Streaming Video in MMS

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Bryce Norwood - NowSMS Support
Board Administrator
Username: Bryce

Post Number: 2553
Registered: 10-2002
Posted on Wednesday, May 12, 2004 - 03:47 pm:   

One of the most frequently asked questions that we get asked is whether or not the Now SMS/MMS Gateway can support streaming video in MMS messages.

The answer to this question is often complicated by the fact that people often use the term "streaming video" when they're not really sure what it means.

So I thought it would be helpful to explain a few things about video in MMS environments.

I'm not an expert on streaming video technology itself, so I'm going to focus on how it relates to MMS.

MMS is basically a store-and-forward messaging technology. For more information on how MMS works, see the following links:

http://www.nowsms.com/discus/messages/1/2879.html
http://www.nowsms.com/discus/messages/1/589.html

An MMS client downloads and receives a message in its entirety before displaying the content of the message.

An MMS message contains one or more content objects. For example, an MMS message can contain text, images, audio, video, and even other content types such as vCard, vCal, or Java applications.

An MMS message also usually contains a SMIL object. SMIL (Synchronized Multimedia Integration Language) is a type of presentation language that allows a slide show type of presentation of the MMS content.

Video in today's MMS messages are limited to 10 to 20 second clips. This is primarily a size limitation. 10 seconds of video on a Nokia 6600 will be just under 100KB in size.

Every MMS phone has a size limit on the maximum size of an MMS message that it will support. Basic phones without video support may support messages no larger than 30KB. Phones with video support (like the Nokia 6600) will support at least 100KB MMS messages, and some higher end phones (like the SonyEricsson P900) may support MMS messages of 300KB to 350KB.

Of course, there are also size limits on operator systems, but they will usually support at least 100KB to accomodate short video clips.

While SMIL was originally intended to handle presentations that include streaming audio and video (referencing the object by URL), SMIL in MMS can only reference objects that are included within the MMS message (referencing the object by "content-location" or "content-id" within the MMS message).

So what is streaming video?

Streaming video is a technique that is used for the transfer and display of larger video clips (or even live video). Instead of the store-and-forward approach, where the client downloads the entire video clip before it is displayed, the client plays the video as it is downloaded. In this way, it is not necessary for the user to wait to download the entire clip before it can be played. Also, it is not necessary for the entire content of the video to be stored on the device (which is especially important when considering devices with limited storage capabilities, such as mobile phones), as the video is simply played as it is downloaded. (Of course, the device must do some buffering of the content, but this is less storage intensive.)

Does MMS support streaming video?

Yes, the MMS standard does define support for streaming video.

However, I am not aware of any devices that are currently on the market which support streaming video within an MMS message.

I am only aware of devices that support the standard video clips within an MMS message (MIME type video/3gpp).

The Open Mobile Alliance (OMA) MMS specifications refer to the 3GPP MMS specifications on the subject of streaming content in MMS (see the download references at the bottom of this message for further information).

Basically, an MMS message would contain an SDP (Session Description Protocol) object, with a MIME type of "application/sdp". An SDP object basically instructs the client how it would connect to the media server to retrieve streaming video using RTSP (Real Time Streaming Protocol).

The Now SMS/MMS Gateway can be used to transmit MMS messages that contain SDP objects, as long as the user-agent profile for the receiving device indicates that it supports "application/sdp".

If you want to allow SDP objects to be forwarded from the e-mail interface to MMS clients, then you would need to add "application/sdp" to the MMSCTYPE.INI file, which among other purposes, is used to limit what file types can be sent from e-mail to MMS.

For more information, refer to the 3GPP MMS Specification, the 3GPP Streaming Service Specifications, as well as the internet RFCs for SDP and RTSP.

It is worth noting that there are devices on the market which support streaming video, just not in the MMS client. Instead, streaming links can be opened through the device's browser, which interfaces with software that can play streaming content. For example, the Nokia 6600 includes a version of the Real Player. Any URL links that start with "rtsp://" are automatically dispatched to the Real Player so that they can be played as streaming video.

You can send one of these "rtsp://" links out to a phone using WAP push.

It is also possible to do limited video streaming over the standard HTTP protocol (or over WAP protocols), but those protocols are not optimised for streaming services. And in the WAP environment, some gateways do not properly support the headers that a streaming client needs to use.

You will find some devices on the market today that have streaming video support, like the Siemens SX1, support streaming over HTTP, but not using RTSP. (I'm not 100% certain about the SX1, but I have seen reports that it does not support rtsp:// linking.)

(Side Note: If you want to split hairs, streaming video technically is video without any sound, while streaming media is video with sound. For the most part, when most of us think of streaming video, we are expecting video with sound. Streaming protocols are not limited to just video content.)


OMA MMS Specifications:

http://www.openmobilealliance.org/tech/affiliates/wap/wapindex.html
http://www.openmobilealliance.org/release_program/enabler_releases.html#MMS

3GPP MMS Specifications:

http://www.3gpp.org/ftp/Specs/archive/23_series/23.140/

3GPP Streaming Service - General Description:

http://www.3gpp.org/ftp/Specs/archive/26_series/26.234/

3GPP Streaming Service - Protocols and Codecs:

http://www.3gpp.org/ftp/Specs/archive/26_series/26.234/

Session Descripton Protocol (SDP):

http://www.ietf.org/rfc/rfc2327.txt

Real Time Streaming Protocol (RTSP):

http://www.ietf.org/rfc/rfc2326.txt

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