(19)
(11)EP 2 546 827 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
28.10.2020 Bulletin 2020/44

(21)Application number: 12187851.6

(22)Date of filing:  10.06.2004
(51)Int. Cl.: 
G06F 3/14  (2006.01)
H04N 21/43  (2011.01)
H04N 19/15  (2014.01)
H04N 21/41  (2011.01)
H04N 21/64  (2011.01)

(54)

Synchronized transmission of audio and video data between a computer and a client via an interface

Synchronisierte Übertragung von Audio- und Videodaten zwischen einem Computer und einem Client über eine Schnittstelle

Transmission synchronisée de données audio et vidéo entre un ordinateur et un client via une interface


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR

(30)Priority: 13.06.2003 US 478336 P
23.12.2003 US 746283

(43)Date of publication of application:
16.01.2013 Bulletin 2013/03

(62)Application number of the earlier application in accordance with Art. 76 EPC:
04776494.9 / 1634180

(73)Proprietor: Apple Inc.
Cupertino CA 95014 (US)

(72)Inventors:
  • Agnoli, Giovanni M.
    San Mateo, CA 94402 (US)
  • Yanowitz, Andrew
    Ben Lomond, CA 95005 (US)
  • Abt, John O.
    Grass Valley, CA 95945 (US)
  • Bowman, Samuel R.
    Colfax, CA 95713 (US)
  • Delwiche, James A.
    Grass Valley, CA 95949 (US)
  • Dillon, Jeffrey C.
    Auburn, CA 95603 (US)

(74)Representative: Rooney, John-Paul et al
Withers & Rogers LLP 4 More London Riverside
London SE1 2AU
London SE1 2AU (GB)


(56)References cited: : 
EP-A2- 0 690 630
EP-A2- 1 024 663
US-A- 5 812 210
US-B1- 6 181 300
EP-A2- 0 875 882
US-A- 5 805 233
US-A- 6 107 984
  
  • "AUTOMATIC VIDEO FREQUENCY/MODE DETECTION AND ADJUSTMENT", IBM TECHNICAL DISCLOSURE BULLETIN, INTERNATIONAL BUSINESS MACHINES CORP. (THORNWOOD), US, vol. 38, no. 3, 1 March 1995 (1995-03-01), pages 45-47, XP000507972, ISSN: 0018-8689
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

FIELD OF THE INVENTION



[0001] The present invention relates broadly to devices in communication over a network. Specifically, the present invention relates to data flow management between devices transmitting and receiving data at different transmission rates. More specifically, the present invention relates to data transmission flow control in an interface between a computer and a video client.

BACKGROUND OF THE INVENTION



[0002] A "bus" is a collection of signals interconnecting two or more electrical devices that permits one device to transmit information to one or more other devices. There are many different types of busses used in computers and computer-related products. Examples include the Peripheral Component Interconnect ("PCI") bus, the Industry Standard Architecture ("ISA") bus and Universal Serial Bus ("USB"), to name a few. The operation of a bus is usually defined by a standard which specifies various concerns such as the electrical characteristics of the bus, how data is to be transmitted over the bus, how requests for data are acknowledged, and the like. Using a bus to perform an activity, such as transmitting data, requesting data, etc., is generally called running a "cycle." Standardizing a bus protocol helps to ensure effective communication between devices connected to the bus, even if such devices are made by different manufacturers. Any company wishing to make and sell a device to be used on a particular bus, provides that device with an interface unique to the bus to which the device will connect. Designing a device to particular bus standard ensures that device will be able to communicate properly with all other devices connected to the same bus, even if such other devices are made by different manufacturers. Thus, for example, an internal fax/modem (i.e., internal to a personal computer) designed for operation on a PCI bus will be able to transmit and receive data to and from other devices on the PCI bus, even if each device on the PCI bus is made by a different manufacturer.

