with some DVD-Audio I have

Elvis: Playing the PPCM 5.1 track(I believe this is an unprotected DVD-Audio)
SPDIF output:
“LPCM (44.1 kHz/ 48 kHz)” set to OFF: receiver shows STEREO PCM 96khz and audio is heard
“LPCM (44.1 kHz/ 48 kHz)” set to ON: receiver shows STEREO PCM 48khz and audio is heard

Analogue output:
Full 5.1 audio is heard

All other DVD-Audio's: Playing the PPCM 5.1 track(I believe all other DVD-Audio's I have are protected)
SPDIF output:
“LPCM (44.1 kHz/ 48 kHz)” set to OFF: receiver shows ANALOG and NO audio is heard
“LPCM (44.1 kHz/ 48 kHz)” set to ON: receiver shows STEREO PCM 48khz and audio is heard

Analogue output:
Full 5.1 audio is heard

I don't think I have any 2channel 24bit/192khz High resolution unprotected DVD-Audio tracks so I can't test this resolution, but as seen below I think my player will convert 192kHz to 96kHz and 176.2kHz to 88.2kHz for output over SPDIF.

Found this on Page 33 of the Denon DVD-2200 manual

When “LPCM (44.1 kHz/ 48 kHz)” is selected:
OFF (Factory default)
When playing linear PCM or packed PCM DVDs that are not copyrightprotected,
for 2-channel PCM audio signals up to 96 kHz, linear PCM
signals are output as such without being converted from the digital
outputs. (176.2 kHz and 192 kHz signals are converted to 88.2 kHz and
96 kHz, respectively.)
For DVDs containing multi-channel PCM signals, the digital signals are
down-mixed for output into two channels, front left and right. (Only the
front left and right channels are output for sources for which downmixing
is prohibited.)
When playing copyright-protected linear PCM or packed PCM DVDs, in
consideration of copyrights, no digital signals are output for sources
exceeding 48 kHz/16 bits. When playing such sources, either set to
“ON” or make analog connections. (See page 14.)

ON
Linear PCM and packed PCM signals are converted to 44.1 kHz or 48
kHz and output. (The PCM digital audio output signals are converted to
48 kHz or less in consideration of copyrights.) When making digital
connections to an AV amplifier that is not compatible with 96 kHz/88.2
kHz signals, set to “ON”.

Interesting subject
cheers

 

[MACCA350]

I think we partially agree. I was mainly thinking of the analog->digital->analog that is internal to the receiver, which can be a full 24/192k. You're right in that DTS 24/96 is not transmitted in PCM form. It's transmitted in compressed form (kinda like streamed MP3) and uses the same bandwith as regular DTS when transmitted as a raw bitstream. I think the DTS 24/96 is a big sham anyway - it's like eating a fancy steak dinner that was dehydrated and rehydrated - it's just not the same. My receiver documentation does say that it can accept 2-channel 24/96 PCM over s/pdif though. I'll refer to this document again, page 3: http://usa.denon.com/avr3300_technotes.pdf The AVR-5800 appears to support 2-channel 24/192k over s/pdif http://usa.denon.com/AVR5800_productsheet.pdf

This may be just because 2-channel 24/96k uses less bandwith than 6-channel 16/48k. You're probably correct about the limit for 6 channels.

Were you refering to this:

2. Digital Interface Receiver Supporting 24 bit, 192 kHz Signals.
The AVR-5800 includes a Digital Interface Receiver (DIR) that distinguishes various types of digital input signals, including 24/192 and 24/96 stereo PCM signals, performs the appropriate signal processing, and transmits the information to the DSP block.

If so, I think this is just referring to the internal circuitry and all they are saying is this DIR can read what type of signal is input and perform the right processing for that signal and then hand it off to the DSP section of the receiver(basically it automatically detects what is input(upto 24/192) and automatically chooses the right processing) . I don't see that this means that it can have 24bit/192khz PCM input over SPDIF(I also read through the 5800 manual and found nothing to support this).

I also found on page 14 of Denons highest player DVD-5910CI's manual, that it will only output up to 24bit/96khz, and I think that refers to any of its Digital connections(SPDIF, IEEE1394, HDMI(not sure what version), Denon Link S.E). I think this is limited by the internal processing even for unprotected discs. I'd love to hear of any user reports on this

cheers

 

[ronnie 1.8]

I've been gone all day, and looking forward to reading/studying these posts tomorrow morning. Thanks for your comments, and cheers...

