Digital Audio Jitter explained in simple terms

jkeny

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Feb 10, 2012
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Amir,
You are welcome to try my USB to SPDIF device & comparing it to my USB DAC which I just posted about sending on tour around WBF members http://www.whatsbestforum.com/showt...hearing-my-DAC&p=119833&viewfull=1#post119833

Indeed, Tim (or any other active member) is welcome to try this out. I will leave it up to yourselves to decide if what you hear is the result of lower jitter or something else!

If anyone has the equipment to measure jitter I have no objection to this.
 

mmg

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Dec 25, 2013
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I was looking for information on jitter when I found your article. It's very interesting and clearly explains what jitter is and how it can (or can't) be solved.

I was wondering, when you guys talk about the SPDIF interface, do you prefer the coaxial or the optical connection?
 

NorthStar

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Digital Audio Jitter Reduction | HDMI Audio Interface

I was searching about "Jitter Reduction" from the HDMI audio signal transfer, and I ended up here in this thread, which is over three years old.
Please forgive me, I need to learn something in all relaxing mode, like @ home.

First, the previous graphs of this thread aren't showing. And same for couple links. I just don't know why. Eg.;
• Post #1 → http://www.whatsbestforum.com/showt...-in-simple-terms&p=84556&viewfull=1#post84556 (The link is dead)
• Post #9 → http://www.whatsbestforum.com/showt...-in-simple-terms&p=84916&viewfull=1#post84916 (The link is dead and the two graphs aren't showing)
• Post #12 → http://www.whatsbestforum.com/showt...-in-simple-terms&p=85069&viewfull=1#post85069 (The graph is not showing)
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Now my question:
There's a new BR player coming up with jitter reduction from its HDMI output.
To take full advantage from it do I need a pre/amp with also a jitter reduction HDMI input?

I'll keep it simple for now, and go from there.
 
Last edited:

pkane

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Jan 6, 2017
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There's a new BR player coming up with jitter reduction from its HDMI output.
To take full advantage from it do I need a pre/amp with also a jitter reduction HDMI input?

Not sure about the jitter reducing BR player. I assume it de-jitters the digital audio before it's sent over HDMI video/audio output, so you just need a DAC, receiver, or pre-amp that takes the video/audio HDMI as input. Note that this is not the same as an HDMI I2S input you might find on some DACs: this will not work with your BR player and may even fry things if you try to plug it in!

Personally, I would split off the digital audio signal from the BR player HDMI output and then feed it over SPDIF into a nice jitter reduction device (such as Mutec 3+) and then into a DAC/digital pre-amp. Look for HDMI audio extractor devices, these are fairly common.
 

NorthStar

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Not sure about the jitter reducing BR player. I assume it de-jitters the digital audio before it's sent over HDMI video/audio output, so you just need a DAC, receiver, or pre-amp that takes the video/audio HDMI as input. Note that this is not the same as an HDMI I2S input you might find on some DACs: this will not work with your BR player and may even fry things if you try to plug it in!

Personally, I would split off the digital audio signal from the BR player HDMI output and then feed it over SPDIF into a nice jitter reduction device (such as Mutec 3+) and then into a DAC/digital pre-amp. Look for HDMI audio extractor devices, these are fairly common.

Thanks Paul for the reply.

The digital HDMI audio jitter reduction as implemented in the Oppo 205 4K BR player is only from its HDMI 2 output (Audio only).
http://www.oppodigital.com/KnowledgeBase.aspx?KBID=129&ProdID=UDP-205

The receiver's end (or pre/pro, or DAC) would only receive the audio from its HDMI input. All video circuitry would be turn off.
For top video performance the Oppo 205's HDMI 1 output would be directly connected to the display's HDMI input (4K TV or 4K front projector).
The Oppo UDP-205 has two HDMI outputs; the first one for video/audio, and the second one for audio only, and only that second one has the jitter reduction feature).

