Dump MP4 Atoms Structure

mp4atoms.py

# Emanuele Ruffaldi 2024
import mmap
import json
import os
import struct
import sys

def extract_boxes(mp4_file,offset=0,size=None):
    """
    Parse the MP4 file and extract all boxes.
    """
    size = len(mp4_file) if size is None else size
    loffset = 0
    while size-loffset >= 8:
        box_header = mp4_file[offset:offset+8]
        box_size, box_type = struct.unpack('>I4s', box_header)
        yield offset+8,box_size-8,box_type.decode("latin1")
        offset = offset + box_size
        loffset = loffset + box_size

def dump_mp4(mmapped_file,offset,size,prefix):
    # Add more containers here if needed
    containers = ["moov","udta","trak","edts","mdia","minf","stbl","dinf","gmhd","clip","matt"]
    
    for box_offset,box_size,box_type in extract_boxes(mmapped_file,offset,size):
        if box_type in containers:
            dump_mp4(mmapped_file,box_offset,box_size,prefix + "/" + box_type + "@" + str(box_offset))
        else:
            print(prefix + "/" + box_type,box_offset,box_size)

# Function to parse MP4 and generate an index for H.265 data
def process_mp4(input_file):

    # Memory-map the MP4 file for efficient reading
    with open(input_file, 'rb') as f:
        mmapped_file = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
        
        dump_mp4(mmapped_file,0,len(mmapped_file),"")

process_mp4(sys.argv[1])