JP2003046976A - Device, method, and program for downloading video - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device, method, and program for downloading video by which an effective transmission rate can be brought closer to a target transmission rate without adjusting the effective transmission rate between the transmitting side and receiving side. SOLUTION: The device is provided with a data downloading means 11 which downloads video/audio data at prescribed time intervals and a detecting means 12. The means 12 detects a delay in transmitting time based on the actual transmitting intervals of the video/audio data. When the detecting means 12 detects the delay, a rate control means 13 raises the transmission rate in accordance with the detected delay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video distribution apparatus, a video distribution method and a program for transmitting real-time data such as video and audio via a network.

[0002]

2. Description of the Related Art Conventionally, this type of video distribution apparatus is shown in FIG.
As shown in FIG. 5, an RTCP packet is created based on the RTP transmission unit 110 that writes transmission information to the packet recording table 140 each time a packet is transmitted to the transmission side terminal 100, and the transmission information from the RTP transmission unit 110, and a predetermined An RTCP transmission unit 120 that outputs RTCP packets at intervals of
RTCP packet from the receiving side terminal 200 is received, and R
The RTCP receiving unit 130 that calculates the effective transmission rate and the RTT of the receiving terminal 200 from the TCP information, and the packet recording table 140 that records the packet sequence number and the packet size at that time are provided. In addition, the RTP receiving unit 210 that receives the packet transmitted from the transmitting terminal 100, the RTCP transmitting unit 220 that creates the RTCP packet based on the transmission state of the network, and outputs the RTCP packet, and the transmitting terminal 1
RTC to receive RTCP packet sent from 00
The P-reception unit 230 is provided, and the transmission-side terminal 100 and the reception-side terminal 200 are connected to each other by RFC1889 RTP (Real-time Tr
As defined by the ansport Protocol), the data is transmitted and received by RTP, the control data is transferred by RTCP, and the transmission rate is controlled.
Further, when it is difficult to obtain the transmission delay time from the transmission protocol like RTP, the transmission delay time is estimated by the packet round trip time RTT (Round Trip Time) on the network 300 to control the transmission rate ( JP-A-11-341064).

[0003]

However, in such a conventional video distribution apparatus, for example, when video / audio data is distributed by multicast communication, fluctuations in network load between a plurality of receiving terminal apparatuses are caused. Since it is necessary to adjust the transmission rate according to the above, there is a problem that the network traffic increases and the bandwidth for transmitting the video data decreases.

The present invention has been made in order to solve such a problem. Even if a transmission delay occurs due to a seek operation of the head or a waiting for rotation due to the reading / writing of the recording medium, the transmitting side and the receiving side are not affected. The present invention provides a video distribution device, a video distribution method, and a program that can bring the effective transmission rate close to the target rate without adjusting the transmission rate between them.

[0005]

A video distribution device of the present invention manages video / audio data composed of at least one of video and audio, and video / audio data recorded in the storage means. And a file management means for temporarily reading out a plurality of video / audio data, an image memory for temporarily storing a plurality of video / audio data, a transfer of the video / audio data read by the file management means to the image memory, and a transmission depending on a transmission rate. Image memory control means for acquiring video / audio data of a transmission size from the image memory, and data distribution means for transmitting video / audio data at predetermined time intervals,
It has a configuration provided with a detection means for detecting a transmission delay time based on an actual video / audio data transmission interval, and a rate control means for increasing the transmission rate according to the detected transmission delay time. With this configuration, by detecting the transmission delay time, the correction amount for bringing the transmission rate closer to the target rate can be obtained.

In the video distribution method of the present invention, a video / audio data composed of at least one of video and audio is read and a read / transfer step of transferring the read video / audio data to an image memory, and the read / transfer step is transferred to the image memory. A transmitting step of transmitting the audiovisual data at predetermined time intervals,
It has a detection step of detecting the transmission delay time based on the actual video / audio data transmission interval, and an adjustment step of increasing the transmission rate according to the detected transmission delay time. By detecting the transmission delay time by this method,
A correction amount for bringing the transmission rate closer to the target rate will be obtained.

Further, in the video distribution method of the present invention, the transmission delay time is detected every predetermined number of times of transmission, and the data capacity required to bring the transmission rate close to the target rate based on the detected transmission delay time. And a transmission step of transmitting the video / audio data obtained by adding the data capacity to the normal video / audio data transmission capacity until the next transmission delay time is detected. By this method, the transmission delay time can be averaged and the correction amount of the transmission rate can be reduced.