[0003] Currently, there is a market push to incorporate various types of consumer electronic equipment with a bus interface that permits such equipment to be connected to other equipment with a corresponding bus interface. For example, digital cameras, digital video recorders, digital video disks ("DVDs"), printers are becoming available with an IEEE 1394 bus interface. The IEEE ("Institute of Electrical and Electronics Engineers") 1394 bus, for example, permits a digital camera to be connected to a printer or computer so that an image acquired by the camera can be printed on the printer or stored electronically in the computer. Further, digital televisions can be coupled to a computer or computer network via an IEEE 1394 bus.

[0004] However, many devices exist without any sort of IEEE 1394 interface. This presents a problem as such devices are unable to be to be connected with other devices as described above. There is a heartfelt need to overcome this problem to provide connectivity to devices that otherwise cannot be connected to an IEEE 1394 bus.

[0005] US patent no. 6,181,300 B1 discloses a display format conversion circuit with resynchronization of multiple display screens. Published European patent application EP 0690630 A2 describes a digital serial data interface suitable for video and audio data. Published European patent application EP 0875882 A2 describes a multi-scan video timing generator for format conversion. US 5 805 233 A1 is directed to produce a digital video signal from an analog signal.

SUMMARY OF THE INVENTION



[0006] The present invention controls the transmission of data between a computer and a video client via an interface device that buffers the data frames sent and communicates to the computer and the video client using different protocols. Described herein is a method of performing data transmission flow control according to claim 1.

[0007] Many other features and advantages of the present invention will be realized by reading the following detailed description, when considered in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS



[0008] 

FIG. 1 illustrates in block diagram form major components used in connection with examples of the present invention;

FIG. 2 illustrates the format of a frame in accordance with examples of the present invention;

FIGS. 3A and 3B illustrate the format of the first data packet and following data packet, respectively;

FIGS. 4A and 4B illustrate the organization of video data within data packets in accordance with the examples of the present invention;

FIGS. 5A and 5B illustrate the organization of audio data within data packets in accordance with the examples of the present invention;

FIGS. 6 and 7 illustrate elements of a header included in the frame in accordance with examples of the present invention;

FIG. 8 illustrates a collection of packets that combine to form a frame in accordance with examples of the present invention;

FIGS. 9A-9D illustrates an alternative example of the present invention in which variations of SDTI frames are used in accordance with examples of the present invention;

FIG. 9E illustrates an alternative example in which the transmitter divides the SDTI stream across multiple channels;

FIG. 10 illustrates in flow chart form acts performed to provide external clocking between a computer and a hardware interface in accordance with examples of the present invention;

FIG. 11 illustrates the register memory map for the interface device in accordance with examples of the present invention;

FIG. 12 illustrates organization of AA/ global registers contained within the interface
of the present invention;

FIG. 13 illustrates organization of global status registers contained within the interface device of the present invention;

FIG. 14 illustrates the isochronous control register contained in the interface device of the present invention;

FIG. 15 illustrates the organization of the flow control register contained in the interface device of the present invention; and

FIG. 16 illustrates the organization of the isochronous channel register contained in the interface device of the present invention.


DETAILED DESCRIPTION



[0009] Directing attention to FIG. 1, there is shown in block diagram form components connected to transmit audio and video data between a computer 100 and client 102, connected by bus 104 to interface 106. Computer 100 in the preferred example is a computing device capable of processing video and audio data and displaying it in a recognizable form to a user. Such devices include desktop, laptop, and palmtop computers. Client 102 as referred to herein is a video consumer or video producer, and includes such devices as digital cameras, and video storage devices, such as linear and random access devices. Bus 104, as referred to herein, includes a physical connection between computer 100 and interface 106, as well as the serial protocol adhered to by devices communicating over bus 104. In the preferred embodiment, bus 104 utilizes the IEEE 1394 serial bus protocol known as Firewire. Interface 106 accepts from client 102 both analog and digital inputs, and converts the input to scanned lines that can be used by an audio/ video player executed on computer 100. In a claimed embodiment, interface 106 accepts from client 102 a digital compressed/uncompressed signal and transmits the entire signal or subsets of that signal. In a claimed embodiment, interface 106 divides the input into frames 108 them over bus 104 to computer 100.

