July 13, 2018

MQA Music production workflow for professional [ Technical seminar report ]

by Bob Stuart and Mick Sawaguchi

This is a seminar report in which held at InterBEE in 2017 November. On the consumer side, MQA (Master Quality Authenticated) technology has attracted attention for several years but since there was not much opportunity to introduce it systematically to the domestic production side, we had a session at the professional exhibition called InterBEE this time has been held.
The session was held on the afternoon of November 15th, when Bob Stuart, MQA developer and C. E. O, came to Japan on MQA's basic technology and MQA-CD production applying it. I also focused on MQA's technology, continuously released albums in MQA format from UNAMAS-Label, and released the world's first MQA-CD [A. Piazzolla a Strings and Oboe] from OTTAVA-Records So I will introduce the overview as I participated in the lecture.

1 Purpose of MQA coding and trend of music

Bob: Thank you for coming all the MQA sessions. Today, I am very pleased that we have the opportunity to systematically introduce MQA to the professional people on the production side and what kind of application it is.

First, let's see the relationship between quality and convenience in music software for the past 50 years.

Analog ·open reel tape can say that quality is equivalent to master, but it is not easy to handle. The quality of the cassette tape is not good, but it can be handled easily. Although DVD-A and SA-CD are high quality, this also requires a special player. Internet stream delivery is extremely convenient, but the quality is not good.

So what is the goal that MQA aims for? As the goal is to have high quality and convenience as shown on the right side of the figure MQA has developed three goals for this purpose. I will introduce MQA approaches in the following order.
2 Studio Master for quality:
MQA-De-Blur technology that emphasizes time axis information rather than frequency domain

Music production by high bit / high sampling exceeding CD quality has been done and sound source has been spreading in the form of downloading. The figure shows the result of subjective evaluation of the relationship between various formats and the quality obtained by our top mastering engineers in Europe and America.

From this result, we can see that no significant improvement in quality has been seen for the amount of data at 96 KHz sampling or later. In general, I thought that recording high-bit and high sampling improves frequency characteristics and improves quality. What we focused on is the result of a recent brain hearing study. That is, "accurate reproduction of time axis characteristics is an important factor to quality" beyond the expansion of the frequency domain. It is said that high bit / high sampling is being performed because it records this time axis information accurately as it makes high bit / high sampling.

The time axis is accurate means that the precision with which the sound source can be perceived correctly improves, and in the case of music it means that the sound quality, localization, depth, distance feeling can be accurately reproduced. Human auditory detection limit is said to be 5 μsec - 8 μsec. This means that you can detect sound sources up to distances of 1 m - 2 m, centered on yourself.

This figure shows the accuracy of the time axis characteristics at Fs: 48 KHz and 192 KHz.

MQA developed with the goal of reducing the fluctuation of the time axis fluctuated in the workflow from recording to playback to the extreme limit and delivering it to the end user.
We call this "De-Blur" [De-Smear].

That is, it is a technology to reproduce the time axis of the digital signal A / D converted in the recording to the same time axis information at the D / A conversion at home.

The accuracy of time axis reproduction of MQA is currently up to 10 μsec resolution, and in terms of distance it can detect distances up to 2.5 m.

3 Coding technologies to realize convenience Audio Origami

In the era when LP and CD were mainstream of music software, I was able to enjoy music simply with just one format. When it comes to the age of digital audio, a vast variety of formats ranging from compressed sound sources to Hi-Res sound sources are flooding, and listeners are confused in the playback equipment. We will provide music in a standardized format as much as possible and consider how to do so in order to be of high quality and the result will be the method called Audio-Origami, which will be described later.

The research, which became the basis, gained a hint from the analysis result of many Hi-Res music files. The average frequency of the music signal analyzed so far has a distribution of triangles we call Golden-Triangle.

In case
The high-frequency region in the high-bit-high-sampling large data volume means that there are many margins. The principle of Audio-Origami is that by dividing this music signal area into three areas ABC, it folds the information which each has, while enciphering while reducing the total amount of data, and at the time of decoding it opens the folded data It is the idea of ​​handling master quality with light data.

Sampling frequency Vs In the graph of sound quality, normal high sampling ·
Although the sound quality is gradually improved from 96 KHz if it becomes high bit, it becomes almost constant from 96 KHz in MQA encode ·decode data. The graph of red is a graph when playing with existing playback equipment without decoding MQA data, but also in this case the sound quality is also improved as the blur of the time axis information is eliminated.

