JP2010041496A - Data reception processing apparatus and data reception processing method - Google Patents

Abstract

The present invention provides a data reception processing apparatus that is not affected by jitter caused by a lost packet restoration process on a receiving side.
In addition to a TTS (Transport Stream with Time Stamp) buffer managed by an adaptive clock method, an RTP buffer is provided. A packet input from the IP processing unit 101 to the RTP buffer 102 is immediately stored in the TTS buffer 105. The RTP buffer 102 stores a packet used for restoring the lost packet. When the restoration unit 103 and the null packet processing 104 detect a missing packet, the restoration unit 103 and the null packet processing 104 temporarily store substitute data in the missing packet portion in the TTS buffer 105. The restoration unit 103 and the packet replacement unit 106 replace the restored packet with alternative data when the lost packet can be restored.
[Selection] Figure 4

Description

The present invention relates to a data reception processing apparatus and method for performing reception processing on data received via a communication network.
In particular, the present invention relates to a data receiving method and a data receiving apparatus for improving “buffering jitter” that occurs when a lost packet is restored when a packet received via a communication network is lost.

When push-type communication is performed using a communication network (network), an overflow that the received data cannot be stored in the buffer on the receiving side or an underflow that the amount of received data stored in the buffer is extremely reduced occurs. Sometimes.
In the present specification, these are referred to as buffer failures.

As one of the measures for preventing the buffer failure, the write clock for writing data to the buffer and the read clock for reading data from the buffer are usually synchronized.
The write clock corresponds to the data transmission clock on the transmission side of the communication network, and the read clock corresponds to the reproduction clock on the reception side. Therefore, it is only necessary to synchronize the data transmission clock on the transmission side and the reproduction clock on the reception side.

However, there is a guarantee that network synchronization is established that there is data delay fluctuation (jitter) in the communication network or communication path, and the clock on the transmission side is synchronized with the clock on the reception side. Usually not obtained.
As such jitter, high-frequency jitter caused by network load spikes and continuously fluctuating fluctuations are known.

  Therefore, in an asynchronous communication network, for example, an ATM (Asynchronous Transfer Mode) network, the buffer retention amount (data accumulation amount) is constantly monitored on the receiving side, and the buffer retention amount is constant. The reproduction clock is controlled so that This is called an “adaptive (adaptive) clock recovery method”.

The concept of “adaptive clock recovery method” is defined in Non-Patent Document 1 (ITU (International Telecommunication Union) -T recommendation 1.3633.1).
In addition, an apparatus using an adaptive clock method that considers data delay fluctuation (jitter) in a communication network or communication path has been proposed (for example, Patent Documents 1 and 2).

Here, an example assuming application of the “adaptive clock recovery method” to real-time streaming (real-time data transmission) in an IP (Internet Protocol) network will be shown.
FIG. 1 shows the configuration of the receiver 200 in that case. The receiver 200 includes a reception processing unit 210 that receives IP data from the communication network 230 and performs signal processing, and a reproduction processing unit 220 that reproduces video data, audio data, and the like.

  Based on the adaptive clock method, the TTS processing unit 215 of the reception processing unit 210 stores the data retention amount (data storage amount) of the time-stamped transport stream (TTS) buffer that is the target of time stamp processing. ).

When a packet passes through the communication network 230, the packet may be lost, and the RTP packet processing and FEC processing unit 213 in the previous stage of the TTS processing unit 215 performs restoration processing of the lost packet. RTP is an abbreviation for Real Time Transport Protocol, and FEC is an abbreviation for Forward Error Correction.
In the RTP packet processing and FEC processing unit 213, when the missing packet processing or restoration processing of the lost packet in the communication network 230 is performed, the buffer processing (buffering) accompanying the restoration processing affects the retention amount of the buffering to be monitored. Arise.

The reason will be explained.
For example, in the packet arrangement illustrated in FIG. 2, assuming that the packet “01” is lost, for the restoration, at least a packet “91” that is continuous with the lost “01” packet, Waiting for the arrival of the “C1” packet, restoration is performed using the “91” packet and the “C1” packet.
In this way, since the lost packet is restored (corrected) after the arrival of the “91” packet and the “C1” packet, a delay occurs in the buffer processing of the TTS processing unit 215.

  As a result, even if the “adaptive clock method” that takes into account data delay fluctuations (jitter) in the communication path is applied, the received packet is buffered in the recovery processing of the missing packet in the reception processing unit. This affects the accuracy of the “adaptive clock system”.

