Video and audio encoder introduction

MPEG stands for (Moving Pictures Experts Group) and belongs to the International Organization for Standardization (ISO). They have developed a series of video and audio codecs. The most familiar one is MP3 and MPEG-1/2/4.

Earlier video encodings were of poor quality and were mainly used for CD-ROM storage of video. The most familiar one in China is VCD (Video CD), and his video encoding uses MPEG-1.

A video codec developed on the basis of MPEG-1. Its quality is far better than that of MPEG-1, so it is used on DVD-Video. MPEG-2 is the only specified video codec for DVD-Video. MPEG-2 is not only used in DVD-Video, but now most HDTV (high-definition television) also uses MPEG-2 encoding, with a resolution of 1920x1080. Due to the popularity of MPEG-2, MPEG-3, which was originally prepared for HDTV, was finally abandoned.

In order to cope with the environment such as network transmission, the traditional MPEG-1/2 can no longer adapt, so the birth of MPEG-4 was promoted. MPEG-4 adopts a series of new technologies to meet the demand of transmitting higher video quality under low bandwidth. DivX, XviD, and MS MPEG4 all use MPEG-4 video coding. In addition to the application on DVDRip, 3GPP now also accepts MPEG-4 as the video coding scheme.

It and MPEG-4 are two different encodings, mainly because MPEG-4 does not perform well at very low bit rates, and AVC is more suitable for low-bandwidth transmission. At high bit rates, AVC performs better than MPEG-4, so there is a trend to replace MPEG-4. The next generation of HD DVD and Blue Ray Disc have officially adopted AVC as one of the video coding schemes. I believe that the future of AVC will be very good.

That is, MP1, MP2, the earlier audio coding, is the predecessor of MP3, mainly used for VCD, DVD, SVCD audio coding.

The well-known MP3 has become the mainstream format of network audio, which can approach CD sound quality at a bit rate of 128kbps.

A new audio codec developed on MPEG-2 is not compatible with traditional MPEG Audio. Its quality is theoretically higher than MP3 and supports multi-channel. Within the code rate range of 96kbps, it can be close to CD sound quality, which is more suitable for bit rate transmission than MP3. MPEG-4 AAC AAC has been used as the MPEG-4 standard audio codec. Of course, MPEG-4 Audio has many other audio codecs.

AAC using SBR band replication technology, SBR technology can reduce the bit rate of audio coding by half without much change in sound quality, and has become a part of the MPEG-4 standard.

An audio format developed by NTT has disappeared for a while, and has only been seen in Nero. Now that the SBR technology has entered the MPEG-4 standard, it seems that it is not reconciled to be forgotten. It is said that it performs better than aacPlus at low bit rates.

MP3 is a product born with the addition of SBR technology, but it has not been promoted much, and it has not entered the standard.

Let MP3 plug in multi-channel wings, another MP3 upgrade product developed by Fraunhofer, I heard that DivX 6 is going to use it as an audio codec. Fraunhofer has always been upgrading MP3, mp3PRO, MP3 Surround, these products are compatible with traditional MP3, but with the endless new encoding, I don't know how far MP3 can go.

Speaking of MPEG, one cannot fail to mention the biggest beneficiary of MPEG-2-DVD. Of course, this refers to DVD-Video and DVD-Audio, and some HD DVDs are also involved. DVD encodings are all application-level, they do not develop their own encoding, which should be distinguished from MPEG.

DVD is the audio coding standard in fact, and all DVDs now use it to compress audio, provide a maximum 5.1-channel output support, and can store high-quality audio in a limited space.

The audio encoding of the next generation of HD DVD is an upgraded version of AC3, supporting 7.1 or more channels, and the code rate range has also been greatly improved.

The lossless audio coding on HD DVD was also developed by Dolby Company, and the highest sampling can reach 192KHz, which is also the audio coding standard of DVD-Audio.

DTS was originally an audio system developed for movie theaters, and then it was applied to DVDs. It is a strong competitor of AC3, but only D9 can be seen in the DVD. Although the majority of enthusiasts are advocating that its effect is better than AC3, the test is not as good as expected, especially in high frequency. Not as good as AC3.

The audio coding of the next generation of HD DVD, it and Dolby Digital Plus are both designated as mandatory coding, and it seems that it will be evenly matched with Dolby in the future.

PCM encoding without compression can only store two channels, but the sampling rate can be as high as 96KHz, which is the best sound quality in DVD-Video, and of course the volume is the largest.

It is mainly MP2, which is applied to DVD of PAL format, with high compression rate and supports multi-channel (MPEG-2 specification supports multi-channel).

This seems to be a long way off, but as the biggest competitor of DVD-Audio SACD, let me introduce it by the way. DSD (Direct Stream Digital), introduced by Sony, can avoid the disadvantages of traditional PCM encoding and achieve very high quality. The highest sampling is the same as DVD-Audio, 192KHz.

The coding series led by "ITU (International Telecommunication Union)" is mainly used in the real-time video communication field, such as conference TV. As the MPEG series has also begun to enter this field, the two organizations have also begun close cooperation. For example, the recently popular AVC/H.264 is the "VCEG (Video Coding Experts Group) Video Coding Experts Group) under the ITU. It was jointly produced and released by "MPEG (Moving Pictures Experts Group)" under the "ISO (International Organization for Standardization) International Standardization Organization".

