从jpegsnoop解码Huffman AC桌子

发布于 2025-02-11 14:19:23 字数 1813 浏览 2 评论 0原文

我有一个AC Huffman表,如下所示:

Destination ID = 1
  Class = 1 (AC Table)
    Codes of length 01 bits (000 total): 
    Codes of length 02 bits (002 total): 00 01 
    Codes of length 03 bits (001 total): 02 
    Codes of length 04 bits (002 total): 03 11 
    Codes of length 05 bits (004 total): 04 05 21 31 
    Codes of length 06 bits (004 total): 06 12 41 51 
    Codes of length 07 bits (003 total): 07 61 71 
    Codes of length 08 bits (004 total): 13 22 32 81 
    Codes of length 09 bits (007 total): 08 14 42 91 A1 B1 C1 
    Codes of length 10 bits (005 total): 09 23 33 52 F0 
    Codes of length 11 bits (004 total): 15 62 72 D1 
    Codes of length 12 bits (004 total): 0A 16 24 34 
    Codes of length 13 bits (000 total): 
    Codes of length 14 bits (001 total): E1 
    Codes of length 15 bits (002 total): 25 F1 
    Codes of length 16 bits (119 total): 17 18 19 1A 26 27 28 29 2A 35 36 37 38 39 3A 43 
                                         44 45 46 47 48 49 4A 53 54 55 56 57 58 59 5A 63 
                                         64 65 66 67 68 69 6A 73 74 75 76 77 78 79 7A 82 
                                         83 84 85 86 87 88 89 8A 92 93 94 95 96 97 98 99 
                                         9A A2 A3 A4 A5 A6 A7 A8 A9 AA B2 B3 B4 B5 B6 B7 
                                         B8 B9 BA C2 C3 C4 C5 C6 C7 C8 C9 CA D2 D3 D4 D5 
                                         D6 D7 D8 D9 DA E2 E3 E4 E5 E6 E7 E8 E9 EA F2 F3 
                                         F4 F5 F6 F7 F8 F9 FA 
    Total number of codes: 162

我需要从此表中找到 mincode maxcode valptr 值。显然,解码过程与DC表不相似。

以下答案从DC表中解释了这些值的检索:

答案

I have an AC Huffman table generated as follows:

Destination ID = 1
  Class = 1 (AC Table)
    Codes of length 01 bits (000 total): 
    Codes of length 02 bits (002 total): 00 01 
    Codes of length 03 bits (001 total): 02 
    Codes of length 04 bits (002 total): 03 11 
    Codes of length 05 bits (004 total): 04 05 21 31 
    Codes of length 06 bits (004 total): 06 12 41 51 
    Codes of length 07 bits (003 total): 07 61 71 
    Codes of length 08 bits (004 total): 13 22 32 81 
    Codes of length 09 bits (007 total): 08 14 42 91 A1 B1 C1 
    Codes of length 10 bits (005 total): 09 23 33 52 F0 
    Codes of length 11 bits (004 total): 15 62 72 D1 
    Codes of length 12 bits (004 total): 0A 16 24 34 
    Codes of length 13 bits (000 total): 
    Codes of length 14 bits (001 total): E1 
    Codes of length 15 bits (002 total): 25 F1 
    Codes of length 16 bits (119 total): 17 18 19 1A 26 27 28 29 2A 35 36 37 38 39 3A 43 
                                         44 45 46 47 48 49 4A 53 54 55 56 57 58 59 5A 63 
                                         64 65 66 67 68 69 6A 73 74 75 76 77 78 79 7A 82 
                                         83 84 85 86 87 88 89 8A 92 93 94 95 96 97 98 99 
                                         9A A2 A3 A4 A5 A6 A7 A8 A9 AA B2 B3 B4 B5 B6 B7 
                                         B8 B9 BA C2 C3 C4 C5 C6 C7 C8 C9 CA D2 D3 D4 D5 
                                         D6 D7 D8 D9 DA E2 E3 E4 E5 E6 E7 E8 E9 EA F2 F3 
                                         F4 F5 F6 F7 F8 F9 FA 
    Total number of codes: 162

I need to find the Mincode, Maxcode and Valptr values from this table. Apparently the decode procedure is not similar to the one of the DC table.

The following answer explains the retrieval of these values from a DC table:

answer

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So要识趣 2025-02-18 14:19:23

对于AC和DC系数,这些表的产生和八位值的Huffman解码完全相同。您的与结果八位值的值不同。

The generation of those tables and the Huffman decoding of the eight-bit value is exactly the same for AC and DC coefficients. What you do with the resulting eight-bit values is different.

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