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Can you recognize them?
These two years mp3 player can be said to be the most popular and fashionable portable entertainment. With the popularity and popularity of mp3 music formats, many well-known manufacturers around the world are launching their own mp3 player, the most famous of which. There are Dimensional Rio series and innovative Nomad series, etc. Today, some brands of mp3 players have developed into the second generation. Rio500 and Nomad II are great things that people have dreamed of.
Since I first came across the mp3 player, I have played no more than 10 mp3 players until today, from the world's first mp3 player - Mpman from Korea Shihan to the Rio 500 It’s a pity that they haven’t gotten the Nomad II player that has always been a good thing for me. It’s really regrettable. From my personal point of view, since I have xxG mp3 in my HD, I feel that the mp3 player is really good when I have not touched the MD. Not long ago, I borrowed a MD (SONY MZ-R55) from a friend. After some research, I found that MD really has a lot of exciting places. Now I will share it here.
Since I have only used one MD, it is inevitable that there will be no place. I hope that everyone will point out that it is grateful.
Before you make a comparison, you need to know some knowledge that you must know.
First, let me introduce the knowledge about MD that you may not be familiar with.
MD is the abbreviation of MiniDisc. It was first published in 1992 by SONY. It is a magneto-optical disc storage medium designed for the record publishing industry. Its sound quality can be close to CD. In 1993, SONY published the MD Data Drive for computer storage (this is almost the same as the MO used on the computer).
The name "MiniDisc" is derived from its small and exquisite appearance. The MD rewritable magneto-optical disc itself is only 64 mm in diameter and 1.2 mm thick. It is built into a 72X68X5 mm hard plastic case and looks like a computer. The three-inch disc used is almost the same structure. So an MD is smaller than a three-inch disc, and a normal CD (120 mm in diameter) is even less able to compare with it.
MD can store 74 minutes (stereo) or 148 minutes (mono) music, if it is MD DATA DRIVE (Sony desktop computer), it can store computer data equivalent to 140M capacity. An MD can record 255 songs with a total subtitle capacity of 1700 words (the text can be displayed in English, Japanese, and special symbols). Now there are products that can display Chinese.
According to SONY, MD has a million times of repeated writes (1 million times, too much), which means that you can continue to use MD in theory, no matter how you listen, record, data can It's been a long time, which is impossible with tape. And the high durability of the MD disc is also obvious to all. Compared to the rather poor recording quality of tapes and the tendency of CDs to wear out, MD has almost no physical defects. Basically, external factors do not affect MD magneto-optical disks.
From the function of the MD machine, it can be divided into a recordable MD (two heads with a head and a laser head), and a single-displacement type MD (only a laser head).
Let me talk about the technologies used by MD and their characteristics:
First, magneto-optic burning
In terms of working principle, MD and MO are the same, it is derived from magneto-optical recording technology (Magneto Optical, MO), and the theoretical basis of magneto-optical recording technology is that the magnetic medium will change at high temperature, and after cooling This change is maintained all the time (recording process), and heating again can restore it to its original state (erasing process).
First, the laser head emits a laser beam of 780 μm wavelength and a power of 4.5 watts to the MD magneto-optical disk, and heats the recording point area to 180 degrees Celsius (that is, the "Curie temperature", which is a specific temperature region in which a substance is magnetized. The "Curie temperature" of the alloy material of the MD disc is 180 degrees Celsius. At the same time, the magnetic head is recorded with the positive or negative signal to record the sound data to the heating point of the magneto-optical disc. With the non-stop rotation of the magneto-optical disc, new data constantly The ground is written in the same way, and the recorded heating point is gradually cooled down and the magnetic signal given when heating is maintained. In the magneto-optical recording process, there is no physical contact between the laser head, the magneto-optical disc itself and the recording head, so that even after repeated reading and erasing, the magneto-optical disc will not be like a CD or a magnetic tape. Gradually wear and wear, this is why SONY will claim that MD magneto-optical discs can be erased more than 1 million times.