[0010] The format of frame 108 is illustrated in FIG. 2. Frame 108 includes a frame header 110, video block 112, audio block 114, and optionally an audio header 116. Audio data in audio block 114 is sampled with respect to the video data in video block 112. The audio sample count per frame varies in accordance with the number defined in the ANSI/SMPTE 272M specification. The audio sample count cadence is necessary to divide the integer number of samples per second across the NTSC frame rate (29.97 fps). Similarly, the size of frame 108 can vary to accommodate various video formats such as PAL or NTSC, and 8 or 10 bit video data, and audio formats such as 48Khz and 96Khz 16 and 24 bit etc. Similarly, the frame size of compressed data can vary to accommodate the compressed format. In an example, video block 112 and audio block or compressed block are of a predetermined size, to make parsing frame 108 simple and requiring little processing overhead by applications such as direct memory access programs. In the event that not all of video block 112 or audio block 114 is not completely full of data, the remaining portions of blocks 112, 114 can be filled with zeros. In one example, data contained in video block 112 and audio block 114 is not compressed, further reducing processing overhead on interface 106, as well as processing overhead required by decompression programs running on computer 100.

[0011] Interface 106, upon converting the input received from client 102 and converting it to scan lines and organizing it into frames 108, sends a frame at each vertical blanking interval to provide synchronization with computer 100. Computer 100 can derive the vertical blanking interval from the frequency of frames received and synchronize itself with the audio and video data of the incoming frames 108 received from interface 106. In this manner, processing resources are preserved, as there is no need to perform synchronization on each frame as it is received, thus providing higher quality performance of audio and video display on computer 100.

[0012] FIGS. 3A and 3B illustrate the format of the first data packet and following data packet, respectively.

[0013] FIGS. 4A and 4F illustrate the organization of video data within data packets. FIGS. 5A and 5B illustrate the organization of audio data within data packets.

[0014] FIG. 6 illustrates the contents of frame header 110. Included are format flags 130, which indicate how many bits per sample, SMPTE time code 132, incrementing frame counter 134, audio cycle count 136, audio sample count 138, channel count 140, block size byte count 142, audio format flags 144, and video format flags 146. Audio sample count 138 indicates a number of samples, which is in accordance with a cadence. The value in audio cycle count 136 indicates location within the cadence. A cadence of frames form a cycling pattern. In an alternative example, some of the contents of frame header 110 can be moved or copied to optional audio header 116. An alternative view of frame header 110 is shown in FIG. 7, showing byte count, data length, and a frame bit.

[0015] As illustrated in FIG. 8, frame 108 is constructed from a plurality of packets 150 of a predetermined size. Associated with each packet is a 1394 isochronous packet header. Data transmission in accordance with the present invention takes advantage of a synchronization bit to find the beginning of a frame. The first packet in frame 108 is marked with the synchronization bit. This allows the stream of data to be identified by computer 100 as it is received, further reducing processing overhead by allowing computer 100 to synchronize the flow of frames received from interface 106.

[0016] In an alternative example, frames adhering to the serial digital interface (SDI) standard can be utilized as illustrated in FIGS, 9A through 9E. In these examples, bus 104 adheres to the IEEE 1394B serial bus protocol to accommodate data rate restrictions set forth by the SDI standard. As described above, interface 106 forms frames from received input by creating scanned lines, performing deinterlacing, packetizing, and creating fixed-size SDT1 frames of audio and video data. Various modifications can be made to SDT1 frames, depending on the processing resources available on computer 100, interface 106, client 102, or other device. As described above, the transmission of SDT1 frames sent over bus 104 are synchronized to the vertical blanking interval of the accepted signal.

