Introduction to video streaming in Nokia devices

The aim of this document is to provide a very basic introduction to the Video Streaming in Nokia devices, for a deeper discussion please refer to the Forum Nokia Audio Video section that contains a lot of information on which this document is based http://www.forum.nokia.com/main/resources/technologies/audiovideo/index…..
In a mobile device you can use the pre-installed video player for two different purposes:

- Video streaming
- Stand alone local video player

The main difference between these two is that in video streaming, the compressed video data is fetched from a server during playback, whereas in the local video viewer, the video is stored locally in the memory of the device or in the memory card.

A video in streaming is often launched through the web browser or through a downloaded definition file (.RAM file), which will launch the device streaming player and open the video URL (rtsp://address/folder/).
Downloading a file first and playing it afterwards is always local playback, because the entire video file has already been stored locally. Progressive downloading means that the entire video clip doesn’t have to be downloaded to start playing it.

In order to create a video clip you have to consider these basic building blocks

When you work on video for mobile devices the compression of the file plays a very important role so you have to consider very deeply the video coding.

Keep always in your mind that a video sequence consists of a series of still images and that video compression methods are based on reducing the redundant and perceptually irrelevant parts of video sequences.
Efficient compression cannot be reached simply by reducing the redundancy of the sequence, this is the reason why video encoders must also discard some non redundant information. When doing this, the encoders take into account the properties of the human visual system and mainly discard the information that is least important for the subjective quality of the image.

In video coding some images sequences can be harder to compress due to movement or texture that have to be rendered, in order to meet a constant bit-rate target, the video encoder controls the frame rate as well as the quality of images.

Codecs

H.263 is a codec used in various multimedia services and it provides a lot of encoding tools and coding complexities for different purposes.
For the wide part of mobile multimedia services the H.263 Profile 0, Level 10 has been defined as a mandatory codec and it’s also the mainstream codec supported in Nokia video players.

MPEG-4 Visual is an optional video codec in several recent multimedia standards and it is widely supported in more recent Nokia devices this codec, also called MPEG-4 Part 2, contains different profiles for different purposes. Nokia platforms support Simple Profile 0.

RealVideo 7 and RealVideo 8 are two proprietary video coding formats developed by Real Networks, the RealPlayer installed on Nokia devices supports the decoding of video in RealVideo 7 and RealVideo 8 formats.
RealVideo 7 is similar to MPEG-4 and H.263 , RealVideo 8 is also similar to the MPEG-4 and H.263 but it is 30% to 40% better than RealVideo 7 due to major differences in the specific techniques used for transform coding.

RealVideo 10 includes enhancements on the encoder side, so it is compatible with all RealVideo 9 capable players. RealNetworks states that RealVideo 10 provides at least the same visual quality as RealVideo 9, using a 30 percent lower bit rate.

File Formats

There is a difference between the video coding format and the video file format. The coding format is related to the action of a specific coding algorithm that codes content information into a code stream. The file format is a way of organizing video and audio code streams so that they can be accessed for local decoding and playback or streamed over a transport channel.
The following list includes some of the most common video file formats today:
Microsoft Audio-Video Interleaved (AVI)Apple QuickTime file format (.mov)MPEG-1 file format (.mpg)3GPP file format (.3gp)3GPP file format (.3gp)MP4 file format (.mp4)

Nokia Platforms

The different Nokia platforms provide different (but often similar) capabilities for the video.

