correct way to decode AAC?

[Adams, Bruce (KMLWG)]

It looks like the avdec_aac_latm element was what I was looking for:

>$ gst-inspect-1.0 | grep aac  

On a related note is it possible to construct a single pipeline that supports both decodings
as in:      

aac -> avdec_aac_latm --> wavenc
        -> faad                         -^

Is there an selectable/'or' element? as in the brackets below:

gst-launch-1.0 wavenc name=y ! filesink location=file.wav \
 filesrc location=out.aac name  x. ! aacparse ! (faad | avdec_aac_latm) !
audioconvert ! .y

or Something like:

gst-launch-1.0 wavenc name=y ! filesink location=file.wav \
 filesrc location=out.aac name  x. ! aacparse ! avdec_aac_latm !
audioconvert ! .y 

which doesn't work - doubled to:

gst-launch-1.0 wavenc name=y ! filesink location=file.wav \
 filesrc location=out.aac name  \
x. ! aacparse ! avdec_aac_latm ! audioconvert ! .y
x. ! aacparse ! faad ! audioconvert ! .y


I do have access to information that identifies the stream type (its in the program mapping table in a DVB MPEG-TS) but I'm curious to know whether a generic pipeline is possible in principle either from the command line or from code.

Would it be a desirable patch to create an element combining both somehow (maybe a bin)?
Or is it better to be creating the pipeline dynamically once the type has been identified which I think is the only solution without changing gstreamer.

Regards,

Bruce.

-----Original Message-----
From: Adams, Bruce (KMLWG) 
Sent: 22 May 2018 14:16
To: gstreamer-devel at lists.freedesktop.org
Subject: RE: correct way to decode AAC?

Hi,
     That’s the same pipeline I'm using except you've added a queue. 
I tried it anyway in case queue are 'more magical than I  think' but perhaps unsurprisingly 
it doesn't work for me.
Could it be something to do with the format. Mediainfo claims the general format is:

General
Complete name                            : cbbc.aac
Format                                   : LATM
File size                                : 2.38 MiB
Overall bit rate mode                    : Variable

Audio
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Bit rate mode                            : Variable
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 spf)
Compression mode                         : Lossy

What format did you test?

Regards,

Bruce.

-----Original Message-----
From: gstreamer-devel [mailto:gstreamer-devel-bounces at lists.freedesktop.org] On Behalf Of new baby
Sent: 22 May 2018 06:20
To: gstreamer-devel at lists.freedesktop.org
Subject: Re: correct way to decode AAC?

Hi bruce,,

for audio decoding to wav format.
Hope this example works for you(i have tested it ) 

gst-launch-1.0 filesrc location=out.aac ! queue ! aacparse ! faad !
audioconvert ! wavenc ! filesink location=file.wav