How to detect AAC audio profile and ensure Android compatibility

I am having problems figuring out how to detect if an AAC audio source is compatible with Android. The supported media formats page for android says 'AAC LC/LTP' when delivered as 3GP, MPEG4 or ADTS raw AAC. It appears the LC means 'Low Complexity" and LTP means "Long Term Prediction" but, my biggest frustration is determining what AAC profiles/modules are supported on Android. When I run the input into ffmpeg, i see its AAC, but no extended info开发者_如何学JAVArmation about the AAC. An example source is http://6693.live.streamtheworld.com:80/WTMJAMAAC_SC . Anyone have any ideas?

You can get extended media information programmatically using the MediaInfo library available here: http://mediainfo.sourceforge.net/en/Download

The "DLL" or other media downloads include example code in C, C#, etc. If you do not want to write any code, the same website has downloads for "MediaInfo", a program that uses the library to display information.

Your Android supported media formats link says: "Mono/Stereo content in any combination of standard bit rates up to 160 kbps and sampling rates from 8 to 48kHz". Notice the sample below shows all of those: Channel(s), Overall bit rate, and sampling rate.

It may be necessary to test for yourself whether "up to 160 kbps" means "Up to 160 kbps overall" or "No part of the file, including those encoded with variable bit rates (VBR), may surpass 160kbps." It is noteworthy that I have played movies on my single-core Android phone which have 256KBit VBR AAC 6-channel audio, though obviously I did not hear the rear surround channels. Because of those, I suspect that the limitations proposed in the link are minimums allowed by Google, but that the audio formats supported in practice are much more broad.

Here is an example from an actual AAC file (using the MediaInfo program):

Format                           : ADTS
Format/Info                      : Audio Data Transport Stream
File size                        : 176 KiB
Duration                         : 30s 707ms
Overall bit rate                 : 46.8 Kbps

Audio
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format version                   : Version 4
Format profile                   : LC
Format settings, SBR             : Yes
Format settings, PS              : Yes
Muxing mode                      : ADTS
Duration                         : 30s 707ms
Bit rate mode                    : Constant
Bit rate                         : 46.8 Kbps
Channel(s)                       : 2 channels
Sampling rate                    : 44.1 KHz
Stream size                      : 176 KiB (100%)

I wrote a wrapper library in C# for MediaInfo. It isn't necessary to use MediaInfo, but makes its use much easier and more ".NET-friendly". It can be found here: MediaInfo.Net.

1. Load the source into Media Player Classic.
2. View its propreties.
3. In the MediaInfo tab it would list:
   • Format : AAC
   • Format profile : LC

If you just want to check the profile used for a few files, you may use VLC or any other program (like Sheepy already suggested) - in VLC it's in Extras -> Media Information -> CodecDetails and in your example stream, it's AAC SBR+PS (this is a High-Efficiency Profile), which is decodable by android.

If you do have control over the media you want to play through android, you may want to check out this blog article on cross platform mobile media for the correct encoding. If not (e.g. because the user might be able to choose his own urls or files), you should instead catch any exceptions and display an error message. That way, you are also future proof against new media types, which might be supported in future android versions.