After the development of the live broadcast APP is completed, the technicians must not only test the integrity of the source code and the compatibility of the equipment, but also take into account the influence of the network on the live broadcast, because network instability is the most important factor that causes the live broadcast picture and sound delay. In fact, there are some non-network factors that can also cause delays in the development of live streaming apps.
Today, the editor will sum up with you all the situations that cause network delays.
1. Network delay
This refers to the time difference between collection from the host and playback at the audience. Even if you don’t consider the host’s collection The time it takes to encode the video and the time it takes the viewer to decode the video model will inevitably cause delays. The reason is that the information on the "distance" from the host to the viewer may pass through many CDN nodes and pass through once. , There will be a distribution process, and this process will inevitably cause delay. In addition, the data transmission process also involves logical interactions, such as packet retransmission and confirmation, and some logic on the cache, which will add many more on this basis.
2. Network jitter
Network jitter refers to the inconsistency of the arrival sequence, interval, and time of data packets. For example, if N+1 data packets are sent, each table is sent out every 1s. As a result, the N-50th packet encounters network congestion during transmission, resulting in packet N-50 not arriving immediately after N-51. Instead, it arrives after N is delayed. This situation will cause the content to be played out in the order of reception, otherwise it will cause distortion. In order not to produce distortion, it is inevitable to cause playback delay.
3. network packet loss
Streaming media transmission protocols such as RTMP and HLS used in live broadcasts are all based on TCP. A very important feature of TCP is its reliability-no data loss problems will occur. In order to ensure reliability, TCP will have a 3-way handshake during the transmission process: First, the client will send a connection request to the server, and after the server agrees, the client will confirm the connection, which is the 3-way handshake. Then, the client starts to send data, each time it sends a batch of data, after getting the "received" confirmation from the server, it continues to send the next batch. Then the problem arises. In order to ensure the transmission, TCP will have an automatic retransmission mechanism. If packet loss occurs during transmission and the "received" signal from the peer end is not received, the local end will automatically retransmit the lost packet until the timeout period expires. Network packet loss is a difficult factor to control, so when the network packet loss rate begins to increase, retransmission will cause the delay to continue to increase.
4. RTMP cumulative delay
Although in the streaming media transmission protocol, RTMP is undoubtedly the most used, but it also has a more significant weakness, that is, cumulative error. The reason is relatively simple, that is, RTMP is based on TCP: When the network status is poor, the server will buffer the packet, which will cause accumulated delays. When the network status is good, they will be sent to the client together. The countermeasure for this is to cause The client's buffer is too large, which causes delays.
5. GOP-Cache (delay caused by image group)
Group of pictures, referred to as GOP. In order to let everyone understand more intuitively, directly put the picture: Image source: https://www.processon.com/view/56ebb341e4b01c9aeb5f137f The above are the main reasons that may cause delays in the live broadcast. If you have other opinions on this, please leave a message to the editor in the comment area.
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How far(long) the transmitter cover?
The transmission range depends on many factors. The true distance is based on the antenna installing height , antenna gain, using environment like building and other obstructions , sensitivity of the receiver, antenna of the receiver . Installing antenna more high and using in the countryside , the distance will much more far.
EXAMPLE 5W FM Transmitter use in the city and hometown:
I have a USA customer use 5W fm transmitter with GP antenna in his hometown ,and he test it with a car, it cover 10km(6.21mile).
I test the 5W fm transmitter with GP antenna in my hometown ,it cover about 2km(1.24mile).
I test the 5W fm transmitter with GP antenna in Guangzhou city ,it cover about only 300meter(984ft).
Below are the approximate range of different power FM Transmitters. ( The range is diameter )
0.1W ~ 5W FM Transmitter ：100M ~1KM
5W ~15W FM Ttransmitter : 1KM ~ 3KM
15W ~ 80W FM Transmitter : 3KM ~10KM
80W ~500W FM Transmitter : 10KM ~30KM
500W ~1000W FM Transmitter : 30KM ~ 50KM
1KW ~ 2KW FM Transmitter : 50KM ~100KM
2KW ~5KW FM Transmitter : 100KM ~150KM
5KW ~10KW FM Transmitter : 150KM ~200KM
How to contact us for the transmitter?
Call me +8618078869184 OR
Email me [email protected]
1.How far you want to cover in diameter ?
2.How tall of you tower ?
3.Where are you from ?
And we will give you more professional advice.
About Us
FMUSER.ORG is a system integration company focusing on RF wireless transmission / studio video audio equipment / streaming and data processing .We are providing everything from advice and consultancy through rack integration to installation, commissioning and training.
We offer FM Transmitter, Analog TV Transmitter, Digital TV transmitter, VHF UHF Transmitter, Antennas, Coaxial Cable Connectors, STL, On Air Processing, Broadcast Products for the Studio, RF Signal Monitoring, RDS Encoders, Audio Processors and Remote Site Control Units, IPTV Products, Video / Audio Encoder / Decoder, designed to meet the needs of both large international broadcast networks and small private stations alike.
Our solution has FM Radio Station / Analog TV Station / Digital TV Station / Audio Video Studio Equipment / Studio Transmitter Link / Transmitter Telemetry System / Hotel TV System / IPTV Live Broadcasting / Streaming Live Broadcast / Video Conference / CATV Broadcasting system.
We are using advanced technology products for all the systems, because we know the high reliability and high performance are so important for the system and solution . At the same time we also have to make sure our products system with a very reasonable price.
We have customers of public and commercial broadcasters, telecom operators and regulation authorities , and we also offer solution and products to many hundreds of smaller, local and community broadcasters .
FMUSER.ORG has been exporting more than 15 years and have clients all over the world. With 13 years experience in this field ,we have a professional team to solve customer's all kinds of problems. We dedicated in supplying the extremely reasonable pricing of professional products & services. Contact email : [email protected]
Our Factory
We have modernization of the factory . You are welcome to visit our factory when you come to China.
At present , there are already 1095 customers around the world visited our Guangzhou Tianhe office . If you come to China , you are welcome to visit us .
At Fair
This is our participation in 2012 Global Sources Hong Kong Electronics Fair . Customers from all over the world finally have a chance to get together.
Where is Fmuser ?
You can search this numbers " 23.127460034623816,113.33224654197693 " in google map , then you can find our fmuser office .
FMUSER Guangzhou office is in Tianhe District which is the center of the Canton . Very near to the Canton Fair , guangzhou railway station, xiaobei road and dashatou , only need 10 minutes if take TAXI . Welcome friends around the world to visit and negotiate .
Contact: Sky Blue
Cellphone: +8618078869184
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Wechat: +8618078869184
E-mail: [email protected]
QQ: 727926717
Skype: sky198710021
Address: No.305 Room HuiLan Building No.273 Huanpu Road Guangzhou China Zip:510620
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English: We accept all payments , such as PayPal, Credit Card, Western Union, Alipay, Money Bookers, T/T, LC, DP, DA, OA, Payoneer, If you have any question , please contact me [email protected] or WhatsApp +8618078869184
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Beneficiary: Fmuser International Group Inc
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For Warranty .
Contact US--->>Return the item to us--->>Receive and send another replace .
Name: Liu xiaoxia
Address: 305Fang HuiLanGe HuangPuDaDaoXi 273Hao TianHeQu Guangzhou China.
ZIP:510620
Phone: +8618078869184
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