METHOD AND APPARATUS FOR CONTROLLING INTRA-REFRESHING IN A VIDEO TELEPHONY COMMUNICATION SYSTEM

• US 20080165246A1
• Filed: 01/07/2008
• Published: 07/10/2008
• Est. Priority Date: 01/06/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: JUNG, Kyung-Hun
• Granted Patent: US 8,233,023 B2
• Time in Patent Office: Days
• US Class Current: 348/14.12
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/166 concerning the amount of transmission errors, e.g. bit error rate [BER]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/895 in combination with error concealment
• CPC Class Codes: H04N 7/141 between two video terminals, e.g. videophone telephonic communication systems combined with television receiver for reception of entertainment or information matter H04M11/085
• CPC Class Codes: H04N 7/148 Interfacing a video terminal to a particular transmission medium, e.g. ISDN

Abstract

A method and apparatus for controlling intra-refreshing in a video telephone communication system are provided. A reception apparatus checks a sequence number and a CRC for received video packet data to detect presence of a packet loss, decodes the received video data to check frame type information, generates a control signal for requesting intra-refreshing in accordance with the checked frame type information and the sequence number, and transmits the generated control signal for requesting intra-refreshing to a transmission apparatus. The transmission apparatus determines whether a control signal for requesting transmission of an I-frame obtained by compressing an independent image is received from the reception apparatus, checks frame type information and a sequence number of video data being compressed, determines whether to transmit a temporary I-frame corresponding to the received control signal or to transmit an I-frame based on a predetermined period, in accordance with the checked frame type information and the sequence number, and transmits the I-frame to the reception apparatus using a variable time according to the determination.

Claims

1. A method for requesting intra-refreshing in a video telephone communication system, the method comprising:

checking, by a reception apparatus, a sequence number and a Cyclic Redundancy Check (CRC) for received video packet data to detect presence of a packet loss;

decoding the received video packet data to check frame type information;

generating a control signal for requesting intra-refreshing in accordance with the checked frame type information and the sequence number; and

transmitting the generated control signal for requesting intra-refreshing to a transmission apparatus.

2. The method of claim 1, further comprising:

computing an arrival time t₂ of an I-frame obtained by compressing an independent image to be temporarily transmitted from the transmission apparatus in response to the control signal transmitted to the transmission apparatus;

comparing an arrival time t₁ of the I-frame transmitted at periods, with the computed arrival time t₂; and

when t₁ is later than t₂, transmitting the generated control signal for requesting intra-refreshing to the transmission apparatus.

3. The method of claim 2, further comprising:

when t₁ is equal to or earlier than t₂, holding the transmission of the generated control signal for requesting intra-refreshing to the transmission apparatus, and waiting for a periodically transmitted I-frame.

4. The method of claim 1, further comprising:

decoding, by the reception apparatus, the received video packet data to determine whether the frame type information indicates a periodically transmitted I-frame, or a P-frame obtained by compressing a difference between video data at a transmission time and video data before the transmission time; and

acquiring a sequence number indicating a sequence of a corresponding P-frame transmitted after the I-frame is transmitted.

5. The method of claim 1, further comprising:

defining, by the reception apparatus, a first region for requesting transmission of an I-frame, a second region for waiting for a periodically transmitted I-frame, and a third region, located between the first region and the third region, for selectively requesting transmission of an I-frame, in accordance with the frame type information and the sequence number; and

selectively transmitting the control signal for requesting intra-refreshing to the transmission apparatus in accordance with the defined regions.

6. The method of claim 2, further comprising:

computing, by the reception apparatus, the time t₁ and the time t₂ depending on a two-way delay between the transmission apparatus and the reception apparatus, comparing the time t₁ with the time t₂, and transmitting the control signal for requesting intra-refreshing to the transmission apparatus according to the comparison result.

7. The method of claim 1, further comprising:

transmitting, by the reception apparatus when it is based on a circuit-switched system, the control signal to the transmission apparatus using a Video Fast Picture Update Command (VFPU), and transmitting, when the reception apparatus is based on a packet-switched system, the control signal to the transmission apparatus using an AVPF Negative Acknowledgement (NACK) signal indicating transmission failure of the packet data, and AVPF Picture Loss Indication (PLI) indicating a loss of the packet during its transmission.

