Patent Application
20090097487
[Not Applicable]
[Not Applicable]
[Not Applicable]
Certain embodiments of the invention relate to processing of audio data. More specifically, certain embodiments of the invention relate to a method and system for transmission of digital audio in SPDIF format to one or more receivers.
Digital data communications have increased in popularity in recent years and have found a wide variety of applications. One such application includes the transmission and reception of digital audio using the Sony/Philips Data Interface Format (SPDIF). The SPDIF protocol is further described in International Electrotechnical Commission publication 60958-3 Ed. 1.0 entitled “Digital audio interface—Part 3: Consumer applications.”
The SPDIF protocol defines a serial data stream organized in sub-frames, frames and blocks. Upon transmission, digital audio data is encoded and is transmitted via specialized SPDIF cable to one or more location for processing. Each of the receiving locations uses an SPDIF receiver/decoder that receives the encoded SPDIF data, decodes it and communicates it to one or more speakers. This conventional digital audio processing scenario is not efficient as the specialized SPDIF cable connecting the SPDIF transmitter to the SPDIF receiver, as well as the SPDIF decoder itself, are very expensive. Furthermore, expenses may increase exponentially if the encoded SPDIF audio data is transmitted to more than one location. In this regard, additional SPDIF cable is required to communicate the encoded data, and additional SPDIF receivers/decoders are required at each location.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.
A method and system for transmission of digital audio in SPDIF format to one or more receivers, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.
Various advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.
Certain aspects of the invention may be found in a method and system for transmission of digital audio in SPDIF format to one or more receivers over a network supporting packet based communication. Aspects of the method may comprise packetizing at least one decoded SPDIF data frame to generate at least one SPDIF packet. The at least one SPDIF packet may be transmitted, via one or more networks supporting packet based communication, for processing. The one or more networks may comprise one or more of the Internet, an Intranet, a wireless LAN, and/or a Bluetooth connection. One or more channel status bits may be extracted from the at least one decoded SPDIF data frame, prior to the packetizing. The extracted one or more channel status bits may be packetized with the at least one decoded SPDIF data frame to generate the at least one SPDIF packet. At least one header may be generated for the at least one SPDIF packet. The generated at least one header may comprise the extracted one or more channel status bits and/or a packet sequence number. The generated at least one header may also comprise 192 channel status bits corresponding to a plurality of SPDIF data frames within an SPDIF block.
The at least one SPDIF packet may be transmitted to at least one receiver for processing. The extracted one or more channel status bits may be packetized to generate at least one channel status bits packet. The at least one channel status bits packet and the at least one SPDIF packet may be transmitted to at least one receiver for processing. The at least one channel status bits packet and the at least one SPDIF packet may be transmitted via one or more networks supporting packet based communication. The at least one channel status bits packet and the at least one SPDIF packet may be transmitted using User Datagram Protocol (UDP) and/or Transmission Control Protocol (TCP). Sample rate information, SPDIF data type information and/or copyright assertion information related to at least a portion of the plurality of SPDIF data frames may be extracted from the transmitted at least one channel status bits packet.
The preamble 116 may comprise 4 bits (b0, . . . , b3). Bits b4, . . . , b27 may be used to represent digital data. In some instances, the auxiliary data field 118 may be used to provide non-audio information, such as information which may be used to identify the type of audio data. For example, in one embodiment of the invention, the auxiliary data field 118 may be used to identify whether the audio data 120 is stereo audio data or multi-channel audio data. The ancillary information may comprise four additional bits 122, . . . , 128, designated as bits b28, . . . , b31. Bit 28 (122) may comprise a validity bit, which may be used to encode a data sample validity flag. Bit 29 (124) may comprise a user data bit 124, which may be used to encode user information. Bit 30 (126) may comprise a channel status bit, which may be used to encode channel status information. Bit 31 (128) may comprise a parity bit.
