[Python] Encoding ac and dc cofficients in jpeg compression after zigzag ordering

I'm trying to implement JPEG compression in python and so far I have done the following steps

• Color Space conversion
• Downscaling chrominance channels
• 8x8 block splitting ( adds padding if size is not perfect )
• DCT
• Quantization
• ZigZag Ordering
• runlength encoding on ac coefficients, transformed into (RUNLENGTH, SIZE)(AMPLITUDE) pattern

e.g [(0, 2), -2, (4, 1), 1, (0, 0)]

• DPCM on dc cofficients

I'm a lil confused about 2 things. how should I encode the dc coefficients before Huffman encoding. Is there a specific pattern just like ac coefficients?

After encoding dc coefficients are stored in their respective blocks ?

[dc],[ac_value],....

or all dc values are stored separately and Huffman encoded separately

[dc value,...]

[ac values,...]

I read that fixed huffman tables are used by most encoders. Where exactly can I find the fixed standard huffman tables. I'm not sure if I am missing any crucial steps so far?

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