That HDMI 2 audio only output is good for stereo music and also for multichannel hi-res from Blu-ray movies (Dolby Atmos, DTS:X 7.1.4-channel).
Digital SPDIF is no go for five, seven, nine, eleven channels of high resolution audio. It has to be through the HDMI connection. SPDFI doesn't have enough bandwidth for all the multiple channels in all their full hi-res audio. And only the 2nd HDMI out of the 205 has the audio jitter reduction.

Now that you are up-to-date with my specific question; I know that some pre/pros and AV receivers have audio jitter reduction in their circuitry, or from the asynchronous USB port or from the HDMI inputs.

Example: http://www.homecinemachoice.com/news/article/pioneer-sc-lx85-review/10421

"To further improve audio performance over HDMI, the receiver offers PQLS jitter reduction for all sources (multichannel, bitstream and LPCM). This requires a matching PQLS-enabled Blu-ray player in order to eliminate timing errors. Unfortunately, Pioneer just doesn’t have a BD deck of the calibre of this receiver in its current range (and I wouldn’t bet on one arriving, either); consequently I suspect enthusiasts will be partnering the thing with other branded models, and so this embellishment will go unappreciated. I auditioned it with Pioneer’s PQLS-friendly BDP-LX54 Blu-ray player, before replacing it with the superior Cambridge Audio Azur 751BD."

So my question was: Would it be best, to take full advantage of the HDMI jitter reduction of the Oppo 205, to mate it with another component like that Pioneer AV receiver from above?

There are few more AV receivers and pre/pro with similar HDMI audio jitter reduction, but many don't have it.
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http://www.oppodigital.com/blu-ray-udp-205/blu-ray-udp-205-Overview.aspx

HDMI Audio Jitter Reduction
"The UDP-205 features a high-stability, high-precision HDMI clock and a special HDMI audio jitter reduction circuit. This unique design significantly reduces jitter and eliminates timing errors, allowing you to enjoy your music with increased accuracy when you use the audio-only HDMI output port for connecting the audio signal. PCM and DSD signals rely on the HDMI clock directly, so the HDMI audio jitter reduction circuitry (HDMI Out - Audio Only) can improve the sound quality of PCM and DSD audio. For compressed bitstream audio, it helps to ensure error-free transmission, and may improve the audio performance depending on whether the audio decoder in the A/V processor or receiver uses a synchronous or asynchronous clock scheme."


 

pkane

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Jan 6, 2017
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You're right. 5.1 or 7.1 will not work lossless over SPDIF.

From what I understand in the OPPO description, the audio HDMI signal is transmitted with a 'blank' video signal that carries a very high quality (low jitter) video clock. This means that any existing or future receiver/DAC capable of decoding HDMI audio+video feed will be able to decode this audio signal. And since most HDMI audio converters derive their audio clock from the video clock at the HDMI input, you should benefit with nearly all receivers. For this, you don't need some special decoder, like would be required for PQLS method that transmits the audio clock over CEC channel.

One caution: if the video/audio clock extraction circuit in the receiver is poorly designed, it may introduce more jitter reducing or negating the effect of the high quality clock at the input. A well-designed receiver will give best results, but it doesn't have to have any special signal handling, like what's required by the PQLS method.
 

NorthStar

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You're right. 5.1 or 7.1 will not work lossless over SPDIF.

From what I understand in the OPPO description, the audio HDMI signal is transmitted with a 'blank' video signal that carries a very high quality (low jitter) video clock. This means that any existing or future receiver/DAC capable of decoding HDMI audio+video feed will be able to decode this audio signal. And since most HDMI audio converters derive their audio clock from the video clock at the HDMI input, you should benefit with nearly all receivers. For this, you don't need some special decoder, like would be required for PQLS method that transmits the audio clock over CEC channel.

One caution: if the video/audio clock extraction circuit in the receiver is poorly designed, it may introduce more jitter reducing or negating the effect of the high quality clock at the input. A well-designed receiver will give best results, but it doesn't have to have any special signal handling, like what's required by the PQLS method.

