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Topic: Why are my AAC files padded with small silent areas? (Read 3742 times) previous topic - next topic

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  • happyman
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Why are my AAC files padded with small silent areas?
I hope you'll entertain a newbie's question.

I see about 0.6 seconds of silence in my AAC file before the music actually begins, and about 0.1 seconds of silence at the end of the file. When I play these files on my iPod I hear pauses, and this is annoying because they are trance tracks meant to be played continuously as one set without pauses. I'm not sure if these are called "gaps" or not. I'm a bit confused.

My source are FLACs. I used Audacity to open and compare the same tracks in FLAC vs AAC, and I do see the silent areas in the AAC, while the FLAC has none at all. I'm playing the files on an iPod Nano 4th generation (model = A1285). To convert I'm using Linux + Wine + Foobar2000 v1.3 + neroAacEnc.exe v1.5. To transfer from laptop => iPod I'm using Banshee v2.6.

How can I play my music on my iPod without incurring these silent pauses?
  • Last Edit: 18 February, 2014, 04:25:19 AM by happyman

  • happyman
  • [*]
Why are my AAC files padded with small silent areas?
Reply #1
I think my numbers are one order of magnitude off (0.06 and 0.01) but whatever the values are the point is I can hear the pause and I don't like it

  • AiZ
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Why are my AAC files padded with small silent areas?
Reply #2
Hello,

I don't know if it's related to your problem but have a look at the "Encoder delay" section here.

        AiZ
AiZ stupid homepage - http://aiz.free.fr

  • saratoga
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Why are my AAC files padded with small silent areas?
Reply #3
Something about your software is breaking gapless playback.

  • DVDdoug
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Why are my AAC files padded with small silent areas?
Reply #4
Quote
To convert I'm using Linux + Wine + Foobar2000 v1.3 + neroAacEnc.exe v1.5. To transfer from laptop => iPod I'm using Banshee v2.6.
I'm going to guess that AAC files encoded with iTunes will play gaplessly on your iPod.  (The gaps will still be there

If you can get your hands on a Windows PC or a MAC, it's probably worthwhile experimenting with iTunes.  You'll probably have to convert your FLACs to ALAC or maybe there's a work-around or CODEC that allows iTunes to work with FLAC.

Or, perhaps your existing AAC files sync'ed to your iPod using iTunes will play gaplessly.

  • [JAZ]
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Why are my AAC files padded with small silent areas?
Reply #5
Originally, the nero gapless information and the iTunes gapless information was different. At one point, i think they made them compatible with iTunes, but I don't really remember the details.
So it might simply mean that the gapless information is not recognized because of the encoder used.

  • happyman
  • [*]
Why are my AAC files padded with small silent areas?
Reply #6
Thanks everyone for the great ideas. I'll try all of them out.

Follow-up question: Does neroAacEnc.exe add metadata to the AAC for these padded silent periods so that players would be able to play them gaplessly? If so, how can I verify if my AACs have the right metadata? When viewing the files in Foobar2000 I don't see anything that stands out, just normal album name, title, etc.

  • Aleron Ives
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Why are my AAC files padded with small silent areas?
Reply #7
If you open an AAC file encoded with Nero using Mp3tag and open the Extended Tags dialogue, you should see one of the tags listed as ITUNSMPB, which contains several hexadecimal numbers, e.g.

Code: [Select]
00000000 00000A40 00000234 0000000000989B8C 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000


The second number (0xA40) is the encoder delay of 2624 samples, which is the amount of silence Nero added to the start of the file. The third number (0x234) is the encoder padding of 564 samples, which is the amount of silence Nero added to the end of the file, and the fourth number (0x989B8C) is the track's length of 10001292 samples. The encoder delay is usually fixed for AAC-LC but differs between encoders (so Nero's and Apple's delay values will be different). The padding and track length values will differ between tracks.

I'm sure nu774 or someone more with more knowledge of AAC than me can step in to correct me, if any of the above is wrong.