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iPod mini 2G stutters when playing LAME aps, Clock speed optimisation is the cause
sehested
post Apr 23 2005, 11:41
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iPod nano/mini 2G use clock speed optimisation to increase battery time.
VBR songs with a sudden increase in bitrate may cause the iPod nano/mini 2G to stutter as the clock speed is not increased fast enough to deal with the increased bitrate.

This has so far been observed for songs encoded with LAME --preset standard and is only true when not using the equaliser.

Examples of songs that stutters can be found here:
David Bowie - Five Years
Nine Inch Nails - Right Where it Belongs

For Five Years the clock speed hovers around 24 jumping to 30 when the stuttering begins. Using the equaliser the clock speed hovers around 36 throughout the song and no stuttering occurs.

Further observations:
- this problem is related to the iPod nano/mini 2G but one sample has been found that makes the 4G Color iPod stutter
- problem with iPod mini software 1.3, 1.4, and 1.4.1
- problem with iPod nano software 1.0, and 1.1
- iPod mini 2G do not use optimisation when connected to a computer
- iPod mini 2G do use optimisation, both when using its battery and when connected to a powered dock that is not connected to a computer
- problem go away when using an EQ setting different from flat/off
- only safe EQ setting to use is Bass Reducer / Treble Reducer in order to avoid distortion of songs with a high recording level
- problem do not occur when using iTunes MP3 encoder
- problem do not occur when LAME VBR song do not contain 320 kbps: options --preset standard -B 256
- problem do not always occur at the same spot in the subtle songs listed below
- iPod mini 1G clock speed for Five Years hoovers aroung 31 rising to 33 where it was 24 / 30 for the 2G
- iPod mini optimisation may be turned off (I don't now how to provoke this) and require a reset of the iPod to turn it back on.
- for the 4G color iPod only the sample with NIN - Right Where it Belongs stutters, even with the EQ set to Bass Reducer. Acoustic EQ setting makes the problem go away.

Songs having the problem (obvious):
- Johnny Cash - A Satisfied Mind
- David Bowie - Five Years
- Nine Inch Nails - Right Where it Belongs
- Cake - Nugget @ 26s

Songs having the problem (subtle):
- Eminem - Drug Ballad
- Eminem - Kill You
- U2 - Miracle Drug
- Musica XM - AWS Hope Xm cut

Album songs not having the problem:
- Pink Floyd - Dark Side of the Moon
- Styx - Pieces of Eight
- Guns N' Roses - Illusions I
- Shirley Bassey - Greatest Hits/This is my Life

Edited: Updated list of songs and albums.
Edited: iPod mini 1G do use speed optimisation. My iPod mini 1G was stuck at a clock speed of 80 and required a reset forcing it to use speed optimisation.
Edited: One user with iPod mini 2G was unable to reproduce problem.
Edited: Work around described
Edited: Added NIN
Edited: Added Cake
Edited: Updated for iPod mini software 1.4
Edited: Added Johnny Cash and updated observations
Edited: Added information about 4G color iPod stuttering
Edited: iPod nano stutters as bad as iPod mini 2G
Edited: Updated for iPod mini software 1.4.1 / iPod nano software 1.1


This post has been edited by sehested: Feb 24 2006, 07:40
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Lucas
post Apr 24 2005, 00:51
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my 2G ipod mini skips with 192k cbr songs too.. very randomly also.. so I don't think it's just the bitrate.. some frames might be harder to decode than others even if they're the same size, right? if not, I don't get it.

Where do you check the clock speed?