In an exemplary embodiment of the invention, one or more of bits b28, . . . , b31 from the ancillary information fields of the SPDIF sub-frames 102, . . . , 108 may be used for transmission of decoded SPDIF digital audio data to one or more receivers. For example, the channel status bit 126 from each of the 192 SPDIF frames 110, . . . , 112 may be extracted to obtain a total of 192 channel status bits (CSBs). The extracted CSBs may be transmitted with the decoded SPDIF digital audio data to one or more receivers via, for example, the Internet and/or an Intranet.
In an exemplary embodiment of the invention, one or more of CSBs from the ancillary information fields 134 and 135 of the SPDIF sub-frames 136 and 138 may be used for transmission of decoded SPDIF digital stereo data to one or more receivers. The extracted CSBs may be transmitted with the decoded SPDIF digital stereo audio data to one or more receivers via, for example, the Internet and/or an Intranet.
The SPDIF data Tx 202 may comprise suitable logic, circuitry, and/or code that may enable encoding and transmission of SPDIF digital audio data. For example, the SPDIF data Tx 202 may encode SPDIF digital audio data and may transmit the encoded SPDIF digital audio data to one or more receivers, such as the audio decoders 204, . . . , 208. The encoded SPDIF digital audio data may be transmitted to the audio decoders 204, . . . , 208 via specialized SPDIF cables 216, . . . , 220, respectively.
The audio decoders 204, . . . , 208 may comprise suitable logic, circuitry, and/or code that may enable receiving and decoding of the SPDIF digital audio data transmitted by the SPDIF data Tx 202. The audio decoders 204, . . . , 208 may communicate the decoded SPDIF digital audio data to corresponding speakers 210, . . . , 214.
In one embodiment of the invention, the implementation cost and the efficiency of the SPDIF digital audio processing system 200 may be significantly improved by using only a single audio decoder to decode the received encoded SPDIF digital audio data. In this regard, only a single SPDIF cable may be used to connect the SPDIF data Tx to the audio decoder. In this regard, at least one decoded SPDIF data frames may be packetized to generate at least one SPDIF packet. The at least one SPDIF packet may then be transmitted via one or more networks supporting packet based communication, such as the Internet, an Intranet, a wireless LAN, and/or a Bluetooth connection. For example, the at least one SPDIF packet may be transmitted to a receiver/depacketizer, which may extract the decoded SPDIF audio data from the received at least one SPDIF packet.
In another embodiment of the invention, during the above-mentioned packetization process, one or more CSBs may be extracted from the decoded SPDIF digital audio data and may be communicated with the packetized SPDIF data to one or more receivers/depacketizers via one or more networks supporting packet based communication, such as the Internet, a wireless LAN, a Bluetooth connection, and/or an Intranet. The extracted CSBs may be communicated as part of one or more headers for the packetized SPDIF data, and/or the extracted CSBs may be communicated as separate packets.
The SPDIF data Tx 302 may comprise suitable logic, circuitry, and/or code that may enable encoding and transmission of SPDIF digital audio data. For example, the SPDIF data Tx 302 may encode SPDIF digital audio data and may transmit the encoded SPDIF digital audio data to a single receiver/decoder, such as the audio decoder 304. The encoded SPDIF digital audio data may be transmitted to the audio decoder 304 via a single SPDIF cable 303.
The audio decoder 304 may comprise suitable logic, circuitry, and/or code that may enable receiving and decoding of the SPDIF digital audio data transmitted by the SPDIF data Tx 302 via the SPDIF cable 303. The audio decoder 304 may communicate the decoded SPDIF digital audio data to the SPDIF packetizer 306. The SPDIF packetizer 306 may comprise suitable logic, circuitry, and/or code that may enable packetizing of SPDIF data into, for example, SPDIF data packets suitable for transmission over the Internet or an Intranet. The SPDIF packetizer 306 may also enable generating one or more headers for the SPDIF data packets, where the headers may comprise one or more extracted CSBs and/or a packet sequence number. In some instances, the SPDIF packetizer 306 may packetize the extracted CSBs into separate CSB packets, which may be transmitted together with the SPDIF data packets to the SPDIF depacketizers 314, . . . , 318. In another embodiment of the invention, the CSBs packets may be sent via Transmission Control Protocol (TCP), and the SPDIF data packets may be sent via User Datagram Protocol (UDP), for example. Yet in another embodiment of this invention, the SPDIF packetizer 306 may receive the CSBs separately from the SPDIF data Tx 302.
