METHOD OF TRANSMITTING A PRE-CODED VIDEO SIGNAL OVER A COMMUNICATION NETWORK

• US 20090232200A1
• Filed: 03/09/2009
• Published: 09/17/2009
• Est. Priority Date: 03/11/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Henocq, Xavier, Onno, Patrice, Le Leannec, Fabrice
• Granted Patent: US 8,792,548 B2
• Time in Patent Office: Days
• US Class Current: 375/240.10
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/164 Feedback from the receiver or from the transmission channel
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 21/234327 by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/440227 by decomposing into layers, e.g. base layer and one or more enhancement layers

Abstract

A transmission method for transmitting, over a communication network, a video signal pre-coded using hierarchical coding comprises the steps of periodically estimating (S41) the bandwidth (BW(t)) of the communication network over evaluation periods, and for a current evaluation period, selecting (S42) a set of hierarchical levels (L_i(t)), compatible with the estimated bandwidth (BW(t)).

It further comprises the steps (S43, S44) of estimating a change tendency of the bandwidth (BW); of determining (S50, S60) additional data of the video signal to transmit depending on the estimated change tendency of the bandwidth; and of transmitting (S51, S54, S55, S61, S64, S65) the data of the selected hierarchical levels and determined additional data during the current evaluation period.

Use among others for transmitting a signal coded in accordance with the SVC standard.

Claims

1. A transmission method for transmitting, over a communication network, a video signal pre-coded using hierarchical coding, said signal being constituted by data distributed into several hierarchical levels, comprising the following steps:

periodically estimating the bandwidth of the communication network over evaluation periods; and

for a current evaluation period selecting a set of hierarchical levels, the transmission rate of the data of said selected hierarchical levels being compatible with the bandwidth estimated for said current evaluation period;

further comprising the following steps;

estimating a change tendency of said bandwidth for a following evaluation period;

determining additional data of said video signal to transmit depending on said estimated change tendency of the bandwidth; and

transmitting the data of the selected hierarchical levels and said determined additional data during said current evaluation period.

2. A transmission method according to claim 1, wherein at the step of determining additional data, said additional data are chosen from among data of said current evaluation period or data of said following evaluation period.

3. A transmission method according to claim 1, wherein at said step of determining additional data, if said bandwidth for the following evaluation period has a tendency to increase, said additional data are chosen in at least one hierarchical level higher than said set of hierarchical levels selected for said current evaluation period.

4. A transmission method according to claim 1, wherein at said step of determining additional data, if said bandwidth for the following evaluation period has a tendency to decrease, said additional data are chosen from among at least one hierarchical level of said following evaluation period, said hierarchical level being identical to a hierarchical level of said set of hierarchical levels selected for said current evaluation period.

5. A transmission method according to claim 1, wherein at the step of determining additional data, said additional data are determined furthermore on the basis of a bandwidth residue calculated on the basis of difference between the current bandwidth and the transmission rate of the data of said selected hierarchical levels.

6. A transmission method according to claim 1, wherein said transmission step comprises the following sub-steps;

sending said data of said set of hierarchical levels selected for said current evaluation period;

searching for data not transmitted during an evaluation period preceding said current evaluation period; and

transmitting said data not transmitted at said preceding evaluation period, then said determined additional data.

7. A transmission method according to claim 1, wherein at said step of estimating a change tendency, said tendency is evaluated on the basis of the bandwidths estimated for at least one preceding evaluation period prior to said current evaluation period.

8. A transmission method according to claim 7, wherein at said step of estimating a change tendency, said bandwidth estimated for the current evaluation period is compared with an average value of said bandwidths estimated for preceding evaluation periods, said bandwidth for a following evaluation period tending to increase when said estimated current bandwidth is less than said average value of the bandwidths, and said bandwidth for a following evaluation period tending to decrease when the estimated current bandwidth is greater than said average value of the bandwidths.

9. A transmission method according to claim 1, wherein at said step of selecting a set of hierarchical levels, said set is selected such that the transmission rate of the data of said selected hierarchical levels is the closest possible to the current bandwidth.

10. A transmission method according to claim 1, wherein said pre-coded video signal is transmitted in real-time between a server and a client of said communication network.

11. A transmission method according to claim 1, wherein said pre-coded video signal is a signal coded in accordance with the SVC standard with CGS hierarchical levels.

15. A server of a communication network adapted to transmit a video signal pre-coded using hierarchical coding, comprising means adapted to implement the transmission method according to claim 1.

16. A server according to claim 15, wherein the pre-coded video signal is transmitted in real-time between said server and a client of the communication network.

17. A server according to one of claims 15 or 16, wherein said pre-coded video signal is a signal coded in accordance with the SVC standard with CGS hierarchical levels.

18. A computer program that can be loaded into a computer system, said program comprising instructions enabling the implementation of the transmission method according to claim 1, when that program is loaded and executed by a computer system.

12. A transmission device for transmitting, over a communication network, a video signal pre-coded using hierarchical coding, said signal being constituted by data distributed into several hierarchical levels, comprising:

a unit configured to periodically estimate the bandwidth of the communication network over evaluation periods; and

for a current evaluation period, a unit configured to select a set of hierarchical levels, the transmission rate of the data of said selected hierarchical levels being compatible with the bandwidth estimated for said current evaluation period;

further comprising;

a unit configured to estimate a change tendency of said bandwidth for a following evaluation period;

a unit configured to determine additional data of said video signal to transmit depending on said estimated change tendency of the bandwidth; and

a unit configured to transmit the data of the selected hierarchical levels and said determined additional data during said current evaluation period.

13. A transmission device according to claim 12, wherein said transmitting unit comprise:

a unit configured to send said data of said set of hierarchical levels selected for said current evaluation period;

a unit configured to search for data not transmitted during an evaluation period preceding said current evaluation period;

said transmitting unit being adapted to transmit data not transmitted at said preceding evaluation period, then determined additional data.

14. A transmission device according to one of claims 12 or 13, comprising:

a unit configured to calculate a residue of current bandwidth on the basis of difference between the current bandwidth and the rate of transmission of the data of said selected hierarchical levels.