METHOD AND SYSTEM FOR PERFORMING RATE CONTROL ADAPTED TO CHANNEL CONDITIONS
A method and system for determining in real time the instantaneous output rate of a low delay video frame encoder/application for encoding a video frame to be transmitted are disclosed. The video frame encoder provides its output for wireless transmission over a telecommunication channel. In one aspect, a method comprises providing an estimate of the instantaneous channel conditions under which the video frame will be transmitted. The method further comprises determining the instantaneous output rate by selecting a high output rate when the channel conditions considered acceptable and selecting a low output rate when the channel conditions are considered unacceptable.
1 . A method of determining in real time the instantaneous output rate of a low delay video frame encoder/application for encoding a video frame to be transmitted, the video frame encoder providing its output for wireless transmission over a telecommunication channel, the method comprising:
providing an estimate of the instantaneous channel conditions under which the video frame will be transmitted; and
determining the instantaneous output rate by selecting a high output rate when the instantaneous channel conditions are considered acceptable and selecting a low output rate when the instantaneous channel conditions are considered unacceptable.
2 . The method of claim 1 , wherein the video encoder and wireless transmission scheme are designed for an average target bit rate frame, and the determining of the instantaneous output rate is performed such that the average target bit rate is maintained.
3 . The method of claim 1 , wherein the selection is performed to minimize the energy needed for the wireless transmission.
4 . The method of claim 1 , further comprising initializing a relationship between the instantaneous output rate and the instantaneous channel condition under which the video frame will be transmitted.
5 . The method of claim 4 , wherein the initialization of a relationship is performed once and before the providing of an estimate of the instantaneous channel conditions and the determining of the instantaneous output rate based on the relationship.
6 . The method of claim 4 , wherein the method is performed for a sequence of video frames and wherein the relationship is updated based on channel measurements after the method is performed for a predetermined amount of video frames.
7 . The method of claim 1 , wherein the instantaneous output rate is used to select the quantization parameter of the video encoder.
8 . The method of claim 1 , wherein the instantaneous output rate is used to decide whether or not to skip a video frame.
9 . The method of claim 4 , wherein the initialization is selected to minimize the video quality degradation due to the output rate selection.
10 . The method of claim 4 , wherein the initialization is based on estimated channel state probabilities.
11 . The method of claim 1 , wherein the estimated instantaneous channel conditions are instantaneous channel conditions received via a feedback telecommunication channel.
12 . The method of claim 1 , wherein the instantaneous output rate of the low delay video frame encoder/application is the amount of bits per video frame.
13 . A computer readable storage medium having stored therein a computer program which, when being executed on a computer, performs the method of claim 1 .
14 . An apparatus for determining in real time the instantaneous output rate of a low delay video frame encoder/application for encoding a video frame to be transmitted, the video frame encoder providing its output for wireless transmission over a telecommunication channel, the apparatus comprising:
means for providing an estimate of the instantaneous channel conditions under which the video frame will be transmitted; and
means for determining the instantaneous output rate by selecting a high output rate when the instantaneous channel conditions are considered acceptable and selecting a low output rate when the instantaneous channel conditions are considered unacceptable.
15 . The apparatus of claim 14 , wherein the apparatus is a part of a video encoder.
16 . The apparatus of claim 14 , further comprising means for initializing a relationship between the instantaneous output rate and the instantaneous channel condition under which the video frame will be transmitted
17 . An apparatus for determining in real time the instantaneous output rate of a low delay video frame encoder/application for encoding a video frame to be transmitted, the video frame encoder providing its output for wireless transmission over a telecommunication channel, the apparatus comprising:
a providing module configured to provide an estimate of the instantaneous channel conditions under which the video frame will be transmitted; and
a determining module configured to determine the instantaneous output rate by selecting a high output rate when the instantaneous channel conditions are considered acceptable and selecting a low output rate when the instantaneous channel conditions are considered unacceptable.
18 . The apparatus of claim 17 , wherein the apparatus is a part of a video encoder.
19 . The apparatus of claim 17 , further comprising an initializing module configured to initialize a relationship between the instantaneous output rate and the instantaneous channel condition under which the video frame will be transmitted.