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WO1996018191A1 - Duplication a grande vitesse de signaux audio numeriques comprimes - Google Patents

Duplication a grande vitesse de signaux audio numeriques comprimes Download PDF

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Publication number
WO1996018191A1
WO1996018191A1 PCT/AU1995/000822 AU9500822W WO9618191A1 WO 1996018191 A1 WO1996018191 A1 WO 1996018191A1 AU 9500822 W AU9500822 W AU 9500822W WO 9618191 A1 WO9618191 A1 WO 9618191A1
Authority
WO
WIPO (PCT)
Prior art keywords
portions
high speed
analogue
data
dubber
Prior art date
Application number
PCT/AU1995/000822
Other languages
English (en)
Inventor
Daniel Shane O'sullivan
Original Assignee
Southern Broadcasting Systems Pty. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Southern Broadcasting Systems Pty. Ltd. filed Critical Southern Broadcasting Systems Pty. Ltd.
Priority to AU41123/96A priority Critical patent/AU4112396A/en
Publication of WO1996018191A1 publication Critical patent/WO1996018191A1/fr

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/10527—Audio or video recording; Data buffering arrangements
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00007—Time or data compression or expansion
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/02—Analogue recording or reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
    • G11B27/028—Electronic editing of analogue information signals, e.g. audio or video signals with computer assistance
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G11B27/031—Electronic editing of digitised analogue information signals, e.g. audio or video signals
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/90—Tape-like record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/90—Tape-like record carriers
    • G11B2220/91—Helical scan format, wherein tracks are slightly tilted with respect to tape direction, e.g. VHS, DAT, DVC, AIT or exabyte
    • G11B2220/913—Digital audio tape [DAT] format
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
    • G11B27/024—Electronic editing of analogue information signals, e.g. audio or video signals on tapes