In the video distribution method of the present invention, a transmission priority level is assigned in advance to each of the video / audio data,
When the transmission delays are continuously detected, there is a stopping step of stopping the transmission in order from the audiovisual data having the lower transmission priority level. According to this method, when the video / audio data transmission exceeding the system performance is performed, the video / audio data having the low transmission priority is stopped, and the transmission rate of the data having the high transmission priority can be secured.

Further, the video distribution method of the present invention has a limiting step of limiting the number of video / audio data read at the predetermined time interval when a plurality of the video / audio data are simultaneously transmitted. With this method, the number of times the recording medium is accessed within a predetermined time interval is reduced, so that it is possible to suppress overhead such as head seek operation and rotation waiting, and it is possible to reduce the transmission delay time.

The program of the present invention stores a computer
File management means configured to at least one of video and audio, for managing and reading out the video / audio data recorded in the storage means, and the video / audio data read by the file management means into a plurality of video / audio data. To an image memory for temporarily storing the image data, and an image memory control means for acquiring the image / audio data of the transmission size from the image memory according to the transmission rate, and transmitting the image / audio data at a predetermined time interval. The data distribution means, the detection means for detecting the transmission delay time based on the actual video / audio data transmission interval, and the rate control means for increasing the transmission rate in accordance with the detected transmission delay time. By detecting the transmission delay time by this program, the correction amount for bringing the transmission rate close to the target rate can be obtained.

Further, the program of the present invention includes a read / transfer step of causing a computer to read video / audio data composed of at least one of video and audio, and transferring the read video / audio data to an image memory, and to the image memory. A transmission step of transmitting the transferred video / audio data at a predetermined time interval, a detection step of detecting a transmission delay time based on the actual video / audio data transmission interval, and a transmission rate increase according to the detected transmission delay time The adjustment step is executed. By detecting the transmission delay time by this program, the correction amount for bringing the transmission rate close to the target rate can be obtained.

Further, the program of the present invention is necessary for causing the computer to detect the transmission delay time every predetermined number of transmissions and to bring the transmission rate close to the target rate based on the detected transmission delay time. The calculation step of calculating the data capacity and the transmission step of transmitting the video / audio data obtained by adding the data capacity to the normal video / audio data transmission capacity until the detection of the next transmission delay time are executed. With this program, the transmission delay time can be averaged and the correction amount of the transmission rate can be reduced.

Further, the program of the present invention assigns a transmission priority level to the computer in advance for each of the video / audio data, and when a transmission delay is continuously detected, the video / audio having the low transmission priority level is obtained. The stop step of stopping the transmission in order from the data is executed.
With this program, it is possible to stop the video / audio data having a low transmission priority and secure the transmission rate of the data having a high transmission priority when the video / audio data transmission exceeding the system performance is performed.

Further, the program of the present invention causes the computer to execute a limiting step of limiting the number of video / audio data read at the predetermined time interval when a plurality of the video / audio data are simultaneously transmitted.
By this program, the number of times the recording medium is accessed within a predetermined time interval is reduced, so that the overhead such as the seek operation of the head and the waiting for rotation can be suppressed, and the transmission delay time can be reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that, in all the drawings, similar components are denoted by the same reference numerals and symbols.

(First Embodiment) As shown in FIG.
The video distribution device 10 according to the first exemplary embodiment of the present invention manages the storage means 17 for recording the video / audio data composed of at least one of video and audio, and the video / audio data recorded in the storage means 17. File management means 16 for temporarily reading and reading, image memory 14 for temporarily storing a plurality of video / audio data, video / audio data read by the file management means 16 is transferred to the image memory 14, and , The image memory 14 according to the transmission rate
The image memory control means 15 for acquiring the video / audio data for the transmission size from the data distribution means 11, the data distribution means 11 for transmitting the video / audio data at a predetermined time interval, and the transmission delay time based on the actual video / audio data transmission interval. Detecting means 12
And rate control means 13 for increasing the transmission rate according to the detected transmission delay time.

In FIG. 1, the video distribution device 10 manages the video / audio data to be transmitted and the transmission channel in association with each other.

