转换编码中宏块编码模式的利用及重新判断

Utilization and Redetermination of Macroblock -typein Video Spatial Definition Downscale Transcoder

视频转换编码是指将已压缩编码的视频流转换成较低码率、不同显示格式或不同编码模式码流的过程,但转换编码应充分利用源码流中的信息来降低再编码的复杂度和计算量。鉴于目前源码流中图像的纹理信息和运动矢量已经得到了利用,因此为进一步减少计算量,提出利用源码流中的宏块编码模式(macroblock-type)来进行转换编码的方法,即在下变换前,先提前获知宏块的状态,以便动态调整下变换的计算过程,同时准确得到下变换后宏块的编码模式。实验表明,该方法确实可以减少转换过程中的计算冗余,并可提高转换编码的效率。

Video transcoding is a process of converting a previously encoded video bit stream into another bit stream with a lower bit rate, a different display format, or a different encoding mode, but in transcoding, the information in soure bit stream should be fully utilized to reduce the computation complexity. At present, texture and motion vectors of pictures in soure bit stream are reused. To reduce more computation, a new scheme is proposed in this paper that the state of a macroblock is obtained before down conversion according to its “macroblock -type”, and then based on it, the computation process of down conversion is adjusted dynamically and at the same time the macroblock -type of downscaled macroblock is achieved accurately. Experiments show that using this scheme, the computation redundance in down conversion process can be reduced and the efficiency of transcoding can be increased.