Hi-MD
From Wikipedia, the free encyclopedia
In January 2004, Sony announced the Hi-MD media storage format.[1] With its release in later 2004 came the ability to use newly-developed, high-capacity 1 gigabyte Hi-MD discs, sporting the same dimensions as regular MiniDiscs.
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[edit] Main features of Hi-MD
- the ability to save non-audio data such as documents, videos and pictures
- longer playback and recording times per disc
- the ability to digitally transfer recordings to and from Hi-MD and computer. (Previously only one-way [lossy ATRAC] digital transfers were possible.)
- the ability to record in lossless linear PCM, offering CD-quality audio. This completely eliminates compression artifacts that occur when recording directly to lossy audio formats such as Sony's ATRAC, or other formats like MP3, AAC, Windows Media Audio (WMA) or Ogg Vorbis (ogg). (Previously only recording to ATRAC lossy codecs was possible.)
- the introduction of a new ATRAC3plus codec with new Hi-LP and Hi-SP bitrates
- compatibility (and enhanced capabilities) with standard MiniDiscs
Hi-MD offers the choice of several codecs for audio recording: PCM, Hi-SP and Hi-LP, each selectable on the Hi-MD Walkman itself. PCM is the highest quality mode, followed by Hi-SP (the default mode), then Hi-LP.
- PCM mode allows 94 minutes (1h:34min) of lossless CD-quality audio to be recorded to a 1 GB Hi-MD disc (or 28 minutes on a standard 80-minute MiniDisc recorded in Hi-MD mode).
- Hi-SP allows seven hours and fifty-five minutes (7h:55m) of audio to be recorded on a 1 GB Hi-MD (or 2h:20min on a standard 80-minute MiniDisc recorded in Hi-MD mode).
- Hi-LP allows 34 hours on a 1 GB Hi-MD (or 10h:10min on a standard 80-minute MiniDisc recorded in Hi-MD mode).
Each of these codecs is available natively for recording on standalone Hi-MD devices. Additional bitrates are available with SonicStage software on the computer. Up to 45 hours of audio can be recorded per disc at the lowest-quality setting via SonicStage PC transfer.
All Hi-MD units have the ability to play back regular MiniDiscs. Most Hi-MD Walkmans also have the capability to record standard MiniDiscs in standard SP, LP2 and LP4 codecs in MD mode (as opposed to Hi-MD mode), ideal for creating discs intended to be played back in older (pre-Hi-MD) MiniDisc units.
[edit] Data and audio on the same disc
Hi-MD discs offer the ability to store computer files in addition to audio data. For example, a Hi-MD disc could have both school or work documents, pictures, videos, etc. as well as music (playable in a Hi-MD Walkman) if desired.
When connected to a computer (via USB cable), a Hi-MD Walkman is seen as standard USB Mass Storage device, just like a USB stick or external hard drive. On a Windows computer, a Hi-MD device is listed as "Removable Disk" in "My Computer". The disc has a FAT filesystem. Hi-MD units are powered by the USB bus when connected—just like USB flash drives, they don't require additional power (and don't use their own battery power) when plugged in to a computer.
Sony's SonicStage music management software is not needed to save and manipulate files on the discs; it is only required to get playable audio on and off the device; all files are manipulated using standard operating-system functions. However, when SonicStage software is active, the recorder is not treated as a data storage device—SonicStage "takes over" the management of the device.
When connected to a PC, "PC--MD" appears on the Hi-MD device's display to indicate the unit is connected in PC--MD mode. In PC--MD mode, pressing Play on the unit, for example, results in "PC--MD" flashing, indicating this function cannot be activated from the device when connected to the computer. It is essentially a slave to the computer in this mode. PC--MD status is constant as long as the unit is connected via USB cable (regardless of whether SonicStage is running or not).
To play back Hi-MD audio data on the PC, SonicStage is needed. It can be done two ways:
- Launch SonicStage. Play audio from Hi-MD inside SonicStage. The audio is played back on the computer's PC speakers. SonicStage reads and decrypts the audio data straight from the Hi-MD disc.
