This article describes how to setup RTSP/RTP based video streaming to FlashLite on Mobile using Darwin streaming server.

1. Streaming 3GP Multimedia Content to Flash Lite Using RTSP
This article explains how to set up 3GP streaming using Real-Time Streaming Protocol (RTSP) in Flash Lite
from Adobe.
Prerequisite
Flash Lite 3.x
All details mentioned in this article have been tested on Flash Lite 3.0 devices on Symbian S60 3rd
Edition mobile devices.
Darwin Streaming Server
Darwin Streaming Server (DSS) is an open source, free-to-use streaming server from Apple. The
commercial version of this server is the Quick Time Streaming Server. The open source version can be
downloaded from the following link:
http://static.macosforge.org/dss/downloads/DarwinStreamingSrvr5.5.5-Windows.exe
Perl
Perl is a prerequisite for DSS installation. Install it before installing DSS:
http://www.activestate.com/activeperl/downloads/
MP4Box
MP4Box is a tool used for “hinting” the 3GP media files. It can be downloaded from the following
location:
http://www.videohelp.com/tools/mp4box
QuickTime Player (optional)
Introduction
There are two major methods of multimedia content delivery on the internet:
1. Streaming
2. Progressive download
Streaming makes use of RTSP/RTP/RTCP protocol stacks to deliver real-time media content over the
internet. It runs on top of the UDP protocol stack, hence the delivery of RTP packets is not guaranteed.
The player has to employ error concealment algorithms to compensate for the lost packets. However,
this method is fast and there is no retransmission overhead, making it the right choice for real-time
media delivery applications such as Live TV, video conferencing, and so on. An RTSP streaming server
such as Darwin or Helix is required.

2. Progressive download, on other hand, uses the same set of protocol stacks that are used for
downloading a web page by a browser—namely, HTTP over TCP/IP protocol stacks. However, the player
doesn’t wait for the entire media file to be downloaded and can start the playback as soon as sufficient
data required for the codec to start decoding has been received. This provides the benefit of having
guaranteed delivery, hence the player doesn’t have to worry about error concealment. As a result, the
video plays without any artifacts. This method requires a standard HTTP server such as Apache.
Another option for streaming is using RTMP, which is a proprietary protocol of Adobe developed for
streaming audio/video data to Flash. RTMP also employs a TCP/IP protocol stack. It tries to achieve real-
time delivery over a reliable connection. Most Content Delivery Networks (CDNs) deploy RTMP for flash
streaming. The method requires Adobe Flash Media Server or Wowza. Red5 is an open-source flash-
streaming server.
A detailed discussion of streaming and progressive download is beyond the scope of this article.
Flash Lite 3.x supports both HTTP-based progressive download and streaming. The codecs below can be
used with each of the delivery mechanisms:
Media Container Video Codec Audio Codec
Format
Progressive Download FLV On2 VP6/Sorenson MP3
Spark
Streaming 3GP/MP4 MPEG-4/H.264/H.263 MP3/AAC
For a more detailed list of supported codecs, please see the device specifications at:
http://www.forum.nokia.com/devices/
Because this article addresses streaming, the discussion will be restricted to 3GP files. 3GP is a container
for audio and video data. Video can be encoded using MPEG-4/H.264/H.263 codecs; audio can be
encoded using the MP3 or AAC codec. Other formats may be possible but were not tested. The following
is the recommended video specification for 3G:
Resolution – 320 x 240
Frame rate – 25 frames per second (fps)
Bit rate – 360 KBps (Kilo Bits Per Second)
The recommended audio encoding is:
Sampling rate – 44.1 KHz
Channel – Stereo
Bit rate – 128 KBps

3. The above settings offer a good tradeoff between the available 3G channel bit rate and quality. H.264
outperforms MPEG-4 and H.263, that is, it gives much better visual quality for the same bit rate.
Similarly, AAC outperforms MP3 for audio. The encoding parameters, such as codec, bit rate, frame per
second, audio sampling rate, and so on, can be decided based on the application needs, available
bandwidth, and device capabilities.
Typically for 3G, a bit rate of 260 to 500 KBps gives a good performance and offers a good tradeoff
between bit rate and quality. Once the 3GP file is created, it has to be “hinted” by MP4Box to allow DSS
to stream that file. Use the following command for hinting:
Mp4box –hint filename.3gp
If hinting is not done, the player will give an unsupported format error. Once “hinted”, the files can be
placed in the following folder and streamed using DSS:
C:Program FilesDarwin Streaming ServerMovies
Darwin installation
The path given for the Movies (above) is the default location of the Darwin installation. The steps for
installing DSS are as follows:

4. Extract the DSS setup to any desired location.

5. Browse to that location and double click on install.bat. The installation will begin.

6. You will be asked for an admin password, which can be specified, or simply press Enter for no password.

7. DSS is installed as a service and there is no need to launch it manually.

8. DSS can be viewed in the list of running services (start->control Panel->administrative Tools->Services).
To test the installation, enter the following URL in the QuickTime Player. Audio and video must play.
Rtsp://IP-ADDRESS/sample_50kbit.3gp
Flash Lite coding
Coding for video playback using Flash Lite is pretty straightforward. In Adobe Flash CS4, place a video
object on the stage by right-clicking on the library, selecting New Video, and then dragging the symbol
to the stage. Give an instance name ‘videowindow_vid’ to the component. Put the following code in the
script:

9. videowindow_vid.play("rtsp://10.55.104.74/sample_50kbit.3gp");
videowindow_vid.onStatus = function(status_obj:Object) {
//handle status “"completed"”
};
The onStatus handler is invoked only for ‘completed’ status. To play back local 3GP files, instead of the
URL, use only the file name with the appropriate path.
The following are the limitations of 3GP in Flash Lite:
1. Because the native player is used, nothing can be overlaid on top of the video.
2. A streaming server is required.
3. The content requires modifications—the 3GP clips need hinting for DSS. If only audio
streaming is desired, the audio (AAC) needs to be packaged as 3GP and hinted for it to work
on a Nokia device.
4. No metadata information or player status information is received. Thus, a mechanism for
separately delivering the metadata information for the media files has to be provided so that
the player can show the duration, progress, and so on. Also, if the player buffers, the status
cannot be shown to the user.
5. Flash Lite volume control doesn’t work, so the application has to rely on the hardware
volume keys for control.