µStreamer

[Русская версия]

µStreamer is a lightweight and very quick server to broadcast MJPG video from any V4L2 device to the net. All new browsers have native support of this video format, as well as most video players such as mplayer, VLC etc. µStreamer is a part of the Pi-KVM project designed to stream VGA and HDMI screencast hardware data with the highest resolution and FPS possible.

µStreamer is very similar to mjpg-streamer with input_uvc.so and output_http.so plugins, however, there are some major differences. The key ones are:

Feature	µStreamer	mjpg-streamer
Multithreaded JPEG encoding	Yes	No
OpenMAX IL hardware acceleration on Raspberry Pi	Yes	No
Behavior when the device is disconnected while streaming	Shows a black screen with NO SIGNAL on it until reconnected	Stops the broadcast 1
DV-timings support - the ability to change resolution on the fly by source signal	Yes	Partially yes 1
Option to skip frames when streaming static images by HTTP to save traffic	Yes 2	No
Streaming via UNIX domain socket	Yes	No
Debug logs without recompiling, performance statistics log, access to HTTP broadcast parameters	Yes	No
Supported input formats	YUYV, UYVY, RGB565, MJPG 3	YUYV, UYVY, RGB565, MJPG
Access to webcam controls (focus, servos) and settings such as brightness via HTTP	No	Yes
Option to serve files with a built-in HTTP server, auth settings	No 4	Yes

Footnotes:

• 1 Long before µStreamer, I made a patch to add DV-timings support to mjpg-streamer and to keep it from hanging up no device disconnection. Alas, the patch is far from perfect and I can't guarantee it will work every time - mjpg-streamer's source code is very complicated and its structure is hard to understand. With this in mind, along with needing multithreading and JPEG hardware acceleration in the future, I decided to make my own stream server from scratch instead of supporting legacy code.

• 2 This feature allows to cut down outgoing traffic several-fold when broadcasting HDMI, but it increases CPU usage a little bit. The idea is that HDMI is a fully digital interface and each captured frame can be identical to the previous one byte-wise. There's no need to broadcast the same image over the net several times a second. With the --drop-same-frames=20 option enabled, µStreamer will drop all the matching frames (with a limit of 20 in a row). Each new frame is matched with the previous one first by length, then using memcmp().

• 3 As µStreamer was made mainly to be used with screencast hardware it supports video formats they usually need. MJPG input means that the screencast device can compress images to JPEG and feed it to the software, which allows to cut down CPU usage and avoid software image encoding. This video format is supported by most webcams, but I've never seen it supported by screencast hardware: neither Auvidea B101, nor EasyCap UTV 007 offer such support. It's not hard to add hardware MJPG sources support, it's just not done yet.

• 4 ...and there'll never be. µStreamer is designed UNIX-way, so if you need a small website with your broadcast, install NGINX.

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TL;DR

If you're going to live-stream from your backyard webcam and need to control it, use mjpg-streamer. If you need a high-quality image with high FPS - µStreamer for the win.

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Building

You'll need make, gcc, libevent with pthreads support, libjpeg8/libjpeg-turbo and libuuid.

It should compile automatically with OpenMAX IL on Raspberry Pi, if the corresponding headers are present in /opt/vc/include.

$ git clone --depth=1 https://github.com/pi-kvm/ustreamer
$ cd ustreamer
$ make
$ ./ustreamer --help

AUR has a package for Arch Linux: https://aur.archlinux.org/packages/ustreamer

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Usage

Without arguments, ustreamer will try to open /dev/video0 with 640x480 resolution and start broadcasting on http://127.0.0.1:8080. You can override this behavior using parameters --device, --host and --port. For example, to broadcast to the world, run:

# ./ustreamer --device=/dev/video1 --host=0.0.0.0 --port=80

The recommended way of running µStreamer with Auvidea B101 on Raspberry Pi:

$ ./ustreamer \
    --format=uyvy \ # Device input format
    --encoder=omx \ # Hardware encoding with OpenMAX
    --dv-timings \ # Use DV-timings
    --drop-same-frames=30 # Save that traffic

You can always view the full list of options with ustreamer --help.

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License

Copyright (C) 2018 by Maxim Devaev mdevaev@gmail.com

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.