JVT (Joint Video Team) was established in Pattaya, Thailand in December 2001. It is composed of video coding experts from two international standardization organizations, ITU-T and ISO. The goal of JVT is to formulate a new video coding standard to achieve the goals of high video compression ratio, high image quality, and good network adaptability. At present, the work of JVT has been accepted by ITU-T. The new video compression coding standard is called H.264 standard. This standard is also accepted by ISO, called AVC (Advanced Video Coding) standard, which is part 10 of MPEG-4.
H.264 standard can be divided into three grades:
basic level (its simple version, wide application);
Main grades (a number of technical measures to improve image quality and increase compression ratio are adopted, which can be used for SDTV, HDTV, DVD, etc.);
Extended grade (can be used for video streaming on various networks).
H.264 not only saves 50% of the code rate than H.263 and MPEG-4, but also has better support for network transmission. It introduces an encoding mechanism for IP packets, which is conducive to packet transmission in the network and supports the streaming of video in the network. H.264 has strong anti-error characteristics and can adapt to video transmission in wireless channels with high packet loss rates and severe interference. H.264 supports hierarchical coding transmission under different network resources to obtain stable image quality. H.264 can be adapted to video transmission in different networks, and has good network affinity.
One, H.264 video compression system
H.264 standard compression system is composed of two parts: Video Coding Layer (VCL) and Network Abstraction Layer (NAL). VCL includes VCL encoder and VCL decoder, the main function is video data compression coding and decoding, which includes compression units such as motion compensation, transform coding, and entropy coding. NAL is used to provide VCL with a unified interface that has nothing to do with the network. It is responsible for encapsulating and packaging video data and transmitting it on the network. It uses a unified data format, including a single byte of header information and multiple bytes. Video data and framing, logical channel signaling, timing information, sequence end signal, etc. The packet header contains storage flags and type flags. The storage flag is used to indicate that the current data does not belong to the frame being referenced. The type flag is used to indicate the type of image data.
VCL can transmit coding parameters adjusted according to the current network conditions.
2. Features of H.264
H.264, like H.261 and H.263, also adopts differential coding of DCT transform coding plus DPCM, that is, a hybrid coding structure. At the same time, H.264 introduces new coding methods under the framework of hybrid coding, which improves coding efficiency and is closer to practical applications.
H.264 does not have cumbersome options, but strives to concisely "return to basics". It has better compression performance than H.263++ and has the ability to adapt to multiple channels.
H.264 has a wide range of application goals, which can meet various video applications of different speeds and occasions, and has better processing capabilities against error and packet loss.
The basic system of H.264 does not need to use copyright, has an open nature, and can well adapt to the use of IP and wireless networks. This is of great significance for the current Internet transmission of multimedia information and mobile network transmission of broadband information.
Although the basic structure of H.264 encoding is similar to H.261 and H.263, it has been improved in many aspects, as listed below.
1. Multiple better motion estimation
High-precision estimation
uses half-pixel estimation in H.263, and further uses 1/4 pixel or even 1/8 pixel motion estimation in H.264. That is, the displacement of the real motion vector may be based on 1/4 or even 1/8 pixel as the basic unit. Obviously, the higher the accuracy of the motion vector displacement, the smaller the residual error between frames, the lower the transmission code rate, that is, the higher the compression ratio.
In H.264, a sixth-order FIR filter is used to obtain the value of 1/2 pixel position. When 1/2 pixel value is obtained, 1/4 pixel value can be obtained by linear interpolation,
For the 4:1:1 video format, the 1/4 pixel accuracy of the luminance signal corresponds to the motion vector of 1/8 pixel of the chrominance part, so 1/8 pixel interpolation operation is required for the chrominance signal.
Theoretically, if the accuracy of motion compensation is doubled (for example, from integer pixel accuracy to 1/2 pixel accuracy), there can be a coding gain of 0.5bit/Sample, but actual verification found that the accuracy of the motion vector exceeds 1/8 pixel After that, the system basically has no obvious gains. Therefore, in H.264, only the motion vector mode with 1/4 pixel accuracy is used instead of 1/8 pixel accuracy.
