JP4361564B2 - Media distribution device, media reception device, and media transmission system - Google Patents

Description

  The present invention relates to a media distribution apparatus that packetizes and distributes media data, a media reception apparatus that receives media data distributed from the media distribution apparatus, and a media transmission system that includes the media distribution apparatus and the media reception apparatus. is there.

If the purpose is to perform data transmission of JPEG2000 (ITU-T T.800 / ISO / IEC 154444-1) as efficiently as possible in a network with poor quality, the most important main header is used in JPEG2000 data. It is necessary to avoid dropping as much as possible.
This is because if the transmission of the main header fails, no image can be decoded from the JPEG2000 data even if all other data can be received correctly.

The conventional media transmission system has the following devices in order to prevent the main header from being lost as much as possible.
The media distribution device of the media transmission system inserts the main header into the leading RTP (IETF RFC3550) packet, divides the bit stream of the media data, and inserts it into subsequent RTP packets.

Also, the media distribution device describes a main header flag for all RTP packets.
However, the flag value of the main header flag is a value from “0” to “15” (a value expressed by 4 bits), and the same flag value is described in the RTP packets of the bit stream having the same division source. Is done. The flag value is incremented every time the main header is updated.

When the media reception device of the media transmission system receives an RTP packet in which the main header is inserted from the media distribution device, the media reception device stores the main header in a pair with the flag value of the main header flag described in the RTP packet.
When the media reception device receives the subsequent RTP packet from the media distribution device, the media reception device refers to the main header and restores the media data from the bitstream inserted in the subsequent RTP packet.

However, when the RTP packet in which the main header is inserted is lost, the media reception device checks the flag value of the main header flag described in the subsequent RTP packet.
Then, the main header to which the same flag value is added is searched from the main headers received and stored in the past.
If there is a main header to which the same flag value is added, the media receiving apparatus refers to the main header and restores the media data from the bit stream inserted in the subsequent RTP packet (for example, Patent Document 1). See).

JP 2003-209839 A (paragraph numbers [0051] to [0057], FIG. 1)

  Since the conventional media transmission system is configured as described above, the same flag value as the flag value of the main header flag described in the subsequent RTP packet in the main header received and stored in the past. If there is a main header to which is added, the media data can be restored from the bit stream inserted in the subsequent RTP packet with reference to the main header. However, the flag value of the main header flag is incremented every time the main header is updated, and when the number of updates increases, the flag value used in the past is used again, so it is described in the subsequent RTP packet. Even if there is a main header to which the same flag value as the main header flag is added, the main header is different from the main header inserted in the missing RTP packet, and the subsequent RTP packet can be received correctly. However, there was a problem that media data could not be restored.

The present invention has been made to solve the above-described problems. Even if reception of an RTP packet in which a main header is inserted fails, media data is extracted from a bit stream inserted in a subsequent RTP packet. It is an object of the present invention to obtain a media transmission system and a media receiver that can be restored.
Another object of the present invention is to provide a media distribution device that can notify the media reception device of identification information that identifies the main header.

  In the media transmission system according to the present invention, the media distribution device inserts identification information for specifying a decoding parameter into the payload of each packet and distributes each packet, while the media reception device receives the identification information from the payload of any packet. The decoding parameter corresponding to the identification information is specified by extracting and referring to the table, and the media data is restored from each bit stream using the decoding parameter.

  Thus, even if reception of the RTP packet in which the main header is inserted fails, the media data can be restored from the bit stream inserted in the subsequent RTP packet.

