Video in Asterisk

The video features in Asterisk 1.4 include

• pass-through calling
• playback (expect some delay)
• record
• video IVR
• voicemail (recording and playback, with difficulties for greeting messages)

Some channels have support for video calls in Asterisk

• SIP
• IAX2

The H.323 channels (chan_h323, chan_oh323, chan_ooh323) do not allow video calls at this moment; however, the ChangeLog of ooh323 notes for release 0.6: "Added H.263 video codec negotiation handling"?!

Supported video codecs

• H.261
• H.263
• H.263p (Asterisk 1.4)
• H.264 (Asterisk 1.4)

It appears, however, that at least Asterisk 1.4.24 does not know about the file format h263p, which means playback and recording of calls with that codec is not supported.

Note that video support in Asterisk 1.4 is still in infancy (see general discussion below). To summarize:

• Asterisk 1.4 has issue regarding video codec negotiation
• Advanced video attributes such as profile/level (H.263+, MPEG4, H.264),bandwidth, standard annexes, framerate and image size are not exchanged and negotiated by Asterisk.
• Asterisk has no capability to playback classical video formats such as .mov, MP4 or 3gp files.
• Asterisk does not provide any video transcoding capabilities

In order to enable video in Asterisk, modify sip.conf to add:

[general]
videosupport=yes

Then for each SIP user / peer, you have to add the supported codecs (see example in this page). if you want to avoid video codec negociation in Asterisk 1.4.x unpatched, make sure that you enable a single video codec in sip.conf. The more adventurous may try the patch mentioned in this page. Of course, codecs need to be supported by the SIP phone connected to Asterisk. Asterisk will works in Passthrough mode for video.

Video IVR for Asterisk

• VXI* VoiceXML browser Video IVR / media server for Asterisk. It manages video interactive open standard applications written in VoiceXML 2.0+
• DiaStar Video play / record and video transcoding functionality allowing IVVR applications to be created for Asterisk using Dialplan commands.

Video converter for Asterisk

• FF* converter It generates video contents for Asterisk. It enables the conversion of MOV files to a pair of .H.263 video and .wav file compatible with Asterisk video rendering.

Video Conferencing Software for Asterisk

• Mediamixer of Sergio Murillo
• app_conference has some limited video support, see app_videoswitch
• Confiance solution
• VMukti Open Source VVoIP solution by VMukti.

General discussion on video support for Asterisk

In asterisk 1.4, video codec negotiation is faulty (see also this bug). A patch has been proposed by IVèS but not accepted. Also, another independent work called Asterisk videocaps was carried out to enable proper SDP negotiation of fmtp attributes related to video. This was to be merged in the trunk to be included in Asterisk 1.6.

In asterisk 1.6, a general overhaul of video support for channels was planned but no precise technical direction was set. Some would like to simply merge videocaps and build on it. Some may have more ambituous plans. Refer the Asterisk video mailing list

Another issue is also the need for a file format to store video prompts. Currently, Asterisk dumps the content of RTP packets including some timing information in .h263, ph263p, .h264 files. Sergio Murillo MP4 asterisk apps that are capable of playing or recording MPEG4 files. Some patent related issue probably prevents Digium from integrating those into Asterisk software.

Video transcoding is also not available and will probably not be integrated in Asterisk. Using ffmpeg libraries for this would again bring licensing and patent issues. Transcoding inside Asterisk would also bring performances issues to be dealt with. Again, Sergio proposes a limited transcoding app build on ffmpeg called app_transcoder. Limited in the current version but would be easy to extend for those who are skilled with ffmpeg programming.

The last topic of interest is the ability to process H324M ISDN / 3G video calls with Asterisk using again some Sergio's dev. A dedicated page in this wiki details the topic.

Clients known to support video calls with Asterisk:

• LEADTEK SIP ProductsXTP 8886 h264 Video Phone / NCP3680 SIP carephone
• Ekiga SIP H323 Video- H261. MPEG4/H263 in SVN -
• AuPix SIP and H.323 video phone
• Call Image Videotel SIP hardphone
• iFon: for PocketPC PDAs
• Linphone for Linux PC's - supports H.263p, Theora, Snow and MPEG4V. H.263p works well with Asterisk
• Microsoft Windows Messenger for Windows PC's
• Wooksung WVP-2000 SIP (hardware phone)
• Xten eyeBeam for Windows and OSX
• Huawei ViewPoint 8220
• Kapanga Sip Video Phone
• GXV-3000 Grandstream h264 and h263 Sip Video Phone (Hardware phone)
• Milliphone Open source mutli-platform softphone

Also see: SIP Video Phones

There is also some information how to make an 3G-H.324M (UMTS Video) - SIP gateway with asterisk: Asterisk H324M

Video Voicemail issue

When you record a message to a voicemail, Asterisk records video too... the only problem cames that first seconds are degraded to Intra-frame (first frame) loss while greeting message...

Call Image Videotel has special feature to get a perfect recording without any modifications on asterisk (Note: this link is dead. Seems that videotel has changed its name or is out of business).

Also: if you record a message using a given codec (let's say H.264) and retrieve the message while negociating another codec, the video part of the message will not be rendered as no transcoding function is available.

Windows Messenger and Asterisk

example sip.conf:
[general]
videosupport=yes

[video2]
type=friend
username=video2
secret=hidden
host=dynamic
context=from-camera
callerid=Video 2 <1222>
canreinvite=no
disallow=all ; Windows Messenger will choose wrong codecs if you allow=all
allow=ulaw
allow=alaw
allow=speex
allow=gsm
allow=h261
allow=h263
allow=h263p


For detailed configuration notes:

• Eyebeam with Asterisk

See also

• TMC net: Mobile video standards (Sep 2008)

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