在哪里可以找到有关 WebM 直播 http 流媒体的信息？

Question

I am doing some research on the video playback features provided by HTML5. I just found that recent versions of Google Chrome and Firefox support playback of WebM encoded live video streams via HTTP with the tag.

I could not find information anywhere on how this is actually implemented. There are plenty of links to be found on the Apple HTTP Live Streaming protocol, but not much on WebM streaming.

Any useful link would be greatly appreciated.

Answer 1

Here is how I did it in Ubuntu:

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://<server_ip>:8090/0.webm and check the status at http://<server_ip>:8090/

Hope this helps.

Answer 2

Basically you need a server that can stream WebM for you.

Wowza and Flumotion are some examples.

You can read a discussion about it here