JP4382230B2 - Transmission apparatus and method in video storage and playback system using MPEG2 encoding technology - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for transmitting a signal from a transmission apparatus to a reception apparatus, and more particularly to a transmission apparatus and method in a video storage / playback system.
[0002]
[Prior art]
MPEG (Moving Picture Experts Group) 2 TS packets (Transport Stream; also referred to as MPEG2-TS; multiple programs are transmitted as a single stream and can be used for television broadcasting, etc.) etc. When data is stored and played back, data continues to be transmitted until it is saturated at the receiver (buffer overflows), and when it is saturated, the receiver discards the data or transmits it at the receiver Control is performed such that a transmission control signal is issued to the apparatus side to suppress transmission data.
[0003]
[Problems to be solved by the invention]
As described above, in the conventional transmission control method, when reception data is saturated on the receiving device side, control is performed such as discarding the data or sending a transmission control signal to the transmitting device side to suppress transmission data. Therefore, reception and transmission of data such as MPEG2 TS packets cannot be performed at the same timing.
[0004]
For example, in Japanese Patent Laid-Open No. 4-329044, when storing an external packet in the packet storage memory, a time stamp indicating the reception time is added to each packet by an absolute time or a relative time, When a packet is transmitted, the packet is generated by separating the time stamped packet stored in the packet storage memory and the time stamp, comparing the time stamp with the output of the time counter by the time comparison circuit, and transmitting the packet according to the time stamp. A circuit configuration is disclosed.
[0005]
Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a transmission apparatus and method capable of sending accumulated TS packets to a reception apparatus at the same timing as the reception timing. .
[0006]
[Means for Solving the Problems]
The present invention that achieves the above object includes a first counter in a device that makes a round of a counter value in a predetermined cycle, a counter adder that adds a counter value of the first counter to a packet received from a transmitting device, The packet with the counter value added is stored in a storage medium, the packet with the counter value added is read from the storage medium, the packet from which the counter value has been separated is temporarily stored in a buffer, and the counter value is stored at a predetermined cycle. A second counter in the device to be cycled, and a comparator that compares the counter value of the second counter with the separated counter value, and when the two counter values match in the comparator, The packet is transmitted from the buffer to the receiving device.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described. In a preferred embodiment of the transmission apparatus according to the present invention, the transmission apparatus in the video storage / playback system using the MPEG2 encoding technique stores the counter packet by adding a counter value to the TS packet. This is transmitted to the receiving device at the same timing. In addition, even when a read error occurs when reading a TS packet stored from a digital storage medium (also referred to as “DSM”), transmission is possible at the same timing.
[0008]
More specifically, in the preferred embodiment of the transmission apparatus of the present invention, referring to FIG. 1, the TS packet input from the MPEG2 TS packet transmitter (1) is sent to the counter adder (3). The counter value generated by 1 counter (2) is added. The TS packet to which the counter value is added is stored in a DSM (Digital Storage Media) (6).
[0009]
At the time of reproduction, the counter separator (8) separates the TS packet and the counter value, and the TS packet is sent to the buffer (11) and the counter value is sent to the counter calculator (7).
[0010]
In the counter computing unit (7), if there is no error when the error detector (4) reads from the DSM (6), the counter value is sent to the comparator (10) as it is.
[0011]
The comparator (10) compares the counter value sent with the value of the second counter (9). If they are equal, the TS packet stored and held in the buffer (11) is converted into an MPEG2 TS packet receiver ( 12). In this way, TS packets are transmitted at the timing of the count value added at the time of accumulation.
[0012]
In Japanese Patent Laid-Open No. 4-329044 in which a time stamp of a reception time is added and stored in a packet storage memory and transmitted according to the time stamp at the time of packet transmission, when a read error occurs, the packet is sent at a timing different from the timing at the time of arrival. In the present invention, a counter that makes a round at a predetermined period is provided, and even when an error occurs when reading the accumulated packet, the timing can be maintained, and the error can be recovered. Sometimes timing gaps can be kept to a minimum.
[0013]
【Example】
In order to describe the above-described embodiment of the present invention in more detail, examples of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. Referring to FIG. 1, a transmission apparatus according to the present invention adds a counter value to a TS packet transmitted from an MPEG2 TS packet transmitter 1 such as digital broadcasting or IEEE1394 (serial interface having a real-time transmission function). A counter 3 for generating a counter value, and a DSM I / F for controlling writing and reading of a TS packet to which the counter value is added to a DSM 6 (Digital Storage Media) such as a magnetic disk or an optical disk (Interface) 5, a TS packet with a counter value read from the DSM 6 via the DSM I / F 5 is input, and the counter separator 8 that separates the counter value into the TS packet is separated by the counter separator 8. A buffer 11 for temporarily storing the TS packets, and a DS 6, an error detector 4 that detects an error when a packet is read from 6 and a counter value separated by a counter separator 8 are input, and a counter that calculates a counter value based on error information detected by the error detector 4 An arithmetic unit 7, a counter 9 that generates a counter value for sending, and a comparator 10 that compares the counter value output from the counter arithmetic unit 7 with the counter value sent from the counter 9. The TS packet is transmitted from the buffer 11 to the MPEG2 TS packet receiver 12 such as an MPEG2 decoder or IEEE1394.
