mp3 HD - New Lossless mp3 encoder - backwards compatible

[Jim HTPC]

I'm surprised no one posted this yet.

I have always had to settle for 320cbr mp3's to maintain portability of my music collection. The downside was it wasn't lossless. I didn't like FLAC or APE since it didn't have all the ID fields of an mp3 plus you are never guaranteed to have all portable players be able to play those formats back.

Now there is a solution - at least for me. I've tested this already and it's very nice. Basically this encodes a normal mp3 like it always did. The difference is that there is a special ID tag that holds the dropped data so that when it's played back with a mp3HD player, it plays it back in a lossless format. If you play it in a non-mp3HD player, it ignores the ID tag (extra data) and plays it back just like any mp3 file.

There is a free program that will allow you to conveniently rip your CDs with a single click of a button. There is only a WinAmp v5.55 plugin to play the mp3HD file at the moment.

Here's the link to read: http://www.pcmag.com/article2/0,2817,2343448,00.asp

You can download the encoder & plug-in here: http://www.all4mp3.com/Software3.aspx

Here's how to setup for one click rips (copy/paste from readme)

To rip mp3HD files from your audio CDs you need an audio CD grabber tool with external Encoder support. For example you can use the Exact Audio Copy CD grabber. The current version of Exact Audio Copy can be downloaded at: http://www.exactaudiocopy.de/en/inde...urces/download

You can include the mp3HD encoder into the Exact Audio Copy grabber by performing the following steps:

- Open the "Compression options" from the "EAC" menu
- Go to the "External Compression" tab
- Enable the "Use external program for compression" option
- Set "Parameter passing scheme" to "User Defined Encoder"
- Write ".mp3" into the "Use file extension" field
- Type the link to your mp3hdEncoder.exe file into the "Program, including Path, used for compression" field
- Insert the following text into the Additional command-line option field: -if %s -of %d -br %r000 -Artist "%a" -Album "%g" -Title "%t" -Year "%y" -Track "%n" -Genre "%m" -Encoder "Thomson mp3HD encoder v1.4"
- Select the desired bit rate in the "Bit rate" field.
- Uncheck the "Add ID3 tag" option


I hope this takes off. The biggest complaint I hear is that the file size is too large (still smaller than wav). Well you'll have to dump the cheapo 2GB player and get a 32GB iTouch. Soon there will be 64 and 128GB.

[FrantzM]

This could be anathema to some here: How does it compare to the "regular" lossless methods in term of sound quality?

[amirm]

Originally Posted by FrantzM

This could be anathema to some here: How does it compare to the "regular" lossless methods in term of sound quality?

There is no way to answer the question... Ask me why .

[FrantzM]

Why?

[Jim HTPC]

I have not done a comparison between WAV vs. mp3HD vs. APE vs. FLAC. I'm too lazy since WAV, APE, and FLAC don't meet all my needs.

Standard mp3's with 320K cbr were as close as I could get to CD quality with all the extras I required, as well as portability to any portable media player.

My situation is definitely different than most. Size is not an issue. I have lots of storage. I didn't want to have both mp3 and FLAC/APE/WAV and now I don't.

The only concern is that media programs paying the licensing fee for mp3HD. There seems to be resistance from the PRO APE/FLAC crowd. Primarily because it's free (at least that is what I was led to believe).

I can hear a difference on my setup between mp3HD and mp3 320K cbr. What you hear are more of the subtleties that were on the original CD.

I wish all music CDs would go to a higher bitrate & sample rate like HRx. One way to boost the sales for high end enthusiasts and audiophiles.

I would be curious if those with higher end systems can tell the difference between them. Unfortunately, these tests use demo material that people are not familiar with, and are left 2nd guessing their responses.

[amirm]

Originally Posted by FrantzM

Why?

Well... wanted to make sure someone cared before I took the time to answer. And also, to see if someone else might know what the answer is....

[robgordon66]

Originally Posted by amirm

Well... wanted to make sure someone cared before I took the time to answer. And also, to see if someone else might know what the answer is....

So what is the answer? [IMG]http://z09a0222gshv273.imageshacknow.info/img/3044************************[/IMG]

[Jim HTPC]

Originally Posted by robgordon66

So what is the answer? [IMG]http://z09a0222gshv273.imageshacknow.info/img/3044************************[/IMG]

LOL.... he posted his reply then left without answering the question. ha-ha

[ehlarson]

Originally Posted by Jim HTPC

I'm surprised no one posted this yet.

