Dynamic information storage or retrieval – Duplication or copying
Reexamination Certificate
1997-12-30
2001-04-10
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Duplication or copying
C369S124060
Reexamination Certificate
active
06215754
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of audio recording and playing, and specifically to audio compact disks players.
BACKGROUND OF THE INVENTION
Compact disks (CDs) are storage devices for audio signals encoded as digital data. Audio CD players convert the CD digital data to analog data, which are directly reproducible as audio signals.
Conventional CDs contain digitized audio data, generally without any data reduction or compression. They are typically capable of storing 650 megabytes of data, which is roughly equivalent to 74 minutes of high-quality standard audio transmission. The conventional audio CD is relatively impervious to normal usage, user-friendly, inexpensive to manufacture, and produces high-quality sound.
The Moving Picture Experts Group (MPEG) has defined encoding standards for moving pictures and audio signals. MPEG encoding compresses signals using encoding algorithms that produce a slightly less than exact reproduction of the picture, or audio signal, but in a way that is normally largely unnoticeable to the human senses. The MPEG standards for encoding audio signals are known as MPEG Audio Layers-1, -2 and -3, with each layer being progressively more compressed than that before it. Layer-1 compresses digital audio data approximately 4-fold; Layer-2, 6- to 8-fold; and Layer-3, 10- to 12-fold. Whereas uncompressed analog-to-digital encoding requires nearly 10 megabytes of data for 1 minute of high-quality stereo sound, with MPEG Layer-3 encoding, the same 1 minute of high-quality stereo sound requires less than 1 megabyte of data.
MPEG encoding is used for visual and video encoding, for example, in DVDs (Digital Video Disks), which are viewable on MPEG-enabled DVD video players. Fraunhofer Gesellschaft IIS-A, of Erlangen, Germany, offers MPEG-encoded audio/visual CD-ROMs designed for use with a personal computer having a sufficiently powerful CPU and suitable decoding software. MPEG Layer-3 audio encoding is also available for use in computers, network-based radio, and other applications that require large audio signal data bases.
To date MPEG compression and decompression require the use of a computer. For on-line, real-time play, particularly of MPEG Layer-3, which is relatively computation-intensive, a powerful computer, based at least on an Intel Pentium MMX processor, for example, is generally needed. Consequently, MPEG audio compression has not been applied to home entertainment or portable audio devices.
European Patent Application EP 0786774 describes a digital portable stereo headphone player for recording and playback of compressed audio data on a mini-disk. The player includes a compression/expansion circuit, but no details of this circuit are described. The player is complex and appears to have many of the features of a personal computer system.
European Patent Application EP 0772192 describes optical disk playback apparatus, which is capable of receiving disks that include either compressed or non-compressed audio data. If a disk including compressed data is received, the apparatus converts the data to non-compressed data.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide a personal audio device that can play audio CDs having extended playing time, preferably at least 800 minutes of playing time.
It is a further object of some aspects of the present invention to provide a system for producing extended-play audio CDs for home and mobile use, preferably using standard-size (12 cm diameter), widely available CD media.
In some preferred embodiments of the present invention, a CD player includes an integrated circuit chip, referred to herein as an MPEG decoder chip, or as an MPEG decompression chip, to decode compressed, MPEG-encoded audio data and read it as digital audio signals. The player receives long-play CDs including digital audio data that have been compressed according to the MPEG standard. The compressed data are read from the CD and passed to the chip, which decodes the data and outputs a stream of standard, uncompressed CD audio data, thereby enabling real-time, on-demand use of MPEG-encoded audio CDs without the necessity of a large and costly computing circuitry.
Preferably, the encoded audio data are compressed at least 4-fold, more preferably at least 8-fold, using MPEG Layer-1 or Layer-2 encoding, respectively. Most preferably, the data are compressed approximately 12-fold, based on the level of compression that is typically achieved using MPEG Layer-3 audio compression. The audio player is thus capable of receiving and playing long-play CDs including 12 times the conventional 74 minutes, or approximately 888 minutes (14.8 hours) of high-quality stereo music or voice recording.
Preferably, the MPEG decoder chip comprises a custom or application-specific integrated circuit, which is fabricated with firmware capability to decompress MPEG Layer-3 encoded audio data in real time. MPEG decoding algorithms are known in the art, but are typically implemented in software using general-purpose computer processors. The CD player of the present invention may include such a general-purpose processor, but those skilled in the art of integrated circuits will appreciate that a custom integrated circuit may be designed and fabricated to implement the MPEG decoding more efficiently and at a lower production cost than the general-purpose processor.
In one preferred embodiment of the present invention, the CD player is used as a component of a home entertainment system. In other preferred embodiments, the MPEG decoder chip is installed in a mobile CD player, for example, a personal portable CD or an automobile CD player. The present invention is particularly advantageous in these mobile applications, since it relieves the user of the need to carry around a large number of short-play (74 minute) CDs. Replacing multiple short-play CDs with one or a few long-play CDs, will also save on storage space in the home, office or vehicle. The CD player, be it the mobile or home entertainment version, is preferably equipped with all the common features and functions of a standard CD player, such as play, stop, pause, forward, rewind, display of track numbers, display of elapsed playing time, etc.
In other preferred embodiments of the present invention, a CD recording system comprises two CD drives: a read drive and a write drive. The read drive receives and reads conventional, non-compressed audio CDs. Data read by the read drive (either entire CDs or specific track(s) as selected by the user) are compressed, preferably using MPEG audio encoding, most preferably MPEG Layer-3. The compressed data are then written onto a recordable CD in the write drive, thus enabling 888 minutes (14.8 hours) of high-quality stereo sound to be recorded on a conventional CD, which normally would hold only 74 minutes of sound. The compression is preferably performed by an MPEG Layer-3 encoder chip, similar in principle to the decoder chip described above.
By using MPEG Layer-3 encoding, the system can condense the entire contents of as many as 12 conventional fully-recorded CDs onto a single, long-playing CD. (In fact, since commercially-recorded CDs are usually not recorded to their full 74 minute capacity, but rather to about 80% capacity, it may be possible to condense up to 15 conventional CDs onto a single long-playing CD.) A user of the recording system can record audio segments from the conventional CDs onto the long-playing CD in any desired sequence and combination. The long-playing CD produced in this manner is particularly suited for use in the CD player described above, but can also be used in a computer CD drive, for example, using software decompression and an appropriate computer sound-card and speakers to play back the recorded audio.
Alternatively, the CD recording system may comprise only a single read/write CD drive, along with a fixed mass-memory device, such as a magnetic hard disk. In this case, the conventional CDs, on which non-compressed audio data are recorded, are first inse
Krashin Ari
Vidal Joel
Gottlieb Rackman & Reisman P.C.
Huber Paul W.
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