The sounds in nature are very complex and the waveforms are extremely complex. Usually we use pulse code modulation coding, ie PCM coding. The PCM converts continuously changing analog signals into digital codes through three steps of sampling, quantization, and encoding. At present, the use of audio coding has been very extensive, so what are the formats of audio coding?
PCM pulse code modulation is an abbreviation of Pulse Code ModulaTIon. In the previous text, we mentioned the general workflow of PCM. We don't need to care about the calculation method used by PCM final encoding. We only need to know the advantages and disadvantages of PCM encoded audio stream. The biggest advantage of PCM coding is that the sound quality is good, and the biggest disadvantage is the large size. Our common Audio CD uses PCM encoding, and a disc can only hold 72 minutes of music information.
Audio encoding format - WAV formatThis is an old audio file format developed by Microsoft. WAV is a file format that conforms to the RIFF (Resource Interchange File Format) specification. All WAVs have a header that contains the encoding parameters of the audio stream. WAV does not have a hard code for encoding audio streams. In addition to PCM, almost all encodings that support the ACM specification can encode WAV audio streams. Many friends don't have this concept. Let's take AVI as a demonstration, because AVI and WAV are very similar in file structure, but AVI has more video streams. There are many kinds of AVIs that we come into contact with, so we often need to install some Decode to watch some AVIs. We have more DivXs as a kind of video encoding. AVI can use DivX encoding to compress video streams. Of course, other ones can be used. Encoding compression. Similarly, WAV can also use a variety of audio encoding to compress its audio stream, but we all commonly use WAVs whose audio streams are PCM encoded, but this does not mean that WAV can only use PCM encoding, and MP3 encoding can also be used in WAV. In the same way as AVI, you can enjoy these WAVs as long as the corresponding Decode is installed. Under the Windows platform, WAV based on PCM encoding is the best supported audio format. All audio software can be perfectly supported. Because it can achieve high sound quality requirements, WAV is also the preferred format for music editing creation. Suitable for saving music material. Therefore, PCM-encoded WAVs are used as an intermediary format, often used in the conversion of other encodings, such as MP3 to WMA.
Audio encoding format - MP3 encodingAs the most popular audio compression format, MP3 is widely accepted by everyone. Various MP3 related software products are emerging one after another, and more hardware products are beginning to support MP3. Many VCD/DVD players we can buy are available. Can support MP3, there are more portable MP3 players, etc., although several major music vendors are extremely disgusted with this open format, but can not prevent the survival and circulation of this audio compression format. MP3 has been in development for 10 years. He is the abbreviation of MPEG (MPEG: Moving Picture Experts Group) Audio Layer-3, which is a derivative coding scheme of MPEG1. In 1993, it was successfully developed by the Fraunhofer IIS Research Institute of Germany and Thomson. MP3 can achieve an amazing compression ratio of 12:1 and maintain a basic audible sound quality. In the days when the hard disk price was high, MP3 was quickly accepted by users. With the popularity of the Internet, MP3 was accepted by hundreds of millions of users. The release of MP3 encoding technology was actually very imperfect at first. Due to the lack of research on sound and human hearing, the early mp3 encoders were almost all coded in a rough way, and the sound quality was seriously damaged. With the continuous introduction of new technologies, mp3 encoding technology has been improved once and for all, with two major technical improvements.
There is an audio code called Ogg Vorbis on the Internet, known as the MP3 killer! What exactly does Ogg Vorbis come from? OGG is the name of a large multimedia development project that will involve coding development in areas such as video and audio. The goal of the entire OGG project is to provide anyone with a completely free multimedia coding solution! OGG's belief is: OPEN! FREE! The term Vorbis is the name of a "Playboy" character in Terry Pratt's fantasy novel "Small Gods." This vocabulary became the official name for audio coding in the OGG project. Vorbis has been developed successfully and an encoder has been developed. Ogg Vorbis is a high quality audio coding solution. Official data shows that Ogg Vorbis can achieve better sound quality than MP3 at relatively low data rates! The Ogg Vorbis code is far more advanced than the MP3 developed in the 1990s. It can support multiple channels. What does this mean? This means that Ogg Vorbis can encode all channels with the support of SACD, DTSCD, DVD AUDIO grabbing software (currently not yet available), instead of MP3 encoding only 2 channels. The rise of multi-channel music has revolutionized music appreciation, especially when it comes to symphony. This revolutionary change is that MP3 can't adapt. Like MP3, Ogg Vorbis is a flexible and open audio encoding that can significantly adjust the sound quality and improve the new algorithm after the encoding scheme has been fixed. Therefore, its sound quality will be better and better, similar to MP3, Ogg Vorbis is more like an audio coding framework, which can be gradually introduced into new technologies. Like MP3, OGG also supports VBR.
