Audio object type 3 is not supported

Question

I am running into an issue with a custom-built ffmpeg. Basically, its a vanilla ffmpeg with x264 and fdk-aac libs enabled. I am feeding an SDP file through ffmpeg API and get the following error while passing the info to avcodec_open2:

Audio object type 3 is not supported

My SDP file:

v=0
o=- 0 0 IN IP4 127.0.0.1
s=Unnamed
i=N/A
c=IN IP4 192.168.1.1
t=0 0
a=recvonly
m=audio 8204 RTP/AVP 96
a=rtpmap:96 mpeg4-generic/32000
a=fmtp:96 streamtype=5; profile-level-id=15; mode=AAC-hbr; config=1a88; SizeLength=13; IndexLength=3; IndexDeltaLength=3;
a=control:trackID=0
m=video 8202 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1;profile-level-id=428028;sprop-parameter-sets=Z0KAKJWgKA9E,aM48gA==;
a=control:trackID=1
m=application 8206 RTP/AVP 96
a=rtpmap:96 smpte336m/10
a=control:trackID=2

The following is the output I get from ffmpeg as I open the input, dump its format, and try to open input streams:

Format sdp probed with size=2048 and score=50
audio codec set to: aac
audio samplerate set to: 32000
audio channels set to: 1
video codec set to: h264
RTP Packetization Mode: 1
RTP Profile IDC: 42 Profile IOP: 80 Level: 28
Extradata set to 0xc8d3dc0 (size: 21)!
File position before avformat_find_stream_info() is 522
Audio object type 3 is not supported.
Could not find codec parameters for stream 1 (Video: h264): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
File position after avformat_find_stream_info() is 522
Dumping input AV format
Input #0, sdp, from 'conf/test.sdp':

Metadata:
title :Unnamed
comment :N/A

Duration:N/A, bitrate:N/A

Stream #0:0, 0, 1/32000: Audio: aac, 32000 Hz, 1 channels, fltp  

Stream #0:1, 0, 1/90000: Video: h264, 90k tbr, 90k tbn, 180k tbc  

Stream #0:2, 0, 1/90000: Data: none, 0/1  

Audio object type 3 is not supported.

I also see the error reported for not finding codec parameters for stream 1:

Could not find codec parameters for stream 1 (Video: h264): unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options

However, I think that is due to me not running an actual rtp at the moment of the test.

In any case, what may be the reason for getting audio object type 3 not supported exception?

UPDATE - Oct 02, 2013

Static ffmpeg build gives the following flags:

Static ffmpeg 2.0.1 build flag output:

ffmpeg version 2.0.1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Sep 30 2013 22:24:00 with gcc 4.1.2 (GCC) 20080704 (Red Hat 4.1.2-54)
  configuration: --enable-gpl --enable-nonfree --enable-shared
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --enable-shared --enable-runtime-cpudetect --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-avfilter --enable-pthreads --enable-x11grab --enable-vdpau --disable-avisynth --enable-libdc1394 --enable-libfaac --enable-libgsm --enable-libmp3lame --enable-libnut --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libx264 --enable-libxavs --enable-libxvid --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --disable-stripping

My build is from ffmpeg 2.0.1 snapshot with the following flags:

--enable-static --disable-shared --enable-gpl --enable-nonfree --enable-libfdk-aac --enable-libfaac --enable-libmp3lame --enable-libx264 --disable-symver --disable-doc --disable-ffplay --enable-ffmpeg --disable-ffprobe --disable-ffserver --disable-avdevice --disable-avfilter --disable-filters --disable-devices --disable-everything --enable-avformat --enable-avcodec --enable-muxers --enable-protocols --enable-parsers --enable-demuxers --enable-decoders --enable-encoders --enable-bsfs --enable-network --enable-swscale  --disable-demuxer=sbg --disable-demuxer=dts --disable-parser=dca --disable-decoder=dca --enable-asm --enable-pthreads --enable-version3

The fdk-aac library version I'm using:

fdk-aac - 0.1.2

So it seems that the same .sdp file causes Audio object type 3 error with my build but not with static but I really do not see what causes it (granted I am not an expert with ffmpeg API and may simply miss important details).

Simplified code for opening .sdp file that doesn't include error checks and logic separation:

AVFormatContext *inputContext = NULL;

av_register_all();
avformat_network_init();

avformat_open_input(&inputContext, "test.sdp", NULL, NULL);
avformat_find_stream_info(inputContext, NULL);

int inAudioStreamIdx = av_find_best_stream(inputContext, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
AVStream *st = inputContext->streams[inAudioStreamIdx];

AVCodecContext *dec_ctx = st->codec;
AVCodec *dec = avcodec_find_decoder(dec_ctx->codec_id);

avcodec_open2(dec_ctx, dec, NULL); // Fails here with Audio object type 3

Am I opening the sdp input improperly?

Answer 1

First of, Object type 3 is AAC-SSR (It is defined in ISO 14496-3), And to the best of my knowledge it is not supported in the ffmpeg deocoder. As for the h.264 error, The 'unspecified size' message refers to the fact the decoder could not be configured with the video resolution. The resolution is specified in the SPS/PPS NALUs int he AVC Elementary Stream.

FFmpeg (specifically libavcodec) will analyze a stream for a few seconds to determine the parameters need to configure the decoders. You had a stream length of 0 seconds, hence the decoders were never configured properly. Hence the errors.