I have always had to settle for 320cbr mp3's to maintain portability of my music collection. The downside was it wasn't lossless. I didn't like FLAC or APE since it didn't have all the ID fields of an mp3 plus you are never guaranteed to have all portable players be able to play those formats back.

Now there is a solution - at least for me. I've tested this already and it's very nice. Basically this encodes a normal mp3 like it always did. The difference is that there is a special ID tag that holds the dropped data so that when it's played back with a mp3HD player, it plays it back in a lossless format. If you play it in a non-mp3HD player, it ignores the ID tag (extra data) and plays it back just like any mp3 file.

There is a free program that will allow you to conveniently rip your CDs with a single click of a button. There is only a WinAmp v5.55 plugin to play the mp3HD file at the moment.

Here's the link to read: http://www.pcmag.com/article2/0,2817,2343448,00.asp

You can download the encoder & plug-in here: http://www.all4mp3.com/Software3.aspx

Here's how to setup for one click rips (copy/paste from readme)

To rip mp3HD files from your audio CDs you need an audio CD grabber tool with external Encoder support. For example you can use the Exact Audio Copy CD grabber. The current version of Exact Audio Copy can be downloaded at: http://www.exactaudiocopy.de/en/inde...urces/download

You can include the mp3HD encoder into the Exact Audio Copy grabber by performing the following steps:

- Open the "Compression options" from the "EAC" menu
- Go to the "External Compression" tab
- Enable the "Use external program for compression" option
- Set "Parameter passing scheme" to "User Defined Encoder"
- Write ".mp3" into the "Use file extension" field
- Type the link to your mp3hdEncoder.exe file into the "Program, including Path, used for compression" field
- Insert the following text into the Additional command-line option field: -if %s -of %d -br %r000 -Artist "%a" -Album "%g" -Title "%t" -Year "%y" -Track "%n" -Genre "%m" -Encoder "Thomson mp3HD encoder v1.4"
- Select the desired bit rate in the "Bit rate" field.
- Uncheck the "Add ID3 tag" option


I hope this takes off. The biggest complaint I hear is that the file size is too large (still smaller than wav). Well you'll have to dump the cheapo 2GB player and get a 32GB iTouch. Soon there will be 64 and 128GB.

Jeez I hope it is smaller than a completely uncompressed lossless format. You could hardly set the bar any lower.

Basically this new variation looks to me like an obvious attempt to extend the on-patent life (which mostly ends in 2012 in the US) of the mp3 format. People should recognize this issue and avoid use of this format variation like the plague.

There have already been times where I've been unable to listen to mp3 music on systems I have because of this nonsense. There is no way I am going participate in something as ridiculous as this.

And as far as Amir's question, the answer is likely that any audible differences would not be predictable since all lossless formats contain the same information. Perceived differences would be the result of specific hardware and software implementation details or listener biases.

[Jim HTPC]

Originally Posted by ehlarson

Jeez I hope it is smaller than a completely uncompressed lossless format. You could hardly set the bar any lower.

What basis do you have for making the claim "set the bar any lower"? The uncompressed WAV of Comfortably Numb on Pink Floyd's - The Wall (Remastered) is 64.61MB according to EAC. After compressing using the mp3HD encoder with a lower rez @ 320kbps is: 48MB. That's a 25% reduction.

Originally Posted by ehlarson

There have already been times where I've been unable to listen to mp3 music on systems I have because of this nonsense. There is no way I am going participate in something as ridiculous as this.

What nonsense? The nonsense that started 3 days ago?

Originally Posted by ehlarson

And as far as Amir's question, the answer is likely that any audible differences would not be predictable since all lossless formats contain the same information. Perceived differences would be the result of specific hardware and software implementation details or listener biases.

Of note; there are different levels of encoding using FLAC. If one were to use a pure lossless codec then they all should sound the same if it is a bit for bit copy once it's decompressed. I'm not stating one is better than the other audio quality wise. What I am stating is that FLAC and APE files are NOT guaranteed to play in ALL portable music players. Mp3's are. Instead of having 2 sets of music, you now have one copy. Similar to DTS with DTS HD/MA. If you don't have DTS HD or MA decoding, you still get the core DTS track.