The data distribution means 11 simultaneously transmits a plurality of video / audio data at a predetermined time interval (hereinafter, SYNC time). When sending the video / audio data to the network, the data distribution unit 11 calculates the transmission size according to the transmission rate, and instructs the image memory control unit 15 to acquire the video / audio data for the transmission size. Further, the data distribution unit 11 distributes the video / audio data acquired from the image memory control unit 15 to the receiving side terminal via a predetermined network.

The detection means 12 detects the transmission delay time based on the actual transmission interval of the video / audio data. For example, the SYNC time is 50 [ms] and the actual transmission interval of the video / audio data is 54 [ms. ms], the transmission delay time is 4 [ms].

The rate control means 13 increases the transmission rate according to the transmission delay time detected by the detection means 12. When the transmission delay time of the video / audio data is Δt, the target transmission rate after correction can be calculated by the following formula: target rate + (target rate × Δt) / (SYNC time). The target rate here refers to a transmission rate preset in the initial state.

The image memory 14 temporarily stores a plurality of video / audio data.

The image memory control means 15 receives the video / audio data acquisition request from the data distribution means 11 and acquires the video / audio data of the transmission size from the image memory 14. Here, when the image memory 14 does not store the audio / video data for the transmission size, the image memory control means 14 instructs the file management means 16 to read the audio / video data. The audiovisual data read from the storage means 17 is transferred to the image memory 14.

The file management means 16 controls the reading of the audiovisual data recorded in the storage means 17. The reading of the video / audio data is performed by an instruction of the image memory control means 15. At this time, a group of data blocks including transmission data may be prefetched together.

The storage means 17 is a hard disk (HD
A recording device capable of high-speed access such as D) is composed of one or a plurality of recording devices.

The channel state table 18 contains information relating to data distribution of video / audio data, and is shown in FIG.
As shown in, one entry is assigned to each channel. One entry is the channel number part 40,
The video / audio data unit 41, the target rate unit 42, the correction rate unit 43, and the operation state unit 44 are included. The video / audio data unit 41 holds information for identifying the video / audio data associated with the transmission channel. The target rate unit 42 holds the target rate of the video / audio data, and is preset in the initial state.
The correction rate unit 43 holds the correction rate calculated by the rate control means 13. This correction rate can be calculated by (target rate × Δt) / (SYNC time). The data distribution means 11
The transmission rate is determined based on the target rate section 42 and the correction rate section 43.

The operation state section 44 holds the operation state of each transmission channel. The data distribution unit 12 distributes the video / audio data based on the operation state unit 44.

In the example shown in FIG. 2, the channel state table 18 is composed of 100 entries (CH1 to CH100).

Now, the audiovisual data D1 and D10 are associated with the channels CH1 and CH4. Also,
The target rates of D1 and D10 are set to 6000000 bps and 128000 bps. Channel CH
Since the operation state of No. 4 is "stop", the data distribution means 1
1 distributes only the audiovisual data D1 associated with CH1 on the network. The correction rate of D1 is 100000 bps, and the target transmission rate after correction of D1 is 6100000 bps.

FIG. 3 shows a flow chart for explaining one video distribution operation of this embodiment.

In step S101, the data distribution means 11 acquires the target rate section 42 and the correction rate section 43 from the corresponding entry in the channel state table 18, and calculates the target transmission rate.

In step S102, the data distribution means 11 calculates the transmission size based on the calculated transmission rate. The transmission size can be calculated by (transmission rate) × SYNC time.

In step S103, the data distribution means 11 instructs the image memory control means 15 to acquire the video / audio data of the transmission size. Data distribution means 11
In response to the request from the image memory control means 15, the video / audio data for the transmission size is acquired from the image memory 14 and transferred to the data distribution means 11.

In step 104, the data distribution means 11 distributes the audiovisual data to a predetermined network.

In step 105, the transmission delay time is detected based on the transmission interval of the video / audio data.

In step 106, the rate control means 13 controls to increase the transmission rate according to the transmission delay time Δt detected by the detection means 12.

In step 107, the correction rate section 43 of the corresponding entry in the channel state table 18 is updated.

At step 108, the timer is set to SY.
Set after NC time and wait.

Thereafter, step 101 to step 108
Is repeated until the operating state of CH1 to CH100 becomes "stop".