It is a block diagram which shows the media transmission system by Embodiment 1 of this invention. It is explanatory drawing which shows the example of a format of the encoding code stream of JPEG2000. It is explanatory drawing which shows the structure of a general RTP packet. It is explanatory drawing which shows the system in the case of carrying out RTP transmission of general still image data. FIG. 10 is an explanatory diagram showing a method in the case of RTP transmission of general JPEG2000 still image data. It is explanatory drawing which shows the table in which the correspondence of config-ID and config information is recorded. It is explanatory drawing which shows the structure of the RTP packet which a media delivery apparatus delivers. FIG. 3 is an explanatory diagram illustrating a method according to the first embodiment when JPEG2000 still image data is RTP-transmitted. FIG. 10 is an explanatory diagram illustrating a method according to the second embodiment when RTP transmission is performed on JPEG2000 still image data. It is explanatory drawing which shows the update process of a table. It is explanatory drawing which shows the update process of a table. FIG. 10 is an explanatory diagram showing a method of a fourth embodiment when JPEG 2000 still image data is RTP-transmitted. FIG. 10 is an explanatory diagram showing a method of the fifth embodiment when JPEG2000 still image data is RTP-transmitted. It is explanatory drawing which shows the information contained in the difference information of config information. It is explanatory drawing which shows the specific example in the case of changing config information using the description format of the difference information of FIG. It is explanatory drawing which shows the example of a division | segmentation of a bit stream. It is explanatory drawing which shows the process which supplements the loss of a part of RTP packet. It is explanatory drawing which shows the example of a division | segmentation of a bit stream. It is explanatory drawing which shows the process which supplements the loss of a part of RTP packet. It is explanatory drawing which shows the packetization of a bit stream. It is explanatory drawing which shows the process which supplements the loss of a part of RTP packet.

Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
1 is a block diagram showing a media transmission system according to Embodiment 1 of the present invention.

In the figure, the media distribution device 1 distributes each RTP packet by inserting a config-ID (identification information) that specifies config information (main header + tile part header), which is a decoding parameter, into the RTP payload header of each RTP packet. .
When the media reception device 2 receives each RTP packet distributed from the media distribution device 1, the media reception device 2 extracts the config-ID from the RTP payload header of any RTP packet, refers to the table, and corresponds to the config-ID. The config information is specified, and the media data is restored from the bit stream inserted in each RTP packet by using the config information.

When the data dividing unit 11 of the media distribution apparatus 1 inputs the distribution target media data, the data distribution unit 11 divides the bit stream of the media data. The data dividing unit 11 constitutes a data dividing unit.
The RTP header construction unit 12 of the media distribution apparatus 1 includes a time stamp (TS) indicating the display time, a sequence number (SQ) indicating the order of the RTP packets, an M bit indicating a break between images, and the like in the RTP header of each RTP packet. insert.

The RTP payload construction unit 13 of the media distribution device 1 inserts the config information necessary for restoring the media data into the RTP payload of the first RTP packet, and sequentially follows the bit stream divided by the data division unit 11. Insert into RTP payload of RTP packet.
The table storage unit 14 of the media distribution apparatus 1 is a memory that stores a table in which a correspondence relationship between config-ID and config information is recorded.

The RTP payload header construction unit 15 of the media distribution device 1 refers to the table stored in the table storage unit 14 and sets the config-ID corresponding to the config information inserted by the RTP payload construction unit 13 to the RTP of each RTP packet. Insert into the payload header.
The RTP header construction unit 12, the RTP payload construction unit 13, the table storage unit 14, and the RTP payload header construction unit 15 constitute packet construction means.
The packet distribution unit 16 of the media distribution apparatus 1 constitutes a packet distribution unit that distributes each RTP packet in order.

The packet receiver 21 of the media receiver 2 constitutes a packet receiver that receives each RTP packet distributed from the media distributor 1.
The table storage unit 22 of the media receiver 2 is a memory that stores a table in which the correspondence between config-ID and config information is recorded. The table storage unit 22 constitutes a table storage unit.

  The config information specifying unit 23 of the media receiving device 2 extracts the config-ID from the RTP payload header of any RTP packet received by the packet receiving unit 21, and refers to the table stored in the table storage unit 22. , The config information corresponding to the config-ID is specified. The config information specifying unit 23 constitutes a decoding parameter specifying unit.