The only downside is re-encoding all my music which is not that big of a deal.

If one took the time to try the plugin with Winamp... one would find there is a button that can be enabled that will allow you to switch between the standard mp3 and the mp3HD quickly. It is quite easy to hear the difference. *edit* --> With my setup. If one were to find the crappiest of gear/ear buds, I'm sure it would be much harder to hear the difference.

Originally Posted by ehlarson

People should recognize this issue and avoid use of this format variation like the plague.

Someone will always have a patent on something. If everything was free then we'd still be using tape recorders as there would be no incentive to innovate. And if someone designs something that everyone uses, why shouldn't they get paid? Mp3s are the sole reason file sharing skyrocketing.

[amirm]

Originally Posted by Jim HTPC

LOL.... he posted his reply then left without answering the question. ha-ha

Hey, what would life be without some suspence?

Seriously, I was hoping someone else would know the answer and this came pretty close:

Originally Posted by ehlarson

And as far as Amir's question, the answer is likely that any audible differences would not be predictable since all lossless formats contain the same information. Perceived differences would be the result of specific hardware and software implementation details or listener biases.

So let me expand on that. First, when science can prove something, then it cannot be disputed. And we can prove that every lossless format recreates its source. Period, end of discussion. I am amazed that articles like latest in Absolute Sound imply that because the bitrate is reduced, there is a quality loss. There is not if we can reproduce the original.

But the answer can be more complex than this. The question was not whether we can reproduce the original bits in digital form but whether once we are in analog domain, do they sound the same. As stated above, one has to look at the entire playback chain. Why? Because the process of conversion to analog is an analog process itself due to timing signal being analog (the thing that tells the DAC to output the samples).

In the case of a PC producing analog samples, those samples are subject to jitter. And jitter can be caused by activity in the rest of the system being telegraphed into the DAC master clock (or its reference voltage). Different algorithms for lossless create different levels of interference because the system load (CPU, Memory, Disk, etc.) changes.

So to the extent the activity of the CPU changes the noise profile (and hence crosstalk into master clock), one can make a case that the sound can be different coming from different lossless algorithms. But that is the end of where you can take the argument. Your PC will be different than mine and the noise profile I get is not the same as yours. Nor is your sound card likely to be the same as mine. So even if I told you this new scheme sounds better than say, WMA Pro (heaven forbid ), in your system the reverse may be true.

So as you see, I had already given the answer . It was the explanation that was missing....

[ehlarson]

Originally Posted by Jim HTPC

What basis do you have for making the claim "set the bar any lower"? The uncompressed WAV of Comfortably Numb on Pink Floyd's - The Wall (Remastered) is 64.61MB according to EAC. After compressing using the mp3HD encoder with a lower rez @ 320kbps is: 48MB. That's a 25% reduction.

The basis for "set the bar any lower" is simple. ANY compression algorithm whatsoever, including all the lossless algorithms would give a file size smaller than WAV. In other words WAV is effectively the WORST format for file size that you are likely to see. Saying mp3HD is smaller than WAV is not a useful thing since all formats are likely to smaller than WAV, except WAV itself.

Originally Posted by Jim HTPC

What nonsense? The nonsense that started 3 days ago?

I will give an example. A few years ago I purchased a PDA that uses a Linux based operating system at its core. Since the purveyors of this OS implementation offer it free and unencumbered of any license fees they are not in a position to pay license fees for proprietary formats such as MP3. The good thing about free OS's is that you can do anything you want with them. One bad thing about them is that if there are standards that require license fees to use them you will not have access to them. The result is that this PDA would not play MP3s. This meant something of an inconvenience since I had to then convert music to a free format to use it on this device.

It is total nonsense because there is NO technical reason to support a non-free format when you build a player.

Originally Posted by Jim HTPC

Of note; there are different levels of encoding using FLAC. If one were to use a pure lossless codec then they all should sound the same if it is a bit for bit copy once it's decompressed. I'm not stating one is better than the other audio quality wise. What I am stating is that FLAC and APE files are NOT guaranteed to play in ALL portable music players. Mp3's are. Instead of having 2 sets of music, you now have one copy. Similar to DTS with DTS HD/MA. If you don't have DTS HD or MA decoding, you still get the core DTS track.