As described above, the video distribution device 10 according to the first embodiment of the present invention stores the video / audio data composed of at least one of video and audio.
A file management means 16 for managing and reading out the audiovisual data recorded in the storage means 17, an image memory 14 for temporarily storing a plurality of audiovisual data,
An image memory control unit 15 that transfers the video / audio data read by the file management unit 16 to the image memory 14, and acquires the video / audio data of the transmission size from the image memory 14 according to the transmission rate. , A data distribution means 1 for transmitting audiovisual data at predetermined time intervals
1, the detection means 12 for detecting the transmission delay time based on the actual video / audio data transmission interval, and the rate control means 13 for increasing the transmission rate according to the detected transmission delay time are provided. By detecting the data transmission delay time, it is possible to obtain a correction amount for bringing the transmission rate closer to the target rate.

Further, in the video distribution method according to the first embodiment of the present invention, the read / transfer step of reading the video / audio data composed of at least one of video and audio and transferring the read video / audio data to the image memory. S103,
A transmission step S104 for transmitting the video / audio data transferred to the image memory at a predetermined time interval, a detection step S105 for detecting the transmission delay time based on the actual video / audio data transmission interval, and a detected transmission delay time. Accordingly, since the adjustment step S106 for increasing the transmission rate is included, the effective transmission rate can be brought close to the target rate without adjusting the transmission rate between the transmission side and the reception side.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
6 is a flowchart illustrating a single video distribution operation of the embodiment. This is different from the first embodiment in that the transmission delay time is detected every predetermined number of transmissions, and the data capacity required to bring the transmission rate closer to the target rate is calculated based on the detected transmission delay time. Calculation steps S203 and S204, and transmission steps S101 to S for transmitting the video / audio data obtained by adding the data capacity to the normal video / audio data transmission capacity until the detection of the next transmission delay time.
The difference is that it has 104. According to this method, the transmission delay time can be averaged and the correction amount of the transmission rate can be reduced. Since the overall configuration of this embodiment is substantially the same as that of the first embodiment, the same reference numerals are given to the same components as in FIG. 1 and the description thereof will be omitted.

In the second embodiment of the present invention, the detection means 12 detects the transmission delay every predetermined number of transmissions,
The rate control means 13 calculates the data capacity required to bring the transmission rate close to the target rate based on the detected transmission delay time, and adjusts the video / audio data for the data capacity until the next transmission delay is detected. I am trying to send it.

The detecting means 12 detects the transmission delay time based on the actual video / audio data transmission interval for each predetermined number of transmissions. For example, the predetermined number of transmissions is set to 5 and the SYNC time is set. When the actual transmission time of 50 [ms] and 5 times audio / video data transmission is 260 [ms],
The average transmission delay time is 10 [msec].

Further, the rate detecting means 13 calculates the data capacity required to bring the transmission rate close to the target rate on the basis of the detected transmission delay time, and calculates the data capacity by the data transmission capacity until the next transmission delay is detected. The video and audio data of is also transmitted. When the transmission interval of video and audio data is Δt, the target transmission rate until the detection of the next transmission delay is: target rate + (target rate × Δt) / (predetermined number of transmissions ×
SYNC time). The target rate here refers to a transmission rate preset in the initial state.

FIG. 4 shows a flow chart for explaining the video distribution operation of this embodiment.

In step 101, the data distribution means 11 acquires the target rate 42 and the correction rate 43 from the corresponding entries in the channel state table 18, and calculates the target transmission rate.

In step 102, the data distribution means 11 calculates the transmission size based on the calculated transmission rate. The transmission size can be calculated by (transmission rate) × SYNC time.

In step 103, the data distribution means 11 instructs the image memory control means 15 to acquire the video / audio data for the transmission size. In response to the request from the data distribution unit 11, the image memory control unit 15 acquires the video / audio data for the transmission size from the image memory 14,
Transfer to the data distribution means 11.

In step 104, the data distribution means 11 distributes the audiovisual data to a predetermined network.

In step 201, the number of transmissions is incremented every time the audiovisual data is distributed to the network.

At step 202, it is confirmed whether the number of transmissions has reached a predetermined number of transmissions. If the number of transmissions has reached the predetermined number of transmissions, the process proceeds to step 203,
If not reached, the process proceeds to step 206.

In step 203, the transmission delay time Δt is detected based on the actual video / audio data transmission interval.

