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Figure 4 MPEG Group Of Pictures structure quence for applications that require random access.

Figure 4 MPEG Group Of Pictures structure quence for applications that require random access.

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Figure 2 DCT basis functions
Figure 2 DCT basis functions
standards.
standards.
Figure 5 Structure of MPEG bitstream
Figure 5 Structure of MPEG bitstream
these experiments is shown in Figure 6.
these experiments is shown in Figure 6.
Table 2 Visual quality grading scale Each observer is presented with a set of video sequences including reference sequences and
Table 2 Visual quality grading scale Each observer is presented with a set of video sequences including reference sequences and
More detailed cell loss models can be found in the literature, for example see papers in by the mean burst length.
More detailed cell loss models can be found in the literature, for example see papers in by the mean burst length.
Figure 13 Error spreading due to motion compensation
Figure 13 Error spreading due to motion compensation
of each B-picture is about 2-3dB lower than that of its neighbouring I/P-pictures. Figure 15 PSNR of error-free decoded sequence
of each B-picture is about 2-3dB lower than that of its neighbouring I/P-pictures. Figure 15 PSNR of error-free decoded sequence
Figure 16 PSNR drop due to error in I-picture
Figure 16 PSNR drop due to error in I-picture
Figure 17 PSNR drop due to error in 1* P-picture
Figure 17 PSNR drop due to error in 1* P-picture
in a GOP, and in Figure 19, where the cell loss occurs in the 3rd and final P-picture in a
in a GOP, and in Figure 19, where the cell loss occurs in the 3rd and final P-picture in a
drop due to cell loss in an I or P-picture. Figure 20 PSNR drop due to error in B-picture value are shown in Figure 20. The average is just over 3dB, significantly lower than the
drop due to cell loss in an I or P-picture. Figure 20 PSNR drop due to error in B-picture value are shown in Figure 20. The average is just over 3dB, significantly lower than the
Figure 21 PSNR of error-free and errored sequences
Figure 21 PSNR of error-free and errored sequences
Figure 22 Drop in PSNR relative to error-free sequence
Figure 22 Drop in PSNR relative to error-free sequence
frames in the decoded sequence is 36.3 dB. Figure 23 Quality loss due to bit errors (Graduation)
frames in the decoded sequence is 36.3 dB. Figure 23 Quality loss due to bit errors (Graduation)
Figure 24 PSNR of decoded MPEG video: bit errors (Nursery)
Figure 24 PSNR of decoded MPEG video: bit errors (Nursery)
quality drops significantly. Figure 25 Quality loss due to cell losses (Graduation)
quality drops significantly. Figure 25 Quality loss due to cell losses (Graduation)
Figure 26 PSNR of decoded MPEG video: cell losses (Nursery)
Figure 26 PSNR of decoded MPEG video: cell losses (Nursery)
contains less detail.
contains less detail.
(mainly P-pictures) and a smaller number between 250-400 cells (mainly I-pictures). Figure 28 Probability distribution
(mainly P-pictures) and a smaller number between 250-400 cells (mainly I-pictures). Figure 28 Probability distribution
Figure 29 Contents of "leaky bucket": leak rate = 2 x MCR “burst” of cells, causing the bucket to fill up rapidly.
Figure 29 Contents of "leaky bucket": leak rate = 2 x MCR “burst” of cells, causing the bucket to fill up rapidly.
Figure 30 Contents of "leaky bucket": leak rate=1.2 x MCR which cells arrive has dropped.
Figure 30 Contents of "leaky bucket": leak rate=1.2 x MCR which cells arrive has dropped.
Table 3 Cell loss effects on decoded video (leak rate = 2 x mean cell rate)
Table 3 Cell loss effects on decoded video (leak rate = 2 x mean cell rate)
of values from 160 (highest number of lost cells) to 220 (lowest number of lost cells).
of values from 160 (highest number of lost cells) to 220 (lowest number of lost cells).