The media data restoring unit 24 of the media receiving device 2 extracts a bit stream from the RTP payload of each RTP packet received by the packet receiving unit 21, and uses the config information specified by the config information specifying unit 23 to set each bit. Restore media data from a stream. The media data restoration unit 24 constitutes media data restoration means.
The decoding unit 25 of the media receiving device 2 converts the media data restored by the media data restoration unit 24 into image data.
The image reproduction unit 26 of the media receiver 2 displays an image on the display 27 according to the image data converted by the decoding unit 25.

Next, the operation will be described.
In the first embodiment, an encoded code stream of JPEG2000 (ITU-T T.800 / ISO / IEC 15444-1) and a media distribution protocol of RTP (IETF RFC3550) will be described. Is merely an example, and is not limited to this in practice.

FIG. 2 is an explanatory diagram showing a format example of a JPEG2000 encoded code stream.
FIG. 2 shows a JPEG2000 encoded code stream when the number of tiles is 1 and the number of tile parts is 1. The config information is composed of the main header and the tile part header, and the bit stream follows the config information. And an end code (EOC).
In the JPEG2000 standard, it is stipulated that a plurality of tile part headers can be included in one image. In the first embodiment, it is assumed that there is one tile part header in one image. Give an explanation.

FIG. 3 is an explanatory diagram showing the structure of a general RTP packet. The general RTP packet is composed of an RTP header and an RTP payload. The configuration of the RTP packet in the first embodiment will be described later.
In the RTP header, a time stamp (TS) indicating display time, a sequence number (SQ) indicating the order of RTP packets, an M bit indicating a break between images, and the like are described.
In addition, a bit stream of media data is stored in the RTP payload. If the media data is image data, the image data is stored.

FIG. 4 is an explanatory diagram showing a method for transmitting general still image data by RTP, and shows an example in which one still image data is divided into four RTP packets for transmission.
In the example of FIG. 4, the bit stream of still image data is divided into four, and the four divided bit streams (1) to (4) are sequentially stored in the RTP payloads (1) to (4) of each RTP packet. Has been.

The sequence number (SQ) in the RTP headers (1) to (4) has the smallest value in the first RTP header (1), and the values in the subsequent RTP headers (2) to (4) are incremented by one. Has been.
The time stamps (TS) in the RTP headers (1) to (4) have the same value for the same still image.
In order to recognize a break between images, "1" is stored in the M bit of the RTP header (4) having the maximum sequence number (SQ) in the same still image, and the RTP header (1) “0” is stored in the M bits of (3) to (3).

FIG. 5 is an explanatory diagram showing a method in which general JPEG2000 still image data is transmitted by RTP, and shows an example in which one still image data is divided into four RTP packets and transmitted. The RTP transmission method in the first embodiment will be described later.
When transmitting JPEG2000 still image data, the main header and tile part header of the encoded code stream are important information. Therefore, the RTP payload of the first RTP packet, that is, the RTP payload (1) includes the config information (main header). + Tile part header) is stored.
Also, the bit stream of the encoded code stream is divided into three, and the three divided bit streams (1) to (3) are sequentially stored in the RTP payloads (2) to (4) of the RTP packet.

The sequence number (SQ) in the RTP headers (1) to (4) has the smallest value in the first RTP header (1), and the values in the subsequent RTP headers (2) to (4) are incremented by one. Has been.
The time stamps (TS) in the RTP headers (1) to (4) have the same value for the same still image.
In order to recognize a break between images, "1" is stored in the M bit of the RTP header (4) having the maximum sequence number (SQ) in the same still image, and the RTP header (1) “0” is stored in the M bits of (3) to (3).

When JPEG2000 still image data is transmitted, the media distribution device converts the encoded code stream into RTP packets and distributes a plurality of RTP packets as described above, but the media reception device transmits the RTP payload of the first RTP packet. If (1) cannot be received correctly, even if the subsequent RTP packet can be received correctly, there is no config information (main header + tile part header), and a still image cannot be reproduced.
In the first embodiment, even when the RTP payload (1) of the leading RTP packet cannot be correctly received, a still image can be reproduced as follows.