The graph on the upper right shows how far the blur on the time axis (Temporal Blur) is distributed. For normal high bit / high sampling etc. SF of about 1536 KHz is required to realize 10 μsec, but in MQA it is almost 10 μsec after the master of 192 KHZ.
The graph on the lower left shows the data transfer rate. In normal digital format, the high sampling rate and high bit will result in a huge transfer rate, which requires time for downloading, but the MQA file is stored at almost 1.4 Mbps. If it is the current network infrastructure, it can be handled as very light data.

How do you embed B and C area signals to a signal level of -140 db or less? And how does De-Blur work? Although I will ask you a question like this, I will spend a lot of time when explaining this principle, so I will skip this time but since I can download MQA's WEB commentary and AES paper freely, I refer to it please. I think that an article translating my paper by Mr. Bike Suzuki to the JAS journal will be helpful.

REF:Stuart, J. R. and Craven, P.G., A Hierarchical Approach to Archiving and Distribution, 9178, 137th AES Convention, (2014). http://bit.ly/JRS_AES

Oppenheim, J. M., et al., Minimal Bounds on Nonlinearity in Auditory Processingq-bio.NC (Jan 2013). arXiv:1301.0513 

Lewicki, M.S. Efficient Coding of natural sounds, Nature Neurosci. 5, 356363 (2002). 
Jackson, H. M., Capp, M. D. and Stuart, J. R., The audibility of typical digital audio filters in a high-fidelity playback system, 9174, 137th AES Convention, (2014).

Stuart, J.R., Sound Board: High-Resolution Audio, JAES 63 No 10 pp. 831-832; (October 2015) http://bit.ly/AES_Soundboard
4 Compatibility with existing media MQA-CD

MQA data is characterized by compatibility with existing formats. Here we introduce the workflow and various tools for encoding to MQA file. MICK SAWAGUCHI will introduce the workflow of MQA-CD production after this.

5 Practice of MQA-CD production workflow

From here, Mr. Mick Sawaguchi of UNAMAS-Label will introduce MQA-CD production practice and points of note. In UNAMAS-Label, the sound source (192-24 WAV format) of distribution downloading is also released at MQA, but in June 2016, the world's first MQA-CD was released from OTTAVA RECORDS, after that the CD of OTTAVA RECORDS, Since it is released as MQA-CD, here we introduce the workflow of MQA-CD.

So, we prepared the actual sound source, so we added the same sound source for you.

1 192-24 WAV Master
2 MQA-CD-MQA decode reproduction (decoded and played from 44.1 - 16 to 176.4 - 24)
3 Normal playbacks without MQA-CD-MQA decoding (played as normal 44.1 - 16)
4 Sound sources produced in normal CD format

Please listen with the type of. Even if you do not decode MQA-CD, since blurring of sound is improved by De-Blur, I think that you can hear that it is superior in localization and sound field reproduction.

Bob: Everyone, thank you very much. I also thank Bike Suzuki of MQA-JAPAN who interpreted my academic story.

April 22, 2018

Dummy Head Sound Production Tips and Pitfall

Mick Sawaguchi UNAMAS Label C.E.O

1 Background of dummy head reevaluation  

Recording with an old and new dummy head makes it easy to enjoy 3D space by targeting listening with headphones. I think that it will be a good tool for activation of mobile audio or smart phone recently and young people's headphones listening tendency, so I would like to introduce the dummy head recording from the production side. 

The idea of ​​a dummy head is to mimic the face of a person and record a small microphone into the ear part, can you faithfully reproduce the sound we hear on a daily basis? It started with the appearance of the prototype "Mr. Oscar" of the dummy head developed at Bell Research Institute in 1933. 
Especially in Europe, dummy head research is still continuing, and academic fields such as hearing research, acoustic field measurement, acoustic analysis, etc. Its characteristics are as described below.

● Popularization of mobile audio and popularization of digital music  
players called DAP, adapted to the needs of listening to music easily anywhere Earphone listeners have increased, software optimized for headphones is also increasing its presence. it is not necessary to prepare separate MIX for achieving both speaker playback and headphone playback with the same sound source, so it is possible to provide a target with a balance that is optimal for listeners limited only to headphones .

