Decoding method and apparatus enabling fast channel change of compressed video

1. A video decoder for receiving compressed stream data and providing decompressed video output, the decoder comprising:

a demultiplexor for receiving the compressed stream data and separating a normal stream and a channel change stream there from, the normal stream and the channel change stream each being generated external to the video decoder and comprising a plurality of pictures for a same program;

a normal decoding portion in direct signal communication with the demultiplexor for selectably receiving at least one of the compressed normal and channel change streams, and providing decompressed video output; and

at least one normal frame store in signal communication with the normal decoding portion for storing reference pictures for use in decoding inter-coded pictures.

2. A video decoder as defined in claim 1 , further comprising:

a lower-resolution decoding portion in signal communication with the demultiplexor for receiving the compressed channel change stream;

at least one channel change frame store in signal communication with the lower-resolution decoding portion for storing reference pictures;

an upsampling unit in signal communication with the lower-resolution decoding portion for upsampling decompressed video data and selectably outputting said data to at least one of the at least one normal frame store and a display.

3. A video decoder as defined in claim 1 , further comprising a postprocessing filter in signal communication with the normal decoding portion for postprocessing decompressed video data and selectably outputting said data to at least the at least one normal frame store.

4. A video decoder as defined in claim 1 , further comprising means for selecting a compressed picture to decode from one of a normal stream and a channel change stream.

5. A video decoder as defined in claim 4 , further comprising means for upsampling lower resolution channel change stream pictures.

6. A video decoder as defined in claim 4 , further comprising means for postprocessing the output of the normal decoder to reduce the abruptness of a transition from lower-quality to normal quality output.

7. A video decoder as defined in claim 1 , further comprising means for decoding redundant picture syntax in compliance with the JVT/H.264/MPEG AVC compression standard.

8. A video decoder as defined in claim 1 , further comprising means for decoding channel change pictures from user data of corresponding normal stream pictures.

9. A video decoder as defined in claim 1 , further comprising means for responding to a signal from an encoder indicating whether to use normal stream or channel change stream pictures for subsequent channel change stream intra-coded pictures.

10. In a video decoder, a video decoding method for receiving compressed stream data and providing decompressed video output, the method comprising:

receiving the compressed stream data and separating a normal stream and a channel change stream there from, the normal stream and the channel change stream each being generated external to the video decoder and comprising a plurality of pictures for a same program;

receiving at least one of the compressed normal and channel change streams, and providing decompressed video output; and

storing reference pictures for use in decoding inter-coded pictures.

11. A video decoding method as defined in claim 10 , further comprising at least one of:

selecting a compressed picture to decode from one of a normal stream and a channel change stream;

upsampling lower resolution channel change stream pictures;

decoding redundant picture syntax in compliance with the JVT standard;

decoding channel change pictures from user data of corresponding normal stream pictures;

responding to a signal from an encoder indicating whether to use normal stream or channel change stream pictures for subsequent channel change stream intra-coded pictures; and

postprocessing the output of the normal decoder to reduce the abruptness of a transition from lower-quality to normal quality output.