Studies On The Technique Of Digital Video Transcoding In DCT Domain

Nowadays, kinds of video coding standards have been developed, which are different from each other in syntax as well as in compressing-rate, bit-rate and picture format. They are designed for diverse networks, decoders and monitors. When the incoming coded video stream with a specific format is not fit for the current network or guest requirement, we need to transfer the coded stream from one format to the required format seamlessly, which is known as the transcoding.At the beginning, early transcoder is emphasis on video bit-rate reduction for fitting the bandwidth of transmission. As time moved on, mobile media services get more and more practical uses, it makes both picture-size transcoding and frame-skipping transcoding become a key direction of transcoding research because of the constraint of display ability. One straightforward approach for implementing a transcoder is to cascade one independent decoder with one independent encoder, commonly known as pixel-domain transcoder. By this method, the incoming video stream is firstly decoded into the pixel domain, and then these frames are recompressed at the desired format according to the capability of the clients'devices and available bandwidth. This procedure suffers from a high processing complexity, memory and delay. In order to solve these drawbacks, the researches focus onto the discrete cosine transform (DCT) domain transcoding recently, which transfers the process of transcoding into the DCT domain in terms of the characters of DCT transformation.In this paper, we make some researches on the key technologies of transcoding in DCT domain, which mainly contains frame-skipping transcoding temporally, picture-size transcoding spatially, syntax transcoding and heterogeneous transcoding...