In order to avoid overflow or underflow of received data in the TTS buffer, the amount of data stored in the TTS buffer is often set with an upper limit and a lower limit as threshold values.
However, the influence of the RTP packet processing in the previous stage of the TTS buffer processing unit 215 and the buffering of the FEC processing unit 213 behaves like jitter when data is input to the monitoring target buffer.

In order to absorb such jitter, it is necessary to increase the threshold value (margin) of the TTS buffer. Then, the disadvantage of increasing the size of the buffer is encountered.
The TTS buffer is usually configured as a FIFO buffer.

The problem described above is a problem caused by limiting the TTS buffer to be monitored.
It is also possible to assume a system in which blocks are gathered to some extent and observe the data retained in the system to include jitter inside the system and ignore its influence.

As a specific method, the total data retention amount of the RTP process and the TTS process in FIG. 1 can be considered, so that data movement inside the system, jitter, and the like can be ignored.
However, in this case, since the restoration processing unit for missing packets is included in the system, the amount of data input to the system and the amount of data output from the system do not match due to restoration of the missing packets. It is necessary to consider.

Further, in the above system, it is necessary not to cause a buffer failure state in which data input / output does not overflow or underflow, but also to control each buffer in the system so that a failure state does not occur.
As a result, the method of taking measures as a system in which the above blocks are combined encounters a problem that the control of the buffer becomes very complicated.

  From the above, it is desired to provide a data reception processing device and a data reception processing method that overcome the above-described problems.

ITU-T recommendation 1.363.1 JP 2006-42273 A JP 2006-49941 A

  According to the present invention, there is provided input means for inputting a stream in which information indicating continuity indicating the output order of each packet is added to packetized content information, and information indicating the continuity input by the input means. A first buffer means for storing the added stream; a second buffer means for storing the stream output from the first buffer means; and at least a stream in the stream input to the first buffer means. Based on the presence / absence of continuity, it is detected that a packet has been lost, and an alternative packet is inserted into the detected lost packet data portion stored in the second buffer means, so that the lost packet can be restored. In this case, a restoration processing means for replacing the substitute packet stored in the second buffer means with the restored packet, and the second buffer Data reception processing device and an output control means for outputting the stored packet data unit is provided.

Preferably, the first buffer unit stores only a stream input from the input unit and a packet necessary for the restoration process.
Further preferably, when the restoration processing unit detects that the order of the packet numbers in the stream stored in the first buffer unit is out of order, the packet stored in the second buffer unit Correct the order.

  Further, according to the present invention, in order to perform data reception processing in the receiving apparatus having the first buffer unit and the second buffer unit, the packetized content information that is input indicates a sequence indicating the output order of each packet. A step of inputting a stream to which information indicating sex is added, and a first buffer processing step of storing the stream to which information indicating continuity input by the input unit is added in the first buffer unit; A second buffer processing step of reading the stream from the first buffer means and storing it in the second buffer means, and at least whether there is continuity in the stream input to the first buffer means; A step of detecting that a packet has been lost based on the packet, and a detection stored in the second buffer means when the packet is lost. A substitute packet inserting step of inserting a substitute packet into the missing packet data portion, and a replacement step of replacing the substitute packet stored in the second buffer means with the restored packet when the missing packet can be restored. And an output control step of outputting the packet data stored in the second buffer means.

In the present invention, two buffer means are provided, and packets necessary for restoring lost packets among the packets received by the first buffer means are stored. Further, the stream input to the first buffer means is immediately transferred to the second buffer means and stored in the second buffer means.
Preferably, an adaptive clock system is applied for writing the packet to the second buffer means and outputting the packet from the second buffer means.
The restoration processing means detects whether or not there is a missing packet in the stream input to the first buffer means. When the missing packet is detected, the restoration processing means temporarily stores the substitute packet in a portion corresponding to the missing portion of the packets accumulated in the second buffer means.
When the lost packet can be restored using the packet that arrives after the missing packet, the restoration processing means restores the packet corresponding to the missing packet and replaces the substitute packet stored in the second buffer means .

According to the present invention, the lost packet restoration processing can be realized without affecting the jitter.
As a result, the fluctuation of the buffer amount in the second buffer means is reduced, and the capacity of the second buffer means can be prevented from increasing.
In addition, the accuracy of the adaptive clock system in which the accumulated amount (retention amount) of the second buffer means is monitored and clock synchronization is performed is improved.

  Furthermore, according to the present invention, the order of packets out of order can be realized without affecting the jitter.

Communication System Configuration FIG. 3 is a diagram showing a configuration of a communication system to which the receiver according to the embodiment of the present invention is applied.
The communication system 1 illustrated in FIG. 3 is configured to transmit packet data in the form of a transport stream (TS) from a transmitter 11 to a receiver 12 via a communication network 10.