[0015]
An operation of the transmission apparatus according to the embodiment of the present invention will be described. Referring to FIG. 1, a counter value generated by the counter 2 is added by a counter adder 3 to a TS packet sent from an MPEG2 TS packet transmitter 1 such as digital broadcasting or IEEE1394. The counter value generated by the counter 2 is generated at an independent timing unrelated to the time reference information PCR (Program Clock Reference) of the TS packet. The counter 2 counts up from 0, for example, reaches a count upper limit value in about several seconds, is reset to 0, and automatically starts the count-up operation from 0 again. The TS packet has a resolution that allows different counter values to be assigned. The timing for counting the counter 9 is the same as that for the counter 2.
[0016]
The TS packet to which the counter value is added by the counter adder 3 is accumulated in the DSM 6 such as a magnetic disk or an optical disk by the DSM I / F 5.
[0017]
The TS packet added with the counter value stored in the DSM 6 is read out via the DSM I / F 5.
[0018]
When the TS packet to which the counter value is added is read, the error detector 4 detects the presence or absence of an error. When the reading is normal, the TS packet to which the read counter value is added is sent to the counter separator 8 and separated into the counter value and the TS packet.
[0019]
The separated counter value is sent to the counter calculator 7, and the TS packet is sent to the buffer 11.
[0020]
The counter calculator 7 sets the counter 9 with the counter value as an initial value at the beginning of reading. In other cases (other than the beginning of reading), the counter value is sent to the comparator 10. Further, the difference from the previous counter value and the previous counter value are temporarily stored.
[0021]
The comparator 10 compares the counter calculator 7 with the counter value sent from the counter 9, and if they are the same value, sends a TS packet transmission permission signal to the buffer 11.
[0022]
The buffer 11 that has obtained the transmission permission signal transmits a TS packet to an MPEG2 TS packet receiver 12 such as IRD (IrDA) or IEEE1394.
[0023]
On the other hand, when reading from the DSM 6 is an error, the error detector 4 that has detected the error sends an error signal to the counter calculator 7.
[0024]
Even when the DSM 6 has a read error, the same operation as in the normal state is performed in the case of a type in which data is transmitted. However, if the counter value is broken due to an error, the difference is added to the previous counter value stored in the counter calculator 7 to generate a new counter value, which is sent to the comparator 10. The subsequent operation is the same as in normal operation.
[0025]
In the DSM 6, in the case of a type that does not transmit data at the time of a read error, the error detector 4 that has detected the error sends an error signal to the counter calculator 7 and the counter separator 8. Upon receipt of the error signal, the counter separator 8 sends a dummy count value to the counter calculator 7 and a Null packet to the buffer.
[0026]
The counter calculator 7 adds the difference to the previously stored counter value, generates a new counter value, and sends it to the comparator 10.
[0027]
The comparator 10 compares the count value from the counter arithmetic unit 7 and the counter 9, and if they are the same, sends the Null packet in the buffer 11 to the MPEG2TS packet receiver 12. Even when an error occurs, the data is sent with the counter value, and therefore, when returning to normal reading, there is no time lag from the original reproduction timing. Or it can be kept to a minimum.
[0028]
【The invention's effect】
As described above, according to the present invention, the counter value of the first counter that makes a round of the counter value in a predetermined cycle is added to the packet received from the transmission device, and the packet is stored in the storage medium. The packet with the counter value added is read from the medium, the counter value and the packet are separated, and the counter value of the second counter that makes a round of the counter value in a predetermined cycle is compared with the separated counter value by a comparator. If they match, the packet is transmitted to the receiving apparatus from the buffer that once holds the packet from which the counter value is separated, and the following effects are obtained.
[0029]
The first effect of the present invention is that when TS packets are accumulated, they can be transmitted at the same timing as the accumulated timing.
[0030]
The second effect of the present invention is that both the MPEG2 TS packet transmitter and receiver do not depend on the timing of TS packet reception and transmission because they are performed independently by the transmission apparatus.
[0031]
The third effect of the present invention is that the timing can be maintained even when an error occurs when reading the accumulated TS packet, and the timing shift can be kept to the minimum when returning from the error. is there.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.