A table in which the correspondence between config-ID and config information (main header + tile part header) is recorded is prepared in advance, and the tables are stored in the table storage unit 14 of the media distribution device 1 and the table storage unit of the media reception device 2. 22.
Specifically, the media distribution device 1 creates the table, and the media distribution device 1 transmits the table to the media reception device 2 using a protocol with a delivery confirmation such as TCP, for example. The distribution device 1 and the media reception device 2 share the table.

Alternatively, the media distribution device 1 and the media reception device 2 store the same table as a fixed value of the system in advance, so that the media distribution device 1 and the media reception device 2 share the table.
FIG. 6 is an explanatory diagram showing a table in which the correspondence between config-ID and config information is recorded. In particular, the lower table is an example when there are three types of config information.

When the data dividing unit 11 of the media distribution device 1 inputs the distribution target media data, for example, the data distribution unit 11 divides the bit stream of the media data into three.
The RTP header construction unit 12 of the media distribution device 1 includes a time stamp (TS) indicating the display time, a sequence number (SQ) indicating the order of the RTP packets, an M bit indicating a break between images, and the like in the RTP header of each RTP packet. Insert into.

FIG. 8 is an explanatory diagram showing the method of the first embodiment when JPEG2000 still image data is RTP-transmitted. The time stamp (TS), sequence number (SQ), M bit, etc. to be inserted into the RTP header are shown in FIG. This is the same as the case of 5.
FIG. 7 is an explanatory diagram showing a configuration of an RTP packet distributed by the media distribution device 1.

When the data dividing unit 11 divides the bit stream of the media data into three, the RTP payload constructing unit 13 of the media distribution device 1 converts the RTP payload of the leading RTP packet, that is, the RTP payload (1) as shown in FIG. Config information (main header + tile part header) is inserted.
Further, the RTP payload construction unit 13 inserts the bit streams (1) to (3) divided by the data division unit 11 into the RTP payloads (2) to (4) of the subsequent RTP packets in order.

When the RTP payload construction unit 13 inserts the config information into the RTP payload (1), the RTP payload header construction unit 15 of the media distribution device 1 refers to the table stored in the table storage unit 14 and stores the config information in the configuration information. The corresponding config-ID is specified.
For example, if the config information is data (1), the config-ID is specified as “0”, and if the config information is data (2), the config-ID is specified as “1”.

When the RTP payload header construction unit 15 specifies the config-ID corresponding to the config information, the RTP payload header construction unit 15 inserts the config-ID into the RTP payload headers (1) to (4) of the RTP packet. It goes without saying that the config-IDs inserted in the RTP payload headers (1) to (4) are all the same value.
Here, config-ID is inserted into all RTP payload headers (1) to (4), but it is inserted only into some RTP payload headers (for example, RTP payload headers (1) and (2)). It may be.

  When four RTP packets are constructed by the RTP header construction unit 12, the RTP payload construction unit 13, and the RTP payload header construction unit 15, the packet delivery unit 16 of the media delivery device 1 sequentially transmits the four RTP packets to the media. Delivered to the receiving device 2.

The packet receiver 21 of the media receiver 2 receives the four RTP packets distributed from the media distributor 1.
When the packet receiving unit 21 receives four RTP packets, the config information specifying unit 23 of the media receiving device 2 extracts the config-ID from the RTP payload header of any RTP packet.
The RTP payload header from which the config-ID is extracted may be any RTP payload header as long as it can be received correctly. For example, the RTP payload header with the highest priority set in advance is extracted. If the RTP payload header is not correctly received, the next highest priority RTP payload header may be set as the extraction target.