That's basically the answer I was looking for.

So a high quality AV receiver (or SSP) would do. Thank you Paul.
 

amirm

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There's a new BR player coming up with jitter reduction from its HDMI output.
To take full advantage from it do I need a pre/amp with also a jitter reduction HDMI input?
Unless this is something new, the answer is yes. ARC or Audio Rate Control (not to be mistaken with Audio Return Channel) puts the receiver in charge of clock instead of the other way around (as is normally the case with HDMI). In doing so, the DAC clock can be used to drive the source and with it, sharply reduce jitter.

Unfortunately ARC is not a common feature in AVRs. I have only seen it from companies like Pioneer who built both ends of it (Blu-ray player and AVR). So having it in the Oppo player by itself doesn't do you any good.
 

amirm

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Here are a set of measurements showing the effect of this in Pioneer (who called it "PQLS"):



You can see how using PQLS on the right sharply reduces all manner of jitter.
 

NorthStar

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From this link I posted earlier: http://www.oppodigital.com/KnowledgeBase.aspx?KBID=129&ProdID=UDP-205

It says:

"Once the signal reaches the receiving end, for PCM and DSD audio, the reconstructed audio clock is usually used directly to drive the audio data. As a result, the HDMI audio jitter reduction circuit can improve the sound quality of PCM and DSD audio directly. For bitstream audio in compressed formats such as Dolby Atmos, Dolby TrueHD, DTS:X or DTS-HD Master, the jitter reduction benefit depends on whether the decoder design in the audio processor/receiver uses a synchronous or asynchronous clock. Compressed audio decoding requires buffering of the audio data and performing mathematic manipulations. If the decoder uses a synchronous clock design, the decoded data is usually driven out with a clock that is 1x, 2x, or 4x that of the reconstructed audio clock but synchronized to it, so the benefit can carry over. If the decoder uses a completely new, locally generated clock to drive out the decoded data, then jitter reduction on the player side is not a benefit, but the same circuit ensures error-free delivery of the bitstream audio data to the decoder thanks to a very stable HDMI video clock and a constant CTS value.

The Conclusion
The HDMI jitter reduction circuit in the UDP-205 is a unique design which can significantly reduce jitter and eliminate timing errors. Customers can enjoy their music with increased accuracy when using the audio-only HDMI output port for connecting the audio signal to an A/V processor or receiver."


In that link they provide graphs and numbers from their measurements.
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Some AV receivers employ the ESS DAC: http://www.pioneerelectronics.com/PUSA/Home/AV-Receivers/Elite+Receivers/SC-LX901

"The highly acclaimed 192 kHz/32-bit ESS SABRE32 Ultra DAC (ES9016S) is adopted to deliver exceptional sound, with ultra-low distortion and high signal-to-noise ratio. It offers jitter-free performance for an astounding audio reproduction with rich deep bass, maximizing the full potential of Pioneer’s Class D3 amplifiers."

And like you mentioned, some of the older Pioneer Elite AV receivers with PQLS, which I also referred previously:

[video=youtube;kWq9fUNet-Q]https://www.youtube.com/watch?v=kWq9fUNet-Q[/video]
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And according to some any quality AV receiver/SSP or separate DAC can take advantage of the digital HDMI audio jitter reduction provided by the Oppo 205's HDMI Out (Audio Only) port (#2) from potential audio improvement. This was indeed my question; can they?
Because someone mentioned that in order to benefit from it the AV receiver or pre/pro would need to also have a jitter rediction circuit in its own digital HDMI audio signal flow, its own clock.

But according to that quote from Oppo above it depends on whether the decoder design in the audio processor/receiver uses a synchronous or asynchronous clock.