[Explanation of symbols]
1 MPEG2 TS packet transmitter 2 Counter 3 Counter adder 4 Error detector 5 DSM IF
6 DSM
7 Counter operator 8 Counter separator 9 Counter 10 Comparator 11 Buffer 12 MPEG2TS packet receiver

Claims (11)

Means for adding a counter value of a first counter for making a round of the counter value in a predetermined cycle with respect to a packet received from a transmitting device;
A storage medium for storing the packet to which the counter value is added;
Means for reading the packet with the counter value added from the storage medium and separating the counter value and the packet;
The counter value of the second counter that makes a round of the counter value in a predetermined cycle is compared with the separated counter value, and if they match each other, the packet from the buffer that once holds the packet from which the counter value is separated Comparing means for controlling to transmit to the receiving device;
Means for detecting a read error of the storage medium;
When reading a packet with a counter value added from the storage medium,
When there is no read error, the counter value separated from the packet is sent to the comparison means, and the difference between the counter value sent to the comparison means this time and the previous counter value when there was no read error And temporarily store the counter value sent this time to the comparison means,
In the case of a read error with a broken counter value, the difference between the previous counter value when there was no read error and the previous counter value is added to the previous counter value when there was no read error. Counter calculation means for generating a correct counter value and supplying it to the comparison means;
With
In the comparison unit, when the counter value of the second counter matches the counter value supplied from the counter calculation unit, a packet is transmitted from the buffer to a reception device.   2. The transmission apparatus according to claim 1, wherein when the packet with the counter value added is read from the storage medium for the first time, the second counter is set to an initial value. A first counter that cycles the counter value at a predetermined period;
A counter adder for adding the counter value of the first counter to the packet transmitted from the packet transmitter;
A storage medium for storing a packet to which a counter value is added;
An interface circuit for controlling writing and reading of the packet to which the counter value is added to the storage medium;
A counter separator that separates the packet with the counter value read from the storage medium via the interface circuit into a counter value and a packet;
A buffer for temporarily storing packets separated by the counter separator;
An error detector for detecting an error when reading a packet from the storage medium;
When the counter value separated by the counter separator is input and no error is detected by the error detector, the separated counter value is sent to the comparator and the counter value sent to the comparator this time And temporarily store the difference between the previous counter value when there was no error and the counter value sent this time to the comparator,
When an error is detected by the error detector, a new counter is obtained by adding the difference between the previous counter value when there is no error and the previous counter value when there is no error. A counter calculator for generating a value and supplying the value to the comparator;
A second counter for generating a counter value for transmission by circulating the counter value in a predetermined cycle;
A counter value output from the counter calculator, said comparator for comparing the counter value from the second counter,
With
When the two counter values coincide with each other, the comparator sends a transmission permission signal to the buffer, and the packet is transmitted from the buffer to a packet receiver.   4. The transmission apparatus according to claim 3, wherein when the packet to which the counter value is added is read from the storage medium for the first time, the counter calculator sets an initial value for the second counter. .   In the case of a method of sending a packet at the time of a read error, when a read error of a packet added with a counter value from the storage medium is detected by the error detector, the error detector sends an error signal to the counter calculator and the counter When the packet is sent to the counter separator, the packet whose counter value is separated by the counter separator is temporarily stored in the buffer, and the counter value of the second counter in the comparator matches the separated counter value, 4. The transmission apparatus according to claim 3, wherein a transmission permission signal is transmitted to the buffer, and a packet is transmitted from the buffer to the packet receiver. If the counter value is broken when reading the packet with the counter value added from the storage medium, the counter arithmetic unit holds the previous counter value held in the counter arithmetic unit in the counter arithmetic unit. The difference between the previous counter value and the previous counter value is added, a new counter value is generated and sent to the comparator,
In the comparator, when the counter value of the second counter matches the generated counter value, a transmission permission signal is transmitted to the buffer, and a packet is transmitted from the buffer to the packet receiver. 6. The transmission apparatus according to claim 5, wherein: In the case of a method that does not send data at the time of a read error, the counter separator temporarily stores a null packet in the buffer and transmits a dummy counter value to the counter arithmetic unit,
The counter arithmetic unit adds a difference between the previous counter value and the previous counter value held in the counter arithmetic unit to the previous counter value stored in the counter arithmetic unit, thereby obtaining a new value. Generate a counter value and send it to the comparator;
In the comparator, when the counter value of the second counter matches the generated counter value, a transmission permission signal is transmitted to the buffer, and a packet is transmitted from the buffer to the receiver. The transmission apparatus according to claim 3, wherein:   The transmission apparatus according to claim 1, wherein the packet is an MPEG2 TS (Transport Stream) packet.   9. The transmission apparatus according to claim 8, wherein the counter value generated by the first counter is generated at a timing independent of the program time base reference value of the TS packet. Receiving a packet from the transmitting device, adding the counter value of the first counter that makes a round of the counter value in a predetermined cycle to the packet and storing it in the storage medium;
A packet to which a counter value is added is read from the storage medium, the counter value and the packet are separated, the packet from which the counter value is separated is temporarily held in a buffer, and the counter value is cycled at a predetermined cycle. The counter value of the counter and the separated counter value are compared by a comparator, and when the two counter values match, a packet is sent from the buffer to the receiving device,
When there is no read error when reading a packet with a counter value added from the storage medium, the counter value separated from the packet is sent to the comparator and the counter value sent this time to the comparator And the difference between the previous counter value when there was no read error and the counter value sent to the comparator this time,
In the case of a read error with a broken counter value, the difference between the previous counter value when there was no read error and the previous counter value is added to the previous counter value when there was no read error. A counter value is generated and supplied to the comparator,
In the comparator, when a counter value of the second counter matches the generated new counter value, a packet is transmitted from the buffer to a receiving device.   11. The transmission method according to claim 10, wherein the packet is an MPEG2 TS (Transport Stream) packet.

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