Many audiophiles who use iTunes as their principal music library tend
to be individuals who accumulate large music collections. I myself have
close to 30,000 tracks. However, I have heard from many BitPerfect
users who have as many as 75,000 tracks. A friend of mine has close to
7,000 CDs arrayed across many, many storage shelves, so I can see how
that would be possible.
When
you have a collection that big, your best solution is to store the music
off-line, on an external HD or, better still, a NAS (which is my
preferred solution). When it comes to iTunes, this naturally raises the
issues of whether or not to allow iTunes to copy your music into your
Media Folder upon import, and whether or not to allow it to Organize
your music fielder for you. Both of those features are implemented as
check boxes in the Advanced tab of iTunes’ Preferences menu. When you
start off using iTunes, and you have a small music collection, having
iTunes do all the heavy lifting for you can be a bonus, but eventually
you reach the point where you are no longer happy with the way iTunes
does things and you want to do it yourself. Most BitPerfect users -
myself included - fall into this camp. There is no way I’m letting
iTunes organize my music for me
However, if you are happy letting iTunes do all the organizing of your
Music Library, then there are some things you need to be aware of when
using DSD Master.
DSD Master has a neat feature which allows
you to automatically import the files it has created into iTunes.
However, if you have iTunes set to “Copy files to iTunes Media Folder
when adding to the library”, you will need to look out for a couple of
things. First, if you set DSD Master’s output directory to be, for
example, a folder on your Desktop, then after the files have all been
created and successfully imported into iTunes, you will have duplicates
of each - one in the folder on your Desktop and the other somewhere in
your iTunes Media folder. You won’t need both copies, so you can safely
delete the original one on your Desktop. Of course, if you specify the
iTunes Media folder as DSD Master’s output directory this problem goes
away completely.
An interesting thing happens if you choose to
check iTunes setting “Keep iTunes Media Folder Organized”. This does
two things. First, it organizes the music files in the iTunes Media
folder into folders by Artist, and sub-folders by Album. This
information is gleaned from the metadata in the music files during the
import process. Secondly, it is also liable to rename the files
according to some internal Apple logic. At this point, I don’t know
what that logic is, but if you are creating Hybrid-DSD files, these will
be renamed from “filename.DSDh.m4a” to “filename.m4a”. There will be
no loss in functionality, but if you were hoping to rely on the “.DSDh.”
to identify the Hybrid-DSD files in future, then this useful feature
will be lost.
Thanks to BitPerfect User Eric Tan for drawing my attention to this.
Thursday, 1 May 2014
Monday, 10 March 2014
Minor Bug in DSD Master
It appears that there is a minor bug in DSD Master. We will issue an update with a fix pretty soon, but in the meantime the workaround is very simple.
If the first thing you try to do with DSD Master is make a Hybrid-DSD file it will fail. Instead, it is necessary to first make an Apple Lossless file. You just have to do it once. That is all that is needed to make the bug go away forever. After you have done that you can create Hybrid-DSD files.
If the first thing you try to do with DSD Master is make a Hybrid-DSD file it will fail. Instead, it is necessary to first make an Apple Lossless file. You just have to do it once. That is all that is needed to make the bug go away forever. After you have done that you can create Hybrid-DSD files.
Sunday, 17 November 2013
History
BitPerfect Sound Inc.
has been interested in DSD playback since early 2012. Initially, our
interest was in learning about the format, and understanding how it
works and how the various playback solutions functioned. We wanted to
understand how Sigma-Delta Modulators work (these are the complex
devices which create a DSD data stream), and to understand why - also
how, and even if - DSD sounded different to high-resolution PCM. We acquired some software, co-opted some fellow-travellers, and began to experiment with converting PCM to DSD and vice-versa.
One of the first things we discovered was that different software which performed the DSD-to-PCM conversions produced PCM tracks which sounded markedly different. On one hand, this should not have been a surprise, since we knew that the conversion process is inherently not lossless, but on the other hand you can never be certain whether the differences will actually be audible, given the superb audio specifications claimed for both DSD and high-resolution PCM. It was therefore a considerable surprise to us that the differences were not only audible, but that the magnitude of the differences was so great. This was concerning to us, since even the poorest performing (at least based on our subjective assessment) software is being used to produce commercial products for purchase and download.
We were interested to see if we could understand the factors which can result in adverse sonic characteristics. It turned out that, yes, we could identify those factors, and having done so we used those results to define an algorithm and methodology which we believed could produce significantly improved results. After substantial testing we came to the conclusion that our results are audibly superior to all of the the alternatives currently on the market. We have now reached the point where we know of no way in which to significantly improve upon these results. These advances are now available to you as DSD Master.
[Note: It is interesting that the opposite is not the case. Converting PCM to DSD is a technical challenge which is exponentially more complicated both to understand and to execute. We have a lot more work ahead of us before we can hope to launch a PCM-to-DSD converter for which we can make similar claims.]