[0017] As shown in FIG. 9A, SDT1 frame 160 generally has two components: vertical blanking portion 162 and horizontal retrace 164. Alternatively, in another example (FIG. 9B), SDI frame header 166, a header having a synchronization bit and a frame count, is added to SDT1 frame 160 for further synchronization and fault detection purposes, such as recovering from data lost in transmission or the occurrence of a bus reset. In this example, a frame count synchronization bit is included in SDT1 frame header 166 and SDT1 frame header 166 is synchronized with vertical blanking portion 162. For example, in an application where interface 106 is unable to read compressed data, or excessive upgrades to interface 106 would be required, SDT1 frame 160 can be transmitted to computer 100, where processing on the SDT1 stream is performed by software in a non-realtime manner. Alternatively, as shown in FIG. 9C, SDT1 frame 160 can be constructed without horizontal retrace 164 to further reduce processing overhead. An SDT1 frame constructed without a horizontal retrace but having header 166, can also be utilized in an example, as shown in FIG. 9D. In yet another example, as shown in FIG. 9E, the SDT1 frame can be split between multiple channels and also include SDT1 frame header 166. In this example, the transmitter splits the SDT1 stream in half, with half of the lines being transmitted across channel A, the other half being transmitted across channel B. An attached header for each partial frame can be used to assist in re-combining frame data.

[0018] In another aspect of the present invention, external clocking can be utilized to synchronize data transmission between computer 100, interface 106 and client 102. In an example, client 102 includes a high-quality reference clock 180 (FIG.1) that can be used to synchronize clock 182 on interface 106 and prevent overflow of buffer 184 on interface 106. In this example, the value of reference clock 180 on client 102 is derived on interface 106 from the frequency at which data is transmitted from computer 100 to interface 106. To perform flow control, cycles are skipped between transmission of frames. A skipped cycle increases the amount of time between transmissions of frames, to slow the data rate of the frame transmission. Directing attention to FIG. 10, at reference numeral 200, computer polls interface 106 to read the size of buffer 184. While for exemplary purposes the buffer is referred to in terms such as "bigger" and "smaller," it is to be understood that in the case of a fixed-size buffer bigger and smaller refer to fullness of the buffer. At reference numeral 202, computer 100 then sends a plurality of frames to interface 106. At reference numeral 204, computer 100 again polls interface 106 to determine the size of buffer 184. If buffer 184 has grown in size from the last poll of its size (decision reference numeral 206), control proceeds to reference numeral 208, where computer 100 increases the delay between frames it is sending to interface 106. In an example, the delay between frames sent is 125 milliseconds. In another example a fractional delay is attained by modulating the delay over a number of frames. For instance if a delay between frames of 2.5 times 1.25microseconds is required, alternating frame delays of 2 and 3 cycles (of 125microseconds) are interspersed. Control then returns to reference numeral 202, where the frames are sent to interface 106 with the additional delay between frames. However, returning to decision reference numeral 206, if buffer 184 has not grown in size since the last polling of its size, control transitions to decision reference numeral 210. At decision reference numeral 210, if buffer 206 has decreased in size, control transitions to reference numeral 212, where the delay between frames sent from computer 100 to interface 106 is decreased. In an example, the amount of this decrease is also 125Ms. Control then transitions to reference numeral 202, where the frames are sent from computer 100 to interface 106 with the reduced delay between frames. Returning to decision reference numeral 210, if the size of buffer 184 has not reduced since the last polling of the size of buffer 184, then no adjustment to the delay between frames is necessary, and control transitions to reference numeral 202.