Definitions

  • This invention relates generally to recording technology, and in particular to dubbing of digitally recorded audio onto analogue tapes at high speeds.
  • the present invention is applicable for the dubbing of recordings of court transcriptions and music quality stereo recordings.
  • the applicants prior invention stores the audio as compressed digital data, such that in order to listen to the transcript a person could not utilise standard analogue tape players unless an analogue copy of the transcript was made.
  • dubbing digital recordings onto analogue tapes at speed ratios greater than 1 :1 is not limited to court transcription systems.
  • the music industry still has substantial sales in standard analogue cassette tapes.
  • most recordings are digitally recorded.
  • a master analogue tape In order to mass produce audio cassettes from such recordings it is usual for a master analogue tape to be produced from the digital recording at a speed ratio of 1:1 , and for further tapes to then be produced from that master tape using standard analogue dubbing hardware.
  • An object of the present invention is to alleviate some of the disadvantages of the prior art.
  • the present invention provides in one aspect a method and/or apparatus of high speed dubbing of a compressed digital audio signal onto an analogue storage means including dividing the compressed signal into a plurality of portions and separately decompressing each portion through a respective decompression means in parallel.
  • this dividing and interleaving presents further problems in that a sound artefact is created at the join points of the recombined audio signal. Therefore another aspect of the present invention relates to solving the problem created by the sound artefacts resulting from the interleaving necessary for parallel processing.
  • This aspect is predicated on the principle of replacing the sound artefact otherwise created by decompression with an overlapping, enlarged or extended portion of signal.
  • the present invention provides in yet a further aspect a method for high speed dubbing of a compressed digital audio signal onto an analogue storage means, including the steps of: dividing the compressed digital audio signal into a plurality of portions, each portion having an overlap, interleaving the portions to respective decompression means, separately decompressing each portion thereof in parallel, recombining the portions wherein the overlap provides for correction of a sound artefact.
  • One alternative used to remove the sound artefact is to provide additional decompression components, such that the additional unit(s) will process data immediately before and after the join point. The data thus provided by the additional unit(s) will then be used to replace those beginning portions which contain the sound artefact.
  • Another alternative useful in removing the sound artefact is to run the decompression unit at greater than normal speed. By running at this increased speed it is then possible to overlap the portions, such that each decompression unit will also decompress the first bytes of the next portion.
  • the overlap between portions is used to eliminate the sound artefact which occurs at the beginning of the decompression of a discontinuous portion of digital audio at the portion boundary. The sound that is distorted at the beginning of the portion will be faithfully decompressed in the overlap on a different decompression digital signal processor. This is then used to replace the first bytes of the next portion thus removing the sound artefact.
  • This invention provides in another aspect a method for high speed dubbing of a compressed digital audio signal onto an analogue storage means, including the steps of: dividing the compressed digital audio signal into a plurality of portions, interleaving the portions to respective decompression means, separately decompressing each portion thereof in parallel, recombining the portions, converting combined portions of decompressed digital audio into analogue data, and transferring the analogue data onto an analogue storage means.
  • the compressed digital audio signal is preferably first retrieved from a digital storage means.
  • the interleaving of the portions may include the step of the decompression means receiving the portions sequentially, and the memory means may also be used to recombine the portions by first reading in the portions from each decompression means and then outputting each portion in order to deinterleave the signal
  • the sound artefact may be removed by additionally decompressing data immediately before and after each join between adjacent portions.
  • the sound artefact may be removed by first dividing the compressed digital audio into a plurality of portions such that a part of each portion is also contained in a part of an adjacent portion.
  • an adjacent portion contains common data such that data immediately at the end of each portion is also contained at the beginning of a next adjacent portion.
  • the common data contained in two adjacent portions should be sufficient to enable the sound artefact to be completely removed between those two portions.
  • the decompression means and memory means can then be operated at a greater than normal speed to enable each portion together with the common data to be processed in the time it would normally take to process each portion had there been no common data.
  • this invention provides a high speed dubber for dubbing of a compressed digital audio signal onto an analogue storage means, the dubber including: a control means adapted to divide the compressed digital audio signal into a plurality of portions, interleave and then transfer the portions, a plurality of decompression means each adapted to receive interleaved portions from the control means and decompress the portions in parallel, a memory means adapted to receive decompressed portions from the decompression means and then effectively deinterleave the portions, a conversion means adapted to convert decompressed digital audio into analogue data, a writing means adapted to transfer the analogue data onto an analogue storage means.
  • the control means preferably receives the compressed digital audio signal from a digital storage means.
