Port AUDIO - RTP 🛈¶
Stimulation¶
This port has no stimulus capabilities.
Specifics¶
Multimedia streams can be sent directly to one or several recipients via IP using the Real-time Transport Protocol (RTP).
The path to an SDP file (Session Description Protocol) must be specified in the testbench configuration. This text file describes the structure of the stream and can also be created manually if the device generating the stream does not provide an SDP file.
The content can look like this, for example:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
m=audio 5004 RTP/AVP 97
a=rtpmap:97 L16/48000/2
b=AS:1536
In this file information about the stream such as the media type, transport protocol, codec
information, and further connection parameters can be defined. Moreover, the file provides essential
session and media configuration details required for establishing and interpreting the media
exchange. In particular, the line m=audio 5004 RTP/AVP 97 describes that an audio stream
arrives on port 5004, which is coded as “dynamic” (RTP/AVP 97). The actual coding of the audio data
is described in the line a=rtpmap:97 L16/48000/2. This is a Linear PCM 16 bit stereo audio
stream with a sampling rate of 48000 Hz. The ecu.test multimedia RTP audio port currently only
supports uncompressed linear PCM 8/16/32 bit audio streams with the payload type “dynamic” (96-127).
If several audio streams are described in the SDP file, the first one with a “dynamic” payload type
is selected.
An audio stream compatible with this SDP file can be generated using the command line tool ffmpeg, for example:
ffmpeg -re -stream_loop -1 -i test.mp3 -f s16le -acodec pcm_s16le -ac 2 -ar 48000 -f rtp rtp://127.0.0.1:5004
The file test.mp3 is read in an endless loop and sent to port 5004 on localhost with the
described format.
Properties 🛈¶
Name |
Available if |
Default value |
Valid values |
Type |
Description |
|---|---|---|---|---|---|
SDP file path |
string |
Path to the SDP file that describes the RTP stream. |
Jobs 🛈¶
StartRecording¶
Starts recording
StopRecording¶
Stops recording