Decoding method and apparatus enabling fast channel change of compressed video
A video decoder, and corresponding method are described for enabling fast channel change of compressed video, where a video decoder for receiving compressed stream data and providing decompressed video output includes receiving the compressed stream data and separating the normal stream and the channel change stream, a normal decoding portion for selectably receiving the compressed normal and channel change streams, and providing decompressed video output, and a normal frame store in signal communication with the normal decoding portion for storing reference pictures.
1. In a video decoder, a video decoding method that receives compressed stream data and provides decompressed video output, the method comprising:
receiving the compressed stream data and separating a normal stream and a channel change stream, 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, wherein the channel change stream comprises images with lower resolution than images of the normal stream;
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.
2. The video decoding method of claim 1 further comprising:
selecting a compressed picture to decode from one of the normal stream and the channel change stream; and
upsampling the lower resolution channel change stream images.
3. The video decoding method of claim 2 further comprising:
decoding redundant picture syntax in compliance with a video compression standard.
4. The video decoding method of claim 2 further comprising:
responding to a signal indicating whether to use normal stream or channel change stream pictures for subsequent channel change stream intra-coded pictures.
5. The video decoding method of claim 2 further comprising:
postprocessing the output of the normal decoder to reduce the abruptness of a transition from lower-quality to normal quality output.
6. A video decoder comprising:
a receiver that receives a compressed stream data and separating a normal stream and a channel change stream, 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, wherein the channel change stream comprises images with lower resolution than images of the normal stream;
a decoder that receives at least one of the compressed normal and channel change streams, and providing decompressed video output; and
a storage that stores reference pictures for use in decoding inter-coded pictures.
7. The video decoder of claim 6 further comprising:
a selector that selects a compressed picture to decode from one of the normal stream and the channel change stream; and
an upsampler that upsamples the lower resolution channel change stream images.
8. The video decoder of claim 7 , wherein the decoder decodes redundant picture syntax in compliance with a video compression standard.
9. The video decoder of claim 7 , wherein the decoder responds to a signal indicating whether to use normal stream or channel change stream pictures for subsequent channel change stream intra-coded pictures.
10. The video decoder of claim 7 wherein the decoder postprocesses the output of the normal decoder to reduce the abruptness of a transition from lower quality to normal quality output.