Advances in Visual Data Compression and Communication

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17.5 Evaluation 389

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Receiver SNR (dB)

PSNR (dB)

Cactus

SoftCast

BPSK 1/2

QPSK 1/2

QPSK 3/4

16-QAM 1/2

Figure 17.14 Compare Cactus against two reference schemes for a CIF sequence in a multicast

session when bandwidth ratio ρ = 1.

and average video PSNR across sequences. To plot the video PSNR as a function

of receiver SNR, we divide the receiver SNR range into 1 dB bins, and average all

the (receiver SNR, PSNR) pairs whose receiver SNR fall into the same bin. Results

show that although both Cactus and SoftCast achieve graceful rate adaptation, Cac-

tus consistently outperforms SoftCast in video PSNR, and