Configuration of Receiver FIG. 3 shows the configuration of the receiver 12.
The receiver 12 is connected to the communication network 10, receives the transport stream data transmitted from the transmitter 11 and performs signal processing, and inputs the data processed by the reception processing unit 100. The content processing unit 110 performs signal processing specific to the data.
The transport stream transmitted from the transmitter 11 includes, for example, television video data and audio data that are compressed and multiplexed, and may include still image data, character information, and the like. It includes television video data and audio data, and can include still image data, character information, and the like. These data are collectively called content data.
The receiver 12 is an IP television receiver, for example, and receives and reproduces content sent from the transmitter 11.
For example, as illustrated as the reproduction processing unit 220 in FIG. 1, the content processing unit 110 decodes the demultiplexed video data and audio data, respectively, a TS demultiplexer that separates the multiplexed video data and audio data. A video decoder and an audio decoder can be included.

  The reception processing unit 100 in the receiver 12 receives the content sent from the transmitter 11 and performs the following reception processing so that the content processing unit 110 can perform reproduction processing such as content decoding processing.

FIG. 4 shows a configuration diagram of the reception processing unit 100.
The reception processing unit 100 includes an IP (Internet Protocol) processing unit 101 and an RTP (Real Time).
Transport Protocol) buffer 102.
The reception processing unit 100 also includes a restoration unit 103, a null packet processing 104, and a TTS (Transport Stream) buffer 105 with a time stamp (TimeStamp).
The reception processing unit 100 further includes a packet replacement unit 106.
The reception processing unit 100 further includes a packet output unit 107 and a clock synchronization unit 108.
The processing contents of each unit will be described below.

IP processing unit 101
The IP processing unit 101 receives an IP packet transmitted from the transmitter 11 via the communication network 10.
The IP processing unit 101 removes data not used for subsequent processing such as an IP header and UDP (User Datagram Protocol) header from the received IP packet S10, for example, processing in the content processing unit 110, and RTP (Real Time Transport Protocol) packet. The process which extracts is performed.
Under the control of the restoration unit 103, the IP processing unit 101 sends the payload portion of the RTP packet data S 101 extracted by the IP processing unit 101 to the RTP buffer 102.

RTP buffer 102
The RTP buffer 102 stores (stores) the RTP packet data S101 sent from the IP processing unit 101.
The RTP packet data stored in the RTP buffer 102 is sent to the TTS buffer 105 as a TS packet S102 with a time stamp (TimeStamp) under the control of the restoration unit 103.

TTS buffer 105
A TTS (Transport Stream with TimeStamp) buffer 105 accumulates (stores) payload data output from the RTP buffer 102 under the control of the restoration unit 103, that is, TS packets with a time stamp.
The TTS buffer 105 monitors the accumulation amount (retention amount) based on the adaptive clock method, and performs clock synchronization between the write packet and the read packet.
The TTS buffer 105 is configured as, for example, a FIFO buffer.

Unlike the TTS buffer 105 to which the adaptive clock method is applied, the RTP buffer 102 stores (stores) the RTP packet data S101 sent from the IP processing unit 101 and immediately controls the restoration unit 103. Thus, the TS packet S102 is sent to the TTS buffer 105 as a TS packet S102 with a time stamp (TimeStamp), and only a packet used for restoring a lost packet, which will be described later, is stored.
Therefore, the capacity of the RTP buffer 102 does not need to be increased as the TTS buffer 105.

As described above, the restoration processing means restoration unit 103 is described below in addition to the control of sending packets from the IP processing unit 101 to the RTP buffer 102 and sending packets from the RTP buffer 102 to the TTS buffer 105. The lost packet restoration process and the process of restoring the received packet out of order to the normal order are performed.

  That is, for example, when there is a missing packet in the communication network 10 between the RTP packet stored in the RTP buffer 102 and the TS packet with a time stamp accumulated in the TTS buffer 105, the restoration unit 103, the packet replacement unit 106 In cooperation with the Null packet processing 104, reception / restoration processing described with reference to FIG. 4 is performed.

The restoration unit 103, the null packet processing 104, and the packet replacement unit 106 constitute a reception restoration processing unit.
On the other hand, the RTP buffer 102 corresponds to the first buffer means of the present invention, is an auxiliary buffer for restoration processing, and can be included in the restoration processing means.
The TTS buffer 105 corresponds to the first buffer means of the present invention, and functions as a buffer for accumulating packets received from the communication network 10 on the basis of the adaptive clock system, while part of the restoration processing means. Also works.