[0019] Interface 106 includes a serial unit 300 for enabling communication across bus 104. Serial unit 300 includes a unit directory 302 as shown in Table 1.
TABLE 1
NameKeyValue
Unit_Spec_ID 0x12 0x000a27
Unit_SW_Version 0x13 0x000022
Unit_Register_Location 0x54 Csr_offset to registers
Unit_Signals_Supported 0x55 Supported RS232 signals


[0020] The Unit_Spec_ID value specifies the organization responsible for the architectural definition of serial unit 300. The Unit_SW_Version value, in combination with Unit_Spec_ID value, specifies the software interface of the unit. The Unit_Register_location value specifies the offset in the target device's initial address space of the serial unit registers. The Unit_Signals_Supported value specifies which RS-232 signals are supported, as shown in the Table 2. If this entry is omitted from the serial unit directory 302, then none of these signals are supported.
TABLE 2
FieldBitDescription
Ready to Send (RTS) 0 Set if RTS/RFR is supported
Clear to Send (CTS) 1 Set if CTS is supported
Data Set ready (DSR) 2 Set if DSR is supported
Data Transmit Ready (DTR) 3 Set if DTR is supported
Ring Indicator (RI) 4 Set if RI supported
Carrier (CAR) 5 Set if CAR/DCD is supported
Reserved [31..6] Reserved


[0021] Also included in serial unit 300 is a serial unit register map 304 that references registers contained in serial unit 300. The organization of serial unit register map 304 is shown in Table 3.
TABLE 3
Hex OffsetNameAccessSize(quads)Value
0x0 Login W 2 Address of initiator's serial registers
0x8 Logout W 1 Any value
0xc Reconnect W 1 Initiator's node ID
0x10 TxFIFO Size R 1 Size in bytes of Tx FIFO
0x14 RxFIFO Size R 1 Size in bytes of Rx FIFO
0x18 Status R 1 CTS/DSR/RI/CAR
0x1c Control W 1 DTR/RTS
0x20 Flush TxFIFO W 1 Any value
0x24 Flush RxFIFO W 1 Any value
0x28 Send Break W 1 Any value
0x2c Set Baud Rate W 1 Baud rate 300->230400
0x30 Set Char Size W 1 7 or 8 bit characters
0x34 Set Stop Size W 1 1, 1.5 or 2 bits
0x38 Set Parity W 1 None, odd or even parity
0x3c Set Flow Control W 1 None, RTS/CTS or Xon/Xoff
0x40 Reserved - 4 Reserved
0x50 Send Data W TxFIFO size Bytes to transmit


[0022] Serial unit register map 304 references a login register. A device attempting to communicate with serial unit 300, is referred to herein as an initiator. For example, an initiator can be computer 100, or other nodes connected on a network via a high-speed serial bus and in communication with interface 106. The initiator writes the 64 bit address of the base of its serial register map to the login register to log into serial unit 300. If another initiator is already logged in, serial unit 300 returns a conflict error response message. The high 32 bits of the address are written to the Login address, the lower 32 bits to Login+4. The serial unit register map also references a logout register. The initiator writes any value to this register to log out of the serial unit. After every bus reset the initiator must write its (possibly changed) nodeID to the reconnect register. If the initiator fails to do so within one second after the bus reset it is automatically logged out. The 16-bit nodeID is written to the bottom 16 bits of this register, the top 16 bits should be written as zero. A read of the TxFIFOSize register returns the size in bytes of the serial unit's transmit FIFO. A read of the RxFIFOSize register returns the size in bytes of serial unit 300's receive FIFO. A read of the status register returns the current state of CTS/DSR/RI/CAR (if supported). The status register is organized as shown in Table 4.
TABLE 4
FieldBitDescription
CTS 0 1 if CTS is high, else 0
DSR 1 1 if DSR is high, else 0
RI 2 1 if RI is high, else 0
CAR 3 1 if CAR is high, else 0
Reserved [31..4] Always 0


[0023] A write to the control register sets the state of DTR and RTS (if supported). The organization of the control register is shown in Table 5.
TABLE 5
FieldBitDescription
RTS 0 If 1 set RTS high, else set RTS low
DTR 1 If 1 set DTR high, else set DTR low
Reserved [31..2] Always 0