edited: typo

This post has been edited by Lucas: Apr 24 2005, 00:52
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Posts in this topic
- sehested   iPod mini 2G stutters when playing LAME aps   Apr 23 2005, 11:41
- - The Belgain   Wow... that's kind of a big bug. Should be re...   Apr 23 2005, 12:12
|- - Busemann   All new iPods use variable clock speed, but there ...   Apr 23 2005, 13:16
|- - sehested   QUOTE (Busemann @ Apr 23 2005, 04:16 AM)All n...   Apr 23 2005, 17:10
|- - Busemann   Have you checked if you can reproduce with VBR fil...   Apr 23 2005, 17:16
|- - sehested   QUOTE (Busemann @ Apr 23 2005, 08:16 AM)Have ...   Apr 23 2005, 17:33
|- - Busemann   QUOTE (sehested @ Apr 23 2005, 08:33 AM)No. A...   Apr 23 2005, 18:16
- - earphiler   all my VBR tracks play fine on my (technically 2G)...   Apr 23 2005, 15:10
- - Jojo   QUOTE (sehested @ Apr 23 2005, 02:41 AM)Furth...   Apr 23 2005, 23:08
|- - sehested   QUOTE (Jojo @ Apr 23 2005, 02:08 PM)I own an ...   Apr 23 2005, 23:43
|- - Jojo   QUOTE (sehested @ Apr 23 2005, 02:43 PM)QUOTE...   Apr 24 2005, 00:18
|- - sehested   QUOTE (Jojo @ Apr 23 2005, 03:18 PM)try to re...   Apr 24 2005, 15:59
- - jrkagan   I have a 4G 20GB iPod and I'm pretty sure its ...   Apr 24 2005, 00:09
|- - Jojo   QUOTE (jrkagan @ Apr 23 2005, 03:09 PM)I have...   Apr 24 2005, 00:22
|- - MoSXS   My 2G 4GB mini is filled with --aps MP3s (ripped u...   Apr 24 2005, 00:51
|- - sehested   QUOTE (MoSXS @ Apr 23 2005, 03:51 PM)My 2G 4G...   Apr 24 2005, 09:15
|- - MoSXS   QUOTE (sehested @ Apr 24 2005, 01:15 AM)QUOTE...   Apr 24 2005, 22:24
|- - sehested   QUOTE (MoSXS @ Apr 24 2005, 01:24 PM)Clock sp...   Apr 24 2005, 22:47
- - Lucas   my 2G ipod mini skips with 192k cbr songs too.. ve...   Apr 24 2005, 00:51
|- - sehested   QUOTE (Lucas @ Apr 23 2005, 03:51 PM)my 2G ip...   Apr 24 2005, 09:40
- - Lucas   I spoke too fast.. I transfered one of the (many) ...   Apr 24 2005, 17:05
- - Lucas   I've found a part of a song that causes my iPo...   Apr 24 2005, 17:23
- - earphiler   i was listening to ipod photo last nite, and it sk...   Apr 25 2005, 12:43
|- - sehested   QUOTE (earphiler @ Apr 25 2005, 03:43 AM)i wa...   Apr 25 2005, 13:30
- - MugFunky   this sounds to me like a simple buffering problem ...   Apr 25 2005, 17:39
- - earphiler   i just used the URL u gave me and told apple... ho...   Apr 27 2005, 03:55
- - NeoRenegade   So much for Apple's claims that the I-Pod supp...   Apr 27 2005, 18:50
- - earphiler   i wonder why we are the first to complain.. what a...   Apr 29 2005, 23:13
- - earphiler   i think downgrading from 1.1 to 1.0 fixes the prob...   Apr 29 2005, 23:26
- - earphiler   i havent given it *insane* testing, but try rollin...   Apr 30 2005, 14:00
- - earphiler   is this not an issue with 1G ipod photo 40GB and 6...   May 2 2005, 04:03
- - Pizzi   I'm encountering exactly the same problems wit...   May 3 2005, 13:11
- - grug   It's not specific to the Mini. I get the same...   May 5 2005, 14:59
|- - sehested   QUOTE (grug @ May 5 2005, 05:59 AM)It's n...   May 6 2005, 09:45
|- - jrkagan   QUOTE (grug @ May 5 2005, 08:59 AM)... I get ...   May 12 2005, 05:10
- - earphiler   cool thanks, only problem is that i returned my ip...   May 11 2005, 21:36
- - earphiler   this is cool that it works with rock eq, but sort ...   May 11 2005, 22:30
- - earphiler   hmmm, any way to fix this besides using the equali...   May 15 2005, 22:00
|- - sehested   QUOTE (earphiler @ May 15 2005, 01:00 PM)hmmm...   May 15 2005, 23:18
- - earphiler   yeah if it isn't fixed in the next software up...   May 15 2005, 23:23
|- - ChiGung   If making fresh vbr mp3s, I see some options which...   May 16 2005, 00:04
|- - sehested   QUOTE (ChiGung @ May 15 2005, 03:04 PM)If mak...   May 16 2005, 10:56
- - ChiGung   You do seem to have located the problem, Im surpri...   May 16 2005, 11:30
- - earphiler   I got annoyed by the skips. selling my 30gb with c...   May 16 2005, 22:13
|- - Busemann   QUOTE (earphiler @ May 16 2005, 01:13 PM)I go...   May 16 2005, 22:31
|- - sehested   QUOTE (earphiler @ May 16 2005, 01:13 PM)cont...   May 16 2005, 22:37
- - earphiler   it is truly ALL of them ? i dont think so. as stat...   May 16 2005, 22:38
- - earphiler   just loaded up Nine Inch Nails - Right Where It Be...   May 22 2005, 18:37
|- - Busemann   QUOTE (earphiler @ May 22 2005, 09:37 AM)if n...   May 22 2005, 19:16