Restoring unit 103
The restoration unit 103 includes a restoration determination unit 103A and a restoration processing unit 103B.
When it is determined that there is no packet loss and the following restoration process is unnecessary, the restoration unit 103 instructs the RTP buffer 102 to send the payload data of the RTP packet from the RTP buffer 102 to the TTS buffer 105 (RTP buffer). 102).

When the restoration unit 103 detects that the RTP packet stored in the RTP buffer 102 is missing, the restoration unit 103 refers to a packet that arrives later, and restores the missing packet if the missing can be restored I do.
In addition, when the order of received packets stored in the RTP buffer 102 is disordered, for example, when the reception order is reversed, the restoration unit 103 performs processing for returning the order to the original order.
Details thereof will be described later.

  The restoration determination unit 103A continuously monitors the packet numbers assigned to the RTP packet data S101 input to the RTP buffer 102 from the IP processing unit 101.

By monitoring the packet number assigned to RTP packet data S101 input to the RTP buffer 102 by restoring recovery determination unit 103A of the missing RTP packets continuously, or restoration determination unit 103A is missing RTP packet It can be determined whether or not.

The restoration determination unit 103A that has detected the loss of the RTP packet determines, for example, whether or not the missing RTP packet can be restored using a packet received after the missing packet.
For example, when the RTP packet is video data, audio data, etc., even if one to several packets are lost, considering the continuity of the video data or audio data, the data corresponding to the lost data is, for example, It can usually be restored by the method described above.

For example, the restoration processing unit 103B refers to packets with numbers before and after the number of missing packets stored in the RTP buffer 102, interpolates the missing packets, and performs an RTP packet corresponding to the missing RTP packet. Restore data. Alternatively, the restoration processing unit 103B analogizes the missing RTP packet from the RTP packet data having a number before the number of the missing RTP packet, and restores the RTP packet data corresponding to the missing packet data.
When the restoration of the missing RTP packet is completed, the restoration processing unit 103B notifies the packet substitution unit 106 of a restoration completion notification signal S103 indicating that the restoration is completed.

Restoration of the order of RTP packet numbers The reception processing unit 100 continuously monitors the packet number assigned to the RTP packet data S101 input to the RTP buffer 102 by the restoration determination unit 103A. It is possible to determine whether or not the order of the received RTP packet numbers is valid.
The reason why the order of the RTP packet numbers is disturbed is that the communication network 10 is faulty or the internal order of the stream of the received IP packet S10 transmitted from the transmitter 11 due to a delay path existing in the communication network 10. May be reversed.
When the restoration determination unit 103A detects that the order of the packet numbers is out of order, the restoration determination unit 103A notifies the restoration processing unit 103B.

  The restoration processing unit 103B rearranges the order of packets stored in the TTS buffer 105 in the reverse order to the correct packet number. As a result, the storage order (storage position) of the RTP packets in the TTS buffer 105 is corrected in the order of the RTP packet numbers.

Null packet processing 104
The Null packet processing unit 104 functioning as an alternative packet processing unit includes a Null data insertion determination unit 104A, a time stamp calculation unit 104B, and a Null data insertion unit 104C.
The Null packet processing unit 104 compensates for the lost packet by inserting dummy data into the portion where the packet is lost as an alternative packet. That is, when a packet is lost, the lost packet may not be restored at the time when the packet loss is detected, for example, because a packet received later is used for the restoration. The Null packet processing unit 104 temporarily inserts a substitute packet into the missing packet part in the TTS buffer 105.

In this embodiment, Null, that is, data having a value of “0” is inserted as data dummy data used as an alternative packet.
Note that, when the lost packet cannot be restored, the substitute packet remains as a missing packet.
Details will be described below.

Similar to the restoration determination unit 103A, the Null data insertion determination unit 104A monitors the packet number assigned to the RTP packet data S101 input to the RTP buffer 102 to determine whether there is a packet loss. .
When the Null data insertion determining unit 104A determines that the packet received by the IP processing unit 101 is missing, the Null data insertion determining unit 104A notifies the time stamp calculating unit 104B of the determination result and causes the time stamp calculating unit 104B to perform processing.

The time stamp calculation unit 104B calculates the number of missing packets. That is, the time stamp calculation unit 104B calculates a time stamp from the time stamp in the RTP packets with numbers before and after the number of missing packets and the number of missing packets.
The Null data insertion unit 104C prepares Null packets corresponding to the number of lost packets, that is, packet data whose data value is “0”, and inserts it into the TTS buffer 105 as insertion dummy data S104A. Send it out.
The number of Null data supplemented by the Null data insertion unit 104C is a number corresponding to the number of missing packets.