In step 204, the data capacity required to bring the transmission rate closer to the target rate is calculated based on the detected transmission delay time Δt, and the video of the data capacity is calculated until the next transmission delay is detected. Control is performed to increase the target transmission rate so that audio data is also transmitted.

In step 205, the correction rate section 43 of the corresponding entry in the channel state table 18 is updated.

At step 206, the number of transmissions is initialized.

At step 207, the timer is set to SY.
Set after NC time and wait.

Thereafter, step 101 to step 207
Is repeated until the operating state of CH1 to CH100 becomes "stop".

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
6 is a flowchart illustrating a single video distribution operation of the embodiment. This is because the transmission priority level is assigned in advance for each video and audio data, which is different from the first embodiment.
The difference is that stop steps S310 to S313 for stopping the transmission in order from the video / audio data having the lower transmission priority level are performed when transmission delays are continuously detected. According to this method, when video / audio data transmission exceeding system performance is performed, video / audio data having a low transmission priority can be stopped, and a transmission rate of data having a high transmission priority can be secured. Can also be obtained. Since the overall configuration of this embodiment is substantially the same as that of the first embodiment, the same reference numerals are given to the same components as in FIG. 1 and the description thereof will be omitted.

In the third embodiment of the present invention, as shown in FIG. 6, the channel state table 18 is provided with a priority level section 45 for holding the transmission priority level. The channel state table 18 contains information about data distribution of video and audio data, and one entry is assigned to each channel. This one entry includes a channel number section 40, video / audio data 41, a target rate section 42, a transmission rate section 43, an operating state section 44,
It comprises a priority level section 45.

When the transmission delay time is continuously detected, the rate control means 13 stops the transmission in order from the video / audio data having the lower transmission priority level.

The video / audio data section 41 holds information for identifying the video / audio data associated with the channel.

The target rate section 42 holds the target rate of the video / audio data, and is preset in the initial state.

The correction rate 43 part is the rate control means 13
The correction rate calculated in step 1 is held. The correction rate can be calculated by (target rate × Δt) / (SYNC time). The data distribution unit 11 determines the transmission rate based on the target rate section 42 and the correction rate 43 section.

The operation state section 44 holds the operation state of each channel. The data distribution unit 12 distributes the video / audio data based on the operation state unit 44.

The priority level 45 holds the transmission priority level assigned to each video / audio data, and is set when the video / audio data is associated with the transmission channel.

In FIG. 6, the channel state table 18 is 1
It consists of 00 entries (CH1 to CH100).

Now, the video / audio data D1, D2, D3 and D4 are associated with the channels CH1, Ch2, Ch3 and CH4. Further, the target rates of D1, D2 and D3 are set to 6,000,000 bps, and D
The target rate of 4 is set to 128,000 bps. The operating states of the channels CH1, Ch2, Ch3, and CH4 are “transmitting”, and the data distribution means 11 displays C
The audiovisual data D1, D2, D3 and D4 associated with H1, Ch2, Ch3 and CH4 are simultaneously delivered. The correction rates of D1, D2 and D3 are 100,
000 bps, and the corrected target transmission rate is 6,1
It shows that it is 0,000 bps. Also, D
The correction rate of No. 4 is 2000 bps, and the target transmission rate after correction of D4 is 130,000 bps. In addition, Ch1, Ch2, Ch3 and Ch4
Has a transmission priority level of 5, 4, 3, 1, and when transmission delay times are continuously detected, Ch4, Ch3, Ch
2 and Ch1 are stopped in this order.

The rate control means 13 calculates the data capacity required to bring the transmission rate close to the target rate based on the detected transmission delay time, and the video / audio corresponding to the data capacity before the next transmission delay is detected. The data is sent together. When the transmission interval of video and audio data is Δt, the target transmission rate until the detection of the next transmission delay is: target rate + (target rate × Δt) / (predetermined number of transmissions ×
SYNC time). When the transmission delay time is continuously detected, the transmission is stopped in order from the audio / video data having the lower transmission priority level based on the priority level section 45 of the channel state table.

Next, the video distribution operation of this embodiment will be described with reference to FIG.

In step 101, the data distribution means 11 acquires the target rate section 42 and the correction rate section 43 from the corresponding entries in the channel state table 18, and calculates the target transmission rate.

In step 102, the data distribution means 11 calculates the transmission size based on the calculated transmission rate. The transmission size can be calculated by (transmission rate) × SYNC time.