[0024] A write of any value to the FlushTxFIFO register causes serial unit 300 to flush its transmit FIFO, discarding any bytes currently in it. A write of any value to the FlushRxFIFO register causes the serial unit to flush its receive FIFO, discarding any bytes currently in it. A write of any value to the send break register causes serial unit 300 to set a break condition on its serial port, after transmitting the current contents of the TxFIFO. A write to the set baud rate register sets serial unit 300's serial port's baud rate. The set baud rate register is organized as shown in Table 6.
TABLE6
Value writtenBaud Rate
0 300
1 600
2 1200
3 2400
4 4800
5 9600
6 19200
7 38400
8 57600
9 115200
10 230400


[0025] The set char size register sets the bit size of the characters sent and received. The organization of the set char size register is shown in Table 7. 7 bit characters are padded to 8 bits by adding a pad bit as the most significant bit.
TABLE 7
Value writtenCharacter bit size
0 7 bits
1 8 bits


[0026] The set stop size register designates the number of stop bits. The set stop size register is organized as shown in Table 8.
TABLE 8
Value writtenStop bits
0 1 bit
1 1.5 bits
2 2 bits


[0027] The set parity register sets the serial port parity. The organization of the set parity register is shown in Table 9.
TABLE 9
Value writtenParity
0 No Parity bit
1 Even parity
2 Odd parity


[0028] The set flow control register sets the type of flow control used by the serial port. The organization of the set flow register is shown in Table 10.
TABLE 10
Value writtenFlow Control
0 None
1 CTS/RTS
2 XOn/Xoff


[0029] The send data register is used when the initiator sends block write requests to this register to write characters into the transmit FIFO. Block writes must not be larger than the transmit FIFO size specified by the TxFIFOSize register. If there isn't enough room in the Tx FIFO for the whole block write, then a conflict error response message is returned and no characters are copied into the FIFO.

[0030] Also included in serial unit 300 is an initiator register map having a plurality of registers, organized as shown in Table 11.
TABLE 11
Hex OffsetNameAcce ssSize (quads)Value
0x0 Break W 1 Any value
0x4 Framing Error W 1 Received character
0x8 Parity Error W 1 Received character
0xc RxFIFO overflow W 1 Any value
0x10 Status change W 1 CTS/DSR/RI/CAR
0x14 Reserved - 3 Reserved
0x20 Received Data W RxFIFO size Bytes received


[0031] When serial unit 300 detects a break condition on its serial port, it writes an arbitrary value to this register. When serial unit 300 detects a framing error on its serial port, it writes the received character to the framing register. When serial unit 300 detects a parity error on its serial port, it writes the received character to the framing register. When serial unit 300 detects a parity error on its serial port, it writes the received character to the parity error register. When serial unit 300's receive FIFO overflows, serial unit 300 writes an arbitrary value to the RxFIFO overflow register. When serial unit 300 detects a change in state of any of CTS/DSR/RI/CAR it writes to the status change register indicating the new serial port signal state. The organization of the status register is shown in table 12.
TABLE 12
FieldBitDescription
CTS 0 1 if CTS is high, else 0
DSR 1 1 if DSR is high, else 0
R1 2 1 if R1 is high, else 0
CAR 3 1 if CAR is high, else 0
Reserved [31..4] Always 0


[0032] When serial unit 300 receives characters from its serial port it writes the received characters to the received data register with a block write transaction. It never writes more bytes than the receive FIFO size specified by the RxFIFOSize register. If the initiator cannot receive all the characters sent it responds with a conflict error response message and receives none of the characters sent.

[0033] FIG. 11 illustrates the register memory map for the interface device in accordance with examples of the present invention. FIG. 12 illustrates organization of A/V global registers contained within the interface of the present invention. FIG. 13 illustrates organization of global status registers contained within the interface device of the present invention. FIG. 14 illustrates the isochronous control register contained in the interface device of the present invention. FIG. 15 illustrates the organization of the flow control register contained in the interface device of the present invention. FIG. 16 illustrates the organization of the isochronous channel register contained in the interface device of the present invention.

