Shulou(Shulou.com)06/03 Report--

This article mainly introduces "how much kHz is the sampling rate of RTP video". In the daily operation, I believe that many people have doubts about the sampling rate of RTP video. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubt of "how much kHz is the sampling rate of RTP video"! Next, please follow the editor to study!

- -

Software download address: http://www.qiyicc.com/download/rtmpd.zip

Github address: https://github.com/superconvert/smart_rtmpd

- -

Why is the sampling rate of RTP video 90kHz?

In fact, I have always had this question, and there are also some explanations on the Internet. I feel a little too far-fetched and imperfect. Today, I'm going to tell you about the origin of this.

Then how can it be more persuasive? Of course, I quote the classics and refer to our RFC.

Among them, section 5 of rfc3551 is introduced in this way.

5. Video

The following sections describe the video encodings that are defined

In this memo and give their abbreviated names used for

Identification. These video encodings and their payload types are

Listed in Table 5.

All of these video encodings use an RTP timestamp frequency of 90000

Hz, the same as the MPEG presentation time stamp frequency. This

Frequency yields exact integer timestamp increments for the typical

24 (HDTV), 25 (PAL), and 29.97 (NTSC) and 30 Hz (HDTV) frame rates

And 50, 59.94 and 60 Hz field rates. While 90 kHz is the RECOMMENDED

Rate for future video encodings used within this profile, other rates

MAY be used. However, it is not sufficient to use the video frame

Rate (typically between 15 and 30 Hz) because that does not provide

Adequate resolution for typical synchronization requirements when

Calculating the RTP timestamp corresponding to the NTP timestamp in

An RTCP SR packet. The timestamp resolution MUST also be sufficient

For the jitter estimate contained in the receiver reports.

For most of these video encodings, the RTP timestamp encodes the

Sampling instant of the video image contained in the RTP data packet.

If a video image occupies more than one packet, the timestamp is the

Same on all of those packets. Packets from different video images

Are distinguished by their different timestamps.

Most of these video encodings also specify that the marker bit of the

RTP header SHOULD be set to one in the last packet of a video frame

And otherwise set to zero. Thus, it is not necessary to wait for a

Following packet with a different timestamp to detect that a new

Frame should be displayed.

From the above we can see that 90 kHz is equivalent to the frequency of MPEG rendering timestamps. At the same time 90 kHz satisfaction

The need for multiple formats and frequency band timestamps to grow to integers is to reduce timestamp deviation. Meanwhile, 90 kHz

It also meets the needs of RTCP SR computing NTP synchronization, and also meets the estimation of jitter in receiving reports.

In a nutshell: 90 kHz is the chosen son of RTP video timestamp!

At this point, the study on "how much kHz is the sampling rate of RTP video" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.