Friday, July 22, 2005

Progress Report

Video Streaming: A Preliminary Report
Jenny Cheng, Jeffrey Louie Quiambao, Lily Joy Regalado

Since it has already been agreed upon by J2L, JSP and our thesis adviser that the media format to be used is 3gp, our group has been researching on technologies that we might possibly use and other related issues.

Introduction to Streaming

We have found steps in processing a video and a few related literature:

1. Acquiring a video is basically shooting a scene with a camera or gathering pre-recorded content.
We have found that MMAPI (Mobile Media API) can control a camera, audio, etc. It has also method that can set the location where to save the video. Video is fetched in this location and uploaded to the server.

2. Capturing the video includes digitizing the video into a standard format.

3. Editing the video. If broadcasting live, this can be the encoding of the streaming video directly from the source.
Editing the video means avoiding certain types of transitions and keeping the scene changes to a minimum to improve video encoding. In live streaming, this stage is skipped.

4. Encoding the clip is the encoding the source into streaming format, targeting network bandwidth(s) or set of bandwidths and choosing a codec.
Compressing or encoding the video is the process of altering the file to reduce its size. Usually, the resulting transformed digitized video file from recorded video is far too big to transmit over the Internet. Our target media format is 3gp. Most of the mobile phones support 3gp format. 3gp is already in a streaming format. It is also popular because it has a smaller size than other media formats, therefore no more encoding operations will be performed.

5. Mounting to server is streaming all relevant files to the streaming server.
We are looking at the Darwin server, an open source server for streaming via RTP or HTTP.

6. Delivering a clip. If the presentation is ready, it is in this stage when the clip made or broadcasted to different devices.

On this six stages, we are deeply looking at the first five stages, delivering the clip from the server to different devices are not very much of our concern.

Setting-up Video Streaming

The following is an option for our group:

1. Download & install Darwin Streaming Server (DSS) from http://developer.apple.com/darwin/projects/streaming/. It is an open source application.
2. Convert current video and audio files to 3GP file.
3. After the video file has been converted to a 3gp file, we can now upload it into the Darwin Streaming Server.
4. To then view it on phone, it must have Internet access. Enter the address of the server e.g. rtsp://my-server/my-file.3gp

We had to address the following issues: platform and media format. We chose Linux to be our platform.

File format is the wrapper for the encoded tracks within the file. There must be a sort of coherency between file format and codecs. The format is important for the server, because it must understand how to handle data in the file and how to properly packetize them according to RTP standards. For example Darwin needs hinted files, but other servers don't. Formats are MP4/3GP, codecs are Mpeg4 or H.263, and protocols are SDP/RTSP/RTP. So, for file based streaming, the file format is important because the streaming server must understand it, but for live streams, the file format does not exist, instead the server must know how to handle the streams, which arrive live from the encoder. As it was said before, we have agreed on using 3GP.

Outsourcing streaming services

We are looking at the differences between Live and On Demand. To stream live content in real time, we’ll need an application powerful enough to encode in real time. This is more expensive than encoding for archival purposes, wherein the media content is stored on a streaming server and is delivered on demand when an end user makes a request, and hence real time encoding is not required. Content that is streamed live is usually also recorded for archival purposes and can actually be enhanced with good editing tools for future playback.



References:
Tips For Capturing. Retrieved July 15, 2005 from http://www.clickandgovideo.ac.uk/capturing2.htm

Steaming Video: Thery, processes and Applications. Retrieved July 13, 2005 from http://aaaprod.gsfc.nasa.gov/teas/TEASStreamingVideo.ppt

Popwire. Retrieved July 13, 2005 from http://www.pats.no/events/workshop1/presentasjoner/ARTS%20pre%20March%200319.pdf

http://www.mobiledia.com/forum/topic30163.html

http://www.via.ecp.fr/via/ml/streaming/2005-05/msg00009.html

0 Comments:

Post a Comment

<< Home