When the config information specifying unit 23 extracts the config-ID from the RTP payload header of any RTP packet, the config information specifying unit 23 refers to the table stored in the table storage unit 22 and specifies the config information corresponding to the config-ID. To do.
For example, if the config-ID is “0”, the config information is specified as data (1), and if the config-ID is “1”, the config information is specified as data (2).
Therefore, even if the RTP payload (1) of the RTP packet in which the config information is inserted is not correctly received, if the other RTP packet is correctly received, the RTP packet is inserted into the RTP payload header of the RTP packet. The config information can be acquired from the configured config-ID.

When the packet receiving unit 21 correctly receives the leading RTP packet, the media data restoring unit 24 of the media receiving device 2 extracts the config information from the RTP payload (1) of the RTP packet.
On the other hand, when the packet receiving unit 21 cannot correctly receive the leading RTP packet, the config information specified by the config information specifying unit 23 is acquired.
Here, when the packet receiving unit 21 cannot correctly receive the leading RTP packet, the config information is acquired from the config information specifying unit 23. However, the packet receiving unit 21 can correctly receive the leading RTP packet. Even if it is, the config information may be acquired from the config information specifying unit 23.

The media data restoration unit 24 extracts the bit streams (1) to (3) from the RTP payloads (2) to (4) of the subsequent RTP packet received by the packet reception unit 21, and uses the above config information. Thus, the media data is restored from the bit streams (1) to (3).
When the media data restoration unit 24 restores the media data, the decoding unit 25 of the media receiver 2 converts the media data into image data.
When the decoding unit 25 converts the media data into image data, the image reproduction unit 26 of the media receiver 2 displays an image on the display 27 according to the image data.

  As is apparent from the above, according to the first embodiment, the config-ID for specifying the config information required when the media distribution device 1 restores the media data is set to the RTP payload headers (1) to (1) to ( 4), the media receiving apparatus 2 extracts the config-ID from the RTP payload header of any RTP packet, and refers to the table to configure the config corresponding to the config-ID. Since the information is identified and the media data is restored from each bit stream using the config information, even if reception of the RTP packet in which the config information is inserted fails, the subsequent RTP packet Restore media data from the inserted bitstream It achieves the effect can be.

Embodiment 2. FIG.
In the first embodiment, the RTP payload construction unit 13 of the media distribution device 1 has shown the configuration information inserted into the RTP payload (1) of the RTP packet. However, the media data restoration unit 24 of the media reception device 2 always If the config information is acquired from the config information specifying unit 23, as shown in FIG. 9, the RTP payload construction unit 13 of the media distribution device 1 does not insert the config information into the RTP payload (1) of the RTP packet. May be.
As a result, the amount of transmission can be reduced by the amount that the config information is not distributed.

Embodiment 3 FIG.
In the first embodiment, the table storage unit 14 of the media distribution device 1 and the table storage unit 22 of the media reception device 2 store a common table. However, the table storage unit 14 of the media distribution device 1 and the media You may make it update the common table which the table storage part 22 of the receiver 2 stores.

Specifically, as shown in FIG. 10, when the correspondence between three types of config-ID and config information is recorded in the table, when adding one type of the correspondence, the media distribution device 1 is, for example, out A set of config-ID “3” and config information “data (4)” is transmitted to the media receiving apparatus 2 as update information using a protocol such as TCP with delivery confirmation in the band.
When the media receiving device 2 receives the set of config-ID “3” and config information “data (4)” from the media distribution device 1 as update information, the config-ID “3” and config information “data (4)”. Is added to the table.

Also, as shown in FIG. 11, when the correspondence between the three types of config-ID and config information is recorded in the table, the config information “data (3)” corresponding to config-ID “2” is changed. In this case, the media distribution device 1 uses, for example, a protocol such as TCP with confirmation of delivery in the out band, and a set of config-ID “2” and config information “data (4)” is sent to the media reception device 2 as update information. Send.
When the media receiving device 2 receives the set of the config-ID “2” and the config information “data (4)” from the media distribution device 1 as the update information, the config-ID “2” is already stored. -The config information corresponding to ID "2" is changed from data (3) to data (4).