  The null data insertion unit 104C notifies the packet replacement unit 106 of the dummy data position / number signal S104B for insertion as a dummy data position / number signal S104B for insertion, and the position where the dummy packet is inserted in response to the packet loss in the TTS buffer 105.

Packet replacement unit 106
The packet replacement unit 106 includes a packet replacement processing unit 106A and a packet replacement table 106B.
When the restoration completion notification signal S103 is input from the restoration unit 103, the packet substitution processing unit 106A does not need to replace the packet and does nothing.
On the other hand, when the dummy data position / number signal S104B for insertion is input from the null data insertion unit 104C of the null packet processing unit 104, the packet replacement processing unit 106A performs the following processing.

The packet replacement processing unit 106A notifies the insertion position of the dummy data (Null packet) and the packet number by the TTS buffer 105, which is output from the Null packet processing unit 104 as the dummy data position / number signal S104B for insertion. Is done.
The packet replacement processing unit 106A adds the content notified to the packet replacement table 106B as a map entry. If a map entry cannot be added to the packet replacement table 106B, the packet replacement processing unit 106A sets a threshold for the packet number and deletes the previous map entry for which the threshold has been set from the packet replacement table 106B. .

  Further, the packet replacement processing unit 106A receives a request from the Null packet processing unit 104 and searches the replacement data stored in the packet replacement table 106B for a pointer corresponding to the number of the packet to be replaced. If the corresponding map entry is found by the search, the packet replacement processing unit 106A outputs packet replacement data S106A indicating the map entry detected by the search to the TTS buffer 105. As a result, the TTS buffer 105 replaces the dummy packet (substitute packet) at the corresponding position in the TTS buffer 105 with the restored packet.

Further, the dummy packet is prevented from being output from the reception processing unit 100 to the content processing unit 110 during the replacement processing of the packet replacement processing unit 106A. That is, the packet replacement processing unit 106A outputs the output stop signal S106B to the packet output unit 107 to stop the processing of the packet output unit 107.
When the replacement is completed, the packet replacement processing unit 106A cancels the output stop signal S106B output to the packet output unit 107, and deletes the map entry in the packet replacement table 106B.

Packet output unit 107
The packet output unit 107 includes an output control unit 107A and a counter 107B.
The packet output unit 107 determines whether to output the TS packet stored in the TTS buffer 105 to the content processing unit 110. If the packet can be output, the packet output unit 107 removes the time stamp from the TS packet with the time stamp stored in the TTS buffer 105 and outputs the result to the content processing unit 110.
For example, a demultiplexer and a decoder illustrated in FIG. 1 are provided in the content processing unit 110, and TS packets from which time stamps have been removed are input.

The output control unit 107A performs clock synchronization processing based on the adaptive clock method.
The stream output control unit 107A compares the time stamp of the TS packet with the time stamp in the TTS buffer 105 with the value of the counter 107B.
When the value of the counter 107B matches the time stamp of the TS packet, the output control unit 107A performs timing control for outputting the data stored in the TTS buffer 105 to the content processing unit 110.
Further, a threshold value can be provided in the TTS buffer 105, and when the time stamp of the TS packet in the TTS buffer 105 is delayed within the threshold value from the count value of the counter 107B, the output control unit 107A immediately Controls the output of TS packets from the TTS buffer 105 to the content processing unit 110.

  The output control unit 107A can also invalidate the output of the TS packet. In that case, the counter 107B continues to increment (increase) the count process.

Furthermore, when the Null packet in which the dummy packet is inserted is not replaced, the output timing comes, for example, when the content processing unit 110 can process the Null packet, the output control unit 107A is replaced. The packets that are not received are output as they are.
On the other hand, when it is not desired to output dummy data to a subsequent device such as the content processing unit 110, the output control unit 107A inserts a special data pattern as a dummy packet. As such a special data pattern, for example, a data processing unit 110 that can be deleted by a filtering process or the like can be used.

Clock synchronization unit 108
The clock synchronization unit 108 monitors the accumulated amount of TS data in the TTS buffer 105, that is, the packet retention amount, and performs clock synchronization processing used by the counter 107B of the packet output unit 107 by an adaptive clock method.

FIG. 5 is a flowchart for explaining reception processing and restoration processing of the IP processing unit 101, the RTP buffer 102, the restoration unit 103, and the Null packet processing 104 over time.
Since the detailed processing contents of the IP processing unit 101, the RTP buffer 102, the restoration unit 103, and the null packet processing 104 have been described above, the following description is only an overview.