- transfer the audio data to the PC in SonicStage. Play the audio back from the PC's hard drive (instead of playing it back from the Hi-MD unit directly).
Once the operation of transferring audio with SonicStage is completed, the audio itself can be saved in any number of ways (and audio formats). Saving audio in SonicStage in standard WAV format is a widely-accepted way to get the audio into many third-party applications like editors and sound analyzers. The user can then proceed to record CDs, edit the audio, archive to format of choice, etc.
[edit] Backward compatibility with standard MiniDiscs
Hi-MD units can play back standard MiniDiscs recorded in non-Hi-MD units, in addition to record on standard MiniDiscs and higher-capacity 1 GB Hi-MD discs. There are two user-selectable operational modes on Hi-MD units (which Sony calls Disc Modes): MD mode and Hi-MD mode.
These are automatically selected whenever a disc with a recording on it is inserted. However, when a blank disc is inserted, the recorder will default to the user-selectable Disc Mode for any recordings made on it. The default Disc Mode on Hi-MD devices is Hi-MD mode, but it can be changed to MD mode if desired.
- MD mode is useful when intending to record on a standard MiniDisc using standard MD codecs for playback on devices that are not Hi-MD compatible. Data storage (and other benefits of Hi-MD mode) cannot be used in MD mode.
- Hi-MD mode is useful when the benefits of Hi-MD mode want to be used, such as increased capacity on standard MiniDiscs, new codec choices (PCM, Hi-SP, Hi-LP) and the ability to save data on the discs along with audio.
Using Hi-MD mode with a standard 80-minute MiniDisc increases the disc's capacity from 177 MB to 305 MB. MD Mode is ignored when a 1 GB Hi-MD is inserted; Hi-MD mode is always used with 1 GB Hi-MD discs.
[edit] Sony removes restrictions
Since the release of SonicStage 3.4 (Sony's music-management program), virtually all computer audio transfer restrictions were removed. These restrictions plagued earlier versions of SonicStage for some time. Sony started a big push to dispense with the DRM restrictions with the release of SonicStage version 3.2, released in July 2005. Version 3.4 dispensed with even more.
Some of these restrictions included:
- limited Hi-MD-to-computer digital transfers of recordings made from MIC and LINE IN inputs
- barring of Hi-MD-to-computer digital transfers of recordings made from a Hi-MD unit's OPTICAL or USB connection
Analogue Hi-MD-to-computer (and computer-to-Hi-MD) transfers were always possible with some quality loss and slower transfer (with appropriate cable), but these early restrictions on digital transfers via USB severely impacted the utility and ease-of-use of Hi-MD.
A side-effect of the removal of SonicStage restrictions is that the wording in many Sony Hi-MD user's manuals regarding "transfer authorizations" don't apply to users using SonicStage versions 3.2 and later. The ability to transfer Hi-MD audio to (and from) computer is now essentially unrestricted, unlike previous versions of the software.
One limit that still remains in current software is the inability to edit tracks on-disc that were transferred from SonicStage to a Hi-MD unit. Attempting to add or erase track marks on-unit from SonicStage-transferred tracks will result in "NO EDIT" (or similar message) being flashed on the unit. No such editing restrictions exist when transferring via optical cable or via LINE-IN.
Sony mention this limitation in their manuals as necessary to prevent "loss of transfer authorization" on the edited tracks. Considering these transfer authorizations are gone now, it seems possible for Sony to get rid of this limitation as well—so that users may add and erase track marks on their Hi-MD units whenever they please, despite them having been transferred from SonicStage.
The latest officially-downloadable release of SonicStage is SonicStage CP 4.3. It is available on the following Sony sites:
[edit] Native support for MP3
In 2005 Sony released its second-generation Hi-MD devices offering native support for the popular MP3 format (earlier, SonicStage would transcode MP3 files to ATRAC format before recording on the disc). Transcoding files to lossy formats always results in lower quality sound.