● Dummy heads that can be used for recording and production have been introduced due to recent improvements in dummy head main body structure and improved sound quality of small internal microphones. Dummy heads of the 1980s had limited models of small microphones that can be used for built-in microphones, and its sound quality was not a preferable sound quality from the viewpoint of engineers.
Recently, the sound quality improvement of the miniature microphone is remarkable, and it is at a level that can be used sufficiently.

● Easily experience the 360 ​​degree surround sound field, since the spreading feeling of the sound field is localized outside the head, even when listening for a long time it is less tired than the sense of oppression due to the regular head position of the normal 2 CH stereo sound.

●The sound quality improvement of headphones and earphones has also
 advanced in recent years and the market of playback equipment called     
 high-quality DAP such as portable audio amplifier called Potaan and USB
 DAC connection etc. was formed and high quality playback became

2 Utilize the features of dummy head  
Compared to microphones commonly used in studio etc., what kind of features does the dummy head microphone have?

● Front Center/ behind Orientation is poor
As dummy head researchers have pointed out, the dummy head is directly in front and the rear orientation is not good.

   It is excellent for the reproduction of +/- 45 degrees on the side  
centered on the ear and +/- 120 degrees above and below the head over the head.

   Ambience recording of natural sound and music can express superior 
3D feeling.

The features of the above two points can be applied to how to use dummy heads recording, Meanwhile, the dummy head is a natural sound recording in the field and the ambience of the music recording.When using it as a microphone, the spatial reproducibility of the dummy head is successfully used.

To faithfully reproduce the sound field of the site to be recorded or the concert venue, it is necessary to pay attention to noise and background noise as much. If the level of the sound source to be recorded is high, you can not raise the S / N ratio because it can be high, but in small organized music and natural sounds of soft sounds, you have to be careful about that point. Even in studio recording, the performer's scripting noise, the squeaking of the performer's chair, movement etc. are clearly reproduced, so it can be said that this is a two-sided nature with the characteristic of realistic reproduction.

3 Utilizing the natural reproduction of 360 degrees  

It is a way of using the superiority of reproducing the3 dimensional space possessed by the dummy head as it is, so there is nothing to pay particular attention to. The choice of where to install for the sound source is the most important.

   How to use as an ambience microphone in classical recording.


Instrumentation of studio recording OFF Mike, how to use as ambience.


 Field Recording General: 
 Field recording is the same for normal equipment, but wind  
 countermeasures are the basic, so dedicated wind shield covering the 
 ears of the dummy heads or even if there is still a shortage, please take 
 countermeasures against strong wind and rain are important.

4  Dummy Head Drama Play production  
Drama production with a dummy head can be used not only to reproduce the feature of naturalness as described above but also various ways of using the front, rear, left and right, top and bottom localization from close-up to far-distance.

● Use objective and subjectivity separately
Among the dialogues, since the monologue is an effective expression when the headphone listener's in-head position is set, a normal microphone is installed at the center position of the dummy head to mix with the dummy head sound, a miniature microphone is dummy head There is a usage such as installing it in the center of, and using it together. In the drama, in the drama etc. where the story progresses by comparison of the subjective scene of the hero with the objective scene, it is possible to effectively use such contrast of the outward / inner rank like a POV.

●Use vertical feeling and ON-OFF distance sense

Since the vertical feeling and the sense of distance can be reproduced
well, the situations such as the conversation of the two people on the
roof and the downstairs and the conversation under the waterfall and
the flow under the scene may also be reproduced by the scene in real
physical situations It will be realistic if you arrange the performance in
the form of up and down of the dummy head. Even in sound effect
creation, you can also create space with that arrangement.

 Clarification of front / rear localization 
  +/- 45 degrees from the center of the ears, as mentioned above, that  
  the reproducibility is good, as mentioned above, there are times when 
  you want to express the localization just in front of you or in the real 
  world with a drama or the like. In such a case, the listener will make a 
  judgment including the prediction by not finding the position from the 
  front or the rear from the beginning, but by making the preroll a little bit 
  and adding a sense of movement and ultimately making it the front or 
  backward localization So the recognition of stereotaxis is improved.
 What about sound effects? 

