Command-line streaming webcam with audio from Ubuntu server in WebM format

Question

I am trying to stream video and audio from my webcam connected to my headless Ubuntu server (running Maverick 10.10). I want to be able to stream in WebM format (VP8 video + OGG). Bandwidth is limited, and so the stream must be below 1Mbps.

I have tried using FFmpeg. I am able to record WebM video from the webcam with the following:

ffmpeg -s 640x360 \
-f video4linux2 -i /dev/video0 -isync -vcodec libvpx -vb 768000 -r 10 -vsync 1 \
-f alsa -ac 1 -i hw:1,0 -acodec libvorbis -ab 32000 -ar 11025 \
-f webm /var/www/telemed/test.webm 

However despite experimenting with all manner of vsync and async options, I can either get out of sync audio, or Benny Hill style fast-forward video with matching fast audio. I have also been unable to get this actually working with ffserver (by replacing the test.webm path and filename with the relevant feed filename).

The objective is to get a live, audio + video feed which is viewable in a modern browser, in a tight bandwidth, using only open-source components. (None of that MP3 format legal chaff)

My questions are therefore: How would you go about streaming webm from a webcam via Linux with in-sync audio? What software you use?

Have you succeeded in encoding webm from a webcam with in-sync audio via FFmpeg? If so, what command did you issue?

Is it worth persevering with FFmpeg + FFserver, or are there other more suitable command-line tools around (e.g. VLC which doesn't seem too well built for encoding)?

Is something like Gstreamer + flumotion configurable from the command line? If so, where do I find command line documentation because flumotion doc is rather light on command line details?

Thanks in advance!

Answer 1

You should consider giving flumotion a try. You can easily set up a webm pipeline capturing from a webcam with flumotion-admin and let it run in the background.

Answer 2

I set this up recently, but it's kind of a pain. Here's what I had to do:

First, build ffmpeg from source to include the libvpx drivers (even if your using a version that has it, you need the newest ones (as of this month) to stream webm because they just did add the functionality to include global headers). I did this on an Ubuntu server and desktop, and this guide showed me how - instructions for other OSes can be found here.

Once you've gotten the appropriate version of ffmpeg/ffserver you can set them up for streaming, in my case this was done as follows.

On the video capture device:

ffmpeg -f video4linux2 -standard ntsc -i /dev/video0 http://<server_ip>:8090/0.ffm

• The "-f video4linux2 -standard ntsc -i /dev/video0" portion of that may change depending on your input source (mine is for a video capture card).

Relevant ffserver.conf excerpt:

Port 8090
#BindAddress <server_ip>
MaxHTTPConnections 2000
MAXClients 100
MaxBandwidth 1000000
CustomLog /var/log/ffserver
NoDaemon

<Feed 0.ffm>
File /tmp/0.ffm
FileMaxSize 5M
ACL allow <feeder_ip>
</Feed>
<Feed 0_webm.ffm>
File /tmp/0_webm.ffm
FileMaxSize 5M
ACL allow localhost
</Feed>

<Stream 0.mpg>
Feed 0.ffm
Format mpeg1video
NoAudio
VideoFrameRate 25
VideoBitRate 256
VideoSize cif
VideoBufferSize 40
VideoGopSize 12
</Stream>
<Stream 0.webm>
Feed 0_webm.ffm
Format webm
NoAudio
VideoCodec libvpx
VideoSize 320x240
VideoFrameRate 24
AVOptionVideo flags +global_header
AVOptionVideo cpu-used 0
AVOptionVideo qmin 1
AVOptionVideo qmax 31
AVOptionVideo quality good
PreRoll 0
StartSendOnKey
VideoBitRate 500K
</Stream>

<Stream index.html>
Format status
ACL allow <client_low_ip> <client_high_ip>
</Stream>

• Note this is configured for a server at feeder_ip to execute the aforementioned ffmpeg command, and for the server at server_ip so server to client_low_ip through client_high_ip while handling the mpeg to webm conversation on server_ip (continued below).

This ffmpeg command is executed on the machine previously referred to as server_ip (it handles the actual mpeg --> webm conversion and feeds it back into the ffserver on a different feed):

ffmpeg -i http://<server_ip>:8090/0.mpg -vcodec libvpx http://localhost:8090/0_webm.ffm

Once these have all been started up (first the ffserver, then the feeder_ip ffmpeg process then then the server_ip ffmpeg process) you should be able to access the live stream at http://:8090/0.webm and check the status at http://:8090/

Hope this helps.