In step 103, the data distribution means 11 instructs the image memory control means 15 to acquire the video / audio data of the transmission size. In response to the request from the data distribution unit 11, the image memory control unit 15 acquires the video / audio data for the transmission size from the image memory 14,
Transfer to the data distribution means 11.

In step 104, the data distribution means 11 distributes the audiovisual data to a predetermined network.

In step 201, the number of transmissions is incremented every time the audiovisual data is distributed to the network.

In step 202, it is confirmed whether or not the number of transmissions has reached the predetermined number of transmissions. If the number of transmissions has reached the predetermined number of transmissions, the process proceeds to step 203,
If not reached, the process proceeds to step 206.

In step 203, the transmission delay time Δt is detected based on the actual video / audio data transmission interval.

In step 204, the data capacity required to bring the transmission rate closer to the target rate is calculated based on the detected transmission delay time Δt, and the video of the data capacity is calculated until the next transmission delay is detected. Control is performed to increase the target transmission rate so that audio data is also transmitted.

In step 205, the correction rate section 43 of the corresponding entry in the channel state table 18 is updated.

At step 206, the number of transmissions is initialized.

In step 300, it is confirmed whether a transmission delay has been detected. When the transmission delay is detected, the process proceeds to step 310, and when the transmission delay is not detected, the process proceeds to step 301.

In step 310, the transmission delay number is incremented.

In step 311, it is confirmed whether or not the transmission delay number has reached the stop start number. Here, the stop start number is a threshold value for starting the stop of the transmission of the video and audio data, and the stop process of the video and audio data is started when the transmission delay number reaches the stop start number. The stop start number may be set in advance in the initial state, or may be reset during system operation.

In step 312, the channel state table 18 is referred to and the video / audio data having the lowest transmission priority level is selected. It should be noted that the video reproduction data set by the operating state unit 44 to “transmitting” is selected.

At step 313, the operation state part 44 of the corresponding entry of the channel state table 18 corresponding to the video / audio data selected as the transmission stop target is set to "temporary stop".

In step 301, if the transmission delay is not detected, the transmission delay number is initialized.

At step 302, the timer is set to SY.
Set after NC time and wait.

Thereafter, step 101 to step 302
Is repeated until the operating state of CH1 to CH100 becomes "stop".

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention.
6 is a flowchart illustrating a single video distribution operation of the embodiment. This is different from the first embodiment in that it further includes limiting steps S401 to S404 for limiting the number of video / audio data read at a predetermined time interval when a plurality of video / audio data are simultaneously transmitted. According to this method, the number of times the recording medium is accessed within a predetermined time interval is reduced, so that overheads such as a seek operation of the head and waiting for rotation can be suppressed, and a transmission delay time can be shortened. Since the overall configuration of this embodiment is substantially the same as that of the first embodiment,
Is used and the same reference numerals are given to the same components, and the description thereof will be omitted.

In the fourth embodiment of the present invention, when a plurality of video / audio data are simultaneously transmitted, the image memory control means 15 can read the number of video / audio data from the storage means 17 within a predetermined time interval. I am trying to limit.

The image memory control means 15 receives the video / audio data acquisition request from the data distribution means 11 and acquires the video / audio data of the transmission size from the image memory 14. Here, when the image memory 14 does not store the video / audio data for the transmission size, the image memory control means 14 instructs the file management means 16 to read the video / audio data. The image memory control means 15 has the storage means 17 within a predetermined time interval as described above.
It is possible to limit the number of audiovisual data that can be read from. The audiovisual data read from the storage means 17 in this way is transferred to a predetermined position in the image memory 14.

The image memory control means 15 includes the image memory 1
4 has an image memory management table 60 (shown in FIG. 8) for managing the video / audio data stored in FIG. In the image memory management table 60, one entry is assigned to each transmission channel, and the number of transmission channels is 100. One entry is composed of a use flag section 51, a valid data capacity section 52, a head position section 53, and an end position section 54.

The use flag section 51 records that the memory area has been allocated to the transmission channel. That is, when the memory area is released, the use flag 51 is cleared as an initial state, and when the memory area is allocated, a mark (“U” in the figure) is added. Here, the memory capacity assigned to the transmission channel is set to 20,000 bytes. In the present embodiment, it is possible to improve the use efficiency of the image memory by allocating the memory area only to the channel that actually performs the transmission operation. The memory area assigned to the transmission channel is used as a ring buffer.

