Recovering crashes manually

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If Audacity is not able to shut down properly (for example because the program crashes, or the computer loses power suddenly), unsaved data may be left in Audacity's temporary folder. The instructions below will help you recover that unsaved data in Audacity 1.2.x versions.
Audacity Beta 1.3.2 and later already has automated data recovery built in, which should offer to recover unsaved data when you restart after a crash. For these versions, you only need to use these instructions if automated recovery does not work, ensuring you leave Audacity open until recovery is complete.

Automated recovery will be added to the next stable 1.4.0 version of Audacity.

How to recover unsaved data

When you first launch Audacity 1.2.x after a crash, a dialogue will appear warning you that there are still files in the temporary folder. These files are 1 MB "blockfiles" with an .au extension. Audacity will ask if you want to delete these files. Say "No."

If you were editing an existing project, the data is in the project's _data folder and this dialogue will not appear. If you still have the .aup project file, open it and you will return to the last saved state of the project. If you don't have the project file, you must recover the .au files by one of the methods below.

Next, check the Directories tab of Audacity preferences to find out where your temporary folder is.

On Mac computers, the temporary folder is usually hidden in the Finder. To access it, use the "Go To Folder" command in the Finder, or type open tmp/ and insert the name of the folder after the / . If that doesn't work, try to make the Finder show its hidden files and folders by entering in the terminal:
defaults write AppleShowAllFiles -bool
or try TinkerTool  to do the same thing.

Manual recovery

Once you have located Audacity's temporary folder, use the "Import Audio" command in the Project to open all of the .au files in Audacity's temporary folder. Use shift-click or control-click to select multiple files. The files will be in approximately 10-second chunks and will be on separate tracks in the Audacity screen. Files from stereo tracks will alternate between left and right channels.

  1. Click in the track panel (by the Mute/Solo buttons) of the first track you want to join to the topmost track and click Edit > Cut.
  2. Click after the end of the topmost track
  3. Click Edit > Paste and the cut track will attach to the end of the topmost track.
  4. Repeat as necessary to join all the tracks onto the topmost track.

Automatic recovery tools

A few tools have been written which can automate data recovery.

Note: all these utilities require the .au files to be input in consecutive number order. This should normally be the case if recovering data from Audacity 1.2.x. If you have to recover data from 1.3.x, the files will not be in consecutive number order and they will need to be made such.

If the files need to be renumbered for any reason, open Audacity's temporary folder in your system File Manager (such as Windows Explorer). Resort the .au files by time modified and then rename them using a numeric sequence whilst they are sorted by time modified. An arrangement looking something like this should work: 15:56:02 15:56:02 15:56:10 15:56:10

If your file manager does not have a suitable renaming tool, you should be able to obtain suitable free tools on the internet such as Flexible Renamer  for Windows.

Also note there is a 2 GB maximum size for any WAV file created from the reconstructed temporary files and there may be errors if this size is exceeded. This implies an upper limit of 2000 .au files. Sometimes (probably due to bugs in the utilities) there can be errors before this limit is reached. In that case you would need to split the .au files in the temporary or_data folder into two or more groups, each containing consecutively numbered files, and recover each group separately.

Audacity Recovery Utility

The Audacity Recovery Utility  was written by an Audacity developer to automate crash recovery. For Windows systems, follow the instructions given on the above page. On Mac and Linux, you may need to install additional libraries before you can use the utility, following the instructions given for Linux. For Mac systems, the easiest way is to use the following utilities instead which are ready-compiled with the necessary libraries:

Then follow the instructions on Audacity Recovery Utility  from "About the Audacity Recovery Utility" onwards.

Aud_Recover command-line recovery utility

This is a portable command line program by Tyler Knott which does much the same as the Audacity Recovery Utility but is not written in python/ wxpython, so does not need those libraries in order to compile it. Due to limitations in the C standard library this program cannot create files larger than 2 GB.

You can download aud_recover version 1.1.1 here . This download contains binaries for Windows (32-bit) and the cross-platform C source code.

