GNOME Bugzilla – Bug 771994
aacparse: Does not rezognize HE-AAC v2 stream
Last modified: 2018-11-03 15:12:04 UTC
Created attachment 336277 [details] ADTS AAC sample file It seems that our parser can't recognize the HE-AAC v2 profile The attached sample file was created with: ffmpeg -i 45s-48khz-16bit-2ch.wav -c:a libfdk_aac -profile:a aac_he_v2 -b:a 48k 45s-48khz-16bit-2ch-48kbps.aac
Does ADTS even provide signalling for HE-AAC v2?
That seems to work fine with gst-launch-1.0 filesrc location=~/Downloads/45s-48khz-16bit-2ch-48kbps.aac ! aacparse ! fdkaacdec ! pulsesink (both with and without https://bugzilla.gnome.org/show_bug.cgi?id=772067). Pipeline starts, I hear guitar.
The "mediainfo" program recognizes this file as HE-AAC v2, so I assume it can be done somehow. The enhancement requested here are: - have aacparse recognize the HE-AAC profiles and set them in the caps - have the pbutils recognize those and print them so that gst-discoverer can print the right thing.
I assume the parser need to find PS and SBR bits in the stream to know which profile it is?
(In reply to Olivier Crête from comment #4) > I assume the parser need to find PS and SBR bits in the stream to know which > profile it is? It depends upon how the stream is encapsulated. In the case of an MP4 file, the ES descriptor should contain the profile information and if PS or SBR are being used. qtdemux should be passing that in the caps, but I don't think it does currently. If LATM/LOAS is used, the signalling can be put in the AudioSpecificConfig section of StreamMuxConfig. Ultimately the PS or SBR data goes in filler elements in the elementary stream. An AAC-LC decoder would skip those and decode the base AAC-LC stream. An HE-AAC or HE-AAC v2 decoder will know how to read this extra data and enhance the base AAC-LC stream. The following white paper from Fraunhofer has a good overview of the different ways in which AAC can be encapsulated: https://www.iis.fraunhofer.de/content/dam/iis/de/doc/ame/wp/FraunhoferIIS_Application-Bulletin_AAC-Transport-Formats.pdf
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