In yet another embodiment of the invention, the one or more headers for the SPDIF data packets may comprise header information which is different from the one or more extracted CSBs and/or a packet sequence number.
The SPDIF depacketizers 314, . . . , 318 may comprise suitable logic, circuitry, and/or code that may enable depacketization of the received SPDIF data packets and/or the CSBs packets. The depacketized SPDIF digital audio information may then be communicated to the corresponding SPDIF Rx (audio players/speakers) 320, . . . , 322.
In operation, the SPDIF data Tx 302 may encode SPDIF digital audio data and may transmit the encoded SPDIF digital audio data to the audio decoder 304 via the SPDIF cable connection 303. The audio decoder 304 may decode the received encoded SPDIF digital audio data. The decoded SPDIF digital audio data may be communicated to the SPDIF packetizer 306. The SPDIF packetizer 306 may collect each block of SPDIF data, comprising 192 frames, and may extract the 192 channel status bits from each SPDIF data block. The SPDIF packetizer 306 may then break up each of the SPDIF blocks into packets using one or more different techniques.
For example, in one embodiment of the invention, the following SPDIF data packetization technique may be used: each SPDIF data block may be broken into n data packets. In this regard, each data packet may comprise 192/n SPDIF data frames. In yet another embodiment of the invention, the following SPDIF data packetization technique may be used: the SPDIF data packet size of X may be used, where X may be a multiple of 8. The SPDIF packetizer 306 may then fill each SPDIF data packet with size X with as many SPDIF frames as possible.
Even though only two packetization techniques used by the SPDIF packetizer 306 are disclosed, the present invention may not be so limited. In this regard, the SPDIF packetizer 306 may also utilize other techniques for packetization of SPDIF data and/or CSBs. In one embodiment of the invention, the SPDIF packetizer 306 may extract the CSBs and may packetize the CSBs using a format other than the format used for packetizing the SPDIF decoded audio data. In this regard, separate formats may be used for packetizing the SPDIF data and the CSBs. Furthermore, the depacketizers 314, . . . , 318 may be adapted to use the same formats used by the SPDIF packetizer 306 for depacketizing the CSBs and/or the SPDIF packets.
In one embodiment of the invention, at least one decoded SPDIF data frames may be packetized by the SPDIF packetizer 306 to generate at least one SPDIF packet. The at least one SPDIF packet may then be transmitted via one or more networks 311 supporting packet based communication, such as the Internet, an Intranet, a wireless LAN, and/or a Bluetooth connection, to one or more receiver/depacketizer, which may extract the decoded SPDIF audio data from the received at least one SPDIF packet.
In another embodiment of the invention, during the above-mentioned packetization process, one or more CSBs may be extracted by the SPDIF packetizer 306 from the decoded SPDIF digital audio data and may be communicated with the packetized SPDIF data to the one or more receivers/depacketizers via the one or more networks 311 supporting packet based communication, Yet in another embodiment of the invention, the SPDIF packetizer 306 may receive the CSBs separately from the SPDIF data Tx 302. The extracted CSBs may be communicated as part of one or more headers for the packetized SPDIF data, and/or the extracted CSBs may be communicated as separate packets. The SPDIF data packets generated by the SPDIF packetizer 306 may be communicated to the SPDIF depacketizers 314, . . . , 318 with or without packet headers. In Instances when the SPDIF data packets comprise a header, each packet header may be used to communicate additional information or information for error recovery, for example. Each header may comprise, for example, 192 CSBs extracted from each SPDIF block (each SPDIF block comprises 192 SPDIF frames, each frame contributing a single CSB). The SPDIF data packet header may also comprise a packet sequence number, which may designate the sequence number of the SPDIF packet in the block. The headers may be used at the SPDIF depacketizers 314, . . . , 318, for error recovery or for transmission of any additional information.