Second, nonlinear storage
What is nonlinear storage, let's talk about what is linear storage, music tape is a linear mode to store songs. The tracks of the music tape are recorded in order from the beginning of the tape to the end of the tape. If you want to change the position of one of the songs on the entire tape, the user can only re-record the entire tape, which is a very troublesome thing. Compared with the shortcomings of music tapes, MD uses a "block" recording mode similar to that of hard disks, and distributes data in a "block" manner throughout the MD disc, making it easy to read quickly and make full use of storage. space. This is nonlinear storage. The user of the MD can simply cut, merge, delete, and move the tracks in the MD magneto-optical disc by simply pressing the edit button on the MD panel. Other information about the track, such as length of time, title, and track number, can be easily stored and edited.
Third, ATRAC compression technology
To store 74 minutes of music data of the same capacity as a CD on a 140M-capacity MD magneto-optical disc, compression technology must be used. This technology is "ATRAC" (Adaptive Transform Acoustic Coding) compression recording technology. A compression ratio of 1:5 stores music data, so that the MD machine can record music data of the same length (74 minutes stereo/148 minutes mono) as the CD at a sampling frequency of 44.1 kHz.
ATRAC's biggest feature is the "noise cancellation system", which is used to eliminate sounds outside the human hearing range, so ATRAC only separates and compresses the digital sound signals that are audible to everyone's ears. At the same time, the "sampling frequency converter" in the MD recording circuit also automatically converts the sound of other sampling rates (48 or 32 kHz) into the standard sampling frequency of MD44.1 kHz to ensure the quality of the recording. The MDs that can be recorded on the market today are generally using Sharp or Sony's ATRAC circuit. Currently Sony uses ATRAC version 4.5, and Sharp uses ATRAC version 6.0. There are some differences between the two. Sharp challenges Sony's 20-bit decoding with 24-bit decoding, so theoretically the sound quality is better than Sony's, but unfortunately there is no way to understand the difference.
Fourth, SRM shockproof
Discs have one of the biggest weaknesses in storage media, which is the fear of vibration, because if the vibration is encountered, the laser head can not read data continuously, so the current Discman generally has anti-shock devices. The anti-shock mechanism adopted by the MD machine is SRM ("Shock Resistant Memory"). The SRM is generally a 4Mbit buffer memory chip that can store up to 10 seconds of music data.
The working mechanism of SRM. It is a bit like the function of a buffer. In normal playback, the laser head transfers the data read from the MD magneto-optical disc to the SRM and stores it, then the data flows from the SRM to the ATRAC decoder, and finally undergoes digital-to-analog (D/A) conversion. The sound that the adult ear can hear, the process of this storage and then the output is continuous.
In the case where the MD body is vibrated and the laser head deviates from the original reading position within 10 seconds, the SRM can still continuously provide audio data streams to the ATRAC decoder, and the SRM also allows the laser head to have time to revert back to the original The location continues to read the data.
Can you recognize them?
These two years mp3 player can be said to be the most popular and fashionable portable entertainment. With the popularity and popularity of mp3 music formats, many well-known manufacturers around the world are launching their own mp3 player, the most famous of which. There are Dimensional Rio series and innovative Nomad series, etc. Today, some brands of mp3 players have developed into the second generation. Rio500 and Nomad II are great things that people have dreamed of.
Since I first came across the mp3 player, I have played no more than 10 mp3 players until today, from the world's first mp3 player - Mpman from Korea Shihan to the Rio 500 It’s a pity that they haven’t gotten the Nomad II player that has always been a good thing for me. It’s really regrettable. From my personal point of view, since I have xxG mp3 in my HD, I feel that the mp3 player is really good when I have not touched the MD. Not long ago, I borrowed a MD (SONY MZ-R55) from a friend. After some research, I found that MD really has a lot of exciting places. Now I will share it here.
Since I have only used one MD, it is inevitable that there will be no place. I hope that everyone will point out that it is grateful.
Before you make a comparison, you need to know some knowledge that you must know.
First, let me introduce the knowledge about MD that you may not be familiar with.
MD is the abbreviation of MiniDisc. It was first published in 1992 by SONY. It is a magneto-optical disc storage medium designed for the record publishing industry. Its sound quality can be close to CD. In 1993, SONY published the MD Data Drive for computer storage (this is almost the same as the MO used on the computer).
