Codec De Audio Y Video Para Windows 7 64 Bits
Gaspard Xenos
This codec samples audio at 44.1 or 48 kilohertz (kHz) using 16 bits, similar to the current CD standard, offering CD quality at data rates from 64 to 192 kilobits per second (Kbps). The resulting sound quality is 20 percent better than audio sampled with Windows Media Audio 8 at equivalent data rates.
The Windows Media Audio 9 codec (WMA 9) supports variable bit rate encoding (VBR), which enables even higher quality audio at smaller file sizes by automatically varying the encoding bit rate according to the complexity of the audio data. With VBR, the encoding bit rate increases to capture complex sections of data and then decreases to maximize the compression of the less complex sections, producing compact, high-quality compression.
WMA 9 is backward-compatible with previous Windows Media Audio-compatible decoders, which means that WMA 9 content can be played with previous versions of Windows Media Player or older consumer electronic devices that support Windows Media. As with all Windows Media 9 Series codecs, it supports the Windows Media digital rights management platform, which is used to securely package and distribute copy-protected digital media.
When using 5.1 surround sound audio compressed at 384 Kbps with WMA 10 Pro, most listeners cannot discern any differences between the compressed music and the original pulse code modulation (PCM) files. WMA Pro also offers dynamic range control using the maximum and average audio amplitudes that are calculated during the encoding process. Using the Quiet Mode feature in Windows Media Player 9 and later, users can hear either the full dynamic range, a medium difference range up to 12 decibels (dB) above the average, or a little difference range up to 6 dB above the average.
If a user tries to play back a file that was encoded using the 5.1 channel, 24-bit, 96 kHz sampling capabilities, but does not have a system or sound card that supports multi-channel or high-resolution sound, multiple channels are combined into stereo audio (for example, 16-bit, two channel audio), ensuring that users get the best playback experience their systems can provide.
The audio quality of content that is compressed using this codec is the best of all Windows Media Audio codecs. It creates a bit-for-bit duplicate of the original audio file so that no data is lost, which makes it ideal for archiving content masters.
Depending on the complexity of the original, content will be compressed at a 2:1 or 3:1 ratio. Although this is lower than the ratio achieved with other Windows Media Audio 9 Series codecs, it provides the same benefits of compression while leaving the data intact.
Like Windows Media Audio 9 Professional, the Windows Media Audio 9 Lossless codec also offers dynamic range control using the maximum and average audio amplitudes that are calculated during the encoding process. Using the Quiet Mode feature in Windows Media Player 9 and later, users can hear the full dynamic range, a medium difference range up to 12 dB above the average, or a little difference range up to 6 dB above the average.
This low-bit-rate codec is primarily targeted for speech content, but performs very well with mixed-mode content that includes both voice and music. In voice mode, the codec takes advantage of the relatively less complicated and narrower frequency range of the human voice to maximize compression. In music mode, the codec operates like the standard Windows Media Audio 9 codec. Encoded content can be configured to switch between voice and music modes automatically.
The Windows Media Audio 9 Voice codec offers superior quality for low-bit-rate streaming scenarios (less than 20 Kbps), such as radio broadcasts, advertising, e-books, podcasts, and voiceovers. The voice codec can also compress content to as low as 4 Kbps at 8 kHz.
* All versions of Windows Media Player for Pocket PC and Smartphone are shipped as part of the Microsoft Windows Mobile operating system. Windows Media Player for Pocket PC and Windows Media Player for Smartphone are not available for download from Microsoft.
The Windows Media Video 9 Simple and Main profiles fully conform to the SMPTE VC-1 standard and provide high-quality video for streaming and downloading. These profiles support a wide range of bit rates, from high-definition content at one-half to one-third the bit rate of MPEG-2, to low-bit-rate Internet video delivered over a dial-up modem. This codec also supports professional-quality downloadable video with two-pass and variable bit rate (VBR) encoding. Windows Media Video 9 is already supported by a wide variety of players and devices.
In the past, interlaced video content was always de-interlaced before encoding with the Windows Media Video codec. Now, encoding applications such as Windows Media 9 Series, and third-party encoding solutions can support compression of interlaced content without first converting it to progressive content. Maintaining interlacing in an encoded file is important if the content is ever rendered on an interlaced display, such as a television.