See my previous comment. MP3's are not guaranteed to play in ALL portable devices. What is guaranteed is that if you produce a portable device that plays MP3's without tithing you will get sued.

Originally Posted by Jim HTPC

Someone will always have a patent on something. If everything was free then we'd still be using tape recorders as there would be no incentive to innovate. And if someone designs something that everyone uses, why shouldn't they get paid? Mp3s are the sole reason file sharing skyrocketing.

Some economists think that patents have an overall negative effect on the rate of innovation, that in fact the rate of progress would be faster without them because of the side effects.

http://news-info.wustl.edu/tips/page/normal/13656.html

It is also quite clear that the confusion of patents related to MP3 has in fact slowed progress in improving the MP3 format itself. The result is other formats like Vorbis, AAC and WMA are significantly superior.

From http://en.wikipedia.org/wiki/MP3#Lic..._patent_issues

These patent issues significantly slowed the development of licensed MP3 software and led to increased focus on creating and popularizing alternatives such as Vorbis, AAC, and WMA. Microsoft chose to move away from MP3 to its own proprietary Windows Media format to avoid licensing issues associated with these patents.

So not only do the MP3 patents hinder innovation, they also result in plethora of incompatible file formats in the marketplace. The new file format, if adopted would result in a continuation of this undesirable situation.

I hope people will take this under consideration when evaluating the formats they ask for when selecting music players.

[Jim HTPC]

Originally Posted by amirm

Hey, what would life be without some suspence?

Seriously, I was hoping someone else would know the answer and this came pretty close:



So let me expand on that. First, when science can prove something, then it cannot be disputed. And we can prove that every lossless format recreates its source. Period, end of discussion. I am amazed that articles like latest in Absolute Sound imply that because the bitrate is reduced, there is a quality loss. There is not if we can reproduce the original.

But the answer can be more complex than this. The question was not whether we can reproduce the original bits in digital form but whether once we are in analog domain, do they sound the same. As stated above, one has to look at the entire playback chain. Why? Because the process of conversion to analog is an analog process itself due to timing signal being analog (the thing that tells the DAC to output the samples).

In the case of a PC producing analog samples, those samples are subject to jitter. And jitter can be caused by activity in the rest of the system being telegraphed into the DAC master clock (or its reference voltage). Different algorithms for lossless create different levels of interference because the system load (CPU, Memory, Disk, etc.) changes.

So to the extent the activity of the CPU changes the noise profile (and hence crosstalk into master clock), one can make a case that the sound can be different coming from different lossless algorithms. But that is the end of where you can take the argument. Your PC will be different than mine and the noise profile I get is not the same as yours. Nor is your sound card likely to be the same as mine. So even if I told you this new scheme sounds better than say, WMA Pro (heaven forbid ), in your system the reverse may be true.

So as you see, I had already given the answer . It was the explanation that was missing....

You forgot to mention one important fact. You are speaking about different hardware. In reality the hardware remains the same, just the codec/file is different. The important question is can you hear a difference in formats using the same hardware? In my case, it is a definite yes. Is it the Nirvana I want? Absolutely Not. However; it is as good as it can be at the present time. I am enjoying HRx music, but it's doesn't work in portable players, plus my favorite musicians have not been released in the HRx format. So what do you do? Use the best format for your needs at the present moment.

While I agree that "computers" can have more/less noise than others, there is something to be said about using better components. Using motherboards with better caps, better power supplies, better sound cards, etc. Short of putting together 50-100 exact systems then putting them on an o-scope to see which is the best is not very economical or convenient. So ultimately you research, buy the best products, and hope for the best. Coincidentally, my sound card is the exact model that HRx used for playback (unbeknownst to me prior to my purchase).

[ehlarson]

Originally Posted by amirm

First, when science can prove something, then it cannot be disputed.

That is my view. Some others dispute this view though. It took the Catholic Church 500 years or so to admit they were wrong in this Galileo thing...

[Jim HTPC]

Originally Posted by ehlarson

It is also quite clear that the confusion of patents related to MP3 has in fact slowed progress in improving the MP3 format itself. The result is other formats like Vorbis, AAC and WMA are significantly superior.

Would it be safe to state that these competing formats came about because of a patent? Which if you use these formats is a good thing.

Does Apple and Microsoft hold patents on AAC and WMA? Do they charge royalties as well?