||- - sehested   QUOTE (Busemann @ May 22 2005, 10:16 AM)(as l...   May 22 2005, 23:08
||- - Busemann   QUOTE (sehested @ May 22 2005, 02:08 PM)Their...   May 22 2005, 23:17
||- - sehested   QUOTE (Busemann @ May 22 2005, 02:17 PM)So it...   May 22 2005, 23:44
|- - sehested   QUOTE (earphiler @ May 22 2005, 09:37 AM)just...   May 24 2005, 22:31
- - earphiler   i just bought an iriver h320 for 210 used shipped...   May 24 2005, 01:55
- - Faelix   Just a hint: Searching about general AAC compatib...   May 25 2005, 01:26
- - soundcheck   Having just acquired a 2nd gen mini, I loaded on s...   Jun 19 2005, 21:40
|- - sehested   QUOTE (soundcheck @ Jun 19 2005, 12:40 PM)Hav...   Jun 19 2005, 23:18
|- - soundcheck   QUOTE (sehested @ Jun 19 2005, 06:18 PM)What ...   Jun 20 2005, 00:29
- - borndevil   hi... I sent my iPod in service (for this and a wh...   Jun 25 2005, 13:45
|- - sehested   QUOTE (borndevil @ Jun 25 2005, 04:45 AM)sehe...   Jun 25 2005, 14:45
- - borndevil   some reported EVERY sample I sent (mine too... and...   Jun 25 2005, 18:53
- - hyper84   Here is one more confirmation of the stated proble...   Jun 27 2005, 17:17
- - sehested   Apple just released iPod Updater 2005-06-26 with i...   Jun 28 2005, 17:47
|- - soundcheck   QUOTE (sehested @ Jun 28 2005, 12:47 PM)Apple...   Jun 29 2005, 05:41
|- - sehested   QUOTE (soundcheck @ Jun 28 2005, 08:41 PM)seh...   Jun 29 2005, 06:54
- - chrisgeleven   I finally am able to confirm this issue (I tried o...   Jun 28 2005, 18:43
- - borndevil   yes update didn't fix.............. .... ... ....   Jun 28 2005, 21:24
- - hyper84   Hey i have great news! More bad samples! ...   Jun 28 2005, 22:51
- - Jojo   the problem doesn't occur if the EQ is on, rig...   Jun 28 2005, 23:18
|- - sehested   QUOTE (Jojo @ Jun 28 2005, 02:18 PM)the probl...   Jun 29 2005, 06:51
- - hyper84   nero vbr aac seems to be fine with the problematic...   Jun 29 2005, 06:55
|- - grug   I installed iPod Linux on my 4G iPod and it handle...   Jun 29 2005, 12:12
|- - hyper84   QUOTE (grug @ Jun 29 2005, 06:12 AM)I install...   Jul 2 2005, 08:12
- - earphiler   I wonder if the "new" 20gb 'color...   Jul 2 2005, 20:13
- - Fuchal   I have a 40GB 4th gen iPod and I have yet to run i...   Jul 3 2005, 00:19
- - stewy   It's good to hear that I'm not the only on...   Jul 9 2005, 17:19
|- - sehested   QUOTE (stewy @ Jul 9 2005, 08:19 AM)I've ...   Jul 9 2005, 18:41
- - stewy   Well, it really does seem to be the same problem t...   Jul 9 2005, 20:46
|- - Jojo   QUOTE (stewy @ Jul 9 2005, 11:46 AM)I'm s...   Jul 9 2005, 23:23
- - stewy   has anyone tried this? http://txfx.net/2005/02/08...   Jul 10 2005, 00:16
|- - Jojo   QUOTE (stewy @ Jul 9 2005, 03:16 PM)has anyon...   Jul 10 2005, 11:51
- - earphiler   QUOTE (Jojo @ Jul 10 2005, 05:51 AM)QUOTE (st...   Jul 10 2005, 17:50
|- - sehested   QUOTE (earphiler @ Jul 10 2005, 08:50 AM)what...   Jul 10 2005, 18:06
|- - Jojo   QUOTE (earphiler @ Jul 10 2005, 08:50 AM)what...   Jul 11 2005, 01:43
- - earphiler   Did you try it on the actual iPod though and see i...   Jul 10 2005, 18:10
|- - sehested   QUOTE (earphiler @ Jul 10 2005, 09:10 AM)Did ...   Jul 10 2005, 18:27
- - earphiler   I'm relieved. I know , with certainty , there ...   Jul 10 2005, 22:41
|- - Busemann   QUOTE (earphiler @ Jul 10 2005, 01:41 PM)I...   Jul 10 2005, 22:53
- - earphiler   I just misunderstood what you said. Sorry   Jul 11 2005, 02:02
- - stewy   yeah, sorry, that's my bad... files i encode m...   Jul 11 2005, 16:22
- - stewy   QUOTE (earphiler @ Jul 10 2005, 06:11 PM)I...   Jul 11 2005, 22:30
|- - Vero   Hi there, I have a brand new 20gig ipod photo. I ...   Jul 12 2005, 02:22
|- - odious malefactor   QUOTE (Vero @ Jul 11 2005, 05:22 PM)Hi there,...   Jul 12 2005, 03:45
|- - Vero   QUOTE The title of this thread would lead one to s...   Jul 12 2005, 16:54
|- - sehested   QUOTE (Vero @ Jul 12 2005, 07:54 AM)QUOTE The...   Jul 12 2005, 20:07
- - earphiler   i'm getting 2g mini today (read below) so i...   Jul 14 2005, 14:27
- - sehested   Just brought a 4G colour iPod. Thought that woul...   Jul 14 2005, 19:13
- - earphiler   good god sehested, why do you go through so many D...   Jul 14 2005, 20:03
|- - sehested   QUOTE (earphiler @ Jul 14 2005, 11:03 AM)good...   Jul 14 2005, 21:33
- - earphiler   just tested my 6gb green and it skipped with both ...   Jul 15 2005, 00:16
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