- Capture video from Raspberry Pi Camera and encode it to H.264 using hardware encoder
- Capture audio from USB microphone or Wolfson Audio Card via ALSA and encode it to AAC-LC using libavcodec (FFmpeg)
- Record audio/video to MPEG-TS files
- Generate files for HTTP Live Streaming with optional encryption
- If microphone is not available, it only records the video
Time from real motion to playback on Strobe Media Player over RTMP:
| Video bitrate | Minimum latency |
|---|---|
| 300 Kbps | 0.3 sec |
| 500 Kbps | 0.6 sec |
| 1 Mbps | 0.8 sec |
| 2 Mbps | 1.0 sec |
| 3 Mbps | 1.3 sec |
In HTTP Live Streaming (HLS), the latency will never go below 3-4 seconds. This limitation stems from the design of HLS.
The above results were tested with:
- Video: 1280x720, 30 fps, GOP size 30
- Audio: 48 Khz mono, 40 Kbps
- RTMP Server: node-rtsp-rtmp-server
- Client: Flash Player 14,0,0,145 on Firefox 31.0 for Mac, using test/strobe_media_playback.html
- Network: Wi-Fi network created by a USB dongle attached to Raspberry Pi
- Raspberry Pi
- Raspberry Pi Camera Board
- USB microphone (see Recommended hardware) or Wolfson Audio Card
- Raspbian
- Arch Linux
picam binary is available at https://github.com/iizukanao/picam/releases/latest
picam preinstalled Raspbian image is also available. If you use an SD card larger than 4GB, run raspi-config and expand the filesystem after you boot Raspbian.
If you want to build picam yourself, see INSTALL.md.
First, find ALSA device name of your microphone.
$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
ALSA device name is consisted of hw:<card>,<device>. In the above example, the ALSA device name is hw:1,0.
If you got no soundcards found error, try sudo arecord -l. If that output looks good, you might want to add your user to audio group.
$ sudo usermod -a -G audio $USER
(once logout, then login)
$ groups
wheel audio pi <-- (make sure that audio is in the list)
$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
Run picam with your ALSA device name.
$ ./picam --alsadev hw:1,0
configuring devices
capturing started
You can take advantage of RAM drive (/run/shm/) and reduce access to SD card. It also provides better quality of recording.
First, stop picam if it is running. Create rec, hooks, and state directories in /run/shm/, then change directories with the same name in picam to symbolic links. Create another symbolic link from /run/shm/rec/archive to somewhere on SD card.
Result:
picam
| ...
|-- archive
|-- hooks -> /run/shm/hooks
|-- rec -> /run/shm/rec
`-- state -> /run/shm/state
/run/shm/
|-- hooks
|-- rec
| |-- archive -> /home/pi/picam/archive
| `-- tmp (automatically created by picam)
`-- state
To start recording, create a file named hooks/start_record while picam command is running.
$ touch hooks/start_record
You will see start rec in the picam command output.
To stop recording, create a file named hooks/stop_record.
$ touch hooks/stop_record
The recorded MPEG-TS file is in rec/archive/ directory.
To convert MPEG-TS to MP4, run:
$ ffmpeg -i test.ts -c:v copy -c:a copy -bsf:a aac_adtstoasc test.mp4
To mute microphone temporarily, create a file named hooks/mute.
$ touch hooks/mute
To unmute microphone, create a file named hooks/unmute.
$ touch hooks/unmute
$ ./picam --help
picam version 1.3.0
Usage: picam [options]
Options:
[video]
-w, --width <num> Width in pixels (default: 1280)
-h, --height <num> Height in pixels (default: 720)
-v, --videobitrate <num> Video bit rate (default: 2000000)
Set 0 to disable rate control
-f, --fps <num> Frame rate (default: 30.0)
-g, --gopsize <num> GOP size (default: same value as fps)
--vfr Enable variable frame rate. GOP size will be
dynamically controlled.
--minfps <num> Minimum frames per second. Implies --vfr.
It might not work if width / height >= 1.45.
--maxfps <num> Maximum frames per second. Implies --vfr.
It might not work if width / height >= 1.45.
--rotation <num> Image rotation in clockwise degrees
(0, 90, 180, 270)
--hflip Flip image horizontally
--vflip Flip image vertically
--avcprofile <str> Set AVC/H.264 profile to one of:
constrained_baseline/baseline/main/high
(default: constrained_baseline)
--avclevel <value> Set AVC/H.264 level (default: 3.1)
--qpmin <num> Minimum quantization level (0..51)
--qpmax <num> Maximum quantization level (0..51)
--qpinit <num> Initial quantization level
--dquant <num> Slice DQuant level
[audio]
-c, --channels <num> Audio channels (1=mono, 2=stereo)
Default is mono. If it fails, stereo is used.