Sorry to hear about your PDA. We have to do the research prior to buying devices. And while I feel your pain- there are devices I wish were different but can't change them, ultimately I have the power to support the device or not; and hope for a better model in the near future. For instance I supported HD DVD. I don't like the DRM B.S. forced on us. And after HD DVD died, I had to choose to watch DVDs or switch to Blu-rays. Not that I wanted to reward the DRM makers, but I couldn't go back to the poor picture quality and standard DTS/DD. So now I have Blu-rays. And hope to have a region code modification for the new Oppo soon

[ehlarson]

Originally Posted by Jim HTPC

Would it be safe to state that these competing formats came about because of a patent? Which if you use these formats is a good thing.

Does Apple and Microsoft hold patents on AAC and WMA? Do they charge royalties as well?

AAC licensing is a lot more liberal than MP3. You do not need to take a license to distribute music in AAC format, for example. Vorbis, which you did not mention is of course completely free. As far as WMA, I don't know.

You are also ducking the real issue - MP3 has been frozen in time because of the patent issues. It is now arguable that MP3 is the WORST lossy compression algorithm in wide use.

Originally Posted by Jim HTPC

Sorry to hear about your PDA. We have to do the research prior to buying devices. And while I feel your pain- there are devices I wish were different but can't change them, ultimately I have the power to support the device or not; and hope for a better model in the near future. For instance I supported HD DVD. I don't like the DRM B.S. forced on us. And after HD DVD died, I had to choose to watch DVDs or switch to Blu-rays. Not that I wanted to reward the DRM makers, but I couldn't go back to the poor picture quality and standard DTS/DD. So now I have Blu-rays. And hope to have a region code modification for the new Oppo soon

I knew about the MP3 issue when I bought the player. It was my decision that the flexibility of Linux was worth the tradeoffs, so I really can't complain about it.

As for the HD format wars - I just sat those out. There just wasn't enough software to make me feel I was missing much.

DRM is another issue. Like you I am not at all happy with some of the things going on in the Blu-Ray area, especially the idea that my player may become incompatible with newer BD releases because of DRM changes.

[amirm]

Originally Posted by Jim HTPC

You forgot to mention one important fact. You are speaking about different hardware. In reality the hardware remains the same, just the codec/file is different. The important question is can you hear a difference in formats using the same hardware?

That is the context in which I answered the question. That the CPU load changes so on identical system, one or the other may sound better. I also addressed the case of someone asking another poster's opinion, in which case the hardware is also different.

In my case, it is a definite yes. Is it the Nirvana I want? Absolutely Not. However; it is as good as it can be at the present time. I am enjoying HRx music, but it's doesn't work in portable players, plus my favorite musicians have not been released in the HRx format. So what do you do? Use the best format for your needs at the present moment.

Hmmm. I think you are addressing a different question . The question was whether there is a difference in sound quality of lossless codecs, not lossy MP3 and lossless. While it is true that average person may not hear the difference between 320kpbs MP3 and lossless/source, it is fair to say that most people who post here agree that there is an audible difference (and to me and probably a few other a much bigger difference).

While I agree that "computers" can have more/less noise than others, there is something to be said about using better components.

Let me be clear that I was not talking about noise by itself. That hopefully is very low for anyone hanging in this part of AVS Forum. I was talking about noise impacting jitter -- something very hard to measure or deal with.

[amirm]

Originally Posted by Jim HTPC

Would it be safe to state that these competing formats came about because of a patent? Which if you use these formats is a good thing.

Does Apple and Microsoft hold patents on AAC and WMA? Do they charge royalties as well?

Since my group developed WMA, I can maybe answer that part .

The motivation for WMA was twofold:

1. To improve efficiency and get better fidelity at low rates. MP3 below 128kbps simply was not all that useful. At then dial up rates, it was equiv. to AM radio (bad thing if you want to stream FM stations over dial-up).

2. As mentioned before, royalties for MP3 encoding was quite high. Given the large distribution volume for Windows, it simply was not feasible to pay a per copy fee. Many years later, we managed to get a reasonable license and included MP3 encoder in Windows Media Player. Until then though, billions of WMAs were created.

As for licensing, WMA licensing costs are far more reasonable than just about any other audio codec (see http://www.microsoft.com/windows/win...dVersion_Final). It is a fixed fee and not per-copy. So for high volume, it is incredibly cheap to implement.