  • the control means can be a computer adapted to retrieve the compressed digital audio signal, divide the signal into a plurality of portions and interleave the portions by transferring each portion in turn to a separate decompression means.
  • the deinterleaving may be achieved by using a double buffered memory, each side of which alternates between reading in the decompressed data and reading out the decompressed data in a deinterleaved order.
  • a first clock means may be adapted to operate the decompression means at a greater than normal speed to enable each portion to also contain a part of an adjacent portion without substantially affecting the throughput of the decompression means.
  • an input address generator and an output address generator are also connected between the double buffered memory and the first clock means so that the memory means can run at a speed equal to that of the decompression means.
  • a second clock means may also preferably be provided to operate the conversion means at its normal operating speed.
  • analogue tape is played at 8 or 16 times speed, digitised and compressed into digital storage.
  • Multiple digital signal processors can again be used in parallel with extra speed clocking margin to suppress the audio artefacts at the boundaries between each portion of audio handled by each digital signal processor.
  • the present invention provides in another aspect a method and/or apparatus for high speed dubbing of an analogue signal into a compressed digital data storage means including converting the analogue signal into digital data, dividing the digital data into a plurality of portions and separately compressing each portion through respective compression means in parallel.
  • the present invention provides a method for high speed dubbing of an analogue signal into a compressed digital data storage means, including the steps of: converting the analogue signal into digital data, dividing the digital data into a plurality of portions, interleaving the portions to respective compression means, separately compressing each portion thereof in parallel, recombining the portions, transferring compressed digital data into a digital data storage means.
  • the present invention provides a high speed dubber for dubbing of an analogue signal into a digital data storage means, the dubber including: a reading means adapted to transfer the analogue signal to a conversion means, the conversion means adapted to convert the analogue signal into digital data, a memory means adapted to receive the digital data from the conversion means and then effectively divide the digital data into a plurality of portions, a plurality of compression means each adapted to receive respective interleaved portions from the memory means and compress the interleaved portions in parallel, and a control means adapted to recombine the interleaved portions into compressed digital data.
  • Figure 1 is a procedural flow diagram outlining the major steps in the invention.
  • Figure 2 is a similar procedural flow diagram outlining the major steps in the invention including suppression of the sound artefact.
  • Figure 3 shows the invention of Figure 2 in reverse to allow analogue audio to be dubbed at high speed into digital storage.
  • multitrack compressed digital audio has been stored on a computer or in some other storage means (1) easily accessible via the computer (2)
  • the means employed is to break the multitrack compressed digital audio into multisecond portions, interleave this data and transmit this time interleaved at multiplied speed to 8 or 16 times the usual number of digital decompression components (3), each decompressing a 1/8 or 1/16 portion of the digital audio in parallel and writing 8 or 16 decompressed digital audio streams per track to a double buffered memory (5).
  • the means employed is to break the multitrack compressed digital audio into multisecond portions, interleave this data and transmit this time interleaved at multiplied speed to 8 or 16 times the usual number of digital decompression components (3), each decompressing a 1/8 or 1/16 portion of the digital audio in parallel and writing 8 or 16 decompressed digital audio streams per track to a double buffered memory (5).
  • the apparatus according to the present invention provides a means of playing back compressed digitally recorded multitrack audio at 8 or 16 times normal playback speed in order to record it on analogue cassette tape at this high speed using the slave unit of an industry standard master/slave 8 or 16 times speed analogue cassette tape dubbing (duplication) machine (7), with the high speed digital playback unit (2,3,4,5,6) replacing the analogue cassette master unit.
  • the digital unit includes multiple digital signal processors (3) connected in parallel, each decompressing a portion of the digital audio, such that the digital audio is converted to analogue audio at a rate comparable to that of the cassette unit.
  • the present invention allows for the dubbing of digital audio onto analogue cassettes by dividing the digital signal into a plurality of discrete portions and interleaving the portions, each of which are then processed in parallel before being recombined.
  • the parallel processing thus enables the digital audio to be converted into a suitable format so as to enable existing analogue dubbing hardware to be utilised.
  • the decompression algorithm maintains a series of rolling coefficients to assist in the processing of the data. These coefficients are updated every sample and effectively track the immediate past. Where standard processing of digital data is performed, such that byte two follows byte one, the value of this coefficient is not an issue as the coefficient correctly reflects the previous value. However, the applicants system differs in that it splits the digital data into discrete portions and interleaves those portions such that byte two does not necessarily follow byte one.
  • the present invention will preferably remove the resultant sound artefacts, by overlapping the sound at the join points such that the beginning of each decompressed portion, which contains the sound artefact, will be replaced by the end of the previous portion overlapping it.
  • the multiple decompression means (10) are run at greater than normal speed, so as to allow overlapping of the audio at the joins caused by the interleaving, in order to suppress the sound artefact.