The effective data capacity section 52 holds the audio / video data capacity stored in the memory area.

The head position portion 53 holds the head position of the effective data range in the memory area. When receiving the acquisition request for the video / audio data from the data distribution unit 11, the image memory control unit 15 acquires the data for the transmission size based on the head position portion 53.

The end position 54 holds the end position of the effective data range in the memory area. When the file management means 16 controls the reading of the video / audio data, the read video / audio data is transferred to a position adjacent to the end position portion 54.

As described above, the image memory management table 6
0 is composed of 100 entries (CH1 to CH100).

Now, memory areas are allocated to the channels CH1 and CH4, and the effective data capacities in the memory areas are 10,000 bytes and 8,000 bytes, respectively.
It is yte. In addition, the head positions of CH1 and CH4 are
It is set to 5,000 and 16,000. Also,
The terminal positions of CH1 and CH4 are 15,000 and 4,
It is set to 000. An example of the image memory 14 at this time is shown in FIG.

Next, the recording medium reading operation of the video distribution apparatus of this embodiment will be described with reference to FIG.

In step 401, the image memory control means 15 selects the transmission channel having the smallest effective data capacity based on the image memory management table 60. When the channel is selected, in step 402, the image memory control means 15 confirms whether or not the selected effective data capacity has reached the read start capacity. Here, the reading start capacity is a threshold value for starting reading the audiovisual data from the storage means 17. The read start capacity may be preset in the initial state, or may be reset during system operation. If the effective data capacity has reached the read start capacity, the operation proceeds to step 403. If the effective data capacity has not reached the read start capacity, the recording medium read operation is terminated.

In step 403, the image memory control means 15 determines the read size. Here, the read size is set to a value exceeding the transmission size × the number of simultaneous transmission channels, and a group of data blocks is prefetched collectively.

In step 404, the file management means 16 is instructed to read the audiovisual data for the calculated read size. In response to the video / audio data read request from the image memory control means 15, the file management means 16 reads a data block of the designated read size from the storage means 17, and in step 405,
The image memory control means 15 transfers the audiovisual data read by the file management means 16 to the image memory 14.

When the video / audio data is transferred, in step 406, the effective data capacity part 52 and the head position part 53 of the corresponding entry of the image memory management table 60 are updated.

The function of the video distribution apparatus shown in each of the above-described embodiments is the magnetic disk, the magneto-optical disk, the RO.
It can be recorded as a program in a recording medium such as an M, a CD-ROM, or an IC card. Therefore, the functions of the video distribution device described in each of the above embodiments may be realized by reading this recording medium with a computer. With this configuration, it is easy to update or move the program by carrying the recording medium.

Further, the program is loaded on the network 30.
It may be acquired from 0 in a file format and executed by the computer. According to this method, it is easy to update and distribute the program by using the network 300.

[0105]

As described above, the present invention detects the transmission delay time based on the actual video / audio data transmission interval, and when the transmission delay is detected, the transmission is performed according to the detected transmission delay time. By increasing the rate, a video distribution device, a video distribution method, and a program having an excellent effect that the effective transmission rate can be brought close to the target rate without adjusting the transmission rate between the transmission side and the reception side. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a video distribution device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a channel state table according to the first embodiment of the present invention.

FIG. 3 is a flowchart of a video distribution operation according to the first embodiment of the present invention.

FIG. 4 is a flowchart of a video distribution operation according to the second embodiment of the present invention.

FIG. 5 is a flowchart of a video distribution operation according to the third embodiment of the present invention.

FIG. 6 is a configuration diagram of a channel state table according to the third embodiment of the present invention.

FIG. 7 is a flowchart of a recording medium reading operation according to the fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of an image memory management table according to a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram of an image memory according to the fourth embodiment of the present invention.

FIG. 10 is a block diagram of a conventional video distribution device.