[0034] In another example, a synthesized vertical blanking signal is derived by polling a vertical blanking register on interface 106. The vertical blanking signal invokes code to programs running on computer 100. In an example, timing information may also be provided to programs running on computer 100, either in combination with the invoked code or instead of the invoked code. In an example of the invention, interface 106 contains a register that holds a counter indicating current progress in the frame, from which the next vertical retrace can be extrapolated or otherwise derived. By deriving boundaries on frame transmission, other data that is within the frame and synchronized to the occurrence of a vertical blanking interval can be located and accessed, such as for sampling operations. Additionally, an example derives frame boundaries for locating data that is coincident with the vertical blanking interval but includes no information about the vertical blanking. In an example data may be obtained that is valid for a period after the occurrence of a video blanking interval, such as a time code contained within the frame, can be read, and used in various processing applications. In an example, computer 100 can then schedule an interrupt to fire at this extrapolated time, thus sending out a frame.


Claims

1. A method of performing data transmission flow control wherein the method comprises:

receiving, at an interface device (106) coupled between a computer (100) and a video client (102), a stream of input video data from the video client (102) according to a first format, wherein the video client (102) is unable to transfer the stream of input video data to the interface device (106) according to a bus protocol used to exchange data between the interface device (106) and the computer (100);

converting, at the interface device (106), the received input video data to scanned lines;

deriving, at the interface device (106), a vertical blanking interval based on the conversion of the scanned lines;

organizing, at the interface device (106), the scanned lines into frames of data (108) that include video data (112); and

at each vertical blanking interval, transmitting one of the frames of data (108) from the interface device (106) to the computer (100) according to the bus protocol, wherein the computer (100) synchronizes the display of the video data (112) from the frames of data (108) by deriving the vertical blanking interval from a frequency of the frames of data (108) received from the interface device (106), wherein the interface device (106) and the computer (100) share an external clock for synchronizing data transmission.


 
2. The method of claim 1, wherein the frames of data (108) additionally comprise audio data.
 
3. The method of claim 1, wherein the frames of data (108) are National Television System Committee (NTSC) compliant.
 
4. The method of claim 1, wherein a size of at least one frame of said plurality of frames of data (108) varies to accommodate various data sizes.
 
5. The method of claim 1, wherein the frames of data (108) are of a predetermined size.
 
6. The method of any preceding claim, wherein the input video data according to the first format comprises one or more analog signals.
 
7. The method of any of claims 1-5, wherein the input video data according to the first format comprises one or more digital signals.
 
8. The method of claim 7, wherein the digital signals are compressed.
 


Ansprüche

1. Verfahren zum Durchführen der Datenübertragungs-Flußsteuerung, wobei das Verfahren umfasst:

Empfangen, an einer Schnittstellenvorrichtung (106), die zwischen einem Computer (100) und einem Video-Client (102) gekoppelt ist, eines Streams von Eingangsvideodaten von dem Video-Client (102) gemäß einem ersten Format, wobei der Video-Client (102) nicht in der Lage ist, den Stream von Eingangsvideodaten zu der Schnittstellenvorrichtung (106) gemäß einem Busprotokoll zu übertragen, das verwendet wird, um Daten zwischen der Schnittstellenvorrichtung (106) und dem Computer (100) auszutauschen;

Umwandeln an der Schnittstellenvorrichtung (106) der empfangenen Eingangsvideodaten in gescannte Linien;

Ableiten, an der Schnittstellenvorrichtung (106), eines vertikalen Austastintervalls auf der Grundlage der Umwandlung der gescannten Linien;

Organisieren, an der Schnittstellenvorrichtung (106), der gescannten Linien in Daten-Frames (108), die Videodaten (112) beinhalten; und
bei jedem vertikalen Austastintervall, Übertragen eines der Daten-Frames (108) von der Schnittstellenvorrichtung (106) an den Computer (100) gemäß dem Busprotokoll, wobei der Computer (100) das Darstellen der Videodaten (112) aus den Daten-Frames (108) synchronisiert, durch Ableiten des vertikalen Austastintervalls aus einer Frequenz der Daten-Frames (108), die von der Schnittstellenvorrichtung (106) empfangen werden, wobei die Schnittstellenvorrichtung (106) und der Computer (100) einen externen Takt zum Synchronisieren der Datenübertragung teilen.


