#G726 audio codec decoder driver#
Also, if for some reason the codec selected by the user does not exist in the codec list in the SDP, then the ONVIF Driver will select the first supported audio codec. In these cases, the ONVIF driver will ignore the user’s selection and will use the codec stated in the SDP. This usually is also the codec of the Audio In track. Unfortunately, a lot of ONVIF devices do not follow this convention and will list in the SDP only one codec for the Audio Backchannel track. Viewed 432 times 0 I have one line of code here but seemingly there is an.
For example, if the user has selected “G726, 32kbps, 8kHz”, the ONVIF driver will encode the audio using the G.726 codec in 32 kbps and set the payload type of the RTP packets sent to 99. Free Lossless Audio Codec (FLAC) is a codec for lossless audio compression.Grossly oversimplified, FLAC is similar to MP3, but lossless, meaning that audio is compressed in FLAC without any loss in quality. Section ”5.3.2.3” of the ONVIF Streaming Specification gives an example of SDP with multple Audio Backchannel codecs supported:īased on this SDP the ONVIF driver will select the needed codec, encode the audio stream, and send the RTP audio packets with the payload type of the codec. With one of the a=rtpmap fields provided by the server so that the server can properly The payload type and the encoded bitstream shall be matched ” The server shall list all supported decoding codecs as own media section and the clientĬhooses which one is used. Section ”5.3.2 Connection setup for a bi- directional connection” of the ONVIF Streaming Specification states: This is done by having multiple rtpmap for the Audio Backchannel track.
The selection of the codec is done in the RTSP. There is no SetAudioDecodecConfiguration in the ONVIF Specifications as there is for Audio In – SetAudioEncoderConfiguration. The ONVIF device does not have a current audio backchannel codec configuration and only lists all the supported ones using GetAudioDecoderConfigurationOptions. Selection of the codec to be used for the Audio Backchannel stream is done in a different way than all the other stream types.