Encoding device, decoding device, streaming system, and streaming method

Abstract

According to an embodiment, an encoding device includes an encoder. The encoder is configured to generate a video stream. The video stream includes at least a first image group including a plurality of images encoded at a first bit rate and a second image group including a plurality of images. The first image group includes an intra-coded image. The plurality of images of the second image group are associated with the intra-coded image serving as a reference image to decode an inter-coded image, and are encoded at a second bit rate different from the first bit rate and having reproduction timing in synchronization with the plurality of images of the first image group.

What is claimed is: 
     
         1 . An encoding device comprising:
 an encoder configured to generate a video stream, the video stream including at least a first image group including a plurality of images encoded at a first bit rate, the first image group including an intra-coded image, and a second image group including a plurality of images, the plurality of images being associated with the intra-coded image serving as a reference image to decode an inter-coded image, the plurality of images being encoded at a second bit rate different from the first bit rate and having reproduction timing in synchronization with the plurality of images of the first image group.   
     
     
         2 . The encoding device according to  claim 1 , wherein the encoder is configured to insert reference information indicating the associated reference image into a file of the video stream or add a reproduction control file indicating the associated reference image to the video stream, and output the video stream. 
     
     
         3 . The encoding device according to  claim 1 , wherein
 the first image group includes the intra-coded image serving as the reference image and the inter-coded image, and   the second image group only includes the inter-coded image to be decoded using the reference image.   
     
     
         4 . The encoding device according to  claim 1 , wherein the second image group includes a plurality of images each including a low-quality part and at least a high-quality part. 
     
     
         5 . A decoding device comprising:
 a receiver configured to receive a video stream, the video stream including at least a first image group including a plurality of images encoded at a first bit rate, the first image group including an intra-coded image, and a second image group including a plurality of images, the plurality of images being associated with the intra-coded image serving as a reference image to decode an inter-coded image, the plurality of images being encoded at a second bit rate different from the first bit rate and having reproduction timing in synchronization with the plurality of images of the first image group; and   a decoder configured to decode the inter-coded image with reference to the received reference image.   
     
     
         6 . The decoding device according to  claim 5 , wherein
 reference image information indicating the associated reference image is inserted into a file of the video stream or a reproduction control file indicating the associated reference image is added to the video stream, and   the decoder is configured to use the reference image indicated in the reference image information or the reference image indicated in the reproduction control file, to decode the inter-coded image.   
     
     
         7 . The decoding device according to  claim 5 , wherein
 the first image group includes the intra-coded image serving as the reference image and the inter-coded image, and   the second image group only includes the inter-coded image to be decoded using the reference image.   
     
     
         8 . The decoding device according to  claim 5 , wherein
 the decoder is configured to either decode either all of the inter-coded images in the same video stream using the intra-coded image associated as the reference image or decode one inter-coded image of a plurality of inter-coded images in the same video stream using the intra-coded image associated as the reference image and decode other inter-coded images using the inter-coded image having been decoded using the intra-coded image.   
     
     
         9 . The decoding device according to  claim 5 , wherein the second image group includes a plurality of images each including a low-quality part and at least a high-quality part. 
     
     
         10 . A streaming system comprising:
 a transmitting device; and   a receiving device, wherein   the transmitting device includes
 an encoder configured to generate a video stream, the video stream including at least a first image group including a plurality of images encoded at a first bit rate, the first image group including an intra-coded image, and a second image group including a plurality of images, the plurality of images being associated with the intra-coded image serving as a reference image to decode an inter-coded image, the plurality of images being encoded at a second bit rate different from the first bit rate and having reproduction timing in synchronization with the plurality of images of the first image group; 
 a transmitter configured to transmit the video stream generated by the encoder, and 
   the receiving device includes
 a receiver configured to receive the encoded video stream; and 
 a decoder configured to decode the inter-coded image with reference to the received reference image. 
   
     
     
         11 . A streaming method comprising:
 generating, by an encoder, a video stream, the video stream including at least a first image group including a plurality of images encoded at a first bit rate, the first image group including an intra-coded image, and a second image group including a plurality of images, the plurality of images being associated with the intra-coded image serving as a reference image to decode an inter-coded image, the plurality of images being encoded at a second bit rate different from the first bit rate and having reproduction timing in synchronization with the plurality of images of the first image group;   transmitting, by a transmitter, the video stream generated by the encoder;   receiving, by a receiver, the encoded video stream; and   decoding, by a decoder, the inter-coded image with reference to the received reference image.