Paul in his reply to my question, and from the Oppo 205's litterature, ...we have some answers.
This is certainly new from the new Oppo 205 just released now. All previous top models (105, 105D, 95) didn't have that special HDMI jitter reduction circuit.
If there wouldn't be any benefit with hi-end receivers and pre/pros, why even bother?

What would be best is to measure the amount of jitter from the main HDMI out versus the HDMI Audio only of the Oppo 205 connected to the same receiver, say for example a Yamaha RX-A3060 flagship: https://ca.yamaha.com/en/products/a...rs_amps/rx-a3060_u/features.html#product-tabs
That receiver too employs an ESS ES9016 DAC, but doesn't mention any "jitter reduction" in its clock implementation.

This Pioneer AV receiver: http://www.pioneerelectronics.com/PUSA/Home/AV-Receivers/Elite+Receivers/SC-87

"PQLS Bit-stream.

Pioneer’s special jitter reduction technology makes reproduced sound more realistic by utilizing the master audio clock in the Elite SC-85 for playback instead of the video clock in a compatible Blu-ray Disc player.

ESS-DAC Sabre32 Bit for All-Channel.

All channels of the Elite SC-87 employ ESS-DAC SABRE32 technology, the world’s highest performance 32-bit audio DAC solution, delivering spectacular sound with a minimum of harmonic distortion."


Or the top Anthem, Arcam, Rotel pre/pro, Denon/Marantz, Onkyo/Integra AV receivers/SSPs, NAD, McIntosh. Krell, Bryston, Classe, AudioControl Maestro, Theta Digital, Steinway Lyngdorf, Datasat, JBL Synthesis, ADA, Trinnov Altitude, ...SSPs.

Which AV receivers and pre/pros can benefit best from the HDMI audio jitter reduction of the new Oppo 205? All of them, some of them, with synchronous clock design, with/without their own jitter reduction system, ...?

We measure, we listen, we evaluate, we analyse, we make a mental and/or fundamental decision based on pleasurable sensory spaces of our own ear drums in harmony with our own emotional chords, or pulsations of the heart and soul, or psychological inclinations, or faith, or a combination of some or all including the best set of measurements?

The Oppo 205 looks great in&out, on paper, on literature, on promotion, on specs, on features, on weight, on versatility, on universality, on ultra hi-res audio, on ultra hi-def video, on the new HDMI audio jitter reduction circuitry, on value (only $1,300 - way too low for the high-end society), on everything but it's ultra low price.
There are simply no other 4K Blu-ray players that cost more. ...And the cheapest one, Samsung UBD-K8500 is $199 (less than the price of a high-end Y RCA connector).

:b Sorry for the mix of technical audio matters with the air we breathe every single day.

I'm the type who believe that matching that HDMI Audio only out with the right HDMI in will result in optimal performance; objectively, and subjectively too.
But with a clause: How do we determine with absolute certainty that "optimal performance"? Because every components matching in the world would need to be tested, and it is impossible.

Anyway it cannot hurt to have a jitter reduction clock in all the audio components of the system's chain.
It's like having truly balanced XLR connections from input to output.

There will be eventual professional reviews of that Oppo 205 with its new HDMI audio circuitry (jitter reduction), and with measurements performed and graphs delivered. It'll be very interesting.

One last thing: In audio the pursuit of excellence is always evolving, in both analog and digital forms.
In video the analog projectors and other analog moving images reproducers aren't coming back; we are truly in the digital video world constantly advancing...4K/UHD, HDR10, HLG, WCG, Dolby Vision, 8K, 3D, 4D, 16K, ....Holo (graphy).