MP3 was created in the days people only thought about hardware so charging people X cents per unit seemed no big deal. But when you have software that is downloaded for free, that doesn't make as much sense. See http://www.mp3licensing.com/royalty/. $2.50 for a media player downloaded for free? I don't think so....

[DougWinsor]

That the CPU load changes so on identical system, one or the other may sound better. I also addressed the case of someone asking another poster's opinion, in which case the hardware is also different.

The load on a processor and the processor its self would be irrelvant to how it sounds. The load on any current CPU would be less then 1% for playing back a MP3 file. The new intel quad core CPU's only use 7% for playing back blu ray movies.

[amirm]

Originally Posted by DougWinsor

The load on a processor and the processor its self would be irrelvant to how it sounds.

I wish what you were saying were true but unfortunately the situation is far more complex than it seems on the surface. The explanation requires total system understanding both at digital and analog levels.

The load on any current CPU would be less then 1% for playing back a MP3 file. The new intel quad core CPU's only use 7% for playing back blu ray movies.

What you say here is true but not material to the current discussion per-se.

Let's first look at how a digital system works. A CPU does work on every clock cycle (the “Gigahertz” refers to this). So billions of times per second, something happens inside your machine. Even when the CPU is "idle" it is executing something (the kernel idle code). Unless you suspend your machine and put it to sleep the thing is running around the proverbial squirrel cage, whether there is something to do or not. So the fact that the CPU is working 1% or 7% is not relevant because the CPU is not shutting off between the intervals (and if it did, it might cause other audible problems).

The CPU and associated digital components connected to it require power to perform work. The circuits are digital meaning they jump from zero to the supply voltage in a very short amount of time. Recall basics of electronics. To generate a perfect transition from zero to supply voltage, requires infinite power. Real life signals are a bit more gentle than this but we are still talking about pretty strong impulses, given the 30 to 70 watt of the CPU and rest of the circuits connected to it. Imagine pulsing a 70 watt light bulb on and off billions of times per second. Do you think it generates noise? You bet. So much so that you can pick it up over the air on a radio many feet from it!

Since the power supply doesn’t have infinite capacity, it winds up having its output voltage modulated rapidly by these pulses (manifesting in noise due to high frequency at work). Its voltage sags with the transition and then goes back up shortly thereafter. Yes, we have filters and decoupling caps on power supply rails to help with this but we can’t filter out all the noise. You can easily verify this with a scope on the power line, with or without the CPU running. With me so far?

Now here is where it gets interesting. The sound subsystem is also sitting on the same power supply line (even with post regulators). The DAC master clock gets its power from the same line as does the reference voltage. Vary either one of these a hair (picoseconds in case of master clock) and the sound changes. Remember, the DAC is not a digital device. It takes digital samples. But what it outputs is analog both in value and timing. The only way it can be accurate in its output is if its input is accurate (clock and reference voltage).

Further, look up DAC power supply rejection ratio rating. You will find specs as low as 20db. Meaning anything noise higher than this will leak into the DAC, distorting its output.

In summary, the CPU is connected through the power supply to the most sensitive parts of the audio reproduction system. Its activities (or lack thereof) have the potential to impact the audio fidelity because it changes the parameters which the DAC sees. As long as you share a connection between the two parts, you can’t eliminate the impact of the CPU at the extreme. You can build a PC that is fairly immune to these problems (say, by having independent power supplies and total isolation) but I suspect none of you have such a system. Putting even a good sound card in a PC subjects it to the issues discussed so far.

So as you see, there can be an impact. What that is in real life in the PC you use is unpredictable due to complexity of the system and the many variables. And of course, how sensitive your ears are in picking up the variations is also a major factor.

[DougWinsor]

I wish what you were saying were true but unfortunately the situation is far more complex than it seems on the surface. The explanation requires total system understanding both at digital and analog levels.

The CPU processes data and can not have an effect on sound.

So the fact that the CPU is working 1% or 7% is not relevant because the CPU is not shutting off between the intervals (and if it did, it might cause other audible problems).

Audible problems? How so, the CPU processes data that the program tells it to do, it does not insert random data.

Now here is where it gets interesting. The sound subsystem is also sitting on the same power supply line (even with post regulators). The DAC master clock gets its power from the same line as does the reference voltage. Vary either one of these a hair (picoseconds in case of master clock) and the sound changes. Remember, the DAC is not a digital device. It takes digital samples. But what it outputs is analog both in value and timing. The only way it can be accurate in its output is if its input is accurate (clock and reference voltage).

