In this paper, we present a slice-based encryption and spatial adaptation technique for H264 videos. The encrypted video is resilient to spatial adaptation. All the encryption and adaptation steps are performed without any cascaded decoding and re-encoding operation. We use MPEG-2I gBSD as a metadata description of the compressed bitstream. This metadata is utilized to execute all the necessary footsteps in compressed domain. The proposed encryption scheme can be applied to a compressed bitstream before or qfter adaptation operations. Moreover, the resultant bitstream conforms to H2641AVC specification. Proof of the proposed encryption scheme and overall performance results established from the implemented system are also presented here.

In this paper, we present a metadata-based compressed-domain spatial adaptation scheme for H.264/AVC video. We have enhanced the H.264/AVC encoder with our proposed adaptation strategies in order to reduce video size by cropping individual frames in an intermediary node prior to transmitting that video to heterogeneous devices. In this regard, we exploit the sliced architecture of the video frames within the first version of the H.264/AVC specification and devise different slicing strategies.The compressed-domain bitstream modification is performed at the intermediary nodes, avoiding the need for any cascaded operations. Here, we briefly present our adaptation scheme as well as evaluation results showing the effectiveness of the slicing strategies on the bitrate reduction and processing time. A comparison of our approach with an existing cropping scheme is also presented.

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