The name "MiniDisc" is derived from its small and exquisite appearance. The MD rewritable magneto-optical disc itself is only 64 mm in diameter and 1.2 mm thick. It is built into a 72X68X5 mm hard plastic case and looks like a computer. The three-inch disc used is almost the same structure. So an MD is smaller than a three-inch disc, and a normal CD (120 mm in diameter) is even less able to compare with it.
MD can store 74 minutes (stereo) or 148 minutes (mono) music, if it is MD DATA DRIVE (Sony desktop computer), it can store computer data equivalent to 140M capacity. An MD can record 255 songs with a total subtitle capacity of 1700 words (the text can be displayed in English, Japanese, and special symbols). Now there are products that can display Chinese.
According to SONY, MD has a million times of repeated writes (1 million times, too much), which means that you can continue to use MD in theory, no matter how you listen, record, data can It's been a long time, which is impossible with tape. And the high durability of the MD disc is also obvious to all. Compared to the rather poor recording quality of tapes and the tendency of CDs to wear out, MD has almost no physical defects. Basically, external factors do not affect MD magneto-optical disks.
From the function of the MD machine, it can be divided into a recordable MD (two heads with a head and a laser head), and a single-displacement type MD (only a laser head).
Let me talk about the technologies used by MD and their characteristics:
First, magneto-optic burning
In terms of working principle, MD and MO are the same, it is derived from magneto-optical recording technology (Magneto Optical, MO), and the theoretical basis of magneto-optical recording technology is that the magnetic medium will change at high temperature, and after cooling This change is maintained all the time (recording process), and heating again can restore it to its original state (erasing process).
First, the laser head emits a laser beam of 780 μm wavelength and a power of 4.5 watts to the MD magneto-optical disk, and heats the recording point area to 180 degrees Celsius (that is, the "Curie temperature", which is a specific temperature region in which a substance is magnetized. The "Curie temperature" of the alloy material of the MD disc is 180 degrees Celsius. At the same time, the magnetic head is recorded with the positive or negative signal to record the sound data to the heating point of the magneto-optical disc. With the non-stop rotation of the magneto-optical disc, new data constantly The ground is written in the same way, and the recorded heating point is gradually cooled down and the magnetic signal given when heating is maintained. In the magneto-optical recording process, there is no physical contact between the laser head, the magneto-optical disc itself and the recording head, so that even after repeated reading and erasing, the magneto-optical disc will not be like a CD or a magnetic tape. Gradually wear and wear, this is why SONY will claim that MD magneto-optical discs can be erased more than 1 million times.
Second, nonlinear storage
What is nonlinear storage, let's talk about what is linear storage, music tape is a linear mode to store songs. The tracks of the music tape are recorded in order from the beginning of the tape to the end of the tape. If you want to change the position of one of the songs on the entire tape, the user can only re-record the entire tape, which is a very troublesome thing. Compared with the shortcomings of music tapes, MD uses a "block" recording mode similar to that of hard disks, and distributes data in a "block" manner throughout the MD disc, making it easy to read quickly and make full use of storage. space. This is nonlinear storage. The user of the MD can simply cut, merge, delete, and move the tracks in the MD magneto-optical disc by simply pressing the edit button on the MD panel. Other information about the track, such as length of time, title, and track number, can be easily stored and edited.
Third, ATRAC compression technology
To store 74 minutes of music data of the same capacity as a CD on a 140M-capacity MD magneto-optical disc, compression technology must be used. This technology is "ATRAC" (Adaptive Transform Acoustic Coding) compression recording technology. A compression ratio of 1:5 stores music data, so that the MD machine can record music data of the same length (74 minutes stereo/148 minutes mono) as the CD at a sampling frequency of 44.1 kHz.
