Gstreamer AAC -> AAC but changing bitrate

Question

I am new with Gstreamer and I have not found on the web any solution to my problem (I only found how to convert from a certain format to another...). I would like to change the bitrate (from a high bitrate to a lower bitrate of course) of an AAC audio file. I am working on Ubuntu and have installed gstreamer-tools and gstreamer0.10-plugins-bad-multiverse to work with AAC format. Can someone give me the pipeline to do so? For example, from a src.aac (112 kbps) to a out.aac (56 kbps).

Thanks a lot.

Answer 1

First AAC is an audio codec. Generally you will need to re-encode. Something like this should work:

gst-launch uridecodebin uri=file://$PWD/src.aac ! faac bitrate=56000 ! filesink location=out.aac

Note: on some systems it may be gst-launch-1.0

Answer 2

Re-encoding twice to a lossy format is definitely not recommended. Be carefull with what the final quality will be. Best would be to find original raw input files and then encode to 56 kbps.

Answer 3

I don't know if that will help you as it is a pretty specific solution (and your post is a bit old...) but I nevertheless put it here as it might help others who came here by googling or other search mechanism.
On the Mac (it might be available on Windows version as well, to be checked) in iTunes:

• Select Preferences/General/Import Settings
• Select "AAC encoder" and "customized"
• Select the options you want (eg 320kbits/sec, no VBR)
• OK

Then with the finder select all the files you want to convert and right-click Open (assuming iTunes is your default reader).
When back in iTunes:

• Select the files you just imported
• Right-click Create AAC version

This will convert all the files with the chosen settings (as copies). If you need to, you can get access to these new converted files in the iTunes library folder (something like /Users/username/Music/iTunes/iTunes Media/Music/).