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Subject: Broken recordings - repair util (alpha)

Broken recordings - repair util (alpha)

From: Bluechip <csbluechip_at_gmail.com>
Date: 2005-11-07

Hey people,

I have examined a number of files now, and there seem to be any number of
problems with Rockbox recorded files.

# Blocks of unwanted 0's (due to Xing header creation)

# Often a recording starts with (what looks like) the last half of an MP3
audio frame

# Most recordings finish with a short audio frame

# Stray 1's and 0's are inserted by the MAS3587 DAC (early revisions)

I have uploaded a program which attempts to spot all the relevant
information in the recording which is required to automatically fix it.

== The current util does NOT attempt to create a repaired file! ==
...not for any reason other than I haven't had time to do it yet.

You can download the walker here:
http://homepage.ntlworld.com/cyborgsystems/rockbox/walkmp3.exe

If a few people could try this out and let me know if it can walk all your
broken recordings then I will progress to stage 2: "Write the output
file" and then Stage 3: "get carried away with reporting and command line
switches"

The stray 1's and 0's can be stripped harmlessly.
The blocks of 0's can be similarly removed or otherwise rendered harmless
Broken start frames can be removed
Broken end frames can be removed

Each audio frame is 26mS ...so worst case, timeplit recordings will lose
52mS (0.05 seconds) at every split point.

Other then these short frames (which I understand can be fixed within the
Rockbox core code) - every file I have walked to date can be fully repaired.

I will work more on this as-and-when I get a chance during the week - look
forward to your feedback.

Bluechip
Received on Mon Nov 7 05:02:51 2005


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