In this paper, we propose algorithms that map the low-level motion compensation and transformation functions of MPEG-1/2, H.263/MPEG-4 ASP and H.264/MPEG-4 AVC video codecs onto common workflows. This way, a single discrete
implementation of luma prediction, chroma prediction and residual transform stages is sufficient for all covered video
The proposed luma prediction is based on 4×4 blocks to cover the H.264 specifications as well as the elder standards. The
design consists of a singular four stage pipeline for two block interpolation and two block averaging stages. Targeted for
hardware implementation, a strictly linear execution is provided, avoiding branch operations. The algorithmic behavior is
entirely dictated by the contents of the parameter ROM.
Since chrominance prediction must cover blocks as small as 2×2 pixels, a distinct operation is proposed for chroma. The
bilinear operation scheme in H.264 is able to carry out the operations for the elder standards with minor changes only.
In H.264, the classic 8×8 DCT transformation was replaced by a simplified 4×4 integer transform, based on a heavily
quantized DCT scheme. By modifications of a well-known multiplier-adder-based scheme, a generalized transformation
stage can be derived.
This paper presents a new watermarking framework, suitable for authentication of H.264 compressed videos. The
authentication data is embedded as fragile, blind and erasable watermark with low video quality degradations. Because
of using a fragile watermark, hard authentication is possible. In contrast to other approaches, the watermarking is done
after the H.264 compression process. Hence, the authentication information can be embedded in already encoded videos.
To reconstruct the original H.264 compressed video the watermark can be removed. The framework is based on a new
transcoder, which analyses the original H.264 bit stream, computes a watermark, embeds the watermark and generates a
new H.264 bit stream. To authenticate the video a hash value is used. This value is encrypted with a private key of an
asymmetric cryptosystem. The payload of the watermark consists of the encrypted hash value and a certificate with the
public key. Some skipped macroblock of the H.264 video are used to embed the watermark. A special process selects
these macroblocks. This process sets the distribution and the number of skipped blocks as well as the number of
embedded bits per block to achieve low video quality degradations and low data rate. To embed the watermark the
performance of several approaches is discussed and analyzed. The result of the framework is a new watermarked H.264
bit stream. All data necessary for authentication are embedded and cannot get lost.
This paper aims to provide an overveiw of the emerging video coding standard H.264/AVC in embedded environments typical for mobile streaming. After a description of the H.264 special network adaption layer and the required functionality of a compliant encoder packetizer and streaming server, reliability and bandwidth efficiency are being discussed using RTP and reliable RTR as possible candidates on the network layer. The main focus of the is paper is put on implementation issues for embedded systems including an analysis of the decoder complexity.