Sony's MP3 file support still means that the MP3s themselves had to go through SonicStage to be put on the device, and couldn't just be copied on the discs outside of SonicStage as you can with data files on Hi-MD (or Hi-MD-formatted MiniDisc media). SonicStage 'wraps' (encrypts) the MP3 files on the disc (as it does with all audio that's playable in a Hi-MD device). To many, the requirement of SonicStage for audio transfers has been a constant drawback.
At the release of the second-generation Hi-MD models in 2005, some controversy erupted. Some users argued that MP3 playback on the devices sounded dull; the treble seemed to be muffled in comparison to ATRAC-encoded files, which sounded 'brighter'. The results were consistent. The devices could be best described as having their MP3 playback crippled, angering many customers. Sony implemented a lowpass on MP3 playback, which could make MP3 sound dull in comparison to ATRAC. Some users believe this was done intentionally in hopes of fooling listeners into believing Sony's ATRAC was superior to MP3. Regardless of the intentions of Sony, the MP3 playback roll-off problem was notably absent with the release of a new model, the MZ-RH1 Walkman, in March 2006.
[edit] Hi-MD Photo
In 2005, Sony announced Hi-MD Photo.[2]
The Sony MZ-DH10P Walkman was released to showcase the format. The unit offers a 1.3 megapixel digital camera and saves pictures to Hi-MD discs, but doesn't offer a microphone input to record live audio, as do most standard Hi-MD Walkmans. The unit was praised for its full-colour display and unique photo & music features, but met with limited market success.
[edit] Upload of 'legacy' MiniDiscs
In March 2006, Sony released the MZ-RH1 Hi-MD Walkman in Japan, which was later followed in other regions. With this unit, Sony enabled faster-than-realtime full digital transfers from standard MiniDiscs to the computer for the first time. Users with extensive MiniDisc collections, for example, could upload their recordings digitally faster than real-time via USB connection, just like Hi-MD recordings already offered.
One limitation is with transfers done from MiniDiscs recorded on NetMD devices. MiniDiscs that have had recordings transferred via USB from computer to the NetMD device cannot have those recordings uploaded to the computer digitally. However, NetMD live audio recordings (via MIC input) as well as LINE IN recordings can be transferred to the computer digitally with no restriction on the MZ-RH1.
These digital transfers of standard (pre-Hi-MD) MiniDiscs are in addition to the essentially unrestricted Hi-MD transfers already available since the online availability of SonicStage 3.4 (and later).
With the MZ-RH1, Sony made tangible speed improvements to the device over previous generations of Hi-MD recorders. The result being that the transfer times to and from computer are—under certain circumstances—cut in half over previous models, but still noticeably slower than flash memory and hard drive-based portables, because of the nature of the Hi-MD magneto-optical system.
[edit] Hi-MD selling points
Sony's Hi-MD models are widely-regarded for their high-quality recording, and are generally considered the highest quality recording devices in their price range.[verification needed]
Hi-MD's strengths over most other digital audio players and recorders on the marketplace include:
- gapless playback
- the ability to record in linear PCM at 16-bit, 44.1 kHz sampling rate (identical to CD with no lossy codecs being employed like WMA, MP3, AAC, ATRAC, etc.)
- Connection flexibility; nearly all recorders offer MIC (microphone), digital OPTICAL and analogue LINE inputs.
- Recording the entire 20 Hz–20 kHz audible frequency range, making Hi-MD suitable for high-quality live audio capture of music in addition to voice. Most voice recorders have a limited frequency range, particularly when employing poor quality internal microphones
- high-quality low-noise components and circuit design[3] (low noise MIC pre-amps, LINE IN input)
- automatic gain control (AGC), manual level adjustment and level meters on all recorders
- high and low sensitivity microphone and variable AGC settings on all recorders with a MIC input
- on-unit disc editing such as track-marking, titling, combining, dividing and grouping tracks without the need for a computer
- USB connection for two-way digital transfers (computer-to-Walkman and Walkman-to-computer)
- Synchro record for synchronising the recording from optical digital inputs
- SpeedControl—available on selected Hi-MD models—makes Hi-MD useful to musicians and language students by slowing down the audio without changing the pitch.