In audio, DTS:X, Dolby Atmos, Auro-3D, ...all digital (multichannel hi-res).
Stereo, analog tubes from tape sources and acetate. Jitter? :b
 

NorthStar

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http://www.esstech.com/files/4614/4095/4305/about-jitter.pdf
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Repeat: HDMI Audio Jitter Reduction
"The UDP-205 features a high-stability, high-precision HDMI clock and a special HDMI audio jitter reduction circuit. This unique design significantly reduces jitter and eliminates timing errors, allowing you to enjoy your music with increased accuracy when you use the audio-only HDMI output port for connecting the audio signal. PCM and DSD signals rely on the HDMI clock directly, so the HDMI audio jitter reduction circuitry can improve the sound quality of PCM and DSD audio. For compressed bitstream audio, it helps to ensure error-free transmission, and may improve the audio performance depending on whether the audio decoder in the A/V processor or receiver uses a synchronous or asynchronous clock scheme."

______

Digital audio through HDMI needs all the help it can gets on this day of the year 2017 with a clean audio sync signal all the way thru from in-out-in-out with the least amount of jitter interference. It cannot hurt to start with the player. This is NEW.



Any insight from anyone is most sought after in the pursuit of advancement knowledge towards a 'cleaner' musical audio world ♫ :b
 

NorthStar

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Bob said:
To take full advantage from it do I need a pre/amp with also a jitter reduction HDMI input?

Unless this is something new, the answer is yes. ARC or Audio Rate Control (not to be mistaken with Audio Return Channel) puts the receiver in charge of clock instead of the other way around (as is normally the case with HDMI). In doing so, the DAC clock can be used to drive the source and with it, sharply reduce jitter.

Unfortunately ARC is not a common feature in AVRs. I have only seen it from companies like Pioneer who built both ends of it (Blu-ray player and AVR). So having it in the Oppo player by itself doesn't do you any good.

It seems that for best fidelity the jitter reduction (clock sync) feature has to be part of the entire audio chain: by dmusoke

That's from the Oppo 205's HDMI Audio Out jitter reduction feature. So yes, it would be beneficial to plug that output into a pre/pro or AV receiver that also has its own HDMI jitter reduction circuit (clock).

Some Pioneer Elite components have that digital HDMI interface called PQLS. Here's just an example (like you and I mentioned earlier):

"As HDMI® has become the new high-definition cable connection of choice, HDMI is susceptible to digital transmission errors known as “jitter.” Jitter is caused by timing errors in the digital bit-stream between two connected components and can cause audibly noticeable problems sonically expressed by a lack of detail, depth, imaging, and ultimately a natural sound-field. The VSX-23TXH is the entry point for Pioneer’s exclusive PQLS-Multi technology that can solve these problems when coupled with a PQLS-Multi equipped Pioneer Blu-Ray Disc® player (BDP-23FD). By using the 2-way HDMI CEC communication capabilities of the HDMI spec, Pioneer Elite PQLS components “talk to each other” and “speed synchronize” the digital clocks between them using the receiver’s Precision Quartz Lock System (PQLS) to buffer and synchronize the digital audio signals, effectively removing the effects of jitter for a clear, pristine, natural sounding digital transfer. PQLS-Multi removes the effects of jitter with 2-channel CD playback and now from multi-channel DVD and Blu-Ray Disc soundtracks."

Pioneer has been @ it for quite some time.
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Some Denon components too, with the Denon Link: http://denon-uk.custhelp.com/app/answers/detail/a_id/918/~/denon-link-configuration
http://www.denon.com/Pages/GlossaryDetail.aspx?GId=14

"DENON LINK 4th uses the master clock in the A/V surround receiver as the reference for controlling the video circuitry and the disc drive in the player, and the digital video and audio signals from Blu-ray disc are transmitted to the A/V surround receiver via an HDMI cable. This is how our DENON LINK 4th works.
DENON LINK 4th is able to transmit digital audio signals with negligible jitter because it has audio devices share the same clock. In addition, DENON LINK 4th has achieved a world first by suppressing jitter to an absolute minimum even for the playback of Blu-ray discs that include video signals."


