[permalink] [id link]
The PASC compression scheme was believed to give better quality audio than the 5: 1 compression used by ATRAC in the original MiniDisc, but not as good as the uncompressed DAT, although both Philips and Sony stated the difference was imperceptible to listeners ' ears ( like MP3 or AAC files today ).
from
Wikipedia
Some Related Sentences
PASC and compression
The DCC was cheaper and simpler mechanically than DAT, but did not make perfect digital copies as it used a lossy compression technique called PASC.
To compensate, Philips used an audio compression codec based upon MPEG-1 Audio Layer I ( MP1 ) and termed PASC ( Precision Adaptive Sub-band Coding ).
PASC lowered the typical bitrate of a CD recording of approximately 1. 4 megabits per second to the much lower bitrate of 384 kilobits per second, a compression ratio of around 4: 1.
* PASC audio compression, a version of MPEG-1 Audio Layer I
PASC and was
Unfortunately this conversion was extremely slow but it was later discovered that the PASC files were simply MPEG-1 Audio Layer I files that used a hardly-used, hardly-documented padding feature from the MPEG standard to make all frames the same length, so it was easy to convert PASC to PCM and vice versa.
PASC and by
Besides storing the data in compressed format, PASC also provided redundancy by adding CIRC ( Cross Interleaved Reed-Solomon Code ) bits for error detection and correction, and by scattering the data across the tracks in what Philips called a " checkerboard pattern ".
PASC and Philips
However, many users complained that they would have liked to have the possibility of using WAV files, and Philips sent registered users a floppy disk in the mail, containing programs to convert a WAV file to PASC and vice versa.
compression and scheme
For instance, a compression scheme for video may require expensive hardware for the video to be decompressed fast enough to be viewed as it is being decompressed, and the option to decompress the video in full before watching it may be inconvenient or require additional storage.
The lossy compression scheme MPEG-1 Layer-3, popularly known as MP3, later revolutionized the digital music domain.
If a compression scheme is lossless — that is, you can always recover the entire original message by uncompressing — then a compressed message has the same quantity of information as the original, but communicated in fewer bits.
Roughly speaking, Shannon's source coding theorem says that a lossless compression scheme cannot compress messages, on average, to have more than one bit of information per bit of message.
Shannon's theorem also implies that no lossless compression scheme can compress all messages.
While there have been many claims through the years of companies achieving " perfect compression " where an arbitrary number N of random bits can always be compressed to N − 1 bits, these kinds of claims can be safely discarded without even looking at any further details regarding the purported compression scheme.
MPEG-2 is considered important because it has been chosen as the compression scheme for over-the-air digital television ATSC, DVB and ISDB, digital satellite TV services like Dish Network, digital cable television signals, SVCD and DVD Video.
MPEG-4 has been chosen as the compression scheme for over-the-air in Brazil ( ISDB-TB ), based on original digital television from Japan ( ISDB-T ).
PackBits is a fast, simple lossless compression scheme for run-length encoding of data.
This compression scheme is one of the types of compression that can be used in TIFF-files.
TGA-files also use this RLE compression scheme, but treats data stream as pixels instead of bytes.
An AVI file may carry audio / visual data inside the chunks in virtually any compression scheme, including Full Frame ( Uncompressed ), Intel Real Time ( Indeo ), Cinepak, Motion JPEG, Editable MPEG, VDOWave, ClearVideo / RealVideo, QPEG, and MPEG-4 Video.
* Entropy encoding, a lossless data compression scheme that is independent of the specific characteristics of the medium
In information theory an entropy encoding is a lossless data compression scheme that is independent of the specific characteristics of the medium.
DV is an intraframe video compression scheme, which uses the discrete cosine transform ( DCT ) to compress video on a frame-by-frame basis.
Sony and Panasonic have created their proprietary versions of DV, which use the same compression scheme, but improve on robustness, linear editing capabilities, color rendition and raster size.
It uses a similar compression scheme but at higher bitrate.
The compression gains over JPEG are attributed to the use of DWT and a more sophisticated entropy encoding scheme.
TIFF Tags numbered 32768 or higher, sometimes called private tags, are reserved for information meaningful only for some organization or for experiments with a new compression scheme within TIFF.
The BBC had suggested that as an alternative to the SI compression scheme, the Freeview HD multiplex may have to adopt encryption.
* FLAC ( Free Lossless Audio Codec ), an audio data compression scheme
The PIZ compression scheme is based on an algorithm by Christian Rouet.
Like any lossless compression scheme, Monkey's Audio format takes up several times as much space as lossy compression formats like AAC, MP3 and Vorbis.
compression and was
His first " continuous tension – discontinuous compression " geodesic dome ( full sphere in this case ) was constructed at the University of Oregon Architecture School in 1959 with the help of students.
The Atkinson cycle engine was one of the first attempts at variable compression.
The innovation of lossy audio compression was to use psychoacoustics to recognize that not all data in an audio stream can be perceived by the human auditory system.
The world's first commercial broadcast automation audio compression system was developed by Oscar Bonello, an Engineering professor at the University of Buenos Aires.
( It was the research of Nicolas Léonard Sadi Carnot that established the thermodynamic value of compression.
* 1962 -' 65: A diesel compression braking system, eventually to be manufactured by Jacobs ( of drill chuck fame ) and nicknamed the " Jake Brake ", was invented and patented by Clessie Cummins.
In spite of the compression due to its form, this work was up to that time probably the ablest defense, based on external evidence, of the Johannine authorship, and certainly the most complete treatment of the relation of Justin Martyr to this gospel.
The first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication.
The first digital fax machine was the Dacom Rapidfax first sold in late 1960s, which incorporated digital data compression technology developed by Lockheed for transmission of images from satellites.
This compression technique was patented in 1985.
GIF became popular because it used LZW data compression, which was more efficient than the run-length encoding that formats such as PCX and MacPaint used, and fairly large images could therefore be downloaded in a reasonably short time, even with very slow modems.
DEFLATE was intended as a replacement for LZW and other patent-encumbered data compression algorithms which, at the time, limited the usability of and other popular archivers.
H. 263 was developed as an evolutionary improvement based on experience from H. 261, the previous ITU-T standard for video compression, and the MPEG-1 and MPEG-2 standards.
Besides additional piping and the switch between fuels, the head gasket was replaced by a much thicker one to diminish the compression ratio ( making the engine less powerful and less efficient, but able to run on kerosene ).
* The Archive Comparison Test ( ACT ) by Jeff Gilchrist included 162 DOS / Windows and 8 Macintosh lossless compression programs, but it was last updated in 2002.
However, no actual compression took place, and the information stored in the names of the files was necessary in order to reassemble them in the correct order into the original file, and this information was not taken into account in the file size comparison.
The Moving Picture Experts Group ( MPEG ) is a working group of experts that was formed by ISO and IEC to set standards for audio and video compression and transmission.
* MPEG-3: MPEG-3 dealt with standardizing scalable and multi-resolution compression and was intended for HDTV compression but was found to be redundant and was merged with MPEG-2, as a result there is no MPEG-3 standard.
Modeled on the successful collaborative approach and the compression technologies developed by the Joint Photographic Experts Group and CCITT's Experts Group on Telephony ( creators of the JPEG image compression standard and the H. 261 standard for video conferencing respectively ), the Moving Picture Experts Group ( MPEG ) working group was established in January 1988.
0.260 seconds.