HydrogenAudio

Hydrogenaudio Forum => Listening Tests => Topic started by: matth6546 on 2004-10-27 02:00:42

Title: itunes added samples? please help
Post by: matth6546 on 2004-10-27 02:00:42
ok, i just ABXed Megadeth - Good Mourning/Black Friday (remaster) with foobar. i converted the original wav once with foobar, using nero aac @ 192kbps CBR and once with itunes 4.7.042 (just came out) @ 192kbps CBR. i couldn't tell the difference between the two with ABX, so i checked their properties to find a difference.

here's what i found:
wav
length: 6:39.773
samples: 17,630,004

foobar
length: 6:39.773
samples: 17,630,004
size: 9,720,300 bytes

itunes
length: 6:39.801
samples: 17,631,232
size: 9,751,127

maybe this is a normal thing, but the itunes converted file has more samples than the original file and has a slightly longer duration. i found this odd because it looks like itunes added something to the file. is this normal or did i just make a 'discovery'?
Title: itunes added samples? please help
Post by: rjamorim on 2004-10-27 02:11:05
Quote
maybe this is a normal thing, but the itunes converted file has more samples than the original file and has a slightly longer duration. i found this odd because it looks like itunes added something to the file. is this normal or did i just make a 'discovery'?
[a href="index.php?act=findpost&pid=250266"][{POST_SNAPBACK}][/a]


It is normal. iTunes AAC isn't gapless. Those added samples are the gap introduced because AAC is a block-based codec (blocks have a fixed size, so often at the end of the track it's padded with zeros to complete the data needed to create a block) and iTunes doesn't compensate for that, unlike MPC and Vorbis.
Title: itunes added samples? please help
Post by: matth6546 on 2004-10-27 14:33:54
i see. thanks.