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Bộ môn truyền thông và mạng máy tính
Bài tập lớn môn học
Truyền thông đa phương tiện
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CHUẨN MPEG 1 và MPEG 2
Tổng quan về MPEG
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gF#xZ*R.U`-fJ*5,/q,=Uƒ-&W-/<\c"Preprocessing 2-K
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1.2.1. Các kiểu khung hình trong MPEG 1
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1.2.2. Motion compensation
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2.2.4. Mã hóa trong Mpeg 1
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2
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Hình 6 Mã hóa Macroblock
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Hình 7 SCRs
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MPEG 2
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p-3./-`J-z0-O-3&'Kp143^2x‚;6O-3&'KpQ^Jrc/,
2‚;6O†
1.3. Sơ đồ nén và giải nén của MPEG 2
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Hình 8 Sơ đồ mã hóa
Hình 9 Sơ đồ giải mã
r
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1.4. Các kĩ thuật nén của MPEG 2
1.4.1. Video filtering
+*Uƒ-&W-g-•, iQlc1 -z,UL,k,//US
1,/3\Z/U-31^-„3,1h]r'Z*/LQBdoZe//„3,1h&'S/-3/
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Hình 10 Hai tiêu chuẩn lấy mẫu 4:2:0 và 4:2:2
3
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1.4.2. DCT
Hình 11 Biến đổi DCT
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1.4.3. Lượng tử hóa
Hình 12 Sơ đồ biến đổi DCT
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Hình 13 Một số ví dụ về biến đổi DCT
1.4.4. Mã hóa VLC
Hình 14 Sơ đồ mã hóa VLC
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Hình 15 Blocks trước và sau khi quét Zig-zag
1.4.5. Motion – Compensated Inter – Frame Prediction
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1.4.6. Bit rate control
Hình 16 Bit rate control
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Hình 17 Ba ma trận lượng từ hóa: (a) MQUANT = 2, (b) MQUANT = 4, (c) MQUANT = 6
p-3\l& (-<b&,/q,//0RSZf-o5,URo &—I1G/
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Hình 18 Dung lượng dữ liệu nén ứng với lượng tử hóa của hình 17
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2
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Hình 19 Hai ma trận lượng tử hóa tiêu chuẩn W(u,v) với MQUANT = 2
(a)W(u,v) với độ dốc thoải (b) W(u,v) với độ dốc lớn
Hình 20 Dung lượng dữ liệu nén với ma trận lượng tử hóa trên hình 19
c,J<JJUl1R-b&-3pZf-o5,-3%\Y-U›-&W-
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