AAC LATM/LOAS Audio Streams

There are two extra levels of multiplexing in the stream: "The MPEG-4 HE AAC or HE AAC v2 elementary stream data shall be first encapsulated in the LATM multiplex format according to ISO/IEC 14496-3 [17]. The AudioMuxElement() multiplex element format shall be used. The LATM formatted MPEG-4 HE AAC or HE AAC v2 elementary stream data shall be encapsulated in the LOAS transmission format according to ISO/IEC 14496-3 [17]. The AudioSyncStream() version shall be used. AudioSyncStream() adds a sync word to the audio stream to allow for synchronization. Semantics: The semantics of the AudioMuxElement() and AudioSyncStream() formatting are described in ISO/IEC 14496-3 [17]. Encoding: The MPEG-4 HE AAC and HE AAC v2 elementary streams shall be formatted with AudioMuxElement() LATM multiplex format, and AudioSyncStream() LOAS transmission format." Somebody needs to make some open source LATM/LOAS demultiplexing code. :) I'm too busy on other things right now.

H.264 + AAC LATM/LOAS:

I've got more if you need them.

This is all sounding (no pun intended) very positive :). I'll see what samples I can get hold of too. I wonder how many broadcasters have elected to use AAC LATM/LOAS audio. Given that AAC audio bit-steams can't be decoded by surround sound amplifiers, its use seems an odd choice :eek:

FWIW, some Japan broadcasters use AAC, too, but they use ADTS instead of LATM/LOAS.

Sure, it's not rocket science. But someone with the skills has to be motivated.

I would do it in a heartbeat but the learning curve for me would be too steep I think, my last programming having been some dabbling in C++. I don't think it's the programming - it's understanding the formats of the data needed to be decoded and I guess, the way to write DS filters. I guess will just have to wait for the motivated person to do it!

Don't sell yourself short. The format specification is readily available and quite clear. And there are good books on DirectShow programming. It's all a matter of how bad you want it. I don't have any need for it, so it's hard to get motivated.

Mplayer is now able to play the AAC LATM/LOAS Audio now directly from .ts; I'm testing using SMPlayer 0.6.4 SVN r2102 It reports the demuxer as: mpegts - MPEG-TS demuxer the video decoder: FFMpeg h.264 the audio decoder: libfaad2 I don't know enough as to how this could work in graphedit/graphstudio or if there is a corresponding directshow splitter /decoder, but perhaps a dump could be used through ffmpeg ? I briefly tried FFMpegSource and FFMpegSource2 but couldn't get either to work, hopefully someone more saavy can use this to figure something out?

Here is a DirectShow filter: