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How to mux AAC to play back on my Sony car stereo?, Proper wrapping/muxing?
post Jan 20 2013, 13:19
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Since pretty much all of my hardware supports mp3, I haven't yet made the transition to more efficient codecs nor do I see this happen soon since storage is getting cheaper every day. However, when I stumbled over this obscure German electro song on Vimeo I downloaded it and extracted the AAC audio track to test it on my Sony car stereo that is advertized as supporting MP3/AAC/WMA (crap)/Atrac3Plus (LOL!). I had tested one AAC song successfully years ago but I don't have this encode anymore and don't remember how I did it. The manual only reads:

- AAC tag is 126 characters.
- When naming an AAC file, be sure to add the file extension .m4a to the file name.

I've tried simply renaming the AAC and also muxing it into an mp4 renamed to m4a but both files just get skipped. Is it because of the format? Mediainfo reports:

Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42
File size                                : 4.33 MiB
Duration                                 : 3mn 48s
Overall bit rate mode                    : Variable
Overall bit rate                         : 159 Kbps

ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 3mn 48s
Source duration                          : 3mn 48s
Bit rate mode                            : Variable
Bit rate                                 : 157 Kbps
Maximum bit rate                         : 163 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 4.28 MiB (99%)
Source stream size                       : 4.29 MiB (99%)
Language                                 : English

This file plays back on my PC in Winamp, iTunes and VLC. How do I make it run on my Sony (preferrably without transcoding)? Thx.

This post has been edited by Moon: Jan 20 2013, 13:20
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post Jan 22 2013, 08:01
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Foobar did the trick, thanks. Curiously enough Mediainfo shows the same info on the file done with foobar and the other one not working on my car stereo. I guess there's only so much nuances it can read from files. BTW, does anyone know why muxing in mp4 should be necessary? Wouldn't using AAC streams be easier?
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post Jan 22 2013, 09:14
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QUOTE (Moon @ Jan 22 2013, 16:01) *
Curiously enough Mediainfo shows the same info on the file done with foobar and the other one not working on my car stereo.

It's only the matter of layout/order of boxes in the MP4 file. Some poor/incomplete MP4 implementations are known to assume specific box layout (or even major branding), and refuse others.

Wouldn't using AAC streams be easier?

ADTS is much simpler in structure, but is hard to seek. It doesn't have seek tables, and each frame headers doesn't contain something like time stamp. Therefore only thing you can do for ADTS is to start from the first frame, then skip frame-by-frame parsing each frame header. Very inefficient.
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