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| | |-+  AAC playback bitrate display wrong on 64kbit target
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Author Topic: AAC playback bitrate display wrong on 64kbit target  (Read 2269 times)

Offline grums

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AAC playback bitrate display wrong on 64kbit target
« on: February 15, 2011, 09:13:48 AM »
I'm on r29308-110214. I've encoded 2 files using neroaacenc (1.5.4.0):

1) ( ~64 kbit): neroAacEnc -q 0.25 -if marlo.wav -of marlo-064.MP4
2) (~146 kbit): neroAacEnc -q 0.45 -if marlo.wav -of marlo-146.MP4

Both play OK, sizes are OK, but 1) shows following info:
?? CBR 135k, total playtime shown is ½ of correct time
Quicktime Player shows it's AAC-Stereo 22.050Hz 67.71 kbps

2) Display info seems to be OK: AAC CBR 154kbit, where Quicktime Player says AAC-Stereo 44.100Hz 154.10 kbps.

I saw another thread looking a bit like this, and upgraded the firmware just to test it - is there still an issue for files with low bitrate?
Is it true that they are CBR and not VBR (is there a program [like ogginfo for ogg-files] which will show that info)?

Regards, Ole
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Offline saratoga

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Re: AAC playback bitrate display wrong on 64kbit target
« Reply #1 on: February 15, 2011, 11:41:42 AM »
Which build are you running?
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Offline Buschel

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Re: AAC playback bitrate display wrong on 64kbit target
« Reply #2 on: February 15, 2011, 11:42:54 AM »
Hi,

there was some rework done on the recognition of AAC-HE files in the past weeks.

Question 1: Is there really "??" displayed? I would expect either "AAC-HE" or "AAC" (AAC-HE will most likely be correct).
Question 2: Can you provide a link to both files? The 64kbps file is of higher interest to me.

regards,
Buschel
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iPod 5.5G 30GB, iPod nano 2G 8GB, 97% MPC and growing...
 

Offline Buschel

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Re: AAC playback bitrate display wrong on 64kbit target
« Reply #3 on: February 15, 2011, 02:30:15 PM »
Seems like I got it. The sample output for _all_ AAC-HE files is doubled, not only for files using upsampled SBR. For all AAC-HE files which state to have a block length <=1024 the duration needs to be doubled.

Edit: Fix submitted with r29312.
« Last Edit: February 15, 2011, 03:37:51 PM by Buschel »
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iPod 5.5G 30GB, iPod nano 2G 8GB, 97% MPC and growing...
 

Offline grums

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Re: AAC playback bitrate display wrong on 64kbit target
« Reply #4 on: February 16, 2011, 04:55:29 AM »
Thanks a lot. All combinations play OK, display correct bitrate and time.

Display of codec: OK - plain (LC) AAC and HHE AAC are shown;
but maybe the HE-AAC v2 encoded files should show this - to distinguish them from normal (v1) HHE-AAC?

Source: http://en.wikipedia.org/wiki/High-Efficiency_Advanced_Audio_Coding

Regards Ole
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Offline Buschel

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Re: AAC playback bitrate display wrong on 64kbit target
« Reply #5 on: February 16, 2011, 05:30:56 AM »
I do not think it is reasonable to differ between v1 and v2. imho this a step to detailed. Main reason to differ between AAC and AAC-HE was that both formats are major different in terms of CPU load and used synthesis (SBR vs. MDCT). v2 is v1 + PS, the underlying synthesis is the same.
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