  • This speed increase can be achieved by incorporating a first clocked state machine (16) that adjusts the clock (18) input to the multiple decompression means (10).
  • the clocking pulse from the first state machine (16) is also used to synchronise the address generators (14,15) linked to the buffered memory (11).
  • the digital compressed interleaved audio is transmitted from the computer (9) to eight or 16 times the usual number of digital signal processors (10), each decompressing a 1/8 or 1/16 portion of the digital audio and writing the decompressed audio to the double buffered memory (1 1 ).
  • the sound artefact however is not written to memory (11 ) and is simply discarded.
  • the address generators (14,15) which are also run at a speed equal to the multiple decompression means (10) effectively deinterleave the audio in the buffer memory (11).
  • the memory (11) is required to run at a speed comparable to that of the multiple decompression means (10) as the non write cycle which discards the sound artefact still takes time.
  • the digital to analogue converters (12) are running at their normal speed, being connected to a second clocked state machine (17). In order, to operate effectively and match the speed of the data from the memory (11), the digital to analogue converters (12), can be configured to function with each clock cycle corresponding to the removed sound artefact suppressed.
  • a computer accesses the compressed digital audio stored in files. 64 seconds of this compressed digital audio for each of four tracks is then read into the computer at eight times the normal speed, that is in eight seconds. This 64 seconds of compressed digital audio is then split into eight sequential portions of eight seconds for each of the four tracks and interleaved into memory as 32 channels.
  • the interleaving is such that the first byte of each channel is processed first, then the second bytes and so on. That is the interleaving results in the reordering of the bytes such that byte one for channels one to 32 is followed by byte two of channels one to 32 and so forth.
  • Decompressed audio is then stored in one half of a buffer memory. Every eight seconds this process is repeated alternating which half of the buffer memory is written to. Simultaneously the other half of the buffer memory (which was written to in the previous eight seconds), is read out in deinterleaved order such that it is once again in four channel order. This results in four track decompressed digital audio which is then passed through four high speed digital to analogue converters, finally giving analogue audio compatible with the input of an eight times speed analogue stereo cassette recorder commonly used for high speed cassette dubbing or duplication.
  • the computer reads in 16 seconds of compressed digital audio for each of four tracks at 16 times the normal speed, that is in one second.
  • the compressed digital audio is then split into 16 sequential portions of 5/4 seconds for each of four channels with a 1/4 second overlap and interleaved into memory as 64 channels.
  • the interleaved audio will then be written to 16 quad channel decompression digital signal processors running at 5/4 times normal speed. This increase in speed is achieved by having the clock input to the decompression means coming from a state machine which effectively divides the system clock running at 20MHz by four, thus providing the decompression means with a clock rate of 5MHz and not the usual rate of 4MHz.
  • the decompressed audio is then alternatively written to one half of the buffer memory. At this time the first 1/4 second of each portion which contains the sound artefact is discarded. The extra 1/4 second overlap between portions is used to eliminate the sound artefact. This is repeated every one second. Simultaneously the other half of the buffer memory (which was written to in the previous one second), is read out in deinterleaved order such that it is once again in four track order. This results in four track decompressed digital audio which is then passed through four high speed digital to analogue converters.
  • the digital to analogue converters are connected to another state machine which suppresses every fifth 5MHz clock cycle, thereby allowing the digital to analogue converters to run at their normal rating of 4MHz.
  • the digital to analogue converters must run at an average of 4MHz but can function with a 5MHz clock with each fifth 5MHz clock cycle suppressed, thus matching the speed of the buffer memory. The result is to produce analogue audio compatible with the input of a 16 times speed analogue stereo cassette recorder commonly used for high speed cassette dubbing or duplication.
  • the present invention provides a system that is significantly cheaper than what is currently available without sacrificing quality.
  • further cost savings can be made by decreasing the size of the buffer memory. This can be achieved by minimising the size of each portion and therefore the size of the buffer memory required, such that each portion is only a fraction of a second.
  • audio is first played at 16 times speed from a high speed tape deck (19), then digitised at 16 times speed by one high speed analogue to digital converter (20) per track into one half of a buffer memory. Simultaneously the other half of the buffer memory is read out in interleave order in multiple overlapping portions which are distributed to multiple digital signal processors (21) in parallel, each of which compresses a portion.
  • a slightly higher than usual clock speed is used to allow a portion plus overlap to be compressed in the time usually allowed for the compression of an unoverlapped portion.
  • MHz this term is to be given its standard digital telecommunications industrial meaning such that 1 MHz is equivalent to 1.024MHz.
  • Standard digital signal processors are used to convert the digital audio into analogue audio which is then passed to existing industry standard high speed dubbing tape decks.
  • standard digital signal processors may require more componentry than specialised digital signal processors.
  • the end result will be a system that is relatively cheaper and able to match market requirements, and in another aspect substantially suppressing the sound artefacts created by the interleaving process.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • General Engineering & Computer Science (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)