- A-B Repeat allows a user to make a certain section of a track within a track repeat itself; (the user selects points A and B).
- Nearly all models include a remote control as a standard accessory and all Hi-MD Walkmans have the capability to accept a remote control.
Audio can be transferred to the units without a computer via OPTICAL input, LINE IN via analogue cable and live audio via the MIC input. Optical inputs found on nearly all Hi-MD devices allow digital transfers from many CE-devices.
Transfers over digital optical cable typically maintain the high sound quality of the original by avoiding quality loss that comes from converting the digital audio to analogue form. The main difference between optical and USB transfers is that the optical transfer is real-time (i.e. 1 hour of material takes one hour to transfer). Many non-computer (and computer) devices offer optical outputs that Hi-MD can record from with high quality.
In addition to digital optical input, recording via analogue sources is possible via the LINE input. On Hi-MD Walkmans, the same physical connector accepts both analogue and optical connections.
All Hi-MD (and older MD and NetMD) devices accept user-replaceable batteries, as opposed to a single non user-replaceable embedded battery popular on most digital audio players. This allows for easy battery switching when travelling and/or after extended recording or playback sessions. Several models accept the ubiquitous AA battery.
[edit] Criticism
Criticisms of the Hi-MD format (nearly all apply to standard MiniDisc and NetMD, too):
- SonicStage
- The requirement of Microsoft Windows-based SonicStage to transfer audio to and from the device when using the USB connection—and SonicStage's own peculiarities and limitations. When a Hi-MD unit records, audio information is encrypted by the device. When transferring content to or from the computer, the same applies, except SonicStage is used to decrypt and encrypt audio. Many argue audio should be able to be placed on the device in standard formats without a proprietary application needing to be installed to view and transfer Hi-MD-playable audio, much the same way as regular files can be placed on Hi-MD discs without encryption or obfuscation. If the encrypted audio data is damaged in any way (whether through normal operation of the unit or abuse) standard operating system disc-checking tools cannot be used to attempt to recover the audio due to its proprietary encrypted nature. Hi-MD recorders natively encrypt audio data regardless of any ATRAC or linear PCM codec recording choices, and regardless of recording source (microphone, optical or line-in). Similarly, files transferred from PC via SonicStage are natively encrypted (but not necessarily transcoded) regardless of source format (AAC, MP3, WAV). Standard audio files such as MP3, FLAC, Ogg Vorbis, AAC, WMA, can be copied to a Hi-MD or Hi-MD formatted MiniDisc without the aid of SonicStage much the same way as pictures and documents are, but the files themselves will not be playable by the Hi-MD device natively (i.e. without the aid of a computer).
- Disc organisation limitations
- Hi-MD units store non-audio information (such as start and end time of tracks) in the "system file" area of the disc. The system file is updated after any recording or edits on disc (like new recordings, moving track positions, adding tracks, removing tracks, track titling, etc). For example, recording and then pressing "stop" on the unit will result in the unit saving any in-memory audio data to disc, then updating the "system file" area of the disc. "SYSTEM FILE WRITING" is commonly seen on the display of a Hi-MD unit at this time ("DATA SAVE" may appear instead, when edited track names, disc name, artist names, etc. are being saved). In both cases, it is at this point the recorder spends several seconds updating the system file area of the disc. Sony warns not to shock the unit at this time or remove the power to the unit because the entire recording can be 'lost' if the system file area is not written to or updated properly. To avert power-related problems when writing, the Hi-MD estimates whether the battery power is adequate in advance of any recording or editing taking place on the unit. "NotENOUGH POWER TO REC" and "NotENOUGH POWER TO EDIT" are two messages that may appear in the display when the recorder estimates the power to not be enough. Power-related problems are largely averted this way, but shocking the unit still may be an issue at this critical stage of writing.