ATRAC's biggest feature is the "noise cancellation system", which is used to eliminate sounds outside the human hearing range, so ATRAC only separates and compresses the digital sound signals that are audible to everyone's ears. At the same time, the "sampling frequency converter" in the MD recording circuit also automatically converts the sound of other sampling rates (48 or 32 kHz) into the standard sampling frequency of MD44.1 kHz to ensure the quality of the recording. The MDs that can be recorded on the market today are generally using Sharp or Sony's ATRAC circuit. Currently Sony uses ATRAC version 4.5, and Sharp uses ATRAC version 6.0. There are some differences between the two. Sharp challenges Sony's 20-bit decoding with 24-bit decoding, so theoretically the sound quality is better than Sony's, but unfortunately there is no way to understand the difference.
Fourth, SRM shockproof
Discs have one of the biggest weaknesses in storage media, which is the fear of vibration, because if the vibration is encountered, the laser head can not read data continuously, so the current Discman generally has anti-shock devices. The anti-shock mechanism adopted by the MD machine is SRM ("Shock Resistant Memory"). The SRM is generally a 4Mbit buffer memory chip that can store up to 10 seconds of music data.
The working mechanism of SRM. It is a bit like the function of a buffer. In normal playback, the laser head transfers the data read from the MD magneto-optical disc to the SRM and stores it, then the data flows from the SRM to the ATRAC decoder, and finally undergoes digital-to-analog (D/A) conversion. The sound that the adult ear can hear, the process of this storage and then the output is continuous.
In the case where the MD body is vibrated and the laser head deviates from the original reading position within 10 seconds, the SRM can still continuously provide audio data streams to the ATRAC decoder, and the SRM also allows the laser head to have time to revert back to the original The location continues to read the data.
Can you recognize them?
These two years mp3 player can be said to be the most popular and fashionable portable entertainment. With the popularity and popularity of mp3 music formats, many well-known manufacturers around the world are launching their own mp3 player, the most famous of which. There are Dimensional Rio series and innovative Nomad series, etc. Today, some brands of mp3 players have developed into the second generation. Rio500 and Nomad II are great things that people have dreamed of.
Since I first came across the mp3 player, I have played no more than 10 mp3 players until today, from the world's first mp3 player - Mpman from Korea Shihan to the Rio 500 It’s a pity that they haven’t gotten the Nomad II player that has always been a good thing for me. It’s really regrettable. From my personal point of view, since I have xxG mp3 in my HD, I feel that the mp3 player is really good when I have not touched the MD. Not long ago, I borrowed a MD (SONY MZ-R55) from a friend. After some research, I found that MD really has a lot of exciting places. Now I will share it here.
Since I have only used one MD, it is inevitable that there will be no place. I hope that everyone will point out that it is grateful.
Before you make a comparison, you need to know some knowledge that you must know.
First, let me introduce the knowledge about MD that you may not be familiar with.
MD is the abbreviation of MiniDisc. It was first published in 1992 by SONY. It is a magneto-optical disc storage medium designed for the record publishing industry. Its sound quality can be close to CD. In 1993, SONY published the MD Data Drive for computer storage (this is almost the same as the MO used on the computer).
The name "MiniDisc" is derived from its small and exquisite appearance. The MD rewritable magneto-optical disc itself is only 64 mm in diameter and 1.2 mm thick. It is built into a 72X68X5 mm hard plastic case and looks like a computer. The three-inch disc used is almost the same structure. So an MD is smaller than a three-inch disc, and a normal CD (120 mm in diameter) is even less able to compare with it.
MD can store 74 minutes (stereo) or 148 minutes (mono) music, if it is MD DATA DRIVE (Sony desktop computer), it can store computer data equivalent to 140M capacity. An MD can record 255 songs with a total subtitle capacity of 1700 words (the text can be displayed in English, Japanese, and special symbols). Now there are products that can display Chinese.
According to SONY, MD has a million times of repeated writes (1 million times, too much), which means that you can continue to use MD in theory, no matter how you listen, record, data can It's been a long time, which is impossible with tape. And the high durability of the MD disc is also obvious to all. Compared to the rather poor recording quality of tapes and the tendency of CDs to wear out, MD has almost no physical defects. Basically, external factors do not affect MD magneto-optical disks.
From the function of the MD machine, it can be divided into a recordable MD (two heads with a head and a laser head), and a single-displacement type MD (only a laser head).