 

[mr-ben]

I don't see that this means that it can have 24bit/192khz PCM input over SPDIF(I also read through the 5800 manual and found nothing to support this).

Hmm... perhaps I'm reading it wrong. I'll just post the text here.

The AVR-5800 includes a Digital Interface Receiver (DIR) that distinguishes various
types of digital input signals, including 24/192 and 24/96 stereo PCM signals, performs
the appropriate signal processing, and transmits the information to the DSP block.

The only digital inputs on the 5800 are the standard coax and optical inputs (pre-denon link days), so I read that to mean it accepts 24/192 over s/pdif (there's some dolby digital RF input too, but I have no clue what that is). Also, the 5800 document also says that the analog->digital converters are 24/96, while the digital->analog converters support 24/192, so I'm not sure why they would need the 24/192 DACs, unless it just looks good on paper.

My DVD player indicates that it sends 24/192 over the denon link, but converts to 24/96 for the regular digital output. Your link to the 5910 manual also says this on page 17. So I guess that unless someone out there can say that they have sent 24/192 over s/pdif, I'll accept that 2-channel 24/96k is the limit.

Denon link is nice for those who can use it, but I think HDMI will be the swift replacement for s/pdif. HDMI since 1.0 can carry 8-channel/192kHz/24-bit audio (PCM I think), while 1.2 can handle both DVD-Audio and SACD natively.

 

[mr-ben]

I would certainly hope there is a difference between the two. The receiver is about 7 years old and the player is new (as a note, its retail is near double what the receiver was)

Although the receiver is old, I'm still happy with it. I actually have another SACD player, made by Sony. I purchased it in 2002, so it's a few years newer than the receiver. The DACs in the sony for regular CDs are not so good. That one was attached to the receiver over both digital and analog (analog for SACD, digital for everything else). One day my wife was listening to a CD and I saw the receiver was on analog, so I hit the button to change to digital. She didn't know what I did, but said something like "That sounds much better. What did you do?". So even though the Sony was newer, the receiver's DACs were that much better. The gap in quality between the old player and the receiver was much more than the receiver and the new player.

Receiver DACs: Analog Devices AD-1855
Denon player DACs: Burr-Brown PCM-1796
Sony player DACs: ???? (probably made by Sony)

Do DACs really continue to improve?

 

[MACCA350]

Hmm... perhaps I'm reading it wrong. I'll just post the text here.

The only digital inputs on the 5800 are the standard coax and optical inputs (pre-denon link days), so I read that to mean it accepts 24/192 over s/pdif (there's some dolby digital RF input too, but I have no clue what that is). Also, the 5800 document also says that the analog->digital converters are 24/96, while the digital->analog converters support 24/192, so I'm not sure why they would need the 24/192 DACs, unless it just looks good on paper.

Maybe it can, but its not specific enough for me

My DVD player indicates that it sends 24/192 over the denon link, but converts to 24/96 for the regular digital output. Your link to the 5910 manual also says this on page 17. So I guess that unless someone out there can say that they have sent 24/192 over s/pdif, I'll accept that 2-channel 24/96k is the limit.

It seems there is a conflict in the manuals on the one hand in the Denonlink section they say "Digital transfer is possible up to 24bit/2ch for 192/176.4kHz, 24bit/6ch for 96kHz or less"

then they show these tables for what the player will output for the specific formats:
3930CI

5910

My opinion is that the Denonlink section is basically saying that their link can handle up to 24/192 BUT the actual output will be as stipulated on those tables. At least thats how I read it..

The only way to find out for sure is to have someone create an unprotected 2hannel 24/192 recording on DVD-AUDIO and test it out(unless there is a commercial option available)

Denon link is nice for those who can use it, but I think HDMI will be the swift replacement for s/pdif. HDMI since 1.0 can carry 8-channel/192kHz/24-bit audio (PCM I think), while 1.2 can handle both DVD-Audio and SACD natively.

All versions of HDMI can support up to 8-channel/192kHz/24. HDMI 1.1 Supports DVD-Audio, HDMI 1.2 adds support for SACD, more info here.

I totally agree with your thoughts on HDMI becoming the defacto digital connection, and this is a good thing....one 'connection' to rule them all

cheers