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View Full Version : Problem: After remux .AAC file got diffence info :(

lintran
22nd February 2011, 06:14
Hi all!
I have some .mov file (exact these are Apple Trailers) and i want to re-encode them (only re-encode video, keep original audio)
Here is original audio info from .mov
----------------------------------------
Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 34s
Bit rate mode : Constant
Bit rate : 96.0 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
----------------------------------------


I used My MP4Box GUI (or Yamb) to demux this .acc from .mov, and i got an .acc file with info:
----------------------------------------
Audio
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Bit rate mode : Variable
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 1.02 MiB (100%)
----------------------------------------


After that i used My Mp4box Gui (or Yamb) to remux this .acc file and .h264 to new MP4 file, and here is infomation of .acc in MP4 file:
----------------------------------------
Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 1mn 26s
Bit rate mode : Variable
Bit rate : 96.0 Kbps
Maximum bit rate : 178 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 1 019 KiB (1%)
Title : Imported with GPAC 0.4.6-DEV (internal rev. 5)
--------------------------------------------

I dont know what happen, and dont know why the .acc in new MP4 file got difference infomation :(. I tried with very other .mov files but same result.
So could you guys please tell me how can remux .acc (without re-encoding) with same infomation like original file.
Thank you
nurbs
22nd February 2011, 10:06
Most likely nothing happened. That mediainfo shows different information for different container types doesn't mean that the content is different. The information for the mov is most likely wrong. AAC is never really CBR anyway.
lintran
22nd February 2011, 15:22
Most likely nothing happened. That mediainfo shows different information for different container types doesn't mean that the content is different. The information for the mov is most likely wrong. AAC is never really CBR anyway.

Thank you, so do you have any solution can help to detect exactly infomation of AAC in MOV container?
nurbs
22nd February 2011, 15:27
Zenitram develops Mediainfo. You can try to ask him about it.