[Explanation of symbols]

10 Video distribution device 11 Data distribution means 12 Detection means 13 Rate control means 14 image memory 15 Image memory control means 16 File management means 17 Storage means 18 channel status table 40 channel number part 41 Video and audio data section 42 Transmission rate section 43 Correction rate section 44 Operation status section 50 channel number part 51 Usage flag part 52 Effective data capacity part 53 Start position 54 End position 60 image memory management table 100 sender terminal 110 RTP transmitter 120 RTCP transmitter 130 RTCP receiver 200 Receiver terminal 210 RTP receiver 220 RTCP transmitter 230 RTCP receiver

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sadaaki Emura             2-1,45, Hikosancho, Kanazawa, Ishikawa Stock             Matsushita Communication Kanazawa Research Institute (72) Inventor Masaaki Sato             3-1, Tsunashima-Higashi 4-chome, Kohoku-ku, Yokohama-shi, Kanagawa             Matsushita Communication Industry Co., Ltd. F-term (reference) 5C064 BA01 BA07 BB05 BB10 BC18                       BC23 BD02 BD08                 5K034 AA19 AA20 CC02 DD01 HH01                       HH02 HH17 HH26 MM08 MM12                       MM22

Claims (10)

[Claims] 1. A storage means for recording video / audio data composed of at least one of video and audio, a file management means for managing and reading out the video / audio data recorded in the storage means, and a plurality of videos. An image memory for temporarily storing audio data, and video / audio data read by the file management means, transferred to the image memory, and video / audio data of a transmission size from the image memory according to a transmission rate. Image memory control means for acquiring the data, data distribution means for transmitting the video / audio data at a predetermined time interval, detection means for detecting the transmission delay time based on the actual video / audio data transmission interval, and the detected transmission delay time And a rate control means for increasing the transmission rate according to the above. 2. A read transfer step of reading out audiovisual data composed of at least one of video and audio, and transferring the read out audiovisual data to an image memory, and the audiovisual data transferred to the image memory for a predetermined time. A transmission step of transmitting at intervals, a detection step of detecting a transmission delay time based on an actual video / audio data transmission interval, and an adjusting step of increasing a transmission rate according to the detected transmission delay time. Video distribution method. 3. A calculation step of detecting the transmission delay time for each predetermined number of transmissions, and calculating a data capacity necessary for bringing the transmission rate close to a target rate based on the detected transmission delay time, 3. The video distribution method according to claim 2, further comprising a transmission step of transmitting the video / audio data obtained by adding the data capacity to the normal video / audio data transmission capacity until the detection of the transmission delay time. 4. A stop step of allocating a transmission priority level to each of the video and audio data in advance, and when the transmission delay is continuously detected, the transmission is stopped in order from the video and audio data having the lower transmission priority level. The video distribution method according to claim 2 or 3, further comprising: 5. The method according to claim 2, further comprising a limiting step of limiting the number of video / audio data read at the predetermined time interval when a plurality of the video / audio data are simultaneously transmitted. Video delivery method. 6. A file management means for managing and reading out video / audio data recorded in a storage means by a computer, comprising at least one of video and audio, and video / audio read out by the file management means. Image memory control means for transferring data to an image memory for temporarily storing a plurality of video / audio data, and for acquiring video / audio data of a transmission size from the image memory according to a transmission rate, a predetermined time As a data distribution means for transmitting video / audio data at intervals, a detection means for detecting a transmission delay time based on an actual video / audio data transmission interval, and a rate control means for increasing a transmission rate according to the detected transmission delay time. A program to make it work. 7. A read / transfer step of reading video / audio data composed of at least one of video and audio to a computer and transferring the read video / audio data to an image memory, and video / audio data transferred to the image memory. Is transmitted at a predetermined time interval, a detection step of detecting a transmission delay time based on an actual video / audio data transmission interval, and an adjusting step of increasing the transmission rate according to the detected transmission delay time are executed. Program for. 8. A calculation for performing the detection of the transmission delay time on the computer every predetermined number of transmissions, and calculating a data capacity required to bring the transmission rate close to a target rate based on the detected transmission delay time. The program according to claim 7, for executing the step and the transmitting step of transmitting the audiovisual data obtained by adding the data capacity to the normal audiovisual data transmission capacity until the next transmission delay time is detected. 9. The computer is assigned a transmission priority level for each of the video and audio data in advance, and when transmission delays are continuously detected, the transmission is sequentially stopped from the video and audio data having the lower transmission priority level. The program according to claim 7 or 8 for causing a stopping step to be performed. 10. The method according to claim 7, wherein the computer executes a limiting step of limiting the number of audiovisual data read at the predetermined time interval when a plurality of the audiovisual data are simultaneously transmitted. The program described in.