So what kind of technologies lie behind DSD Master? DSD-to-PCM conversion is at its core a two-step process. First, the DSD datastream is passed through a low-pass filter. Second, the output of the filter is passed through a sample rate converter. Optimizing these processes is, at least in part, a matter of trading off several factors: (i) the time taken to perform the calculations; (ii) the amount of memory needed to store the intermediate calculation results; and (iii) the minimum CPU specification demanded; against the performance of the filter and converter. The design of filter is crucial here as the filter's characteristics will impact - among other things - the frequency and phase responses of the converter (and also the impulse response, which is a convolution of the frequency and phase responses). Each of these characteristics is very important, and you cannot achieve ideal behavior from all three simultaneously. A critical aspect of filter design comes from your choice of which compromises are acceptable and which are not. Additionally, if you expect a lot from your filter, you must be aware of the numerical precision with which both the hardware and software will execute the calculations, and assure yourself that it will be able to deliver the accuracy you require at the output. Finally, you can easily throw away all the benefits of a well-executed filter by adopting a sample rate converter of less than comparable quality. Where compromise is called for, DSD Master has chosen wherever possible to sacrifice process speed for performance.
As we developed this product, we were thinking that a significant motivation for BitPerfect users was to enable them to make the best possible versions of their DSD tracks so they could load them into iTunes and play them through BitPerfect. But this was not too persuasive an argument, since if customers had gone to the trouble and expense of purchasing DSD music, then they wanted to play it natively, and would probably instead use a different player to play them. This was a doubly frustrating realization for us, since BitPerfect internally has long been able to play DSD. The problem has always been that you cannot load DSD files into iTunes. We realized, however, that we could use DSD Master as the basis for a very elegant solution to this problem - we call this solution our "Hybrid-DSD" file. You can read more about that here. These "Hybrid-DSD" files can be loaded into iTunes, will automatically play PCM music if iTunes is used without BitPerfect, and, if BitPerfect is in use, will play DSD if the DAC supports it and PCM otherwise. This, finally, is the solution we have been looking for for some time.
One of the first things we discovered was that different software which performed the DSD-to-PCM conversions produced PCM tracks which sounded markedly different. On one hand, this should not have been a surprise, since we knew that the conversion process is inherently not lossless, but on the other hand you can never be certain whether the differences will actually be audible, given the superb audio specifications claimed for both DSD and high-resolution PCM. It was therefore a considerable surprise to us that the differences were not only audible, but that the magnitude of the differences was so great. This was concerning to us, since even the poorest performing (at least based on our subjective assessment) software is being used to produce commercial products for purchase and download.
We were interested to see if we could understand the factors which can result in adverse sonic characteristics. It turned out that, yes, we could identify those factors, and having done so we used those results to define an algorithm and methodology which we believed could produce significantly improved results. After substantial testing we came to the conclusion that our results are audibly superior to all of the the alternatives currently on the market. We have now reached the point where we know of no way in which to significantly improve upon these results. These advances are now available to you as DSD Master.
[Note: It is interesting that the opposite is not the case. Converting PCM to DSD is a technical challenge which is exponentially more complicated both to understand and to execute. We have a lot more work ahead of us before we can hope to launch a PCM-to-DSD converter for which we can make similar claims.]
So what kind of technologies lie behind DSD Master? DSD-to-PCM conversion is at its core a two-step process. First, the DSD datastream is passed through a low-pass filter. Second, the output of the filter is passed through a sample rate converter. Optimizing these processes is, at least in part, a matter of trading off several factors: (i) the time taken to perform the calculations; (ii) the amount of memory needed to store the intermediate calculation results; and (iii) the minimum CPU specification demanded; against the performance of the filter and converter. The design of filter is crucial here as the filter's characteristics will impact - among other things - the frequency and phase responses of the converter (and also the impulse response, which is a convolution of the frequency and phase responses). Each of these characteristics is very important, and you cannot achieve ideal behavior from all three simultaneously. A critical aspect of filter design comes from your choice of which compromises are acceptable and which are not. Additionally, if you expect a lot from your filter, you must be aware of the numerical precision with which both the hardware and software will execute the calculations, and assure yourself that it will be able to deliver the accuracy you require at the output. Finally, you can easily throw away all the benefits of a well-executed filter by adopting a sample rate converter of less than comparable quality. Where compromise is called for, DSD Master has chosen wherever possible to sacrifice process speed for performance.
As we developed this product, we were thinking that a significant motivation for BitPerfect users was to enable them to make the best possible versions of their DSD tracks so they could load them into iTunes and play them through BitPerfect. But this was not too persuasive an argument, since if customers had gone to the trouble and expense of purchasing DSD music, then they wanted to play it natively, and would probably instead use a different player to play them. This was a doubly frustrating realization for us, since BitPerfect internally has long been able to play DSD. The problem has always been that you cannot load DSD files into iTunes. We realized, however, that we could use DSD Master as the basis for a very elegant solution to this problem - we call this solution our "Hybrid-DSD" file. You can read more about that here. These "Hybrid-DSD" files can be loaded into iTunes, will automatically play PCM music if iTunes is used without BitPerfect, and, if BitPerfect is in use, will play DSD if the DAC supports it and PCM otherwise. This, finally, is the solution we have been looking for for some time.
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