深入理解RTSP协议：RFC2326标准解读

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"rfc2326_Real_Time_Streaming_Protocol(RTSP).pdf" 本文档描述了互联网标准轨道协议RTSP（Real-Time Streaming Protocol），适用于互联网社区，并邀请进行讨论和改进建议。RTSP是一种应用层协议，用于具有实时特性的数据传输的控制，如音频和视频。它可以控制实时数据的按需分发，数据源可以是现场数据流或存储的片段。该协议旨在管理多个数据传输会话，选择如UDP、多播UDP和TCP等不同的交付通道，并提供选择手段。 RTSP协议的主要目标是提供一个可扩展的框架，允许对实时媒体的流式传输进行精细控制。它不仅支持即时数据流，还支持预先录制的内容。通过使用RTSP，用户可以启动、暂停、停止、快进和倒退媒体播放，就像操作本地媒体播放器一样，但控制的是远程服务器上的媒体资源。在RTSP中，客户端发送请求到服务器，指示如何处理媒体流。这些请求包括： 1. `DESCRIBE`: 客户端请求获取媒体资源的描述信息，通常包含SDP（Session Description Protocol）信息，描述媒体的编码格式、速率等。 2. `SETUP`: 客户端选择传输协议（如TCP或UDP）并建立数据传输通道。 3. `PLAY`: 启动媒体流的播放。 4. `PAUSE`: 暂停当前的媒体流。 5. `TEARDOWN`: 结束会话，关闭连接。 6. `SEEK`: 在媒体流中跳转到特定位置。 RTSP协议还支持多播，这意味着单个媒体源可以同时向多个接收者分发，节省带宽资源。此外，RTSP还可以与其他协议结合使用，例如与RTCP（Real-Time Control Protocol）一起工作，用于监测和控制媒体传输质量。 RTSP的一个关键特性是其交互性，它允许在播放过程中动态调整流的质量或方向，以适应网络条件的变化。这使得RTSP成为在线直播、视频会议和远程教育等应用场景的理想选择。尽管RTSP最初设计时考虑到了实时性和交互性，但随着时间的发展，其他技术如HTTP Live Streaming (HLS) 和MPEG-DASH也成为了流媒体领域的有力竞争者，它们通常更易于部署和实现，但可能缺乏RTSP的一些高级控制功能。 RTSP协议是实现高质量、可控的实时流媒体传输的核心工具，对于理解网络媒体传输机制和技术人员深入开发相关应用至关重要。随着物联网、5G等技术的发展，RTSP及其变体仍然在某些特定场景下保持着重要地位。

RFC 2326

Real Time Streaming Protocol April 1998

RFC 1123 \cite{rfc1123}>

port = *DIGIT

abs_path is defined in [H3.2.1].

Note that fragment and query identifiers do not have a well-defined

meaning at this time, with the interpretation left to the RTSP

server.

The scheme rtsp requires that commands are issued via a reliable

protocol (within the Internet, TCP), while the scheme rtspu identifies

an unreliable protocol (within the Internet, UDP).

If the port is empty or not given, port 554 is assumed. The semantics

are that the identified resource can be controlled by RTSP at the

server listening for TCP (scheme "rtsp") connections or UDP (scheme

"rtspu") packets on that port of host, and the Request-URI for the

resource is rtsp_URL.

The use of IP addresses in URLs SHOULD be avoided whenever possible

(see RFC 1924 [19]).

A presentation or a stream is identified by a textual media

identifier, using the character set and escape conventions [H3.2] of

URLs (

RFC 1738 [20]). URLs may refer to a stream or an aggregate of

streams, i.e., a presentation. Accordingly, requests described in

Section 10 can apply to either the whole presentation or an individual

stream within the presentation. Note that some request methods can

only be applied to streams, not presentations and vice versa.

For example, the RTSP URL:

rtsp://media.example.com:554/twister/audiotrack

identifies the audio stream within the presentation "twister", which

can be controlled via RTSP requests issued over a TCP connection to

port 554 of host media.example.com.

Also, the RTSP URL:

rtsp://media.example.com:554/twister

identifies the presentation "twister", which may be composed of

audio and video streams.

This does not imply a standard way to reference streams in URLs.

The presentation description defines the hierarchical relationships

in the presentation and the URLs for the individual streams. A

presentation description may name a stream "a.mov" and the whole

presentation "b.mov".

Schulzrinne, et. al. Standards Track [Page 15]

RFC 2326

Real Time Streaming Protocol April 1998

The path components of the RTSP URL are opaque to the client and do

not imply any particular file system structure for the server.

This decoupling also allows presentation descriptions to be used

with non-RTSP media control protocols simply by replacing the

scheme in the URL.

