Originally Posted by mlknez
When you say the source is hi-res, are you referring to everything in the chain? such as microphones, pre-amps, ADCs, storage media, etc? If ANY one of these is not Hi-Res capable, should the term Hi-Res be associated with the source recording?
Someone else had a related question in the pre-AMA thread and here it is along with my response.
AVSForum member 1984kapil asked:
“What are the specifications for high-res audio (HRA) and what devices available presently can record that? What is needed in a device to play HRA?
As I mentioned in my first post, the basic definition and specs for high-resolution audio are better than CD-quality, which translates to greater than 16-bit resolution and higher than a 44.1 kHz sampling rate. Devices that are capable of recording that resolution have been available for a long time and have now reached extremely low price points. In fact, if you do a quick search around sites like Musician’s Friend, Guitar Center, etc., you can find computer audio interfaces that support 24-bit, 192 kHz recording for under $100. So, there is an enormous range and diversity of equipment in the wild that can easily create audio files that meet high-resolution audio standards—from bedroom studios to concert halls to professional recording studios.
Of course, this gets back to a comment I made earlier. Just because you can create high-resolution files doesn’t mean it’s necessarily going to sound good. Everything from the instruments, microphones, cables, signal processing equipment, acoustic environment and, oh yeah, engineering talents and skill can (and does) have a much bigger impact on overall audio quality than the “type” of file that it is.
As a result, many people want to know the entire history, or provenance, of how a musical recording came to be. What mics were used, what type of mixing board (if any), what type of recording equipment, which instruments, which software, what recording formats, etc. Plus, for some, it’s not enough to know how the basic tracks were recorded because for most recordings, you also have to deal with mixing and mastering, where yet more equipment and adjustments affect the audio path. Realistically, it’s almost impossible to get all this type of information for a single recording (with a few notable exceptions), let alone enormous libraries of music.
This also relates to the concepts of remixing or remastering, where someone will leverage the original individual recorded tracks and then redo the final process of creating a stereo track we can all listen to. In some cases, yes, a good engineer with newer, higher-performing, better-sounding equipment might be able to create a “better” sounding final mix, but that’s not always the case. Sometimes remixes sound worse.
Of course, this brings up a whole other issue regarding the subjectivity of what sounds “good” to one person vs. another. Music is an art form that creates strong emotional responses in people. Just as our emotions can impact how we feel, they can also impact how we hear. The exact same piece of music played back on the exact same set of equipment can sound different to us on different days—it’s a basic fact of being human. From a scientific perspective, it might generate the same waveform (although even that can be impacted by environmental factors ranging from the quality of the electrical power, the equipment, and lots more), but we can still hear it differently. That’s not a bad thing…it’s just life.
On to the second half of your question. In order to play high-res audio files, you need a source device that is capable of “reading” the high-res file format you’re choosing to play (not all high-res devices support all high-res audio formats) and some kind of audio reproduction system, such as amplifiers, an AV receivers speakers, and/or headphones.
Note that because different file “wrapper” formats can also support several different types of raw audio resolutions, you sometimes need to dig a bit deeper into the specifications than just knowing, for example, if a device supports FLAC files. You need to know if it supports FLAC files recorded at 192 kHz with 24-bit resolution, as an example. In addition, in the case of compressed audio-file formats, you need to know if, for example, your AV receiver, DAC (digital-to-analog convertor), or other audio component can decode and decompress the specific file format/compression method that you want to play. In some instances, you’ll also need to worry about audio-encoding formats—typically PCM and DSD—which technically aren’t file formats (they are different ways to represent audio in the digital domain), but are commonly grouped with them.
As to the exact type of components, well, that’s where things get interesting once again. Here’s where we get into even more spec wars (and much more heated arguments about science vs. subjectivity!). In theory, because high-resolution audio offers the potential for a wider frequency and dynamic range than standard CD-quality audio, the entire playback system chain, from source to amp to transducer (either speakers or headphones) should be able to handle a frequency response above 22 kHz and dynamic range of greater than 96 dB.
In reality, however, that’s difficult to do—and there is an enormous range of factors that can influence this. For one thing, no equipment exists that provides a perfect reproduction of audio waveforms. From the flatness of the frequency response over a range of frequencies to inconsistencies in output levels, anomalies exist and are compensated for in a wide range of different ways. The bottom line is that there are inevitable alterations to the sound that may vary across different types of music and may be more or less offensive to one set of ears than another. As I said, music and audio have a very subjective element to them.
In order to translate this extremely complicated set of requirements into something a bit more understandable to interested music consumers, it’s time to turn to yet another definition of high-res audio. The Hi-Res Audio logo program was first created by the Japan Audio Society, which includes a number of consumer electronics companies such as Sony, Pioneer and others, back in 2013, and was then licensed to the Consumer Electronics Association (now called the Consumer Technology Association) in 2014. The idea behind the logo program was to help provide both some additional technical requirements for different audio components, as well as allow consumers to easily identify which components meet those specs. Basically, if the components meet the spec, they are allowed to have a logo sticker identifying that they do. Easy.
A document outlining the specific elements of this definition (which was linked to in a few posts from the pre-AMA thread and, for the record, is not proprietary to Sony and is linked to again here
) requires source devices to be able to playback 96 kHz, 24-bit files stored in WAV, FLAC and PCM formats, and recommends they can playback 192 kHz, 24-bit files for those three plus ALAC, AIFF and DSD-formatted DSDIFFF and DSF files (which feature 2.8 MHz, 1-bit sampling). In addition, any signal processing and digital-to-analog conversion, such as through the audio DACs, needs to support 96 kHz, 24-bit or higher data streams. Finally, any amplifiers, headphones or speakers are also expected to support frequencies to at least 40 kHz, although the frequency response can drop by as much as 30 dB from a flat response at 40 kHz. There are a few additional speaker specs that go into off-axis frequency response as well for those who want to dive even deeper.
One notable exemption from the Hi-Res Audio logo program is multichannel audio, such as Dolby TrueHD and DTS-HD Master Audio. They are not included because the program is focused solely on stereo files and equipment (or systems) designed to playback two-channel audio.
While we’re on the topic of logo programs, it’s also worth mentioning that the RIAA (Recording Industry Association of America), which is a group of music publishing and record companies that certify a recording as being “gold” among other things, has a related definition and logo for Hi-Res Music (not Audio) that was just introduced last year. The Hi-Res Music logo, which can be assigned to both digital downloads and music-streaming services, requires that hi-res music be “lossless audio capable of reproducing the full spectrum of sound from recordings which have been mastered from better than CD quality (48kHz/20-bit or higher) music sources which represent what the artists, producers and engineers originally intended.”
The Hi-Res Music logo is meant to be complementary to the Hi-Res Audio logo and is designed to make it much easier for consumers to find music that will play properly on their audio equipment. Essentially, all digital audio files labelled Hi-Res Music will play back on all Hi-Res Audio labelled audio equipment. Given how ridiculously complicated this can get for even very tech- and audio-savvy consumers, this type of effort was desperately needed and should be applauded.