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Topic: exact blocklength necessary for burning tracks to cd? (Read 1309 times) previous topic - next topic
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exact blocklength necessary for burning tracks to cd?

I’ve done a fair bit recently with editing some bootleg cd’s that I have.  As is often the case with bootlegs, some of mine don’t have the tracks divided up very well... sometimes two songs will be together in a "medley" (which means that whoever mastered the cd didn’t make a division where one should have been placed) or the cut comes after the beginning of the main track or before the previous track has ended, or in the middle of talking or whatever.  So I rip the cd tracks and use EAC’s Wave Editor program to cut and paste so that the tracks end and start where I’d like them to... sometimes I end up with more tracks than were on the cd, if I make "technical difficulty" portions of the concert and longer talking portions and such into their own clips.  This is all well and good, and is very nice to listen to from the computer using ogg (-q 5.5), seamless playback and each segment of the concert is easily accessible without any seeking.

However, I failed to keep in mind that cd audio is set up in blocks, 75 to a second.  Given the sample rate of 44100 hz, that’s 588 samples per block (44100/75 = 588).  Since I set the track beginnings and endings where it sounded best, I haven’t created tracks with a clean blocklength, meaning the track has a length not cleanly divisible by 588.  With my setup of the following:
burning program - NTI CD-Maker 2000 Plus
burner - BTC 12x8x32
driver - Adaptec 4.60 Aspi
the cd comes out with tracks of a clean blocklength by having silence added to the end of each track to fill up the remainder of each block.  Say a track is made up of 16,556,786 samples = 28,157 blocks and 470 remaining samples that don’t quite fill up the final block.  That’s 6 minutes, 15 seconds, and 19,286 samples of what would be the 16th second.  19,286 samples would be 32 blocks of 1/75 second each, leaving 470 blocks remaining that don’t fill up a block.  When burned to a cd, then, 118 silent samples are added to the end of the track to fill up the tracklength to a clean 6 minutes, 15 seconds, and 33 blocks.

As might be imagined, this slight gap of silence - anywhere between 0 and 587 samples in length - can slightly screw up a live recording, as I can often hear the tiny pause in the live sound, which should be continuous.  Typically, I can’t notice these gaps when they are less than 300 samples in length, but I’d still ideally like for my live cd to be fully continuous.

What I’d like to know is, is there any way to set up the burning program so that the audio information will be continuous despite the input files not being of even blocklength?  That is, might it be possible to set up NTI CD-Maker (or get another burning program which could do this) to round up or down depending on the length of the leftover samples?  That is, if the leftover samples are less than half a blocklength of 294 samples, the beginning of the next track would be placed at the end of the previous clean block, and the remaining samples of the track would be placed at the beginning of the next track, and if the end of a track leaves more 294 or more samples after the last complete block, a final block would be formed from those followed by the necessary number of samples taken from the beginning of the next track...

The only other alternative that I see, if I want cd’s without tiny gaps between tracks, is to laboriously go back through my ripped tracks and cut and past so that the sample length of each track is cleanly divisible by 75.  And that could take a very long time.  And while a year off before grad school without a job affords me a lot of time, I don’t care to do too much busy-work such as would be required to manually round out the blocklength of a lot of wav files.

Any suggestions are appreciated.  Thanks much.
God kills a kitten every time you encode with CBR 320

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