To recover files using this program:

  1. Find the first and last files in the recording by listening to them (if you've only done one recording then that should be the first and the last files in the directory).
  2. Place the aud_recover program in your Audacity temp directory
  3. aud_recover requires several settings to run. You can either enter them as command-line options (use --help for more infmormation) or interactively by simply running the program.
  4. aud_recover will generate one or more files (depending on how many channels of audio you recorded, usually one or two for mono and stereo). You need to import these into Audacity using the Import Raw Data option. To configure the dialog, follow these directions:
    • You can determine the sample format (the first drop-down) and the endianness (the second) using the included auinfo utility.
    • The header offset should be zero and the amount to import should be 100%. No matter how many channels were recorded you should keep it set to 1 (see the next numbered step).
    • The sample rate should be set to the sample rate you recorded at (the sample rate given by auinfo is always 44100, even if that is incorrect, due to a bug in Audacity).
    • Repeat this step for every output file.
  5. For stereo files set the left channel to left, the right channel to right, then select "Make Stereo Track" from the track popdown menu to convert it to a stereo track.

The resulting track should be exactly what was recorded before Audacity crashed.

If you have any questions, comments, or bug reports please don't hesitate to email me  (tknott _at_gmail_dot_com).

Other Tools

This freeware tool can automatically join large numbers of files. (Note: One Audacity user reported an audible noise at the places where the files were joined.)

  • tail and cat (On Linux/UNIX systems)
   - I found that 123 AV Merger gave me exactly what I would get with cat.
   I  was able to get around this with the following procedure:
   1. I had to throw out all odd-numbered files (1,3,5...)
   2. Using tail's byte-count switch "-c" I copied each remaining .au to a new .au.tmp file
   3. Using cat I  ran all the .au.tmp files into on long .au
   4. Imported the final .au with "Import RAW Data"
   5. Exported the track as wav
   I played around with exactly how many bytes to tail until there was no longer any sharp noises at each joint. I don't have that number with me right now - I'll try to get it later.

This could be theoretically written into a script. I'll try to add more details later.

<a href="">sox</a> can concatenate the files together.

Usage: sox file1 .. filen outfile

(Sox can handle up to 32 files at a time.)

e.g. for a mono recording:

  % sox b0000*.au b0001*.au b0002*.au

After I'm done, I have just several au files to import (a lot fewer than before).

I created a hard-link backup of a directory full of 256 files named etc. with names that did not correspond to modification times, then used sox:

  % cp -la d00 d00.bak
  % cd d00
  % mv `ls --full-time e*.au|sort|head -n1|cut -d ' ' -f 9`
  % counter=0; while [ `ls e*.au|head -n1` ]; do sox ${counter}.au `ls --full-time e*.au|sort|head -n30|cut -d ' ' -f 9` $[counter+1].au; rm -f `ls --full-time e*.au|sort|head -n30|cut -d ' ' -f 9` ${counter}.au; let counter=$[counter+1]; done

When the operation was completed, I moved the resulting .au file to the next directory full of files (d01 in this case) and renamed it to, then ran again:

  % counter=0
  % while [ `ls e*.au|head -n1` ]; do
  >sox ${counter}.au `ls --full-time e*.au|sort|head -n30|cut -d ' ' -f 9` $[counter+1].au
  >rm -f `ls --full-time e*.au|sort|head -n30|cut -d ' ' -f 9` ${counter}.au
  >let counter=$[counter+1]

rinsed & repeated for 4 directories with a total of 1.2GB

--- I found it easier to write the following Python script that I used under Mac OS X to recover 1.2GB of data. It was easier than the above solutions.

% cat

# python script to recover audacity recording after crash

import os

directory = raw_input('Enter directory where temp data files are: ')

rawfiles = os.listdir(directory)  # grab directory listing

files = []           # only interested in .au files and
for i in rawfiles:   # prepend each with the directory name
   if i[-3:] == '.au': files.append(directory+'/'+i)

files.sort()  # sort files so the result will be in proper sequence

# open the output file for the recovery
fp = open('','wb')

# write the whole first file because it has the header
dd = open(files[0],'rb').read()

# for every other file, write from the data offset on
for i in files[1:]:
   dd = open(i, 'rb').read()[12380:]

# close recovered sound file

I had problems using the above script. I found that it didn't really write every other file, so if you try to recovery stereo recordings you get a nasty echo effect since every other file is the left or right channel.

