How to reduce HLS delay to 4 seconds

In live broadcast application, RTMP and HLS are two mature and widely used streaming media protocols, which can cover all clients basically. RTMP is the protocol of application layer in the five layer Internet tcp/ip architecture. The main advantage is high real-time performance, which can basically control the live broadcast delay within 3 seconds, so it is widely used in low delay live broadcast.

HLS is an HTTP based streaming media transport protocol implemented by Apple company, which has the advantages of high performance and perfect support for IOS. Compared with RTMP, HLS does not need to install app on mobile side and is compatible with HTML5. Therefore, HLS has great advantages in the spread and experience of mobile live broadcast. However, the real-time performance of HLS is poor, and the average live broadcast delay in the industry is 10s-35s.

In the HLS delay problem that makes many users most headache, the cloud shooting has been targeted to optimize the technology, and the ultra-low delay of HLS is realized, and the HLS delay is stable controlled for about 4 seconds.

Analysis of the reason of HLS high delay
Theoretically, HLS delay = the length of time of 1 slice + 0-1 TD (TD is ext-x-targetduration, which can be simply understood as the interval time between player chip taking) + 0-n startup slices (Apple officially suggests that the player should start playing after three pieces of film) + network delay of the first requested slice (Network connection time consuming).

From the formula of delay composition, the delay of HLS is mainly composed of the following four parts:
When the encoder and stream divider at the server generate TS files, HLS protocol is used to cut the media files into TS files corresponding to the media segment when they are used in live video transmission.
The interval between player chip taking and before the client starts downloading, it is necessary to wait for the encoder and stream divider on the server side to generate at least one TS file.
The time of client downloading slice and the number of slices required to start playing. Usually, after downloading two media files, seamless connection between different segments of audio and video can be ensured.
The time when the client first decodes and starts playing.
The delay optimization of HLS is mainly for the first three parts, and the fourth part is dependent on the performance of the user client.
Detailed explanation of delay hls+ technology of cloud 4S
Since the client requests ts or m3u8 every time it is a new connection request, we can not identify the client effectively. Once there is a problem, it is impossible to locate the problem effectively. Therefore, the general server will make some improvements to the traditional HLS.
It is also called streaming HLS technology. It can greatly reduce the delay of standard HLS and improve the compatibility of HTML5 live broadcast, and has the advantages of small amount of return source, simple system, easy error elimination, anti-theft chain and avoiding HLS 404.
The cloud hls+ can mark the HLS requests of each client, establish a connection for each HLS request, then dynamically generate an independent m3u8 list for each playback request, and dynamically and quickly generate the small slice file only for the playback request.
In order to solve the problem of unfriendly HLS request, the cloud uses variant hls+http 302 to identify the behavior of the client.

1、Variant HLS
First, download a m3u8 file that takes pictures of the cloud again:
one
wget  http://uplive.bo.upaiyun.com/live/loading.m3u8
Then, open the playlist file that you downloaded:
#EXTM3U
#EXT-X- VERSION:3
#EXT-X-ALLOW- CACHE:YES
#EXT-X-MEDIA- SEQUENCE:0
#EXT-X-TARGE TDURATION:1
# EXTINF:0.998 , no desc
http://183.158.35.12 :8080/uplive.b0. upaiyun.com/live/loading -0.ts?shp_ uuid=e4989f34fcab282e21ef1fd2980284cb&shp_ ts=1490172420851&shp_ cid=17906&shp_ pid=3370578&shp_ sip0=127.0.0.1&shp_ sip1=183.158.35.12&domain=uplive.b0. upaiyun.com&shp_ seqno=0
It can be seen that the hls+ which is shooting cloud supports this variant HLS method to identify an HLS connection, and UUID is used to represent an HLS connection.