3.3 Conference Identifiers

Conference identifiers are opaque to RTSP and are encoded using

standard URI encoding methods (i.e., LWS is escaped with %). They can

contain any octet value. The conference identifier MUST be globally

unique. For H.323, the conferenceID value is to be used.

conference-id = 1*xchar

Conference identifiers are used to allow RTSP sessions to obtain

parameters from multimedia conferences the media server is

participating in. These conferences are created by protocols

outside the scope of this specification, e.g., H.323 [13] or SIP

[12]. Instead of the RTSP client explicitly providing transport

information, for example, it asks the media server to use the

values in the conference description instead.

3.4 Session Identifiers

Session identifiers are opaque strings of arbitrary length. Linear

white space must be URL-escaped. A session identifier MUST be chosen

randomly and MUST be at least eight octets long to make guessing it

more difficult. (See

Section 16.)

session-id = 1*( ALPHA | DIGIT | safe )

3.5 SMPTE Relative Timestamps

A SMPTE relative timestamp expresses time relative to the start of

the clip. Relative timestamps are expressed as SMPTE time codes for

frame-level access accuracy. The time code has the format

hours:minutes:seconds:frames.subframes, with the origin at the start

of the clip. The default smpte format is "SMPTE 30 drop" format, with

frame rate is 29.97 frames per second. Other SMPTE codes MAY be

supported (such as "SMPTE 25") through the use of alternative use of

"smpte time". For the "frames" field in the time value can assume

the values 0 through 29. The difference between 30 and 29.97 frames

per second is handled by dropping the first two frame indices (values

00 and 01) of every minute, except every tenth minute. If the frame

value is zero, it may be omitted. Subframes are measured in

one-hundredth of a frame.

Schulzrinne, et. al. Standards Track [Page 16]

RFC 2326

Real Time Streaming Protocol April 1998

smpte-range = smpte-type "=" smpte-time "-" [ smpte-time ]

smpte-type = "smpte" | "smpte-30-drop" | "smpte-25"

; other timecodes may be added

smpte-time = 1*2DIGIT ":" 1*2DIGIT ":" 1*2DIGIT [ ":" 1*2DIGIT ]

[ "." 1*2DIGIT ]

Examples:

smpte=10:12:33:20-

smpte=10:07:33-

smpte=10:07:00-10:07:33:05.01

smpte-25=10:07:00-10:07:33:05.01

3.6 Normal Play Time

Normal play time (NPT) indicates the stream absolute position

relative to the beginning of the presentation. The timestamp consists

of a decimal fraction. The part left of the decimal may be expressed

in either seconds or hours, minutes, and seconds. The part right of

the decimal point measures fractions of a second.

The beginning of a presentation corresponds to 0.0 seconds. Negative

values are not defined. The special constant now is defined as the

current instant of a live event. It may be used only for live events.

NPT is defined as in DSM-CC: "Intuitively, NPT is the clock the

viewer associates with a program. It is often digitally displayed on

a VCR. NPT advances normally when in normal play mode (scale = 1),

advances at a faster rate when in fast scan forward (high positive

scale ratio), decrements when in scan reverse (high negative scale

ratio) and is fixed in pause mode. NPT is (logically) equivalent to

SMPTE time codes." [5]

npt-range = ( npt-time "-" [ npt-time ] ) | ( "-" npt-time )

npt-time = "now" | npt-sec | npt-hhmmss

npt-sec = 1*DIGIT [ "." *DIGIT ]

npt-hhmmss = npt-hh ":" npt-mm ":" npt-ss [ "." *DIGIT ]

npt-hh = 1*DIGIT ; any positive number

npt-mm = 1*2DIGIT ; 0-59

npt-ss = 1*2DIGIT ; 0-59

Examples:

npt=123.45-125

npt=12:05:35.3-

npt=now-

The syntax conforms to ISO 8601. The npt-sec notation is optimized

for automatic generation, the ntp-hhmmss notation for consumption

by human readers. The "now" constant allows clients to request to

Schulzrinne, et. al. Standards Track [Page 17]

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深入理解RTSP协议：RFC2326标准解读

RTSP 协议中文版(可链接目录)

RTSP协议PDF文件，主要用vod、iptv等系统

rfc2326-RTSP.pdf

rfc2326_rtsp

rfc2327_sdp.pdf

rfc7826_rtsp2_0

rfc2326中文版pdf

from sklearn.feature_selection import SelectFromModel from sklearn.ensemble import RandomForestClassifier as RFC RFC_=RFC(n_estimators=10,random_state=0) X_embedded=SelectFromModel(RFC_,threshold=0.005).fit_transform(x,y)

linux 怎么打开RFC_FEATURE_INFO.db

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