Fixing Non DAO CD's

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I will show you how to fix non DAO CD's. Let's say you get a CD in a trade and it is not a clean disc-at-once (DAO) disc. When it is clean, the sound will move cleanly from one track to the next. This is especially important in live concert discs. A track-at-once (TAO) disc will have a 2-second gap between tracks. This can be very annoying in the middle of a jam (ie. the band is still playing and goes from one song to the next.) It can also be irritating when the sound goes from the background noise of the crowd to absolute silence for two seconds and then back to crowd noise. Another glitch that can creeep in is the click between tracks. This is sometimes the result of a disc being created from MP3's and not having it done properly. Fixing this can be easy.

To do this you will need:

The general strategy is to copy the disc to the hard drive, use the software tools to fix the wave files and then to reburn it to a new disc.

The first thing to do is determine what the flaw is in the disc you want to repair. If you have a TAO disc, you will hear a two second gap between each track. If you have a DAO disc, the problem may be that it has clicks between tracks. Listen to the disc to determine the problem.

The first step is to copy the disc. I recommend that you use Exact Audio Copy (EAC). It is free and works extermely well. Get it here. If you are fixing a TAO disc, you will want to use EAC to eliminate the two second gaps. To eliminate these gaps, select all of the tracks and then click Action|Detect Gaps. This will check each track and fill in the Pre-Gap column for that track. Each one should say that it has a gap of 2 seconds. Then click Action|Leave Out Gaps. Now, select all of the tracks and copy them to the hard drive. Be aware that each time a disc is inserted into the drive, its pre-gaps are unknown and EAC will not leave out the gaps if you don't detect them. If your disc was already DAO, just select and copy the tracks.

The next step is to edit the wave files to eliminate any clicking at track boundaries. If you are fixing a TAO disc, you should test your gap-less wave files to decide if this step is necessary. To do so, make a temporary file, that joins two consecutive tracks together using an append operation. Then listen to the join area. It should sound clean. There should be no clicks. Check this for all of the track boundaries (or as many as it takes to be convinced that they are fine. Usually, either all have a click or none will.) If there are no defects proceed to writing.

To edit the wave files, do the following. Cut off the first and last 5 seconds of every track and save these pieces to files. Now listen to these pieces. See if there is a click within the pieces. I t can be one of three things (usually the same for all junctions): click in the end of the track, click in the beginning or the click only occurs when playing the joined version. If you can find the click (beginning or end) then just cut it out and discard it. If not, then the click is caused by small amounts of silence between the tracks and the transition causes the click. In this case, cut off and discard the last sector (1/75 of a second). Once you have cut out the ugly parts, you must rejoin the parts.

At any cut, if you just put the edges back together, you will hear an abrupt cut. To fix this, you perform a fade and mix join. To do this, at any edge that will be joined cut off and save the end sector of the first part and the beginning sector of the last part. Then fade out the end sector and fade in the beginning sector. After that, mix the two together to form one sector. This sector can be appended to the first part or prepended to the last part. Now when the join is made, the sound of one fades out quickly as the sound of the other fades in over it. Done over a sector's length, you can't hear the fade but the cut is not noticeable, especially when done over similar volumed and pitched areas.

After the gaps and everything have been removed, double check all of your files by making temporaries that have the files joined together. Listen at the joins. If there is something wrong repeat the editing steps to correct it. Then go about burning your CD, making sure that your have selected DAO.

GOOD LUCK!

If you have any questions, compliments, complaints or suggestions regarding this page, please email me at danny_pav@hotmail.com.