8. A reception apparatus for requesting intra-refreshing in a video telephone communication system, the apparatus comprising:

an error detection block for checking a Cyclic Redundancy Check (CRC) attached to received video data to detect an error, and checking a sequence number of the received video data;

a decoder for decoding the error-detected video data to check frame type information; and

a controller for generating a control signal for requesting intra-refreshing in accordance with the checked frame type information and the sequence number, and transmitting the generated control signal for requesting intra-refreshing to a transmission apparatus.

9. The reception apparatus of claim 8, wherein the controller:

computes an arrival time t₂ of an I-frame obtained by compressing an independent image to be temporarily transmitted in response to the transmitted control signal after transmitting the generated control signal for requesting intra-refreshing to the transmission apparatus;

compares the arrival time t₂ with an arrival time t₁ of an I-frame transmitted at periods; and

when t₁ is later than t₂, transmits the generated control signal for requesting intra-refreshing to the transmission apparatus.

10. The reception apparatus of claim 9, wherein the controller:

holds the transmission of the generated control signal for requesting intra-refreshing to the transmission apparatus, and waits for a periodically transmitted I-frame, when t₁ is equal to or earlier than t₂.

11. A method for transmitting by a transmission apparatus an I-frame obtained by compressing an independent image in response to a request for intra-refreshing in a video telephone communication system, the method comprising:

determining whether a control signal for requesting transmission of an I-frame obtained by compressing an independent image is received from a reception apparatus;

checking frame type information and a sequence number of video data being compressed;

determining whether to transmit a temporary I-frame corresponding to the received control signal or to transmit an I-frame based on a predetermined period, in accordance with the checked frame type information and the sequence number; and

transmitting the I-frame to the reception apparatus using a variable time according to the determination.

12. The method of claim 11, further comprising:

computing a time t₄ at which the control signal was requested from the reception apparatus;

comparing the computed time t₄ with a transmission time t₃ of an I-frame transmitted at periods; and

when t₃ is earlier than t₄, temporarily transmitting the I-frame to the reception apparatus according to the control signal.

13. The method of claim 11, further comprising:

holding the transmission of the temporary I-frame according to the control signal, and transmitting the I-frame based on a predetermined period, when t₃ is equal to or later than t₄.

14. The method of claim 11, further comprising:

determining, by the transmission apparatus, transmission of the intra-refreshing requested I-frame in accordance with a two-way delay between the transmission apparatus and the receiver apparatus, and the number of P-frames obtained by compressing a difference between current video data being lost due to the transmission of the I-frame and previous video data.

15. The method of claim 12, further comprising:

variably adjusting, by the transmission apparatus, a transmission period of an I-frame intra-refreshing requested from the reception apparatus in accordance with a sequence number of a P-frame obtained by compressing a difference between the current video data and the previous video data.

16. The method of claim 13, further compressing:

variably adjusting, by the transmission apparatus, a transmission period for transmitting the I-frame in accordance with a channel condition between the transmission apparatus and the reception apparatus after transmitting the I-frame, and transmitting an I-frame to the reception apparatus using the adjusted transmission period.

17. A transmission apparatus for transmitting an I-frame obtained by compressing an independent image in response to a request for intra-refreshing in a video telephone communication system, the apparatus comprising:

a controller for determining whether a control signal for requesting transmission of an I-frame obtained by compressing an independent image is received from a reception apparatus, checking frame type information and a sequence number of video data being compressed, and determining whether to transmit a temporary I-frame corresponding to the received control signal or to transmit an I-frame based on a predetermined period, in accordance with the checked frame type information and the sequence number; and

an encoder for compressing video data into an independent image using a variable time and transmitting the video data to the reception apparatus according to the determination of the controller.

18. The transmission apparatus of claim 17, wherein the controller:

computes a time t₄ at which the control signal was requested from the reception apparatus;

compares the computed time t₄ with a transmission time t₃ of an I-frame transmitted at periods; and

when t₃ is earlier than t₄, temporarily transmits the I-frame to the reception apparatus according to the control signal.

19. The transmission apparatus of claim 18, wherein the controller:

when t₃ is equal to or later than t₄, holds the transmission of the temporary I-frame according to the control signal, and transmits the I-frame based on a predetermined period.