  If you create a dummy head drama at an outdoor location, sound effects  
  other than speech can be used naturally as a sound caught by a dummy 
  head without discomfort, but if you want to express a sound effect with 
  intention, you need a little ingenuity . Foley material etc. If you place 
  Foley material sound in the necessary localization of the dummy head 
  and record it in the studio, Foley for the dummy head is completed. As 
  mentioned earlier, materials with low levels such as rusting clothes and  
  it may pick up the background noise inside the studio in three  
  so you should record at the Foley studio with a low NC value or when the 
  S / N ratio is severe, It is also necessary to forcibly choose not to record 
  with a dummy head.  Plug-ins that applied HRTF conversion technology 
  that it sounds like listening on the dummy head has also appeared (many
  binaural coding etc.), but when it can not be convinced with .
  Realistic solution is that to play back the sound source once to the 
  studio with a speaker and to rerecord it with the dummy head with the  
  method of"Worldizing".


For example, if you want to create a sound design such as an object falling from overhead, a flame running around 360 degrees, FLY-OVER going through the head over the missile group, set up 4 to 5 surround speakers Or you can play each sound source from up and down speakers, perform surround panning and rerecord with the dummy head installed at the center. There is no way to deteriorate in terms of sound quality, but by physically converting it to the HRTF transfer function via the dummy head, we can express the satisfaction better than the plug-in at present.

5 Balance attention point between on dummy head production and speaker playback

The dummy head has merit in that it can easily provide virtual reality to the headphone listener. As for the point of note when recording, microphone picks up every sound of 360 degrees with omni-directionality, so we recommend you to select a studio with less air conditioning noise. (Please use it if it is effective depending on the scene.) The dummy head is recommended without having to bother with noise due to the effect of location style recording outdoors.

The point of caution about speaker playback is that when you mix with headphones, the BG level such as music and bass sound and the ambience level such as reverb tend to be lower than the speaker playback, so please also check the balance by playing the speakers when mixing these scenes .
The sound recorded by the dummy head will be sound whose 4-5 KHz is emphasized and the vicinity of 8 KHz is attenuated due to its structure. Although it is not a particular problem in headphone playback, consonants etc. of serifs are emphasized when considering playing back speakers, so it is also important to keep the peak component at the time of recording with peak limiter etc.

6 What is suitable for a dummy head Production ? 
The reproducibility of the dummy head microphone is excellent if it is within 60 degrees with the ear tab as the axis. For this reason, the scenes such as the sound of the ear and oblique behind are effective so the story of the mystery or thriller psycho-touch is recommended. Adventure and spectacular stories are also genres that can be enjoyed with plenty of sound effects.

7 Dummy Head Mixing Tips
As mentioned above, the dummy head is not good at reproducing the center of the front and just behind. For this reason, in order to effectively utilize the sound field, sounds and localization are also effective if narration by the ordinary microphone and monologue recording are used together. Since the height also comes out a little, you should try the relationship between the top and bottom of the dummy head, for example the first floor and second floor scenes. Tools such as pan pot for dummy head are not currently in practical use, so we have difficulty in producing sound effects using 360 degrees. (There is a mixing console for RSS and dummy head, but it is not practical anymore ...) Also, there are not many different sound effects libraries recorded by dummy heads, and music also has less software to meet these objectives, so please think about the content balancing these points etc.

Even in Japan, people who recorded natural sounds with dummy heads and made them into CDs, and in the USA, Cesky Label produces music of various genres recorded by dummy heads for DAP listeners. If you have the opportunity, please experience dummy head production that can easily reproduce 3D stereophonic sound.

Mick Sawaguchi Bio:Fellow member AES and ips 

1971 Chiba Institute of Technology graduated from Electronics Engineering, the same year started to work in NHK as a drama mixer, he is in charge of winning works such as Arts Festival Grand Prize, Broadcast Culture Fund Award, IBC Non-Bull Doll Award, Vatican Prize Winner.

From 1985 He has been deep involved surround production. He has been respected as "Surround Syogun". Since 2001, AES and Southeast Asia focused on workshops, seminars and technical presentations, promoting Asian surround production. SurroundTerakoya opened for promotion from 2002. Since 2007 he has launched the high-quality music production label UNAMAS label and is doing high-quality music distribution. The 4 times award winning on Japan Pro Music Recording by Hi-Res music .From 2015, focusing on immersive surround sound.