  As apparent from the above, according to the third embodiment, when the media receiving device 2 receives the update information of the table from the media distribution device 1, the table is updated according to the update information. There is an effect that the config information can be appropriately updated according to the target media data.

Embodiment 4 FIG.
In the first embodiment, the config information specifying unit 23 of the media reception device 2 extracts the config-ID from the RTP payload header of any RTP packet, and refers to the table stored in the table storage unit 22. As shown in FIG. 12, the packet reception unit 21 of the media reception device 2 receives a config-ID “FF” (specific identification) from the media distribution device 1 as shown in FIG. Information) is received, the config stream information inserted into the RTP payload (1) of the RTP packet is used without referring to the table stored in the table storage unit 22, and the bit streams (1) to (3) are received. The media data may be restored from

Specifically, it is as follows.
The config information specifying unit 23 of the media receiving device 2 determines whether or not the config-ID inserted in the RTP payload header of any RTP packet is a specific value. That is, it is determined whether or not the config-ID is “FF”.

If the config-ID is not “FF”, the config information specifying unit 23 specifies the config information as in the first embodiment.
However, if the config-ID is “FF”, the config information inserted in the RTP payload (1) of the RTP packet is acquired without referring to the table stored in the table storage unit 22. .

  The media data restoration unit 24 of the media reception device 2 extracts the bit streams (1) to (3) from the RTP payloads (2) to (4) of the subsequent RTP packet received by the packet reception unit 21, and configure information Using the config information acquired by the specifying unit 23, the media data is restored from the bit streams (1) to (3).

  As is apparent from the above, according to the fourth embodiment, when the packet receiving unit 21 of the media receiving device 2 receives the config-ID “FF” (specific identification information) from the media distribution device 1, the table storage unit The media data is restored from the bitstreams (1) to (3) using the config information inserted in the RTP payload (1) of the RTP packet without referring to the table stored in FIG. Since it comprised, there exists an effect which can restore | restore media data using the config information which is not recorded on the table, without updating the table stored in the table storage part 22. FIG.

Embodiment 5 FIG.
In the first embodiment, the config information specifying unit 23 of the media reception device 2 extracts the config-ID from the RTP payload header of any RTP packet, and refers to the table stored in the table storage unit 22. As shown in FIG. 13, when the packet reception unit 21 of the media reception device 2 receives the difference information of the config information from the media distribution device 1, the table is shown. The media data may be restored from the bit streams (1) to (3) using the config information in the table stored in the storage unit 22 and the difference information.

Specifically, it is as follows.
The difference information of the config information is difference information with respect to the config information (config information in the table) corresponding to the config-ID, and FIG. 14 shows information included in the difference information of the config information.

The difference information of the config information includes one config-ID and a change indicating the number of locations where the config information (config information in the table) corresponding to the config-ID is to be changed.
Further, the difference information of the config information includes an offset indicating the change location, the erase_length indicating the length of the data to be deleted, the insert_length indicating the length of the data after the change, and the data indicating the data after the change. Is included.

FIG. 15 shows a specific example in the case where the config information is changed using the difference information description format shown in FIG.
Example (1) shows that the config information of config-ID = 0x0 is changed in two places, and example (2) shows that the byte length is changed simultaneously with changing the value of the config information.

  As is apparent from the above, according to the fifth embodiment, when the packet reception unit 21 of the media reception device 2 receives the difference information of the config information from the media distribution device 1, the table stored in the table storage unit 22 is stored. Since the media data is restored from the bitstreams (1) to (3) using the config information and the difference information, the config information is inserted as in the first embodiment. Even if reception of the RTP packet fails, the media data can be restored from the bit stream inserted in the subsequent RTP packet.

  In addition, since the config-ID is included in the difference information, it becomes possible to transmit the difference with the most similar config information among the config information recorded in the table. There is an effect that the transmission amount of the distribution apparatus 1 can be reduced.