Please tell me at what point jitter becomes audible.

In summary, the CPU is connected through the power supply to the most sensitive parts of the audio reproduction system. Its activities (or lack thereof) have the potential to impact the audio fidelity because it changes the parameters which the DAC sees. As long as you share a connection between the two parts, you can’t eliminate the impact of the CPU at the extreme. You can build a PC that is fairly immune to these problems (say, by having independent power supplies and total isolation) but I suspect none of you have such a system. Putting even a good sound card in a PC subjects it to the issues discussed so far.

So as you see, there can be an impact. What that is in real life in the PC you use is unpredictable due to complexity of the system and the many variables. And of course, how sensitive your ears are in picking up the variations is also a major factor.

The load on a CPU will not change the sound, running an intel or AMD processor will not change the sound. If you want to talk about jitter we can do that but the CPU is irrelevant. If the entire computer changed the 0's and 1's that much just imagine what it would do with the rest of the data, booting into windows or a mac OS would not be possible.

[Dizzman]

damm... there goes that record skipping again!

I think it may be broken

[DougWinsor]

damm... there goes that record skipping again!

I think it may be broken

If you don't have anything to add why are you posting?

[markrubin]

Originally Posted by Dizzman

damm... there goes that record skipping again!

I think it may be broken

Originally Posted by DougWinsor

If you don't have anything to add why are you posting?

that is quite enough

[faberryman]

Originally Posted by DougWinsor

Please tell me at what point jitter becomes audible.

This is a debate which is recurring. Perhaps it would be better if we start a thread devoted to the subject.

[amirm]

Originally Posted by DougWinsor

The CPU processes data and can not have an effect on sound.

I wrote an entire post to address why this assertion was wrong. And there you go saying it again as if that makes your point stronger. It doesn't.

Audible problems? How so, the CPU processes data that the program tells it to do, it does not insert random data.

Then explain this. I have a Dell workstation with a seperate, half decent sound card (i.e. not the garbage that comes on the motherboard). I hook said PC to an HP all-in-one fax/printer over USB cable. As soon as I turn on the fax machine, I hear nice static and noise synchronized to activities of that box. You like to explain to me why that noise exists if what the digital circuit is doing has nothing to do with analog sound coming out of the PC?

Please tell me at what point jitter becomes audible.

I don't know that I want to do that when I have presented a much simpler case above. Surely you have heard PCs where you connect a headphone to them and hear your CD-ROM or Hard Drive activity coming through it loud and clear. Have you not? If so, what explains that if the system activity means nothing? Have you heard a stand-alone CD player do the same? I suspect not. Why is that?

The load on a CPU will not change the sound, running an intel or AMD processor will not change the sound. If you want to talk about jitter we can do that but the CPU is irrelevant.

Where do you think jitter comes from? From the heavens? It comes from crosstalk through the power supply that is the common link between the digital circuits and analog (some also gets induce by RF signals).

If the entire computer changed the 0's and 1's that much just imagine what it would do with the rest of the data, booting into windows or a mac OS would not be possible.

That is an unrelated topic. "Data" by definition is digital. Digital circuits tolerate jitter because they can latch onto the data within their timing window. So they either work or don't.

The topic here is analog, not digital. You don't hear 1s and 0s, do you? Let's skin the cat this way. Why don't you explain to us how a DAC works. And while you at it, specify what kind of timing data and reference accuracy you need to reproduce 16-bits of resolution (what you rip from your CDs). I think in the process of doing so, you will see that your assertions are incorrect .

[DougWinsor]

Then explain this. I have a Dell workstation with a seperate, half decent sound card (i.e. not the garbage that comes on the motherboard). I hook said PC to an HP all-in-one fax/printer over USB cable. As soon as I turn on the fax machine, I hear nice static and noise synchronized to activities of that box. You like to explain to me why that noise exists if what the digital circuit is doing has nothing to do with analog sound coming out of the PC?

Noise through what?

I don't know that I want to do that when I have presented a much simpler case above. Surely you have heard PCs where you connect a headphone to them and hear your CD-ROM or Hard Drive activity coming through it loud and clear. Have you not? If so, what explains that if the system activity means nothing? Have you heard a stand-alone CD player do the same? I suspect not. Why is that?

