Huffman Encoding

Once you have the code table, encoding is just table lookup + bit packing:

Two practical concerns:

Bit packing: codes are bit-strings of varying length, but storage is in 8-bit bytes. Pack with a shift register:

Codebook storage: the decoder needs the same code table. Three options:

1. Static table (pre-agreed for the data type, e.g., JPEG uses fixed tables)
2. Stored in the file header (the tree, or just the frequencies)
3. Adaptive (encoder + decoder both update the tree as they go — no need to store)

For this lesson we just emit the bit string (no header, no packing yet). The decoder lessons cover packing.