This is a small library which can be used to serve up RTSP streams from resource constrained MCUs. It lets you trivially make a $10 open source RTSP video stream camera.
This library works for ESP32/arduino targets but also for most any posixish platform.
This library will work standalone, but it is super easy to use if your app is platform.io based. Just "pio lib install Micro-RTSP" to pull the latest version from their library server. If you want to use the OV2640 camera support you'll need to be targeting the espressif32 platform in your project.
See the example platform.io app. It should build and run on virtually any of the $10 ESP32-CAM boards (such as M5CAM). The relevant bit of the code is included below. In short:
- Listen for a TCP connection on the RTSP port with accept()
- When a connection comes in, create a CRtspSession and OV2640Streamer camera streamer objects.
- While the connection remains, call session->handleRequests(0) to handle any incoming client requests.
- Every 100ms or so call session->broadcastCurrentFrame() to send new frames to any clients.
void loop()
{
uint32_t msecPerFrame = 100;
static uint32_t lastimage = millis();
// If we have an active client connection, just service that until gone
// (FIXME - support multiple simultaneous clients)
if(session) {
session->handleRequests(0); // we don't use a timeout here,
// instead we send only if we have new enough frames
uint32_t now = millis();
if(now > lastimage + msecPerFrame || now < lastimage) { // handle clock rollover
session->broadcastCurrentFrame(now);
lastimage = now;
// check if we are overrunning our max frame rate
now = millis();
if(now > lastimage + msecPerFrame)
printf("warning exceeding max frame rate of %d ms\n", now - lastimage);
}
if(session->m_stopped) {
delete session;
delete streamer;
session = NULL;
streamer = NULL;
}
}
else {
client = rtspServer.accept();
if(client) {
//streamer = new SimStreamer(&client, true); // our streamer for UDP/TCP based RTP transport
streamer = new OV2640Streamer(&client, cam); // our streamer for UDP/TCP based RTP transport
session = new CRtspSession(&client, streamer); // our threads RTSP session and state
}
}
}
There is a small standalone example here. You can build it by following these directions. The usage of the two key classes (CRtspSession and SimStreamer) are very similar to to the ESP32 usage.
Supporting new camera devices is quite simple. See OV2640Streamer for an example and implement streamImage() by reading a frame from your camera.
Most players do a buffering. For example VLC by default sets a cache to 1000ms, resulting in a noticable delay. If you want to remove the delay set the :network-caching=0 - in the UI it's hidden under Show more options.
Please report issues and send pull requests. I'll happily reply. ;-)
The server code was initially based on a great 2013 tutorial by Medialan.
Copyright 2018 S. Kevin Hester-Chow, [email protected] (MIT License)
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