CD-rom and hard drive noise coming through the head phones? I have never heard of any of these problems you are experiencing.

Where do you think jitter comes from? From the heavens? It comes from crosstalk through the power supply that is the common link between the digital circuits and analog (some also gets induce by RF signals).

Again the CPU does not and can not cause and audible change, you are talking about seperate hardware. Since you do not know when jitter becomes audible why are you concerned about it in a PC environment?

That is an unrelated topic. "Data" by definition is digital. Digital circuits tolerate jitter because they can latch onto the data within their timing window. So they either work or don't.

The topic here is analog, not digital. You don't hear 1s and 0s, do you? Let's skin the cat this way. Why don't you explain to us how a DAC works. And while you at it, specify what kind of timing data and reference accuracy you need to reproduce 16-bits of resolution (what you rip from your CDs). I think in the process of doing so, you will see that your assertions are incorrect

How is processing a MP3 file thought a processor analog? You said that the CPU can affect the sound.

[amirm]

Originally Posted by DougWinsor

Noise through what?

Through the output of the sound card.

CD-rom and hard drive noise coming through the head phones? I have never heard of any of these problems you are experiencing.

Do you have a laptop? If so, plug in a headphone and turn up the volume to max without playing anything. Then access your PC. Do you hear any noise? Does it change? Try the same with other PCs around your home/work.

Again the CPU does not and can not cause and audible change, you are talking about seperate hardware. Since you do not know when jitter becomes audible why are you concerned about it in a PC environment?

Trust me, I am more than capable to run with the jitter argument . But am refusing to take the bait and get into that rathole when there is a much easier argument per above. But if you are interested, search for my recent posts in this very forum where I discussed the topic at length, and cited papers answering your very question. But be forewarned, they are much more technical than this discussion .

How is processing a MP3 file thought a processor analog? You said that the CPU can affect the sound.

I spent two posts explaining how so if the point is still not clear, it surely means the fundamentals are not understood.

These are the questions you must be able to answer to understand the argument:

1. What is the dynamic range you need to have to not hear the noises I talk about above?

2. How does a DAC convert digital samples to analog?

3. What jitter spec must you have to reproduce the lower order bit in a 16-bit sample?

4. What accuracy do you need to have in the DAC reference voltage to reproduce the low order bit in a 16-bit sample?

5. What causes jitter?

6. What type of jitter is bad?

BTW, there is no shame in not knowing the answers above. Many people wouldn't. But understanding them is key to continuing this discussion at a sane level .

[DougWinsor]

Through the output of the sound card.

Do you have a laptop? If so, plug in a headphone and turn up the volume to max without playing anything. Then access your PC. Do you hear any noise? Does it change? Try the same with other PCs around your home/work.

This makes no sense, you are saying that some type of interference is being transmitted through a USB cable via a fax machine and that some type of noise from the hard drive/CDrom is also working its way through the entire PC to the audio outputs of a sound card. No I have never heard of this or experienced that is anyway. Also why would you turn any type of volume control to max, this can cause damage, maybe that is the problem with your equipment.

I spent two posts explaining how so if the point is still not clear, it surely means the fundamentals are not understood.

A processor/CPU is not a analog device.

1. What is the dynamic range you need to have to not hear the noises I talk about above?

The noise you talked about does not exist or else PC hardware would not be used for anything audio.

2. How does a DAC convert digital samples to analog?

What does this have to do with a CPU affecting the sound?

3. What jitter spec must you have to reproduce the lower order bit in a 16-bit sample?

You said you did not know when jitter becomes audible so why are you asking this?

4. What accuracy do you need to have in the DAC reference voltage to reproduce the low order bit in a 16-bit sample?

That would depend on the DAC but this is irrelevant to the conversation.

5. What causes jitter?

6. What type of jitter is bad?

What does jitter have to do with a CPU changing the sound?

BTW, there is no shame in not knowing the answers above. Many people wouldn't. But understanding them is key to continuing this discussion at a sane level .

You stated that not only a CPU can affect the sound by simply processing data but you also stated that the % of load on the CPU can change the way something sound. As of yet you have not explained any of this.

[markrubin]

Doug: This has to stop

every thread in this forum is being derailed

[no reply is necessary]