- Mechanical noise
- Hi-MD units are mechanical devices, and as such, emit a noise intermittently. A disc is read (or written to) in bursts. This means that when recording (for example), the audio data is fed to a memory buffer first, then written to disc as that memory buffer is filled. The audible manifestation of this is that a spinning motor noise is heard for a short period, followed by a far longer period of silence. Then some spinning whir again, then silence. The cycle is repeated. The same applies to playback, only differently: a disc is spun faster than required for normal playback (to fill the memory buffer), then stops spinning and the audio information is emptied (played back) from memory normally. As the memory buffer depletes, the disc spins up again, maintaining the fill of the memory buffer, only to spin down the disc again (into silence). The buffer memory allows the disc to spin down completely most of the time, conserving battery life. However, during live recording operations with a microphone, this can be a problem. If the microphone is directly connected to the unit (i.e. directly connected to the MIC jack without a wire), or simply in close enough proximity with a fairly quiet background, this intermittent motor noise can be audibly present in the recording—if some basic precautions aren't taken. This contrasts with flash-based recorders with no moving parts for recording, who are able to record in silence with no self-noise. In practice, unfortunately, too many flash recorders in Hi-MD's price range are simply poor recorders, chiefly due to poor component choice, lossy encoding methods, inadequate recording features and/or poor circuit design).
- Storage capacity
- Relatively small storage capacity (1 GB per disc) compared to hard drives and some recent flash-based digital audio players. However Hi-MD's recording methods offer a large supplement to this as recordings can range from 94 mins (44.1 kHz Linear PCM) to 45 hours (48 kbit/s ATRAC3plus).
- Slow transfer rates
- When transferring audio (and data) to and from the computer. Most Hi-MD units offer far lower speeds than flash memory-based and hard drive-based devices.
- Miniaturization constraints
- The larger size of Hi-MD units in comparison to some far smaller units available on the market today. Most of these smaller portable audio devices are flash memory-based units not limited in their miniaturization by the physical dimensions of a Hi-MD.
[edit] Marketing moves
In 2006, Sony positioned Hi-MD as a Digital Audio Tape (DAT) alternative, placing the MZ-M200 Hi-MD Walkman under the Pro Audio section of its "Broadcast & Business Solutions Company" website, alongside its flash memory-based recorder, the PCM-D1.[4] Digital Audio Tape (DAT) is a high-quality digital tape format that found a niche with musicians and studios, and is valued for its high-quality sound reproduction. DAT portables have commonly been used for field recording, but have gradually been replaced by solid-state and hard drive-based units like the Aaton Cantar, the Zaxcom Deva, and similar units from Fostex and Sound Devices. (Sony and Fostex ceased manufacturing DAT devices at the end of 2005, though parts and blank tapes should be available through 2010.)
The MZ-M200 Walkman is Sony's MZ-RH1 with a powered stereo microphone included. The MZ-RH1 is targeted to a more general customer on Sony's consumer electronics sites and comes with no microphone bundle. The microphone is included to enable Hi-MD as a field recorder, and the higher price reflects the added value of the microphone.
Given the improvements in Hi-MD, such as linear PCM recording (offering truly CD-quality sound without lossy compression), as well as improvements in SonicStage, MD users may hope that marketing efforts like this might see Hi-MD's use as a field recording tool grow.
While MD has been a reasonable success in Asia (particularly in Japan and Hong Kong), North America and Europe have leaned more often towards either flash or hard drive-based systems. For professional recording, many offer features such as professional XLR microphone inputs, among other pro-centric features. These units are typically significantly larger and heavier than a Hi-MD Walkman, often with reduced battery life and higher prices. It's for these reasons Hi-MD fills a niche for high-quality recording and editing purposes in a compact size—and still remains a quality playback device. Stealth recordists, in particular, continue to favour Hi-MD.
In 2006, Hi-MD Walkman models released were the MZ-RH1 and MZ-M200. These units were designed with a particular focus on ease-of-recording, and have received a positive reception from many recording enthusiasts.
