Okay, to summarize:
  1. The mp3 spec does not inherently provide a facility to make songs gapless. They must be of particular (although variable) lengths, and ending at an arbitrary point is impossible.
  2. Due to some other technical issues with the mp3 spec, it's possible that there might also be leading silence introduced when an audio file is encoded.
  3. The id3v2 tagging spec provides a facility to ``mark'' these erroneous silent segments at the beginning and end. An mp3 player that understood these marks could notice them and edit them out. Currently, no known mp3 player does so.
  4. Also, inserting those id3v2 marks might be non-trivial to the point of requiring human intervention. Then again, it might be possible for a ripper or encoder to do it automatically. Regardless, the point is again moot, as no current ripper or encoder does.
  5. It is feasible that a quick crossfade architecture in an mp3 player could make two mp3 files seem gapless. WinAMP has such a facility, and reviews are mixed.
  6. The mp3 encoder LAME provides a ``nogap'' option when encoding. It apparently slightly modifies the beginning and ending points of the tracks given to it so that they fit the natural mp3 break points. By all accounts, this works perfectly when encoded in either CBR or VBR mode. However, it does not write a VBR header when encoding to VBR mode, which causes the empeg player to not be able to calculate absolute positions properly, which makes internal FFs and REWs nearly impossible.
  7. The current version of LAME has a bug that writes incorrect VBR headers all the time (that is, nogapped or not -- in fact, you have to hack VBR header support for nogapped encoding into current LAME builds; it had been disabled to fix this problem, due to a misdiagnosis on the LAME developers' part based on this unnoticed bug), which makes many players fail to play the final mp3 frame. At least one VBR header fix program also deletes the final frame when trying to fix it. Not hearing the final frame of one mp3 before playing the next sounds very similar to the standard mp3 gap when the two are meant to flow into each other, and is essentially unnoticeable when they're not. The VBR header bug in LAME should be fixed in current development sources.
  8. The empeg player software also has a bug that introduces a gap, apparently when it sees a VBR header, even if it's correct. This bug is also reported to have been fixed in current builds, but there's been no independent verification.
  9. Ogg Vorbis does not have a gapping problem at all.
Edit: Fixed major problems.

Edit again: One. More. Time.

Edit trifecta: Once again


Edited by wfaulk (21/02/2003 20:30)
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Bitt Faulk