How to divide file into several files using python

Question

I have a video file and i need to divide it into several smaller files of size 256KB and save all files names in a text file then i need to read all the small files and merges them into the original file.

is this possible to do it in python and how ?

It is possible with Python, but there exist programs that already do that for you: split and cat — Andrea Corbellini
– Andrea Corbellini, Commented Oct 8, 2016 at 15:47
Do the small files need to be readable as video? If you just split the big file into chunks, they won't be. — John Gordon
– John Gordon, Commented Oct 8, 2016 at 15:48
@AndreaCorbellini Thank you for your reply. I know about that but i need to do it using python. — Mahmoud Al-Nafei
– Mahmoud Al-Nafei, Commented Oct 8, 2016 at 15:50
@JohnGordon No, i don't need the small files to be readable as video. i just need to split the big file into several files of size 256KB . — Mahmoud Al-Nafei
– Mahmoud Al-Nafei, Commented Oct 8, 2016 at 15:52

wildwilhelm · Accepted Answer · 2016-10-08 16:31:20Z

2

First stab at splitting:

input_file = open(input_filename, 'rb')
blocksize = 4096
chunksize = 1024 * 256
buf = None
chunk_num = 0
current_read = 0
output_filename = 'output-chunk-{:04d}'.format(chunk_num)
output_file = open(output_filename, 'wb')
while buf is None or len(buf) > 0:
    buf = input_file.read(blocksize)
    current_read += len(buf)
    output_file.write(buf)
    if chunksize <= current_read:
        output_file.close()
        current_read = 0
        chunk_num += 1
        output_filename = 'output-chunk-{:04d}'.format(chunk_num)
        output_file = open(output_filename, 'wb')
output_file.close()
input_file.close()

This might get you partway there; adapt as needed.

Merging:

blocksize = 4096
chunk_num = 0
input_filename = 'output-chunk-{:04d}'.format(chunk_num)
output_filename = 'reconstructed.bin'
output_file = open(output_filename, 'wb')
while True:
    try:
        input_file = open(input_filename, 'rb')
    except IOError:
        break
    buf = None
    while buf is None or len(buf) > 0:
        buf = input_file.read(blocksize)
        output_file.write(buf)
    input_file.close()
    chunk_num += 1
    input_filename = 'output-chunk-{:04d}'.format(chunk_num)
output_file.close()

edited Oct 8, 2016 at 16:31

answered Oct 8, 2016 at 16:08

wildwilhelm

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5 Comments

Mahmoud Al-Nafei Over a year ago

Thank you for your answer and it's work great but how i can read all files and merges them into the original file?

wildwilhelm Over a year ago

Um, cat output-chunk-* > reconstructed.bin.

Mahmoud Al-Nafei Over a year ago

sorry i can't understand your comment! How i can merges them using python?

wildwilhelm Over a year ago

Apologies, I didn't fully read your question. My comment was echoing the sentiment from @AndreaCorbellini which is don't do splitting and merging in python if you can help it. There's well-developed tools out there that will do the job for you; don't reinvent the wheel.

Mahmoud Al-Nafei Over a year ago

it's ok. Now i have the full answer. Thank you a lot for helping me.

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