Building house on rock. (Matthew 7:24)

Mobile Applications

RTSP the future

Posted Mon, 06/22/2009 - 12:00 by eric

The first time I know about RTSP is from streaming low bit rate audio through my real player. I even thought the R in RTSP means "Real Network". It is common in this decade for using RTSP for streaming on mobile phone however the use case is getting limited.

The history was because streaming starts from PC, as RTSP make uses of RTP/UDP, it is good for real time content. Real time means instant viewing rather than download then view. Even packet lost is ok. Just like you could tolerate some noise and ghost images for your radio and TV rescpectively. However the world has changed.

Email

Posted Thu, 11/02/2006 - 13:00 by eric

Yesterday, Joe has called me. He asked me something about Email on mobile phones.

I think most people use Email just use 2 kinds of Emails:

1, POP3 for personal mails, or from ISP

2, Exchange, at work in office

When it comes across the difference between mail, exchange and blackberry, people are not sure. Well, I think many places you can find the information, but I can briefly describe here.

Streaming

Posted Mon, 07/31/2006 - 12:00 by eric

The streaming history is probably since the use of internet. At the very beginning Real Media has used an inter-based streaming, which can use either HTTP or RTSP to setup streaming.

However, as the common client is Windows based users, therefore, Microsoft has also developed their own streaming protocol, MMS (MultiMedia Streaming).

MMS - SMIL

Posted Fri, 03/31/2006 - 13:00 by eric

There are mainly 2 kinds of MMS, with or without SMIL. SMIL is Synchronized Multimedia Integration Language defined by W3C. When there is SMIL, the mime-type of body would become multipart-related, if not, it is multipart-mixed.

MMS without SMIL is just a mail with attachments, without any context. On the other hand, MMS with SMIL, then the handset should open the SMIL first and then according defined in the SMIL, it positions images, video or text with defined duration (looks like a slide show).

MMS - PDU

Posted Thu, 03/30/2006 - 13:00 by eric

Actually, since MMS is an old thing since 2G. I should say, better to refer to OMA stardard for the latest information. (Multimedia Messaging Service
Encapsulation Specification)

Same as every protocol, MMS PDU includes headers and body. The headers includes some user addresses in form of phone numbers (MSISDN) or Email addresses. There are also something about priority, delivery report, creation date... The body itself is actually a MIME Body.

MMS - Architecture

Posted Wed, 03/29/2006 - 13:00 by eric

Actually, since MMS is an old thing since 2G. I should say, better to refer to OMA stardard for the latest information. (Multimedia Messaging Service
Architecture Overview)

MMS is pretty simple, you only need a phone with PS connection (3G or GPRS) and then you send the mms content (PDU) to the MMSC via HTTP using a proxy as WAP Gateway (convert HTTP to WSP). MMSC proxy would also do user authenication so that not everyone can send or retrieve message from everyone.