The problem with the script above is that you coded the slice wrong:

>>> x=(1,2,3,4,5,6,7,8,9,10)  # sample data
>>> x[1:]                     # doesn't do what you wanted
(2, 3, 4, 5, 6, 7, 8, 9, 10)
>>> x[::2]                    # this gets the odd-numbered items
(1, 3, 5, 7, 9)
>>> x[1::2]                   # this gets the even-numbered ones
(2, 4, 6, 8, 10)

So, you just need to change the line "for i in files[1:]:" to either "for i in files[::2]:" (for the first channel), or "for i in files[1::2]:" (for the other).

I wrote this modified version of the script to try to put the two tracks into two recovery files. Unfortunately, just importing the recovered files doesn't seem to give you perfect stereo again because of sync issues, possibly due to missing files in the recovery set. Give it a shot, it might work for you.

# python script to recover audacity recording after crash

import os

directory = raw_input('Enter directory where temp data files are: ')

rawfiles = os.listdir(directory)  # grab directory listing

files = []           # only interested in .au files and
for i in rawfiles:   # prepend each with the directory name
   if i[-3:] == '.au': files.append(directory+'/'+i)

files.sort()  # sort files so the result will be in proper sequence

# open the output file for the recovery
fp = open('','wb')

# write the whole first file because it has the header
dd = open(files[0],'rb').read()

#this is intented for recoverying stereo and the second file should be the
# first part of the second track, so write the whole file.

fpp = open('','wb')
# write the whole second file because it has the header for track 2
dd = open(files[1],'rb').read()

#it's stereo, so the .au files should alternate left & right channels, so files
#should be written to our two recovery files alternately starting with the 3rd file in our list

#count serves as a quick hack to let us alternate recovery files
count = 1
#this is just to give a quick count so you can see if the two recovery files got the same number of files added to them
track_one_files = 1
track_two_files = 1
# for every other file, write from the data offset on
for i in files[2:]:
   	if count == 1:
		#write to first recovery file
   		dd = open(i, 'rb').read()[12380:]
   		count = 0
		track_one_files = track_one_files + 1
		#write to second recovery file
		dd = open(i, 'rb').read()[12380:]
		count = 1
		track_two_files = track_two_files + 1

print "Files recovered for track 1:"
print track_one_files
print "Files recovered for track 2:"
print track_two_files
# close recovered sound files

I was unable to get sox to work as the above tip instructed. Sox always complained about a missing operation or misinterpreted the filename of one of the Audacity temp files as a filter to perform on the other files.

So, I used sox in a different way. I was trying to rescue an hour-long mono recording on a Unix-like system (a Fedora Core 3 GNU/Linux system). First, I made a copy of the temp directory and its files:

$ cp -r /tmp/audacity1.2-jbn ~/rescue

Then I used sox to convert the AU temp files into raw files (headerless files). Since Audacity had already numbered the files with leading zeroes (and perhaps because I didn't have that many of them to work on), I could use an ordinary shell wildcard to do the work:

$ for f in b*.au ; do sox ${f} -t raw ${f}.raw ; done

I concatenated the raw files together to make one hour-long mono raw file. I had to use raw files to do this, concatenating the AU files together (each with its own header) would have produced a periodic noise (because Audacity was trying to interpret the AU header data as sound data).

$ cat *.raw > bigfile.raw

And then I imported the raw file into Audacity specifying the appropriate number and signedness of the samples (16-bit signed PCM, in my case), endianness (Big-endian, in my case), channels (1 channel for mono), and sample rate (44,100 samples per second, in my case). I wanted to import the whole file (100%) starting from the beginning (0 byte offset).

I was left with a file I could export to WAV, play, and edit normally. 1

I recently have to kill audacity and as a result I lost the aup project file for my recording of 3000+ au files. What exactly should I do to restore the aup project file from the thousands au files?

i tried to add the .au files to a winamp playlist ordered by date (ascending) then save the output as a wav file this solved my problem. i hope it will help yours. (My project was a recording project so the order of files were easily understood)

I also had success with the winamp method using the write to disk output utility. Didn't work for me until I first converted each individual .au into .wav files then converted all the .wav files into a single .wav file.