2、HTTP 302
First, the playback address is requested in HTTP 302 mode.
❯ curl -v  http://uplive.b0.upaiyun.com/live/loading.m3u8 \?shp_ identify\=302 -o playlist
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
Dload  Upload   Total   Spent    Left  Speed
0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0*   Trying 183.158.35.59...
* TCP_ NODELAY set
* Connected to uplive.b0. upaiyun.com  (183.158.35.59) port 80 (#0)
> GET /live/loading.m3u8?shp_ identify=302 HTTP/1.1
> Host: uplive.b0. upaiyun.com
> User-Agent: curl/7.51.0
> Accept: */*
>
< HTTP/1.1 302 Found
< Server: marco/0.26
< Date: Wed, 22 Mar 2017 08:54:11 GMT
< Content-Type: text/plain; charset=utf-8
< Content-Length: 259
< Connection: keep-alive
< Access-Control-Allow-Methods: GET
< Access-Control-Allow-Origin: *
< Location:  http://183.158.35.19 :8080/uplive.b0. upaiyun.com/live/loading .m3u8?shp_ uuid=2862b1b817a74cf719b1cd8f554616cd&amp;shp_ ts=1490172851450&amp;shp_ cid=59553&amp;shp_ pid=1730488&amp;shp_ sip0=127.0.0.1&amp;shp_ sip1=183.158.35.19&amp;domain=uplive.b0. upaiyun.com&amp;shp_ identify=302
<
{ [259 bytes data]
* Curl_ http_ done: called premature == 0
100   259  100   259    0     0   4813      0 --:--:-- --:--:-- --:--:--  4886
* Connection #0 to host uplive.b0. upaiyun.com  left intact

 

 

 

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 WhatsApp: +8618078869184 Wechat: +8618078869184 E-mail: [email protected] QQ: 727926717 Skype: sky198710021 Address: No.305 Room HuiLan Building No.273 Huanpu Road Guangzhou China Zip:510620 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 PayPal.  www.paypal.com We recommend you use Paypal to buy our items ,The Paypal is a secure way to buy on internet . Every of our item list page bottom on top have a paypal logo to pay. Credit Card.If you do not have paypal,but you have credit card,you also can click the Yellow PayPal button to pay with your credit card. --------------------------------------------------------------------- But if you have not a credit card and not have a paypal account or difficult to got a paypal accout ,You can use the following: Western Union.  www.westernunion.com   Pay by Western Union to me : First name/Given name: Yingfeng Last name/Surname/ Family name: Zhang Full name: Yingfeng Zhang Country: China City: Guangzhou  --------------------------------------------------------------------- T/T .  Pay by T/T (wire transfer/ Telegraphic Transfer/ Bank Transfer)  First BANK INFORMATION (COMPANY ACCOUNT): SWIFT BIC: BKCHHKHHXXX Bank name: BANK OF CHINA (HONG KONG) LIMITED, HONG KONG Bank Address: BANK OF CHINA TOWER, 1 GARDEN ROAD, CENTRAL, HONG KONG BANK CODE: 012 Account Name : FMUSER INTERNATIONAL GROUP LIMITED Account NO. : 012-676-2-007855-0 --------------------------------------------------------------------- Second BANK INFORMATION (COMPANY ACCOUNT): Beneficiary: Fmuser International Group Inc Account Number: 44050158090900000337 Beneficiary's Bank: China Construction Bank Guangdong Branch SWIFT Code: PCBCCNBJGDX Address: NO.553 Tianhe Road, Guangzhou, Guangdong,Tianhe District, China **Note: When you transfer money to our bank account, please DO NOT write anything in the remark area, otherwise we won't be able to receive the payment due to government policy on international trade business. * It will be sent in 1-2 working days when payment clear. * We will send it to your paypal address. If you want to change address, please send your correct address and phone number to my email [email protected] * If the packages is below 2kg,we will be shipped via post airmail, it will take about 15-25days to your hand. If the package is more than 2kg,we will ship via EMS , DHL , UPS, Fedex fast express delivery,it will take about 7~15days to your hand. If the package more than 100kg , we will send via DHL or air freight. It will take about 3~7days to your hand. All the packages are form China guangzhou. * Package will be sent as a "gift" and declear as less as possible,buyer don't need to pay for "TAX". * After ship, we will send you an E-mail and give you the tracking number. 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 Please return to this address and write your paypal address,name,problem on note:

Our other product:

Professional lightning protection system for Tower	Professional FM Radio Station Equipment Package	FMUSER FU-1000C 1000W FM Transmitter With USB Audio Input Interface
FMUSER 200W FM Radio Broadcasting Package	Hotel IPTV Solution	FMUSER FSN-1000T V5.0 1KW FM Radio Broadcast Transmitter