Platforms Capabilities
Serie 40 Can record video clips using the integrated camera of the device. The video clip is saved to the internal memory of the device or to a memory card if available. The maximum file size for a video clip is set to 100 or 300 KB by default to be able to send it as an MMS message
Serie 60 1st This serie has the Video Recorder and has two different players, the Nokia embedded Video Player and RealPlayer.
The Video Recorder can record video clips using the integrated camera. Image size is set to 128 x 96 and the maximum frame rate is 10 frames per second. The maximum multimedia file size is set to 100 KB. RealPlayer can be used to play back the recorded video clip.
The Nokia Video Player is not visible in the application grid, but it has been integrated to e-mail and the MMS client.
The optimal size for clips is 176 x 144 pixels.
Serie 60 2nd The Video Recorder can record video clips using the integrated camera. The video clip is saved either in the internal memory of the device or to a memory card. Clips are coded according to the H.263 Profile 0, Level 10 standard, or MPEG-4 Visual in some devices, image size can be selected between 128 x 96, 176 x 144, or 352 x 288 with a maximum 15 fps frame rate.
RealPlayer has been integrated to e-mail and the MMS client and is used to play back local content such as files in the memory card, e-mail, and MMS attachments.
It can also be used to stream video content from remote streaming servers over GPRS, EGPRS, Wideband CDMA (WCDMA), and CSD connections.
The optimal size for clips is 176 x 144 pixels.
Serie 60 3rd The Video Recorder can record video clips using the integrated camera. The video clip is saved either in the internal memory of the device or to a memory card. Clips are coded according to the H.263 Profile 0, Level 10 standard, or MPEG-4 Visual in some devices, image size can be selected between 128 x 96, 176 x 144, or 352 x 288 with a maximum 15 fps frame rate.
RealPlayer has been integrated to e-mail and the MMS client and is used to play back local content such as files in the memory card, e-mail, and MMS attachments.
It can also be used to stream video content from remote streaming servers over GPRS, EGPRS, Wideband CDMA (WCDMA), and CSD connections.
The optimal size for clips is 176 x 144 pixels. Note that some devices may include hardware accelerated codecs, thus allowing better resolution and bit rates.
Serie 80 This serie reflect all the capabilities of Serie 60 3rd edition but it support a maximum of 10 fps.

Use this table as a basic reference, you find more info on Forum Nokia.

Streaming

Streaming is the transmission of real-time data, both audio and video, from a server to a client, where the client decodes and plays the data as it is received. Streaming lets the viewer see the content immediately after a short buffering period. One advantage compared to local playback is that no data will be stored permanently to the terminating client. The end user cannot forward or send the content to another user, so the content can be charged each time it is consumed. This is one great advantage for service providers.
If the content is to be served within a particular operator’s service domain only, appropriate authoring guidelines are usually available from the operator or the service provider.

Server products

There are several products that you can use in order to deliver your video on mobile devices: Open Streaming Server is an digital media delivery. Main characteristics are: – Streaming of mp4, 3gp, WMF, QT files – Dynamic Bandwidth adaptation – Load balancing – Content distribution Technology: C++, Java and CORBA http://sourceforge.net/projects/openstreamingQuickTime Streaming Server is Apple’s industrial-strength, standards-based streaming server for delivering media in real time over IP networks. Using the open standard RTP/RTSP streaming protocol, QuickTime Streaming Server provides native streaming of MPEG-4 and 3GPP files http://www.apple.com/quicktime/streamingserver/Helix Server is the only multi-format, cross platform streaming server for delivering the highest quality experience to wired and wireless devices http://www.realnetworks.com/products/media_delivery.html

Terms and meanings

Use this table as a quick reference for the most common terms used in the video streaming on mobile devices

Term Meaning
3GPP MIME subtype for 3GPP file format; also Third Generation Partnership Project (gen.)
3GP or 3gp File name extension for 3GPP file format
ADPCM Adaptive Pulse Code Modulation
AMR-NB Adaptive Multi-Rate Narrow Band speech codec
AMR-WB Adaptive Multi-Rate Wideband speech codec
API Application Programming Interface
AVI Microsoft Audio-Video Interleaved file format
CSD Circuit Switched Data
DCT Discrete Cosine Transform
GPRS General Packet Radio System
GSM Global System for Mobile Communication
HSCSD GSM High-Speed Circuit Switched Data
Hz Hertz, 1/sec >
IMA Interactive Multimedia Association
ITU-T International Telecommunication Union, Telecommunication Standardization Sector
Kbit/s kilobits per second
MMS Multimedia Messaging Service
MOV or mov File name extension for Apple QuickTime file format
MPEG ISO/IEC Moving Pictures Experts Group
MPG or mpg File name extension for MPEG-1 file format
MP3 MPEG-1 Audio Layer 3 audio coding
MP4 MIME subtype for MPEG-4 file format
mp4 File name extension for MPEG-4 file format
NIM Nokia Interleaved Multimedia file format
PCM Pulse Code Modulation
QCIF Quarter Common Intermediate Format
RAM or ram File extension for RealNetworks’ simple URI descriptor files
RGB Red-Green-Blue color space
RM or rm File extension for RealMedia file format

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