Transport independence also enables the delivery of Windows Media Video 9 Advanced Profile over systems that are not Windows Media-based, such as standards-based broadcast infrastructures (through native MPEG-2 transport streams), wireless infrastructures (using real-time transfer protocol [RTP]), or even DVDs.
The Windows Media Video 9 Screen codec is optimized for compressing sequential screen shots and highly static video that is captured from the computer display, which makes it ideal for delivering demos or demonstrating computer use for training. The codec takes advantage of the typical image simplicity and relative lack of motion to achieve a very high compression ratio.
During the encoding process, the codec automatically switches between lossy and lossless encoding modes, depending on the complexity of the video data. For complex data, the lossless mode preserves an exact copy of the data. For less complex data, the lossy mode discards some data to achieve a higher compression ratio. By automatically switching between these two modes, the codec maintains video quality while maximizing compression.
Overall, the Windows Media Video 9 Screen codec delivers better handling of bitmap images and screen motion, even on relatively modest CPUs. It is also up to 100 times more efficient than the commonly-used run length encoding.
The Windows Media Video 9 Image Version 2 codec is different from the other video codecs. Instead of processing uncompressed video, it transforms still images into video by using pan, zoom, and cross-fade transitions between clips to create an unlimited number of effects.
The Video Compression Manager (VCM) version of the Windows Media Video 9 Series codec enables earlier versions of encoding and editing applications to support the Windows Media Video 9 Series codec in file containers such as Audio Video Interleaved (AVI). This codec package also allows Windows Media Video (WMV) files based on Windows Media Format 9 Series to be played in Windows Media Player 6.4, in both ASF and AVI file containers.
*All versions of Windows Media Player for Pocket PC and Smartphone are shipped as part of the Microsoft Windows Mobile operating system. Windows Media Player for Pocket PC and Windows Media Player for Smartphone are not available for download from Microsoft.
Over a decade ago, Skype invented the Silk audio codec to transmit speech over the internet and it catalyzed the voice over internet protocol (VoIP) industry. The primary codec used in VoIP then was G.722 that required 64 kbps to transmit wide band (16 kHz) speech, Silk on the other hand offered wideband quality starting at just 14 kbps. Additionally, Silk was an adaptive variable bitrate codec that seamlessly switched from delivering narrow band (8 kHz) speech at ultra-low bandwidth of 6 kbps to offer a near transparent quality of speech at higher bit rates. This was critical for dial-up and limited broadband internet available at that time and served us well as the default codec for Skype and Microsoft Teams. Silk is also the basis of voice mode in the Opus codec, one of the default WebRTC codecs.
Silk took this a step further with the introduction of super wideband voice, capturing frequencies up to 12 kHz, sampled at 24 kHz (energy drops off rapidly at frequencies above 12 kHz for human voice). As mentioned earlier, higher sampling rates imply a higher bitrate. Satin re-defines super wideband to cover frequencies up to 16 kHz (sampled at 32 kHz) for greater clarity and sibilance, and its efficient compression enables super wideband voice at 6 kbps.
Listen to these two samples below on your headphones. The Satin super wideband speech sample sounds a lot more natural and intelligible, much like what you hear when you are talking to someone in person.
How do you achieve super wideband at 6 kbps?
To achieve super wideband quality at 6 kbps, Satin uses a deep understanding of speech production, modelling and psychoacoustics to extract and encode a sparse representation of the signal. To further reduce the required bitrate, Satin only encodes and transmits certain parameters in the lower frequency bands. At the decoder, Satin uses deep neural networks to estimate the high band parameters from the received low band parameters, and a minimal amount of side information sent over the wire.
How resilient is Satin to packet loss?
The majority of calls are on Wi-Fi and mobile networks, where packet loss is common and can adversely affect call quality. Satin is uniquely positioned to compensate for this. Unlike most other voice codecs, Satin encodes each packet independently, so the effect of losing one packet does not affect the quality of subsequent packets. The codec is also designed to facilitate high quality packet loss concealment in an internal parametric domain. These features help Satin seamlessly handle random losses where one or two packets are lost at a time.