b. Figure 10(b) shows the dB output levels from the first 8 critical sub-bands of an MP3 encoder, at two consecutive ana

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B Figure 10 B Shows The Db Output Levels From The First 8 Critical Sub Bands Of An Mp3 Encoder At Two Consecutive Ana 1 (295.36 KiB) Viewed 116 times

b. Figure 10(b) shows the dB output levels from the first 8 critical sub-bands of an MP3 encoder, at two consecutive analysis frames 25ms apart: MP3 Sub-band Number 1 2 3 4 5 6 7 8 Output Level (dB) at T 15 53 27 10 33 65 38 5 * * 0 12 0 0 0 71 0 0 Output Level (dB) at T +25ms Figure 10(b) During the analysis at time T1, it is found that the output from Band #2 provides 18dB of masking to both Band #1 and Band #3, while that from Band #6 provides 28dB of masking to Band #5, 25dB to Band #7 and 6dB to Band #8. Determine the following: i. Which of the 8 sub-bands will need to be encoded at time T1? Give reasons for each of the 8 sub-bands. (8 marks) ii. For the sub-bands you identified to be encoded in part (i), how many bits per sample must be allocated? (6 marks) iii. Figure 10(b) shows that during the next critical band analysis at time T1 + 25ms, only Band #2 and Band #6 have non-zero outputs. Explain with reasons, including any assumptions you make, whether Band #2 and Band #6 need to be encoded and, if so, how many bits per sample will need to be respectively allocated? (3 marks)