And Meridian also (but this one is not HDMI, it uses three coaxial cables...I believe): http://www.meridianunplugged.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=85498&page=1
Bob Stuart

"A digital DVD-Audio interface is part of Meridan’s v3 upgrade for their 800 series products.
Known as MHR Smart Link, the proprietary, encrypted digital interface enables multi-channel content from either DVD-Audio or DVD-Video discs to be delivered from Meridian’s 800 DVD player to the company’s 861 reference surround controller and DSP loudspeakers via a trio of RCA coaxial cables. Meridian MHR is the first proprietary link to be approved for the transmission of DVD-Audio content entirely within the digital domain. The link also carries meta information about the format and type of material being played, enabling the 861 to accurately identify all incoming formats without needing to analyse the bitstream itself, something that often leads to processing delays. According to Bob Stuart, Chairman of Meridian Audio, even incorrectly flagged DTS material from DTS music discs can be reliably identified and decoded this way.
The benefits are clear; not only can the 861 be programmed to react in a desired way to any type of incoming data and channel content, but also by transmitting DVD-Audio material digitally it allows the processor to perform bass management and time alignment entirely within the digital domain."

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There are other audio companies that use their own proprietary digital interface between the pre/pro and the source, to have a cleaner (jitter-free) audio signal transmission. I think Theta Digital, and I'm sure others.

So, in order to take full advantage of digital HDMI jitter reduction (like in the Oppo 204 HDMI Audio Out), it would be preferable to connect it to a pre/pro or AV receiver having its own master clock with jitter reduction circuitry. If the pre/pro produces more jitter than the source, the full benefit won't be achieved.

In real life listening test, I too doubt that we can discern with absolute certainty. But from measurements it is for sure in the pudding below the cream. ...Way of speech.
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In regards to ARC (CEC activated in order to activate ARC - Audio Channel Return): It is a nice feature, but often diabolical.
The other ARC (Audio Rate Control); you are right Amir, not to be confused, is the way to go. And you're also right; I don't know many AV receivers and pre/pros advertising that feature. Maybe Oppo can design their own pre/pro with it, to match its 205 4K BR player?

If someone who buy the Oppo 205 and mate it with say an inexpensive receiver ($1,000 or less), can he benefit? I would say not.
But what about with a high end pre/pro ($10,000 or more)? The pre/pros of that price caliber must all have a top notch HDMI jitter reduction clock, right?
How do we know for sure short of measuring; from the given specs, the literature, the advertisement, ...?
Between a lo end receiver ($149) and a hi end pre/pro (state-of-the-art) ... $40,000 plus; the difference from their digital HDMI interface with the source connected to them, which one has a factual benefit in reducing digital jitter?

We most likely get what we pay for. ...In & out. The less jitter (pico seconds) the better the synchronization of our audio signal transmission reproduced from our speakers to our ears...cleaner, more accurate music reproduction, as the artist musician with his sound mixer/recording engineer intended.
@ our end we prefer reference sound. ...Or we can go home and buy our own DSP engine to fabricate and metamorphose the reference (good and bad) to our own taste.
The law says nothing about personal sound preference, only to not awake our neighbors in the middle of the night with loud music, or between 10:00 pm and 7:00 am. If living underground in a waterproof and soundproof bunker with two-foot thick concrete cement walls, the extended arm of the law has no reach.

True, it's important to have fun, to have a good sense of humor, to not take ourselves too seriously, and put the emphasis where it counts the most; friends and family.
Having friends and family who are jitter-free is like living happy in a better world.
Jittery people; it starts @ the source and ends up @ the other hand.
_____

I know more today than what I knew then. Thanks Paul and Amir.
It's from discussions in search of higher learning that we can all advance, no matter how slow or how fast the level of our own affinity, towards the path of the holy grail...immortality...music ecstasy...a world free of jittery turbulence. We take good care of our audio, of our picture...for the love of music and movies. ...Because people matter first; artists, musicians, filmmakers, composers, actors/actresses, singers, operas, ballets, jazz bands, blues bands, classical orchestras, ...creators of the arts in the entertainment world. ...All that jazz.
 

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