reads the encoding decisions made by the encoder that produced the compressed version of the original video and passes the encoding decisions to slave encoder 415 slave encoder 415 encodes the watermark sequence using the same decisions dct adder recoder combines the encoded watermark sequence and the compressed content thus the original video sequence and the watermark sequence are encoded in a compatible way and can be combined efficiently in the dct or other linear transform domain without full decoding fig5 illustrates one embodiment of dct adder recoder 420 bitstream x is for example a compressed data stream carrying compressed content bitstream x is variable length decoded vld by vld 520 to recover the quantized dct coefficients for each macroblock in dct recovery block 516 bitstream w is also variable length decoded vld by vld 536 to recover the quantized dct coefficients for each macroblock in dct recovery block 540 the temporal reference motion vectors and mode decisions must also be variable length decoded in vld 524 recovered in recovery block 528 and used to partially encode the watermark w the recovered absolute dct coefficients of x main bitstream and w watermark bitstream are added by adder 512 in the dct domain in one embodiment the addition of the dct coefficients is accomplished by piping 64 floating point numbers per block into the adder if desired the addition of the dct coefficients may be accelerated in one embodiment.