Embodiment 6 FIG.
Although not particularly mentioned in the first embodiment, in the case of a transmission method using a protocol without delivery confirmation such as RTP, if reception of any of the RTP packets in which the divided bitstream is inserted fails When decoding is performed using a correctly received bitstream, a decoding error may occur or an unnatural image may be displayed.
In the sixth embodiment, even if reception of a part of RTP packets distributed from the media distribution device 1 fails, the occurrence of a decoding error or the like is prevented as follows.

FIG. 16 is an explanatory diagram showing an example of bit stream division. A JP2K packet is a unit constituting an encoded stream. In the example of FIG. 16, the bit stream is divided so as to include one or more JP2K packets.
FIG. 17 is an explanatory diagram showing a process for complementing a part of missing RTP packets. When a bit stream divided in units of JP2K packets is transmitted as shown in FIG. 16, that is, one piece of media distribution device 1 is used. In this example, when a bitstream that is JPEG2000 still image data is divided into five and distributed, an RTP packet including the bitstream (4) is missing during transmission.

As shown in FIG. 17, the media data restoring unit 24 of the media receiving apparatus 2 has received the RTP packet including the bit streams (1) to (3) correctly by the packet receiving unit 21, but the bit stream (4) is received. When it is not possible to correctly receive the included RTP packet, that is, when it is recognized that the RTP packet including the bit stream (4) is missing from the sequence number (SQ) of the RTP header, the conf information specified by the config information specifying unit 23 is Are combined with bitstreams (1) to (3), followed by end code (EOC).
The media data restoration unit 24 analyzes the combination result and restores the media data.

  According to the sixth embodiment, since the bit stream (5) is lost, there is a slight deterioration in image quality. However, due to the nature of JPEG2000, in many cases, there is an effect that an image having a practically sufficient image quality is decoded. .

Embodiment 7 FIG.
FIG. 18 shows an example in which a bit stream includes a fixed number of JP2K packets. In the example of FIG. 18, each of the bit streams (1) to (3) includes three JP2K packets.
FIG. 19 is an explanatory diagram showing a process for compensating for the loss of some RTP packets. When a bit stream is transmitted by a division method in which each bit stream includes a fixed number of JP2K packets as shown in FIG. An example in which an RTP packet including the bit stream (4) is missing is shown.

  As shown in FIG. 19, the media data restoration unit 24 of the media reception device 2 has received the RTP packet including the bit streams (1) to (3) correctly by the packet reception unit 21, but the bit stream (4) When it is not possible to correctly receive the included RTP packet, that is, when it is recognized from the sequence number (SQ) of the RTP header that the RTP packet including the bit stream (4) has been lost, Are combined with bitstreams (1) to (3).

Next, the media data restoration unit 24 combines null data (1 byte of “0” data (0x00)) as many as the number of JP2K packets included in the bit stream (4) after the bit stream (3). To do.
Next, the media data restoration unit 24 combines the bit stream (5) and the end code (EOC) after the null data.
The media data restoration unit 24 analyzes the combination result and restores the media data.

According to the seventh embodiment, since the missing back bitstream (5) is also used, the image quality deterioration can be suppressed as compared with the sixth embodiment.
According to the JPEG2000 rule, complementing a JP2K packet with a null packet is an error complementing method that eliminates inconsistencies as a bit stream.

Here, FIG. 20 is an explanatory diagram showing packetization of a bit stream.
In the example of FIG. 20, offset and include are included in the RTP payload header.
“offset” and “include” are numerical values related to the JP2K packet. In particular, “offset” indicates the cumulative number of JP2K packets from the head, and “include” indicates the number of JP2K packets included in the bit stream of the RTP payload.