Abstract

Technique de duplication à grande vitesse de signaux audio numériques comprimés dans un support d'informations analogique (1), consistant à diviser le signal audio numérique comprimé en une pluralité de parties, à entrelacer ces parties pour les transférer vers des moyens de décompression respectifs (3) qui décompressent séparément chaque partie en parallèle, puis à rassembler les parties et à les convertir en signaux analogiques pour les transférer vers le support d'informations analogique (1). Les moyens de décompression (3) peuvent fonctionner à une vitesse supérieure à la normale afin de permettre la suppression des distorsions du son à la jonction entre les parties, l'utilisation de données communes ou redondantes sur une jonction étant également décrite. L'invention se rapporte également à une technique de duplication d'un signal analogique dans un support de données numériques comprimées, qui consiste à convertir le signal analogique en signal numérique, à diviser les données numériques en une pluralité de parties qui sont séparément comprimées en parallèle par des moyens de compression, à rassembler les parties et à les transférer vers le support numérique. Une mémoire (5) peut être utilisée pour entrelacer et désentrelacer les parties, cette mémoire pouvant être à double tampon.
PCT/AU1995/000822 1994-12-05 1995-12-05 Duplication a grande vitesse de signaux audio numeriques comprimes WO1996018191A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU41123/96A AU4112396A (en) 1994-12-05 1995-12-05 High speed dubbing of compressed digital audio

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPM9875 1994-12-05
AUPM9875A AUPM987594A0 (en) 1994-12-05 1994-12-05 High speed dubbing of compressed digital audio

Publications (1)

Publication Number Publication Date
WO1996018191A1 true WO1996018191A1 (fr) 1996-06-13

Family

ID=3784385

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1995/000822 WO1996018191A1 (fr) 1994-12-05 1995-12-05 Duplication a grande vitesse de signaux audio numeriques comprimes

Country Status (2)

Country Link
AU (1) AUPM987594A0 (fr)
WO (1) WO1996018191A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0889470A3 (fr) * 1997-07-03 1999-02-17 AT&T Corp. Dégradation de la qualité par compression/décompression
US6760443B2 (en) 1997-07-03 2004-07-06 At&T Corp. Custom character-coding compression for encoding and watermarking media content
US7634599B2 (en) * 2001-06-29 2009-12-15 Hewlett-Packard Development Company, Lp. Method for improving inline compression bandwidth for high speed buses

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4541089A (en) * 1982-02-17 1985-09-10 Sony Corporation Apparatus for connecting digital data
US4858217A (en) * 1986-11-18 1989-08-15 Sony Corporation Optical disk recording and reproducing device
US5167034A (en) * 1990-06-18 1992-11-24 International Business Machines Corporation Data integrity for compaction devices
EP0596398A2 (fr) * 1992-10-31 1994-05-11 Sony Corporation Appareil pour l'enregistrement de signaux vidéo numériques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4541089A (en) * 1982-02-17 1985-09-10 Sony Corporation Apparatus for connecting digital data
US4858217A (en) * 1986-11-18 1989-08-15 Sony Corporation Optical disk recording and reproducing device
US5167034A (en) * 1990-06-18 1992-11-24 International Business Machines Corporation Data integrity for compaction devices
EP0596398A2 (fr) * 1992-10-31 1994-05-11 Sony Corporation Appareil pour l'enregistrement de signaux vidéo numériques

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0889470A3 (fr) * 1997-07-03 1999-02-17 AT&T Corp. Dégradation de la qualité par compression/décompression
US6111844A (en) * 1997-07-03 2000-08-29 At&T Corp. Quality degradation through compression/decompression
US6760443B2 (en) 1997-07-03 2004-07-06 At&T Corp. Custom character-coding compression for encoding and watermarking media content
US7492902B2 (en) 1997-07-03 2009-02-17 At&T Corp. Custom character-coding compression for encoding and watermarking media content
US8041038B2 (en) 1997-07-03 2011-10-18 At&T Intellectual Property Ii, L.P. System and method for decompressing and making publically available received media content
US7634599B2 (en) * 2001-06-29 2009-12-15 Hewlett-Packard Development Company, Lp. Method for improving inline compression bandwidth for high speed buses

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