Aup3 and blockfiles

freddyjohn via audacity-devel <[email protected]>
Newsgroups gmane.comp.audio.audacity.devel
Message-ID <Ms1npsGlWcktUr1tKARabdUyVhwQLpAF6tEnCf9BJkLnK6p6_c5Y0yygjweogfnNoWX44sWSEBfT5Zsd6F32D4xQYznVX6xhyuvKUvmoZYs=@protonmail.com>
Hello, I am writing an application similar to audacity for android. I am currently working on the data structure to support editing. I was studying the old format with what I think was B-tree inside xml doc until I read the articles about 3.0 yesterday. It is a lot easier to reverse. But one thing I ask out of Curiosity, what is with the encoding for the block files? It looks like the samples are aligned in some pattern. If you drop the output of these files into HxD for example.It’s like this with spacing increasing linearly

s1.s2
s100..s101
s200...s201
If you unpack these bytes as 32 bit float and graph the samples it looks like audio data. But if I multiply each sample by 32767 and throw on a wav header it sounds like the bytes are offset(very horrible noise you don’t want to be familiar with). So is there more going on in a blockfile than just raw audio data? If so why?

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get.py (application/octet-stream, 367 B)
import sqlite3

db=sqlite3.connect("three.aup3")
cur = db.cursor()
num_blocks=len(cur.execute("SELECT blockid FROM sampleblocks").fetchall())


for i in range(1,num_blocks+1):
  block_bytes=cur.execute('SELECT samples FROM sampleblocks WHERE blockid = '+ str(i)).fetchall()[0][0]
  open(str(i),'x')
  with open(str(i),'wb') as f:
    f.write(block_bytes)
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