 
2. Verfahren nach Anspruch 1, wobei die Daten-Frames (108) zusätzlich Audiodaten umfassen.
 
3. Verfahren nach Anspruch 1, wobei die Daten-Frames (108) mit dem National Television System Committee (NTSC) konform sind.
 
4. Verfahren nach Anspruch 1, wobei eine Größe von mindestens einem Frame der Vielzahl von Daten-Frames (108) variiert, um verschiedene Datengrößen aufzunehmen.
 
5. Verfahren nach Anspruch 1, wobei die Daten-Frames (108) eine vorbestimmte Größe haben.
 
6. Verfahren nach einem der vorherigen Ansprüche, wobei die Eingangsvideodaten gemäß dem ersten Format ein oder mehrere Analogsignale umfassen.
 
7. Verfahren nach einem der Ansprüche 1-5, wobei die Eingangsvideodaten gemäß dem ersten Format ein oder mehrere digitale Signale umfassen.
 
8. Verfahren nach Anspruch 7, wobei die digitalen Signale komprimiert werden.
 


Revendications

1. Un procédé pour effectuer un contrôle de flux de transmission de données, le procédé comprenant :

la réception, au niveau d'un dispositif d'interface (106) couplé entre un calculateur (100) et un client vidéo (102), d'un flux de données vidéo d'entrée provenant du client vidéo (102) selon un premier format, le client vidéo (102) n'étant pas capable de transférer le flux de données vidéo d'entrée au dispositif d'interface (106) selon un protocole de bus utilisé pour l'échange de données entre le dispositif d'interface (106) et le calculateur (100) ;

la conversion, au niveau du dispositif d'interface (106), des données vidéo d'entrée reçues en lignes de balayage ;

la dérivation, au niveau du dispositif d'interface (106), d'un intervalle d'effacement vertical basé sur la conversion des lignes de balayage ;

l'organisation, au niveau du dispositif d'interface (106), des lignes de balayage entre trames de données (108) qui incluent des données vidéo (112) ; et

à chaque intervalle d'effacement vertical, la transmission, du dispositif d'interface (106) au calculateur (100), de l'une des trames de données (108) conformément au protocole de bus, le calculateur (100) synchronisant l'affichage des données vidéo (112) provenant des trames de données (108) par dérivation de l'intervalle d'effacement vertical à partir d'une fréquence des trames de données (108) reçues en provenance du dispositif d'interface (106), le dispositif d'interface (106) et le calculateur (100) partageant une horloge externe pour la synchronisation de la transmission des données.


 
2. Le procédé de la revendication 1, dans lequel les trames de données (108) comprennent en outre des données audio.
 
3. Le procédé de la revendication 1, dans lequel les trames de données (108) sont conformes au standard du Comité national de système de télévision (NTSC).
 
4. Le procédé de la revendication 1, dans lequel une dimension d'au moins une trame de ladite pluralité de trames de données (108) varie pour prendre en compte des tailles de données différentes.
 
5. Le procédé de la revendication 1, dans lequel les trames de données (108) sont d'une taille prédéterminée.
 
6. Le procédé de l'une des revendications précédentes, dans lequel les données vidéo d'entrée selon le premier format comprennent un ou plusieurs signaux analogiques.
 
7. Le procédé de l'une des revendications 1 à 5, dans lequel les données vidéo d'entrée selon le premier format comprennent un ou plusieurs signaux numériques.
 
8. Le procédé de la revendication 7, dans lequel les signaux numériques sont comprimés.
 




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REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description