Multi-macroblock partition mode estimation
In the H.264 prediction mode, a macro block (MB) can be divided into 7 different mode sizes. This multi-mode flexible and subtle macro block division is more suitable for the shape of the actual moving object in the image, so , There can be 1, 2, 4, 8 or 16 motion vectors in each macro block.
Multi-parameter frame estimation
In H.264, motion estimation of multiple parameter frames can be used, that is, there are multiple parameter frames that have just been coded in the buffer of the encoder, and the encoder selects one of them to give a better coding effect as a parameter Frame, and indicate which frame is used for prediction, so that you can get a better coding effect than just using the last coded frame as the prediction frame.
2. Integer transformation of small size 4 to 4
The usual unit used in video compression coding is 8 to 8 blocks. In H.264, however, small-sized 4 to 4 blocks are used. As the size of the transform block becomes smaller, the division of moving objects is more accurate. In this case, the amount of calculation in the image transformation process is small, and the convergence error at the edge of the moving object is also greatly reduced.
When there is a large smooth area in the image, in order to avoid the grayscale difference between blocks caused by small-size transformation, H.264 can perform the DCT coefficients of 16 4~4 blocks of the intra-frame macroblock brightness data. For the second 4 to 4 block transformation, the 4 4 to 4 block DC coefficients of the chrominance data (one for each small block, a total of 4 DC coefficients) are transformed into 2 to 2 blocks.
H.263 not only reduces the size of the image transformation block, but this transformation is an integer operation, not a real number operation, that is, the accuracy of the transformation and inverse transformation of the encoder and the decoder is the same, and there is no "inverse transformation error".
3. More accurate intra prediction
In H.264, each pixel in each 4~4 block can be used for intra-frame prediction with the different weighted sum of 17 closest to the previously coded pixels.
4. Unified VLC
There are two methods for entropy coding in H.264.
Unified VLC (UVLC: Universal VLC). UVLC uses the same code table for encoding, and the decoder can easily identify the prefix of the code word, and UVLC can quickly resynchronize when a bit error occurs.
Content Adaptive Binary Arithmetic Coding (CABAC: Context Adaptive Binary Arithmetic Coding). Its coding performance is slightly better than UVLC, but the complexity is higher.
Three, performance advantage
H.264 and MPEG-4, H.263++ encoding performance comparison uses the following 6 test rates: 32kbit/s, 10F/s and QCIF; 64kbit/s, 15F/s and QCIF; 128kbit/s, 15F/ s and CIF; 256kbit/s, 15F/s and QCIF; 512kbit/s, 30F/s and CIF; 1024kbit/s, 30F/s and CIF. The test results indicate that H.264 has better PSNR performance than MPEG and H.263++.
The PSNR of H.264 is 2dB higher than MPEG-4 on average, and 3dB higher than H.263++ on average.
Four, new fast motion estimation algorithm
The new fast motion estimation algorithm UMHexagonS (Chinese patent) is a new algorithm that can save more than 90% of the original fast full search algorithm in H.264. The full name is "asymmetric cross multi-level six-sided Unsymmetrical-Cross Muti-Hexagon Search", which is an integer pixel motion estimation algorithm. Because it is in the condition of maintaining better rate-distortion performance when encoding high bit rate and large motion image sequences The computational complexity is very low and has been officially adopted by the H.264 standard.
H.264 (MPEG-4 Part 10) developed jointly by ITU and ISO may be accepted by broadcasting, communication and storage media (CD DVD) as a unified standard, and most likely to become a new broadband interactive media standard. my country's source coding standard has not yet been formulated. Pay close attention to the development of H.264, and the work of formulating my country's source coding standard is stepping up.
The H264 standard brings moving image compression technology to a higher stage, and it is the application highlight of H.264 to provide high-quality image transmission on a lower bandwidth. The popularization and application of H.264 places high requirements on video terminals, gatekeepers, gateways, MCUs and other systems, which will effectively promote the continuous improvement of video conferencing software and hardware equipment in all aspects.
|
|
|
|
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: |
|