Audio coding format - MPC codingMPC is another impressive player. Its popularity is very low-key, and there is no complicated background story. Her appearance is only one, smaller and better sound quality! MPC was formerly known as MP+, and it is clear that she can see who her competitors are. However, anyone who has used this code will have a deep impression, that is, her superior sound quality.
Audio encoding format - mp3PRO encodingOn June 14, 2001, Thomson MulTImedia SA and Fraunhofer InsTItute released a new music format version on June 14 called mp3PRO, which is a kind. The improved solution based on mp3 coding technology is indeed quite attractive from the officially published features. According to various data, mp3PRO is not a new format. It is based on the improvement of traditional mp3 coding technology. The biggest technical highlight of itself is SBR (Spectral Band ReplicaTIon band replication), which is a new kind. Audio coding enhancement algorithm. It offers the possibility to improve the performance of audio and speech coding in low bit rates. This method can increase the bandwidth of the audio or improve the coding efficiency at a specified bit rate. The biggest advantage of SBR is that it achieves very efficient coding at low data rates. Unlike traditional coding techniques, SBR is more like a post-processing technique, so the quality of the decoder's algorithm directly affects the quality of the sound. . The high frequency is actually generated by the decoder (player), and the SBR encoded data is more like a command set that generates high frequencies, or an instructional source, which is a bit of a way of working with idi. We can see that mp3PRO is actually a mixed data stream encoding of mp3 signal stream and SBR signal stream. According to relevant information, SBR technology can improve the high-frequency sound quality under low data flow, and the improvement is about 30%. We don't care how this 30% is obtained, but we can predict that this improvement can make 64kbps mp3 reach 128kbps. The sound quality level of mp3 (Note: under the same coding conditions, the data rate is improved and the sound quality is not directly proportional, at least the human ear is like this), which is comparable to the officially claimed 64kbps mp3PRO comparable to 128kbps mp3. The promotion is basically the same.
WMA is the file format encoded by Windows Media Audio. It is developed by Microsoft. WMA is not aimed at the stand-alone market, it is the network! Competitors are the famous Real Networks in the online media market. Microsoft claims that WMA can achieve near-CD sound quality at a bit rate of only 64 kbps. Unlike previous encodings, WMA supports anti-copying. She supports adding protection through Windows Media Rights Manager, which limits playback time and playback times to even playback machines. WMA supports streaming technology, which means that it can be played while reading. Therefore, WMA can easily realize online broadcasting. Because it is a masterpiece of Microsoft, Microsoft has added support for WMA in Windows. WMA has excellent technical features at Microsoft. Under the promotion, this format has been accepted by more and more people.
Audio encoding format - RA formatRA is the RealAudio format, which is a format that many worms have come into contact with. The online audition of most music websites uses RealAudio. This format is completely aimed at the media market on the network and supports very rich functions. The biggest flash point is that this format can control the bit rate according to the bandwidth of the listener, and improve the sound quality as much as possible while ensuring smoothness. The RA can support multiple audio encodings, including ATRAC3. Like WMA, RA not only supports side-by-side reading, but also supports the use of special protocols to hide the real network address of the file, thus enabling the only way to play online without providing downloads. This is very important for record companies and record sales companies. Under the promotion of all parties, RA and WMA are the most popular audio media formats on the Internet for online audition.
Audio encoding format - APE formatAPE is a lossless compression format provided by Monkey's Audio. Monkey's Audio provides Winamp plugin support, so this means that the compressed file is no longer a simple compression format, but an audio file format that can be played like MP3. This format has a much lower compression ratio than other formats, but it can be truly lossless, so it has won the favor of many fever users. In the existing lossless compression schemes, APE is a format with outstanding performance, satisfactory compression ratio and fast compression speed, which has become the only choice for many friends to exchange fever music privately.
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