View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0004695 | MMW v4 | Synchronization | public | 2008-05-16 10:55 | 2008-06-05 05:38 |
| Reporter | jiri | Assigned To | |||
| Priority | immediate | Severity | minor | Reproducibility | always |
| Status | closed | Resolution | fixed | ||
| Product Version | 3.0 | ||||
| Fixed in Version | 3.0 | ||||
| Summary | 0004695: Some auto-converted tracks don't play on iPod | ||||
| Description | I got a M4A track from a user that does play on iPod, but when it's auto-converted (again) to M4A (e.g. because of volume leveling), it doesn't play on iPod (tested with 3rd gen Nano). | ||||
| Tags | No tags attached. | ||||
| Fixed in build | |||||
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Some results of my tests: 1. Auto-converted M4A: 1a. Doesn't play on iPod (stops after 12 seconds). 1b. Does properly play in MM or iTunes. 2. M4A converted using FAAC - the same as 1. 3. M4A converted using FAAC with mid/side encoding disabled - works! I don't know whether iPod doesn't properly support mid/side encoding, or whether there's some problem in FAAC (probably not, iTunes can play the file well). Ludek, please make more tests... Based on what we find, a possible solution would be to enhance configuratin of f_aaccodec.dll so that user could disable mid/side and possibly also other options (like profile selection). Note that this is only a problem of f_aaccodec.dll, MM itself shouldn't be influenced by the necessary fix. |
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Reminder sent to: rusty |
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Just tested auto-converted M4A by using iPod Nano 2G and the file plays fine on iPod. This seems to be problem of iPod Nano 3G ?? My encode setting was 80%, VBR. |
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Note that the track causing problems is now uploaded to FTP. I tried to sync it to various devices (iPhone, iPod Nano 3G and Ipod 5th Gen Video) and in various settings (50% VBR or 80% VBR) and the results are similar, playback stops at e.g. 0:18 or 0:21. What should we do: 1. Try to find out why these tracks don't play. It is that mid/stereo? Or VBR in general? iTunes seems to default to CBR? 2. Does there exist some VBR or ABR mode that doesn't fail? |
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fyi possibly related: http://www.hydrogenaudio.org/forums/lofiversion/index.php/t37064.html |
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Yes, now I can reproduce, so my results are so far: a) It is specific to the track. b) It fails despite the fact whether it has been encoded using VBR or ABR mode. c) If the track is firstly converted to MP3 and then auto-converted to M4A then the problem doesn't occur. So there is not clear whether it is problem of M4A decoding or encoding. I am going to test this furher. |
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There are further results: -The orig. file synced -> plays fine -The orig. file auto-converted to M4A and synced -> plays only 6 seconds -The orig. file converted to WAV and synced -> plays fine -The orig. file converted to WAV then auto-converted to M4A and synced -> plays only 6 seconds -The orig. file converted to MP3 and synced -> plays fine -The orig. file converted to MP3 then auto-converted to M4A and synced -> plays fine !!! -The orig. file converted to WAV then converted to M4A by using FAAC and synced -> plays only 6 seconds -The orig. file converted to WAV then converted to M4A by using FAAC then auto-converted to M4A and synced -> plays and stops in half of playback (1:13) !! -The orig. file converted to WAV then converted to M4A by using FAAC with mid/side disabled and synced -> plays fine !! (as Jiri has already tested) -The orig. file converted to WAV then converted to M4A by using FAAC with mid/side disabled then auto-converted to M4A and synced -> plays only 6 sec. So in summary it looks like that the MID/SIDE stereo mode is the root of this problem while ecoding? But why this problem doesn't occur in case the track is pre-converted to MP3 beforehand? Does the conversion to MP3 change automatically the stereo mode from mid/side to left/right? |
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As for the root of the problem, I don't think that Mid/Stereo is necessarily the only problem, it rather seems that it helps exhibit some iPod's issue, possibly related to varying bitrate (as suggested by the link Rusty posted above). We still need to find out more: 3. Does there exist some VBR or ABR mode that doesn't fail? I.e. ABR 64, ABR 96, ABR 128, VBR 30, VBR 50, etc. This way we could at least set some default the works on iPod... 4. As mentioned, VBR/ABR could possibly cause the problem, can we force FAAC to create a CBR stream? My guess is that it could help... 5. What about using an alternative codec? How does Nero perform on this track? Does http://www.nero.com/eng/nero-aac-codec.html work well? It offers VBR, ABR and CBR, do all of these modes work? Note that this could imply additional licensing cost... 6. http://www.codingtechnologies.com/products/aacPlus.htm would be another alternative, but they don't have any working demo downloadable. |
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Btw, somewhat similar issue on iPod using FAAC is described here: http://sourceforge.net/tracker/index.php?func=detail&aid=1373631&group_id=704&atid=100704 |
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OK, further test results are: Re: 3. -It seems that there doesn't exist any VBR or ABR mode that doesn't fail. Re: 5. -The orig. file converted to WAV then converted to MP4 by using the Nero codec (default settings) and synced -> plays fine -The orig. file converted to WAV then converted to MP4 by using the Nero codec (default settings) then auto-converted to M4A and synced -> plays fine !!! -The orig. file converted to WAV then converted to MP4 by using the Nero codec (128kbps, CBR) and synced -> plays fine -The orig. file converted to WAV then converted to MP4 by using the Nero codec (128kbps, CBR) then auto-converted to M4A and synced -> plays fine !!! So it really looks like that the problem is rather in iPod ability to play files in MID/SIDE stereo mode rather then VBR files in general. So I would suggest either to have MID/SIDE stereo mode disabled as default or make the stereo mode configurable. |
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Ok, so let's add that Mid/Side stereo option and turn it off by default (so that iPod sync works well). It could look like: [ ] Mid/Side stereo (I choose such a simple text since we don't have a localization, this is quite an international string). |
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Added in version 1.0.4 |
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Verified 1183. |