Bitstream (1) includes 3 JP2K packets, bitstream (2) includes 1 JP2K packet, bitstream (3) includes 4 JP2K packets, and bitstream (4) has 5 The bit stream (5) includes three JP2K packets.
FIG. 21 shows a case where the RTP packet including the bit stream (4) is lost in the transmission of FIG.
The number of JP2K packets included in the bitstream (4) is calculated from the offset and include values described in the correctly received RTP payload header.

In the example of FIG. 21, since the bit stream (4) is missing, it is included in the bit stream (4) using the values of offset and include described in the RTP payload headers before and after being successfully received. The number X of JP2K packets that are present is calculated.
X = offset5-offset3-include3
Then, the number of JP2K packets X is complemented with null packets. The null packet is 1 byte of 0x00. At this time, one JP2K packet is complemented with one null packet.

  As described above, the media transmission system according to the present invention needs to improve the transmission efficiency by allowing the media data to be restored without discarding the correctly received bitstream even when the decoding parameters cannot be correctly received. Suitable for some things.

Claims (11)

  Data dividing means for dividing the bit stream of media data, and the bit stream divided by the data dividing means are inserted in the payload of each packet in order, and identification information for specifying the decoding parameter of the media data is added to each packet. A media distribution apparatus comprising: a packet construction unit to be inserted into a payload; and a packet delivery unit to deliver each packet in which a bit stream and identification information are inserted by the packet construction unit.   Packet receiving means for receiving each packet distributed from the media distribution apparatus, table storage means for storing a table in which the correspondence between the identification information and the decoding parameter is recorded, and any of the packets received by the packet receiving means The identification information is extracted from the payload of the packet, the table stored in the table storage means is referenced, the decoding parameter specifying means for specifying the decoding parameter corresponding to the identification information, and the packet receiving means received A media receiving device comprising media data restoring means for extracting a bit stream from the payload of each packet and restoring media data from each bit stream using the decoding parameter specified by the decoding parameter specifying means.   The bit stream of the media data is divided, and the divided bit stream is sequentially inserted into the payload of each packet, and identification information for specifying the decoding parameter of the media data is inserted into the payload of each packet, Stores the media distribution device to be distributed and the table in which the correspondence between the identification information and the decoding parameter is recorded in advance. When each packet distributed from the media distribution device is received, the identification information is obtained from the payload of any packet. Extract and refer to the above table to identify the decoding parameter corresponding to the identification information, while extracting the bitstream from the payload of each packet and using that decoding parameter to restore the media data from each bitstream Transmission with media receiving device Stem.   4. The media transmission system according to claim 3, wherein when the media receiving device receives update information of the table from the media distribution device, the media receiving device updates the table according to the update information.   The media receiving device, when receiving the specific identification information and the decoding parameter from the media distribution device, restores the media data from each bit stream using the decoding parameter without referring to the table. Item 4. The media transmission system according to Item 3.   The media reception device, when receiving the difference information of the decoding parameter from the media distribution device, restores the media data from each bitstream using the decoding parameter recorded in the table and the difference information. Item 4. The media transmission system according to Item 3.   The media receiving device, when receiving a part of the packets delivered from the media delivery device fails, extracts the bit stream from the payload of the correctly received packet and restores the media data. Item 4. The media transmission system according to Item 3.   When the media receiver combines the first bit stream to the last bit stream, if there is a packet that failed to be received, it is inserted from the first bit stream into the payload of the packet immediately before the packet that failed to be received. The media transmission system according to claim 7, wherein up to a bit stream is combined.   When combining media from the first bit stream to the last bit stream, the media receiver shall combine null data instead of the bit stream inserted in the packet that failed to be received if there is a packet that failed to be received. The media transmission system according to claim 7.   10. The media transmission system according to claim 9, wherein the media receiving apparatus combines null data by a fixed number set in advance.   10. The media receiving apparatus according to claim 9, wherein the media receiving device calculates the number of null data to be combined instead of the bit stream with reference to the description content of the payload of the correctly received packet, and combines the null data by that number. Media transmission system.

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