H.261 was formulated by ITU-T for the development of two-way audio-visual services (video telephony, video conferencing) on the Integrated Services Digital Network (ISDN). It is the earliest moving image compression standard, and it has formulated the video coding system in detail. Each part includes motion-compensated inter-frame prediction, DCT transformation, quantization, entropy coding, and rate control adapted to a fixed-rate channel.

H.263 is a video coding standard formulated by ITU-T for narrowband communication channels lower than 64kb/s. It is developed on the basis of H.261.

The second version of H.263 has added many new technologies to expand the application range of H.263.

Several options have been added to H.263+ to enhance the error-resistance performance of the bit stream on harsh channels and at the same time improve the enhanced coding efficiency.

It is the aforementioned MPEG-4 AVC. H.264 is a new generation video compression coding standard formulated by the Joint Video Group (JVT) composed of ISO/IEC and ITU-T. In ISO/IEC, the standard is named AVC (Advanced Video Coding), as the 10th option of the MPEG-4 standard; it is officially named as the H.264 standard in ITU-T.

Now one of the hottest topics in the communications field, since we talked about MPEG and ITU, and these two intricate 3GPP applications, we have to mention it. 3GPP’s video uses MPEG-4 and H.263 encoding, and may also add H.264. Audio uses AAC for music compression, and uses advanced AMR for voice. Another aacPlus is introduced with the V2 version. The effect under the rate is more prominent, and it is also expected to join the standard.

The audio and video coding series led by Microsoft, which appeared mainly for network video transmission, has now marched into HDTV and developed the WMV HD application.

The earliest video encoding used by ASF was developed based on MPEG-4 technology. DivX3.11 was cracked based on Microsoft MPEG-4 v3 and was rewritten later.

The first Windows Media Video officially developed by Microsoft began to break away from MPEG-4 and was incompatible with MPEG-4. From this point, we can see Microsoft's ambitions. Unfortunately, the compression effect of this version is very bad, breaking Microsoft's soaring dream, but it is very fast in compression. Now there are many WMV compressed in this format on the Internet.

Microsoft's highlight is not only this encoding, but the V9 series is a platform that allows Microsoft to challenge MPEG, ITU and other standardization organizations. Although this version is not as strong as Microsoft's, especially at low bitrates, it is relatively poor, but compared with the previous version, it is still very much improved. In particular, the application of WMV HD has allowed Microsoft to enter the field of video standards.

The encoding used by WMV HD is compatible with WMV9, optimized for high bit rate, and the picture is excellent. (But can the bit rate of dozens of megabytes be excellent? It's all because of the volume.)

The encoder introduced with Windows Media Player 10 can further control the quality of WMV9. But it cannot be played on the old version of WMP9, which means it is not compatible with the old version of WMP9. I really don’t know what Microsoft is doing?

Lossless compression encoding for static screens, with very good quality and high compression rate, only for environments with very small changes such as screens.

Microsoft's earliest audio coding technology, used in ASF, was later cracked and used in DivX Audio, and the quality was relatively poor.

With the corresponding audio coding introduced by various WMVs, the quality has been improved steadily, but it has not yet reached the deification of 64kbps CD sound quality.

The new coding in WMA9 is mainly used for multi-channel coding and high sampling rate audio coding, and the quality is good.

For voice coding, the maximum is 20kbps, but compared with AMR, the effect is too bad.

Lossless audio coding can perfectly preserve the original quality of the CD, and is a good choice for CD backup, but at the cost of being too large.

The series of encoding technologies developed by RealNetworks are also mainly used for network transmission and perform well at the bottom bit rate.

The early RealVideo encoding was of poor quality, but it was very advanced on the Internet at that time. After all, not many people were able to watch videos on the Internet at that time.

The video format introduced with RealPlayer 8 is now one of the mainstream network video encoding. The encoding speed is slow, and the quality is only average.

RealNetworksThe quality of the new generation of code developed has improved a lot, especially at the bottom bit rate, and the coding speed is very fast, achieving a good unity of speed and quality.

On the basis of RealVideo 9, some parameters have been added, such as EHQ, etc., to control the bit rate more accurately and be compatible with RealVideo 9.

Earlier audio coding, but it seems that the quality is still good, but the maximum bit rate is 96kbps. Applied to two generations of audio coding: RealAudio G2, RealAudio 8.

The improved version of Cook adds 5.1 channel support and is applied to RealAudio 10 Multichannel.

It adopts Sipro speech coding technology, mainly for speech coding, and is used in the earlier RealAudio 4.0 and RealAudio 5.0.

The ATRAC3 codec developed by Sony was purchased by RealNetworks and applied to RealAudio 8 to make up for the lack of Cook's high bitrate.

The aacPlus audio codec is used in RealAudio 10, but it is not distributed with RealProducer and needs to be purchased separately. RealAudio Lossless Lossless audio coding.

QuickTime is not an encoding, but a multimedia platform. There are many encodings on it. Only a few mainstream encoders are introduced here.

The encoder developed by Sorenson Media is mainly used for QuickTime 4 video encoding, and the quality is poor.

The encoder released by Sorenson Media with QuickTime 5 is of very good quality and has become the standard video encoding of QuickTime. Most movie trailers on the Internet use this encoding.

The MPEG-4 encoder developed by Apple itself was released with QuickTime 6, and the quality is very poor.

The H.264 encoder developed by Apple, released with QuickTime 7, supports HDTV. QDesign Music 1 This version of the audio encoder developed by QDesign is no longer available.

The second and final version of QDesign Music, in the face of these advanced audio coding, it has no vitality, mainly used in online movie trailers.

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.

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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 .

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