Okay, now that you've burned a Compact Disc Digital Audio (CDDA) - why doesn't it sound good? We have to begin with how the information is recorded to understand how it can go wrong.
There is a directory of sorts on each CDDA which identifies and locates the individual tracks. A track is located by its starting block and its length. There are about 330,000 blocks of 2K each on a standard blank; each one represents somewhat more than 10 milliseconds of sound. If you start a CD without specifying a track, it begins to play at the first byte of the first block and keeps on playing through to the last. There is no information on the track about the track - for that reason, it is not a 'file'. It's just a sequence of bytes.
If you write a track to the disc that is not an integer number of blocks, there are bytes to be written which don't come from your source (WAV) file. Most modern WAV editors will fix that by making sure that the number of bytes is a multiple of the block size (2K). If yours does not, there will be a click at the track transition for the random bytes that fill the last block. Solution: break the tracks on block boundary using appropriate software. (CDWAV from Mike Looijmans is linked from this site. It will split a long track into short ones on block boundaries.)
If you write a disc using Track at Once (TAO), the laser is turned off between tracks. When it is turned on, it writes a gap of two seconds before the start of the next track - that is dictated by the standard but there is software which allows you to violate the standard. You can also avoid that gap by recording in DAO - Disc at Once - where the laser burns continuously through the full set of tracks. Not all CD-R's support DAO, some do not support it well, and some which do support it are not implemented for DAO by some software. In general, if you have DAO problems, check the software from Goldenhawk; it does whatever can be done along those lines on any hardware yet manufactured. Or if you are really hard up, check the DAO page in this primer.
That covers getting a WAV file onto the CD-R in good shape. How about creating the WAV file or copying directly (on the fly) from a source disc? If you are having problems copying on the fly, first extract the files to your hard drive as WAVs and check them there. If the files sound bad, the problem is in your reader, not in your writer. (If you have problems with the last tracks of a CD, don't judge by extracting only the first ones.) You should look at the extracted files in a WAV editor to see if there are sharp spikes which you might not hear easily - they are the clicks and pops. In that case, please turn the 'page' in this primer and go to Snap, Crackle and Pop. Then you can get into the really complicated parts by reading about the complexity of WAV Files.
The CD writer needs a continuous supply of data. If something interrupts that flow for a significant time, the buffers can empty and underrun. If the interruption is shorter, a buffer - particularly that in the reader - may not cause an immediate underrun but may supply either zeroes or a repeat of the last information. In that case, you get a silence (zeroes) or a repeat lasting a fraction of a second.
Of course, the right way to fix such a problem is to ensure that the buffers do not empty. If you are writing on the fly from a reader, check the lights for regular operation. If you see a significant inactivity, then a burst you may have spun down (typically, between tracks) and if spinup is not fast enough the flow is interrupted. Another cause is a slightly damaged source disc which must be reread on the fly. If the problem arises when writing from the HD (very rare, indeed), then something is interrupting HD access and you should check for the usual villains: FastFind, anti-virus monitoring or another concurrent program.
If the problem occurs when writing on the fly and you have no remedy for the cause, extract the files to the HD and burn from there.
E-mail me at cdrecording@mrichter.com
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