In another embodiment of the invention, the 192 CSBs extracted from each SPDIF block may be packetized and transmitted in one or more separate packets. In such instances when the CSBs are packetized separately, the SPDIF data packet header may comprise only the packet sequence number. The CSB packets and the SPDIF data packets may then be encapsulated and transmitted over the Internet or an Intranet to the SPDIF depacketizers 314, . . . , 318. The SPDIF packetizer 306 may encapsulate the SPDIF data packets and/or the CSBs packets as Ethernet packets, as transport layer protocol packets, such as TCP and/or UDP packets, as Wireless LAN (802.11) packets, and/or as Bluetooth packets.
After the SPDIF packetizer 306 generates the SPDIF data packets (with or without headers) and/or the CSBs packets, the SPDIF data packets (with or without headers) and/or the CSBs packets may be transmitted via the Internet/Intranet/WLAN, or Bluetooth and the connections 308, . . . , 312 to the SPDIF depacketizers 314, . . . , 318. The SPDIF depacketizers 314, . . . , 318 may depacketize the received SPDIF data packets and/or CSBs packets and communicate the depacketized and decided SPDIF digital audio data to the corresponding audio players/speakers 320, . . . , 324.
In accordance with an embodiment of the invention, there may be instances when there may be no headers generated for the SPDIF data packets. In yet another embodiment of the invention, there may be instances when there may be no channel status bits (CSBs) packets generated with the SPDIF data packets.
Even though the audio decoder 304 and the SPDIF packetizer 306 are shown in
Referring to
In instances when a SPDIF data packet has been lost in transmission, the SPDIF DPB 400 may use the frame sequence number from the header and the CSB information to formulate and insert the correct channel status bit information for the frames contained in the missing packet. The SPDIF DPB 400 may also extract critical information from the CSBs, such as sample rate information, SPDIF data type information and/or copyright assertion information. The depacketizer 406 may communicate the critical information to, for example, the SPDIF Rx 405 and to one or more of audio players/speakers. The SPDIF Rx 405 may use the extracted critical information to maintain its clock functioning without interruption, in instances when one or more SPDIF data packets are lost in transmission. In this regard, even if some of the frames containing crucial channel status information are lost, the SPDIF Rx 405 may recover and play SPDIF frames from the decoded and depacketized SPDIF data block.
At 606, the SPDIF packetizer 306 may packetize the extracted one or more channel status bits to generate at least one channel status bits (CSBs) packet. At 608, the SPDIF packetizer 306 may transmit the at least one channel status bits packet and the at least one SPDIF packet to at least one receiver for processing. The at least one channel status bits packet and the at least one SPDIF packet may be transmitted via the Internet, an Intranet, a Bluetooth connection and/or a wireless LAN. At 610, the SPDIF depacketizer 314 may extract from the transmitted at least one channel status bits packet sample rate information, SPDIF data type information and/or copyright assertion information related to at least a portion of the plurality of SPDIF data frames.
Certain embodiments of the invention may comprise a machine-readable storage having stored thereon, a computer program having at least one code section for communicating information within a network, the at least one code section being executable by a machine for causing the machine to perform one or more of the steps described herein.
Accordingly, aspects of the invention may be realized in hardware, software, firmware or a combination thereof. The invention may be realized in a centralized fashion in at least one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware, software and firmware may be a general-purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.
One embodiment of the present invention may be implemented as a board level product, as a single chip, application specific integrated circuit (ASIC), or with varying levels integrated on a single chip with other portions of the system as separate components. The degree of integration of the system will primarily be determined by speed and cost considerations. Because of the sophisticated nature of modern processors, it is possible to utilize a commercially available processor, which may be implemented external to an ASIC implementation of the present system. Alternatively, if the processor is available as an ASIC core or logic block, then the commercially available processor may be implemented as part of an ASIC device with various functions implemented as firmware.
The present invention may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context may mean, for example, any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form. However, other meanings of computer program within the understanding of those skilled in the art are also contemplated by the present invention.
While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.