-r, --samplerate <num> Audio sample rate (default: 48000)
-a, --audiobitrate <num> Audio bit rate (default: 40000)
--alsadev <dev> ALSA microphone device (default: hw:0,0)
--volume <num> Amplify audio by multiplying the volume by <num>
(default: 1.0)
--noaudio Disable audio capturing
[HTTP Live Streaming (HLS)]
-o, --hlsdir <dir> Generate HTTP Live Streaming files in <dir>
--hlsenc Enable HLS encryption
--hlsenckeyuri <uri> Set HLS encryption key URI (default: stream.key)
--hlsenckey <hex> Set HLS encryption key in hex string
(default: 75b0a81de17487c88a47507a7e1fdf73)
--hlsenciv <hex> Set HLS encryption IV in hex string
(default: 000102030405060708090a0b0c0d0e0f)
[output for node-rtsp-rtmp-server]
--rtspout Enable output for node-rtsp-rtmp-server
--rtspvideocontrol <path> Set video control socket path
(default: /tmp/node_rtsp_rtmp_videoControl)
--rtspaudiocontrol <path> Set audio control socket path
(default: /tmp/node_rtsp_rtmp_audioControl)
--rtspvideodata <path> Set video data socket path
(default: /tmp/node_rtsp_rtmp_videoData)
--rtspaudiodata <path> Set audio data socket path
(default: /tmp/node_rtsp_rtmp_audioData)
[MPEG-TS output via TCP]
--tcpout <url> Enable TCP output to <url>
(e.g. --tcpout tcp://127.0.0.1:8181)
[camera]
--autoex Enable automatic control of camera exposure between
daylight and night modes. This forces --vfr enabled.
--autoexthreshold <num> When average value of Y (brightness) for
10 milliseconds of captured image falls below <num>,
camera exposure will change to night mode. Otherwise
camera exposure is in daylight mode. Implies --autoex.
(default: 5.0)
If --verbose option is enabled as well, average value of
Y is printed like y=28.0.
--wb <value> Set white balance. <value> is one of:
off: Disable exposure control
auto: Automatic white balance control (default)
sun: The sun provides the light source
cloudy: The sun provides the light source through clouds
shade: Light source is the sun and scene is in the shade
tungsten: Light source is tungsten
fluorescent: Light source is fluorescent
incandescent: Light source is incandescent
flash: Light source is a flash
horizon: Light source is the sun on the horizon
--metering <value> Set metering type. <value> is one of:
average: Center weight average metering (default)
spot: Spot (partial) metering
matrix: Matrix or evaluative metering
backlit: Assume a backlit image
--evcomp <num> Set Exposure Value compensation (-10..10) (default: 0)
--shutter <num> Set shutter speed in microseconds (default: auto).
Implies --vfr.
--iso <num> Set ISO sensitivity (100..800) (default: auto)
-p, --preview Display fullscreen preview
--previewrect <x,y,width,height>
Display preview window at specified position
--query Query camera capabilities then exit
[misc]
--recordbuf <num> Start recording from <num> keyframes ago
(default: 5)
--statedir <dir> Set state dir (default: state)
--hooksdir <dir> Set hooks dir (default: hooks)
-q, --quiet Suppress all output except errors
--verbose Enable verbose output
--version Print program version
--help Print this help
HTTP Live Streaming is disabled by default. To enable HTTP Live Streaming and generate files in /run/shm/hls, run:
$ ./picam -o /run/shm/hls
Optionally you can enable encryption for HTTP Live Streaming. We will use the following settings as an example.
- HTTP Live Streaming output directory: /run/shm/hls/
- Encryption key: 0xf0f1f2f3f4f5f6f7f8f9fafbfcfdfeff
- Encryption IV: 0x000102030405060708090a0b0c0d0e0f
- Encryption key file: enc.key
First you have to create a file named "enc.key" which contains 16-byte encryption key. To create such file, run:
$ echo -n $'\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff' > enc.key
Put enc.key in /run/shm/hls/ directory. Then, run picam with the following options:
$ ./picam -o /run/shm/hls --hlsenc --hlsenckeyuri enc.key \
--hlsenckey f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff \
--hlsenciv 000102030405060708090a0b0c0d0e0f
You can watch the HTTP Live Streaming by accessing /run/shm/hls/index.m3u8 via HTTP or HTTPS with QuickTime Player.
To use picam with nginx-rtmp-module, add the following lines to nginx.conf:
rtmp {
server {
listen 1935;
chunk_size 4000;
application webcam {
live on;
exec_static /path/to/ffmpeg -i tcp://127.0.0.1:8181?listen
-c:v copy -ar 44100 -ab 40000
-f flv rtmp://localhost:1935/webcam/mystream;
}
}
}
Note that /path/to/ffmpeg should be replaced with the actual absolute path to ffmpeg command.
Start nginx server, then run:
$ ./picam --tcpout tcp://127.0.0.1:8181
You can access your live stream at rtmp://YOUR_RASPBERRYPI_IP/webcam/mystream.
To upload streams from picam to Ustream, run ffmpeg with the following options. RTMP_URL and STREAM_KEY can be obtained from Ustream's Channel settings → Broadcast settings → Encoder settings.
$ ffmpeg -i tcp://127.0.0.1:8181?listen -c:v copy -c:a aac -strict -2 -ar 44100 -ab 40000 -f flv RTMP_URL/STREAM_KEY
Then, run picam to start streaming.
$ picam --tcpout tcp://127.0.0.1:8181
Any cheap USB microphone should work as long as it is supported by ALSA. I have tested this program with the combination of:
- USB to 3.5mm audio adapter: PLANEX PL-US35AP
- Microphone: ELECOM MS-STM95
LGPL v2.1, as some parts of FFmpeg source is included.