Preface:
This article organizes ISMA-related knowledge to provide you with reference to reading related information. About Microsoft's streaming media knowledge, you can refer to other articles. Welcome everyone to discuss.
First, ISMA introduction
In order to convert the existing MPEG-4 technology to the product as soon as possible, in order to maximize the interests of each major video industry company, an important member of some video industries in December 2000 set up an organization called Internet stream media Alliance, referred to as ISMA (Internet Streaming Media Alliance). There are many familiar companies such as Cisco, IBM, Sony, Sun, NEC, Apple, Philips, Hitachi, Dolrabase, Sigma, and so on.
Second, ISMA standard introduction
ISMA has made some progress in product standardization. In August 2001, ISMA made some defined from the MPEG-4 standard, and the initial implementation of the ISMA standard See the main content of the Open source project MPEG4IP, including:
1. Video compression uses Chapter 2 of MPEG-4 (ISO14496-2)
The video resolution level defined by ISMA is only two:
a. Profile 0
· Recommended Simple Profile @ Level 1
b. Profile 1
· Name as Advanced Simple Profile @ Level 3
Comparison of SP and SAP:
The related pictures of this topic are as follows:
2. General audio compression adopts AAC format Advanced Audio Codec
3. Voice: CELP code excitation linear prediction
MPEG-4 CELP (Code Excited Linear Prediction) is a speech coding technology. Unlike general audio coders, such as AAC, which do not make any assumptions about the types of audio signal that will be represented, CELP coding is specifically designed to represent human speech. Optimizations resulting from a knowledge of the particular type of signal that will be encoded allow MPEG-4 CELP to achieve better compression than can be obtained from a general audio coder when used to encode speech.
MPEG-4 CELP operates in a narrowband (8 kHz sample rate) or a wideband mode (16-kHz sample rate) in order to achieve bit rates in the range of 4 to 12 kbps for a narrowband configuration, or approximately 11 to 24 kbps in a wideband configuration. in addition, MPEG-4 CELP supports scalable coding that allows multiple low bit-rate streams to be embedded in a single stream such that a lower quality rendering can be played back if the full rate bitstream is not completely available. 4. Media Transport Agreement: RTP, RTCP, see RFC1889 A Transport Protocol for Real-Time Applications
5. Media Control: RTSP, see RFC2326 Real Time Streaming Protocol (RTSP)
6. Media Announcement: SAP (see RFC2974 Session Announcement Protocol), SDP (see RFC2327 SESSION Description Protocol (SDP))
7. Content exchange format (Media Distribution) uses Apple's MP4 file format
a. Basic format of the MP4 file:
Atom Media Data
ATOM establishes the index of Media Data, and Media Data includes video audio data. Atom and Media Data can be in different files, or in different files.
Document illustration:
The related pictures of this topic are as follows:
b. Fluidization Technology (HINT)
Follow the corresponding standard to establish Hint Track [RTP split, INDEX, etc.], so that the file is suitable for the Internet.
Standards used by fluidization:
- RFC3640: RTP PAYLOAD FORMAT for Transport Of MPEG-4 Elementary
- RFC3016: RTP PAYLOAD FORMAT for MPEG-4 AUDIO / VISUAL STREAMS
- RFC2250: RTP PAYLOAD FORMAT for MPEG1 / MPEG2 VIDEO
Third, ISMA development estimation
DRM system
Related Standard IPMP (Intellectual Property Management and Protection)
Standard definitions and related implementations See Open Source Project OpenIPMP
2. Apply to the mobile system to go (3GPP)
File format, .3GP, compatible with MP4. The corresponding fluidization standard is estimated:
- RFC2429: RTP PAYLOAD FORMAT for the 1998 Version of Itu-t REC. H.263 Video (H.263 )
- RFC3267: RTP PAYLOAD FORMAT AND FILE Storage Format for adaptive multi-rate (amr) And Adaptive Multi-rate Wideband (AMR-WB) AUDIO CODECS3.H.264
MPEG-4 AVC (Advanced Video Codec), better compression quality. After the development of hardware, this technology will be used in a lot.
Fourth, the URL of related knowledge
ISMA organization: http://www.isma.tv
OpenIPMP item: http://sourceforge.net/projects/openipmpmpmp
MPEG4IP project: http://sourceforge.net/projects/mpeg4ip
MPEG4 Forum: http://www.m4if.org
RFC lookup: http://www.faqs.org
MPEG organization: http://www.mpeg.org