Step S1, packet input, RTP packet extraction, RTP packet storage IP processing unit 101 inputs a packet from communication network 10 and extracts the RTP packet from the input packet.
The RTP buffer 102 stores the RTP packet data S101 output from the IP processing unit 101. The RTP packet data stored in the RTP buffer 102 is used for detection of missing packets and restoration of missing packets.

Step S2, packet loss determination The restoration determination unit 103A of the restoration unit 103 continuously monitors RTP packets input to the RTP buffer 102, and determines whether or not the packet received by the reception processing unit 100 is missing. Determine.
When the restoration determination unit 103A detects a missing packet, the process proceeds to step 3, and in steps S3 to S5, an alternative packet is inserted and registered in the packet replacement table.
If there is no missing packet, the process proceeds to step 6.

Step S3: Time stamp to be inserted , time stamp calculation unit 104B of the Null packet processing 104 performs the time stamp of the TS packet with the latest time stamp in the TTS buffer 105 and the time stamp at the beginning of the input packet to the RTP buffer 102. Then, the number of time stamps to be inserted is calculated from the number of lost packets.

Step S4, Insertion of Alternative Packet (Dummy Packet) The null data insertion unit 104C of the null packet processing 104 outputs dummy dummy data S104A for insertion to the TTS buffer 105 as the number of alternative packets corresponding to the number of missing packets. The TTS buffer 105 rewrites the data corresponding to the missing packet based on the input dummy data for insertion S104A.

In step S5, the registration time stamp calculation unit 104B in the packet replacement table outputs the dummy data position / number signal S104B for insertion indicating the position of the lost packet and the lost packet number to the packet replacement unit 106. Based on the dummy data position / number signal S104B for insertion, the packet replacement processing unit 106A registers a set of the position and number of the missing packet in the packet replacement table 106B.

In step S6, the Null packet processing 104 of the packet reception order determination / restoration unit 103 continuously monitors the packet number assigned to the RTP packet input to the RTP buffer 102, and the received packet order is determined. Judge whether it is not disturbed.
If the order of received packets is normal, the process proceeds to step S10. If there is a disorder such as the reverse order of the received packets, the process proceeds to step S7.

In step S7, the replacement table search packet replacement processing unit 106A searches the replacement data recorded in the packet replacement table 106B for a pointer corresponding to the number of the packet to be replaced.
If the corresponding pointer can be retrieved, the process proceeds to step S8. If the corresponding pointer cannot be retrieved, the process proceeds to step S11.

Step S8: The TS packet output prohibition packet replacement processing unit 106A from the TTS buffer 105 outputs an output stop signal S106B to the packet output unit 107, and outputs a TS packet S105 without a time stamp from the TTS buffer 105. Is prohibited.

Step S9, Packet Replacement Processing The packet replacement processing unit 106A cooperates with the TTS buffer 105 to perform processing to return the reception order of the disordered packets stored in the TTS buffer 105 to normal.

In step S10, the TS packet output restart packet replacement processing unit 106A instructs the packet output unit 107 to cancel the packet replacement data S106A. As a result, the packet output unit 107 resumes outputting the TS packet from the TTS buffer 105.

Step S11, Restorability Determination Restoration determination unit 103A determines whether or not a lost packet can be recovered.
If restoration is possible, the process proceeds to step S12. If restoration is not possible, the process ends. If restoration is not possible, Null data is inserted as a substitute packet in the packet lost in step S4.

Step S12
The packet replacement processing unit 106A of the packet replacement unit 106 searches the packet replacement table 106B for a corresponding map entry.
If the corresponding map entry can be searched, the process proceeds to step S13.
If the corresponding map entry cannot be searched, the process is terminated. In this case, a dummy packet remains as a substitute packet in the portion corresponding to the missing packet.

Step S13, Restoration Processing The restoration processing unit 103B performs restoration processing for the lost packet part.

Step S14, packet replacement processing The packet replacement table 106B replaces the missing packets stored in the TTS buffer 105 based on the result of the recovery processing performed by the recovery processing unit 103B.

  Through the above processing, first, null data is inserted as a substitute packet for the lost packet, and if restoration is possible, the portion where the substitute packet is inserted is replaced with the restored packet.

  FIG. 6 is a flowchart showing TS packet output processing from the TTS buffer 105 to the content processing unit 110, that is, buffer processing of the TTS buffer 105, based on the adaptive clock method.