Figure 32 Leaky bucket contents with adaptive rate control reduced variation in data rate compared to the unconstrained data rate shown in Figure 27.
Figure 32 Leaky bucket contents with adaptive rate control reduced variation in data rate compared to the unconstrained data rate shown in Figure 27.
Figure 34 Quantization step size Figure 34 shows how the quantization step size varies during the sequence.
Figure 34 Quantization step size Figure 34 shows how the quantization step size varies during the sequence.
Figure 35 Bit rate variation (JPEG encoding)
Figure 35 Bit rate variation (JPEG encoding)
Figure 36 Bit rate variation of H.261 sequence
Figure 36 Bit rate variation of H.261 sequence
Figure 37 Bit rate for 1 GOP of MPEG sequence
Figure 37 Bit rate for 1 GOP of MPEG sequence
Figure 38 Effect of encoding parameters on bit rate
Figure 38 Effect of encoding parameters on bit rate
Figure 41 Compexity measure for Graduation and Nursery
Figure 41 Compexity measure for Graduation and Nursery
In both sequences, the Standard Deviation is significantly reduced by the new method. The Table 5 Mean and Standard Deviation of PSNR
In both sequences, the Standard Deviation is significantly reduced by the new method. The Table 5 Mean and Standard Deviation of PSNR
Figure 42 PSNR of decoded sequences
Figure 42 PSNR of decoded sequences
Figure 45 DC and 2 lowest AC coefficients a subset of the spatial frequencies. Figure 44 DC coefficients only
Figure 45 DC and 2 lowest AC coefficients a subset of the spatial frequencies. Figure 44 DC coefficients only
Figure 47 All coefficients Figure 46 DC and lowest 9 AC coefficients
Figure 47 All coefficients Figure 46 DC and lowest 9 AC coefficients
Table 6 Decoded sequences
Table 6 Decoded sequences
Figure 50 Data rate of PSS JPEG
Figure 50 Data rate of PSS JPEG
The Baseline JPEG sequence with 10° bit errors showed very poor visual quality with Table 7 Quality of decoded video sequences many obvious “streaks” across the decoded frames (see the example in Figure 51). JPEG
The Baseline JPEG sequence with 10° bit errors showed very poor visual quality with Table 7 Quality of decoded video sequences many obvious “streaks” across the decoded frames (see the example in Figure 51). JPEG
pixels as shown in this example. Figure 51 Baseline JPEG with bit errors resynchronization marker. This means that an error can often cause a “streak” of corrupted
pixels as shown in this example. Figure 51 Baseline JPEG with bit errors resynchronization marker. This means that an error can often cause a “streak” of corrupted
Figure 52 Mean PSNR of decoded sequences The mean PSNR for the two sequences (averaged across 5 experiments) is shown in Table
Figure 52 Mean PSNR of decoded sequences The mean PSNR for the two sequences (averaged across 5 experiments) is shown in Table
Each macroblock consists of 16 x 16 luminance samples and so each slice in the 20_20_20 Table 11 Test sequences
Each macroblock consists of 16 x 16 luminance samples and so each slice in the 20_20_20 Table 11 Test sequences
These slice sizes were chosen such that the file size (and hence the compression efficiency) Table 12 Varying slice sizes
These slice sizes were chosen such that the file size (and hence the compression efficiency) Table 12 Varying slice sizes
Sizes of 500-frame sequences (percentage of 20 20 20 sequence) Figure 53 Relative sizes of encoded sequences
Sizes of 500-frame sequences (percentage of 20 20 20 sequence) Figure 53 Relative sizes of encoded sequences
The re-animated 20_20_20 sequence showed a number of obvious, large disturbances Table 13 Improvement in PSNR due to varying slice size
The re-animated 20_20_20 sequence showed a number of obvious, large disturbances Table 13 Improvement in PSNR due to varying slice size
Figure 54 PSNR, 5 in 10° bit errors
Figure 54 PSNR, 5 in 10° bit errors
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