[Vorbis-dev] Reg. getting codewords from codelengths

[Dominik Kuhlen]

Hi
On Monday 08 August 2005 18:08, Shashank Khanvilkar wrote:
> Hi,
> I am a bit confused on how code-words are derived from the codeword
> lengths. I will appreciate if someone can point me in the correct
> direction.
>
> I will take the example of an actual codebook that i found in a valid
> vorbis encoded file as shown below.
>
> [SK] +------Codebook [0] --------
> [SK] Codebook Dimensions = 1
> [SK] Codebook Entries = 8
> [SK] Unordered
> [SK] 1, 6, 3, 7, 2, 5, 4, 7,
> [SK] NO Mapping
> [SK] +------Codebook [1] --------
>
> What are the correspnding codewords? I have written below a few, but I
> think they might be wrong.
>
> ---------------------------
> Entry len   |    Codeword |
> ---------------------------
> 1           |  0
> 6           |  100000
> 3           |  000
> 7           |  10000000
> 2           |
> 5           |
> 4           |
> 7           |
If you have access to graphviz / dot you may try
dot -Tpng < foo.dot > foo.png
This is what my decoder has created.
Heres the debug output:
Node 0x804b050 @ 1 : Left = 0
Node 0x804b050 @ 1 : right subnode : 0x804b060
Node 0x804b060 @ 2 : left subnode : 0x804b070
Node 0x804b070 @ 3 : left subnode : 0x804b080
Node 0x804b080 @ 4 : left subnode : 0x804b090
Node 0x804b090 @ 5 : left subnode : 0x804b0a0
Node 0x804b0a0 @ 6 : Left = 1
Node 0x804b0a0 @ 6 : right subnode : 0x804b0b0
Node 0x804b0b0 @ 7 : Left = 3
Node 0x804b0b0 @ 7 : Right = 7
Node 0x804b090 @ 5 : Right = 5
Node 0x804b080 @ 4 : Right = 6
Node 0x804b070 @ 3 : Right = 2
Node 0x804b060 @ 2 : Right = 4

>
> Shank
>
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Dominik
-------------- next part --------------
/* Warning! This file has been created automagically by huffmantree.cpp */
digraph Codebook {
node [shape = record, height = 0.1];
node0[label = "<f0> 0 | <f1> | <f2> 1"];
node1 [shape = ellipse, label = "0"];
node0:f0 -> node1;
node2[label = "<f0> 0 | <f1> | <f2> 1"];
node3[label = "<f0> 0 | <f1> | <f2> 1"];
node4[label = "<f0> 0 | <f1> | <f2> 1"];
node5[label = "<f0> 0 | <f1> | <f2> 1"];
node6[label = "<f0> 0 | <f1> | <f2> 1"];
node7 [shape = ellipse, label = "1"];
node6:f0 -> node7;
node8[label = "<f0> 0 | <f1> | <f2> 1"];
node9 [shape = ellipse, label = "3"];
node8:f0 -> node9;
node10 [shape = ellipse, label = "7"];
node8:f2 -> node10;
node6:f2 -> node8:f1
node5:f0 -> node6:f1
node11 [shape = ellipse, label = "5"];
node5:f2 -> node11;
node4:f0 -> node5:f1
node12 [shape = ellipse, label = "6"];
node4:f2 -> node12;
node3:f0 -> node4:f1
node13 [shape = ellipse, label = "2"];
node3:f2 -> node13;
node2:f0 -> node3:f1
node14 [shape = ellipse, label = "4"];
node2:f2 -> node14;
node0:f2 -> node2:f1
}