Let me talk about the technologies used by MD and their characteristics:
First, magneto-optic burning
In terms of working principle, MD and MO are the same, it is derived from magneto-optical recording technology (Magneto Optical, MO), and the theoretical basis of magneto-optical recording technology is that the magnetic medium will change at high temperature, and after cooling This change is maintained all the time (recording process), and heating again can restore it to its original state (erasing process).
First, the laser head emits a laser beam of 780 μm wavelength and a power of 4.5 watts to the MD magneto-optical disk, and heats the recording point area to 180 degrees Celsius (that is, the "Curie temperature", which is a specific temperature region in which a substance is magnetized. The "Curie temperature" of the alloy material of the MD disc is 180 degrees Celsius. At the same time, the magnetic head is recorded with the positive or negative signal to record the sound data to the heating point of the magneto-optical disc. With the non-stop rotation of the magneto-optical disc, new data constantly The ground is written in the same way, and the recorded heating point is gradually cooled down and the magnetic signal given when heating is maintained. In the magneto-optical recording process, there is no physical contact between the laser head, the magneto-optical disc itself and the recording head, so that even after repeated reading and erasing, the magneto-optical disc will not be like a CD or a magnetic tape. Gradually wear and wear, this is why SONY will claim that MD magneto-optical discs can be erased more than 1 million times.
Second, nonlinear storage
What is nonlinear storage, let's talk about what is linear storage, music tape is a linear mode to store songs. The tracks of the music tape are recorded in order from the beginning of the tape to the end of the tape. If you want to change the position of one of the songs on the entire tape, the user can only re-record the entire tape, which is a very troublesome thing. Compared with the shortcomings of music tapes, MD uses a "block" recording mode similar to that of hard disks, and distributes data in a "block" manner throughout the MD disc, making it easy to read quickly and make full use of storage. space. This is nonlinear storage. The user of the MD can simply cut, merge, delete, and move the tracks in the MD magneto-optical disc by simply pressing the edit button on the MD panel. Other information about the track, such as length of time, title, and track number, can be easily stored and edited.
Third, ATRAC compression technology
To store 74 minutes of music data of the same capacity as a CD on a 140M-capacity MD magneto-optical disc, compression technology must be used. This technology is "ATRAC" (Adaptive Transform Acoustic Coding) compression recording technology. A compression ratio of 1:5 stores music data, so that the MD machine can record music data of the same length (74 minutes stereo/148 minutes mono) as the CD at a sampling frequency of 44.1 kHz.
ATRAC's biggest feature is the "noise cancellation system", which is used to eliminate sounds outside the human hearing range, so ATRAC only separates and compresses the digital sound signals that are audible to everyone's ears. At the same time, the "sampling frequency converter" in the MD recording circuit also automatically converts the sound of other sampling rates (48 or 32 kHz) into the standard sampling frequency of MD44.1 kHz to ensure the quality of the recording. The MDs that can be recorded on the market today are generally using Sharp or Sony's ATRAC circuit. Currently Sony uses ATRAC version 4.5, and Sharp uses ATRAC version 6.0. There are some differences between the two. Sharp challenges Sony's 20-bit decoding with 24-bit decoding, so theoretically the sound quality is better than Sony's, but unfortunately there is no way to understand the difference.
Fourth, SRM shockproof
Discs have one of the biggest weaknesses in storage media, which is the fear of vibration, because if the vibration is encountered, the laser head can not read data continuously, so the current Discman generally has anti-shock devices. The anti-shock mechanism adopted by the MD machine is SRM ("Shock Resistant Memory"). The SRM is generally a 4Mbit buffer memory chip that can store up to 10 seconds of music data.
The working mechanism of SRM. It is a bit like the function of a buffer. In normal playback, the laser head transfers the data read from the MD magneto-optical disc to the SRM and stores it, then the data flows from the SRM to the ATRAC decoder, and finally undergoes digital-to-analog (D/A) conversion. The sound that the adult ear can hear, the process of this storage and then the output is continuous.
In the case where the MD body is vibrated and the laser head deviates from the original reading position within 10 seconds, the SRM can still continuously provide audio data streams to the ATRAC decoder, and the SRM also allows the laser head to have time to revert back to the original The location continues to read the data.