Step S21: Determine whether TTS buffer 105 is empty The output control unit 107A of the packet output unit 107 determines whether the TTS buffer 105 is empty.
If the TTS buffer 105 is empty, the process proceeds to step 31. If there is a packet in the TTS buffer 105, the process proceeds to step 22.

Step S22, Timestamp Comparison Validity The output control unit 107A compares the time stamp of the TS packet with the time stamp stored in the TTS buffer 105 with the count value of the counter 107B to determine the validity of the comparison. judge.
If the comparison is not valid, the process proceeds to step 31.

In step S23, the time stamp comparison output control unit 107A compares the time stamp of the first packet of the time-stamped TS packet stored in the TTS buffer 105 with the count value of the counter 107B.

Step S24, 25
If the time stamp of the first packet of the TS packets stored in the TTS buffer 105 is larger than the count value of the counter 107B as a result of comparison of the output control unit 107A in step S24, the process proceeds to step S25.
In step S25, the output control unit 107A determines whether or not the time stamp difference is within a threshold value.

If the output control unit 107A determines that the time stamp difference is within the threshold value in step S26, the immediate packet output step S25, the output control unit 107A cooperates with the TTS buffer 105 to output the packet from the TTS buffer 105. The TS packet is immediately output to the content processing unit 110.

In step S27, packet discarding step S25, if the output control unit 107A does not determine that the time stamp difference is within the threshold value, the output control unit 107A cooperates with the TTS buffer 105 before the TS packet. Process to discard.

In step S28, the time stamp match determination output control unit 107A compares the time stamp of the TS packet stored in the TTS buffer 105 with the count value of the counter 107B, and determines whether or not both values match. judge.

Step S29, the TS packet output output control unit 107A cooperates with the TTS buffer 105 if the time stamp of the TS packet stored in the TTS buffer 105 matches the count value of the counter 107B. The TS packets stored in the TTS buffer 105 are output to the content processing unit 110.

In step S30, the output control unit 107A waiting for the counter match waits until the time stamp of the TS packet accumulated in the TTS buffer 105 does not match the count value of the counter 107B.

In step S31, the increment output control unit 107A of the counter 107B increases the count of the counter 107B in accordance with the buffer processing.

  The processing in the reception processing unit 100 described with reference to FIGS. 5 and 6 eliminates the influence of the buffer processing of the TTS buffer 105 due to the restoration processing of the lost packet in the packet restoration processing means. As a result, the fluctuation of the buffer amount of the TTS buffer 105 is reduced. Therefore, the accuracy of the adaptive clock system that performs clock synchronization by monitoring the accumulated amount (staying amount) of the TTS buffer 105 is improved. In other words, the adaptive clock method can be effectively utilized.

Hereinafter, the results of this embodiment and the conventional method will be compared.
FIG. 7A is a diagram showing a result of the conventional adaptive clock method, and FIG. 7B is a diagram showing a result according to the above embodiment of the present invention.
When the accumulated amount of the buffer (TTS buffer 105 of the embodiment of the present invention) reaches a certain threshold value, clock synchronization control is performed.
This threshold value may be set in consideration of jitter experienced when TS data passes through the communication network in order to avoid buffer overflow or underflow.

  According to the content processing unit 110 of the embodiment of the present invention, since the lost packet restoration processing does not affect the buffer processing of the TTS buffer 105 of the restoration processing means, as shown in FIG. The threshold value of the TTS buffer 105 can be set small. As a result, the capacity of the TTS buffer 105 can be reduced.

The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the illustration illustrated in FIG. 4, the configuration of the reception processing unit 100 is the IP processing unit 101, the RTP buffer 102, the restoration unit 103, the Null packet processing 104, the TTS buffer 105, the packet replacement unit 106, and the packet output unit 107. Although the configuration is separated from the clock synchronization unit 108, the configuration is not necessarily limited to this exemplary configuration.
It is necessary to separate the RTP buffer 102 as the first buffer means and the TTS buffer 105 as the second buffer means. However, for example, the restoration unit 103, the null packet processing 104, and the packet replacement unit 106, as is obvious from the processing content described with reference to FIG. It can also be realized by an integrated signal processing device, for example, a signal processing device using a computer.

  Similarly, for example, the configuration of the restoration unit 103 is separated into a restoration determination unit 103A and a restoration processing unit 103B, and an apparatus that integrates these processes can also be realized.

  On the other hand, the configurations of the Null packet processing 104, the packet replacement unit 106, the packet output unit 107, and the like are also exemplifications. For example, these devices can be configured as integrated devices.

  Therefore, as the data reception processing method of the present invention, for example, any content that realizes the exemplified processing content described with reference to FIGS. 4 and 5 may be used.

  As an embodiment of the present invention, for example, application to an IP television device has been illustrated, but the data reception processing method and data reception processing device of the present invention are not limited to application to an IP television device. The above processing contents can be applied to various applicable devices.

FIG. 1 is a configuration diagram assuming a conventional data reception processing apparatus to which an adaptive clock method is applied. FIG. 2 is a diagram for explaining a conventional method of recovering a lost packet. FIG. 3 is a block diagram of an embodiment of the receiver of the present invention. FIG. 4 is a block diagram of the reception processing unit of the embodiment of the present invention illustrated in FIG. FIG. 5 is a flowchart showing packet reception signal processing in the reception processing unit illustrated in FIG. FIG. 6 is a flowchart showing packet output processing in the reception processing unit illustrated in FIG. FIG. 7A is a diagram showing a result of the conventional adaptive clock method, and FIG. 7B is a diagram showing a result according to the above embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Communication system, 10 ... Communication network, 11 ... Transmitter, 12 ... Receiver, 100 ... Reception processing part, 110 ... Content processing part, 101 ... IP processing part, 102 ... RTP buffer, 103 ... Restoration part, 103A ... Restoration determination unit, 103B ... Restoration processing unit, 104 ... Null packet processing unit, 104A ... Null data insertion determination unit, 104B ... Time stamp calculation unit, 104C ... Null packet insertion unit, 105 ... TTS buffer, 106 ... Packet replacement unit, 106A ... Packet replacement processing unit, 106B ... Packet replacement table, 107 ... Packet output unit, 107A ... Output control unit, 107B ... Counter, clock synchronization unit S10 ... Received IP packet, S101 ... RTP packet data, S102 ... Time stamp TS packet with), S103 ... Notification of restoration completion No., S104A ... inserting dummy data (alternative data), S104B ... dummy data position-number signal for insertion, S105 ... no time stamps TS packets

Claims (7)

Input means for inputting a stream in which information indicating continuity indicating the output order of each packet is added to the packetized content information;
First buffer means for storing a stream to which information indicating the continuity input by the input means is added;
Second buffer means for storing the stream output from the first buffer means;
Detecting that a packet is lost based on at least the presence or absence of continuity in the stream input to the first buffer means, and detecting the detected lost packet data stored in the second buffer means A replacement processing unit that inserts a substitute packet into a part and replaces the restored packet with a substitute packet stored in the second buffer means when the lost packet can be restored;
An output control means for outputting the packet data stored in the second buffer means. The first buffer means stores only the stream input from the input means and the packets necessary for the restoration process.
The data reception processing device according to claim 1. When the restoration processing unit detects that the order of the packet numbers in the stream stored in the first buffer unit is out of order, the restoration processing unit correctly sets the order of the packets stored in the second buffer unit. To fix,
The data reception processing device according to claim 1. The restoration processing means includes
A restoration unit;
An alternative packet processing unit;
A packet replacement unit, and
The restoration unit includes a restoration determination unit that detects a loss of the packet and detects irregularities in the order of the packets, and a restoration processing unit that restores the missing packet,
The alternative packet processing unit includes an alternative packet data insertion determination unit, a time stamp calculation unit that calculates the number and position of missing packets, and an alternative packet insertion unit that performs processing to insert an alternative packet into the second buffer means And
The packet replacement unit includes a packet replacement processing unit that performs replacement processing of a lost packet, and a packet replacement table.
The data reception processing device according to claim 1. Accumulation of the stream output from the first buffer means to the second buffer means and output of the packet data from the second buffer means by the output control means are based on clock synchronization based on an adaptive clock system. ,
The data reception processing device according to claim 1. The packetized content information includes packet data obtained by compressing and multiplexing video data and audio data,
The information indicating the continuity indicating the output order of each packet includes a time stamp,
The data reception processing device according to claim 1. In order to perform a data reception process in a receiving device having a first buffer means and a second buffer means,
Inputting a stream in which information indicating continuity indicating the output order of each packet is added to the input packetized content information;
A first buffer processing step of storing in the first buffer means a stream to which information indicating the continuity input by the input means is added;
A second buffer processing step of reading the stream from the first buffer means and storing it in the second buffer means;
Detecting at least a packet loss based on the presence or absence of continuity in the stream input to the first buffer means;
An alternative packet insertion step of inserting an alternative packet into the detected lost packet data portion stored in the second buffer means when detecting the loss of the packet;
When the lost packet can be restored, the replacement packet replaces the substitute packet stored in the second buffer means, and output control for outputting the packet data stored in the second buffer means A data reception processing method comprising:

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