An audio codec, or audio decoder is a device or computer program capable of encoding or decoding a digital data stream (a codec) that encodes or decodes audio.[1][2][3][4] In software, an audio codec is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format. The objective of the algorithm is to represent the high-fidelity audio signal with a minimum number of bits while retaining quality. This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most software codecs are implemented as libraries which interface to one or more multimedia players. Most modern audio compression algorithms are based on modified discrete cosine transform (MDCT) coding and linear predictive coding (LPC).
In hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains both an analog-to-digital converter (ADC) and digital-to-analog converter (DAC) running off the same clock signal. This is used in sound cards that support both audio in and out, for instance. Hardware audio codecs send and receive digital data using buses such as AC-Link, IS, SPI, IC, etc. Most commonly the digital data is linear PCM, and this is the only format that most codecs support, but some legacy codecs support other formats such as G.711 for telephony.
RTC products use many building blocks to deliver the full experience, and one of the critical components is audio/video codecs. These codecs help compress the captured audio/video data so it can be sent across the internet efficiently to the recipient, keeping the experience real time. For example, the size of raw audio captured for a typical call is 768 kbps (mono, sampling at 48kHz, bit depth 16), which modern codecs are able to compress down to 25-30 kbps. Often this compression comes at the cost of some quality (loss of information), but good codecs can strike a balance among the trio of quality, bitrate, and complexity by exploiting deep knowledge about the nature of the audio signal as well as by using psychoacoustics.
Over the last two years, we have seen development of some new machine learning (ML)-based audio codecs that provide good quality audio at very low bitrates. In October of 2022, Meta released Encodec, which achieves amazingly crisp audio quality at very low bitrates. While these AI/ML-based codecs are able to achieve great quality at low bitrates, it often comes at the expense of heavy computational cost. Consequently, only the very high-end (expensive) mobile handsets are able to run these codecs reliably, while users running on lower-end devices continue to experience audio quality issues in low-bitrate conditions. So the net impact of these newer computationally expensive codecs is actually limited to a small portion of users.
Figure 2 below shows a MOS (Mean Opinion Score) plot on a 1-5 scale and compares the POLQA scores between Opus and MLow at various bitrates. As the chart makes evident, MLow has a huge advantage over Opus at the lowest bitrates, where it saturates quality faster than Opus.
Being able to encode high-quality audio at lower bitrates also unlocks more effective Forward Error Correction (FEC) strategies. Compared with Opus, with MLow we can afford to pack FEC at much lower bitrates, which significantly helps to improve the audio quality in packet loss scenarios.
MLow builds on the concepts of a classic CELP (Code Excited Linear Prediction) codec with advancements around excitation generation, parameter quantization, and coding schemes. Figure 3 is a high-level visual of how the codec works internally. On the left we have an input signal (raw PCM audio) feeding into the encoder, which then splits the signal into two low and high-frequency bands. Then, each band is encoded separately while making use of shared information to achieve better compression. All the output is passed through a range encoder to further compress and generate an encoded payload. The decoder does the exact opposite when given the payload to generate output audio signals.
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I have my my Wharfedale 802 mixer plugged into my MAC Mini (late 2012), Processor - 2.5 GHz Intel Core i5, Memory - 4 GB 1600 MHz DDR3, via USB however it is not being recognised as USB audio CODEC what so ever. I have also tried searching for this to set the outputs in Logic and it is not recognised there either.
I understand that your Wharfedale 802 mixer is not recognized in Logic when you connect it to your Mac mini. In this situation, I would recommend reading over and working through the basic Logic Pro X troubleshooting to help isolate and resolve this issue.
I have come to the conclusion that this codec only worked on Macs that used PPC chips,not Intel Macs.Apple must have dropped it when switching to Intel.No where on the net can I find anything about this codec on newer mac OS's and newer intel Macs.
Attached is a screenshot from Audacity and it shows the USB Audio Codec. I was pulling my hair out,wondering why I couldn't see it in my audio sound setup in OSX 10.6.8 on my black Macbook.I couldn't find it in my system anywhere.This attachment showing the codec installed MUST have been done on a PPC G3,4 or 5. Nowhere does it exist on Intel Macs.
If you stream music (and who doesn't these days) you've obviously come across abbreviations at the end of the audio files. The acronyms reading WAV, FLAC, MP3 and so on, are called audio codecs. You may have wondered what they mean and even Googled them only to be overwhelmed by complex information catering strictly to audiophiles. Therefore, we decided to put together a guide explaining the concepts in layman terms.
The quality of an audio file is dependent primarily on three variables: sample rate, sample depth and bit rate. These variables are used when analog audio is converted into digital audio, and affect the overall audio quality. The higher each of these three variables are, the better your audio is going to sound.
The sampling rate refers to the number of times a sample of an audio file is taken in a second or the number of samples recorded in a single second. It is measured in samples per second or Hertz (Hz/kHz). These samples are taken at equal intervals, and affect the depth of the audio. The more samples there are in a second, the greater detail that audio signal is going to carry.
Sample rate in audio is analogous to frame rate in video. The higher the frame rate, the more depth and detail you can capture of every split-second within the video and the smoother the end product is going to be. The most common values for sample rate are 44.1kHz (most common for music CDs), and 48kHz (most common for audio tracks in movies).
The second most important variable affecting audio resolution is sample depth. Also known as sample size or sample precision, it refers to the quality of a sample. While sample rate is just a quantitative measure of the number of samples in a second, the sample depth represents the quality of each recorded sample.
As with sample rate, sample depth can also be compared to video/image quality by being analogous to 8bit or 16bit images. The bit depth of an image affects how many colors it will be able to represent. A picture that has a higher bit depth will host pixels that are more color-accurate since the pixel will have a larger color palette to be able to show the picture as realistically as possible.
In order to compress an audio file to be significantly smaller in size, certain data is strategically removed from the file. The data removed is almost always frequencies that are not audible by the human ear. Removing this data leads to a considerable amount of information being taken out from the bit stream, resulting in an overall smaller file size.
Can you please have the audio for mp4 files that are written to the memory card be more universally supported by media players? With the current audio codec used one must use ONE specific player (VLC Player) when there are tons of perfectly good codecs and players already in widespread use is a pain.
If you view a video created by a Wyze camera on a computer, you may not hear audio depending on the media player you are using. Windows' default media player does not have the proper audio codex, b...
So what you are asking is for the A-Law format to be changed. I think that is within the realm of something Wyze might be interested in, as there are so many audio problems at the moment that they may want to change that audio format as part of the cleanup process.
We can play recorded events on the device, but not if downloaded or shared with others. The issue is the codec used by Wyze is not natively supported on Andriod, iOS, Mac, PC or Chrome systems/devices. Requiring a 3rd party product, such as VLC, is not an acceptable solution. I tried using Camtasia and heard only a small burst of static then nothing. This needs fixing asap.
Downloaded directly from app, When played on my phone, no audio. Copied to my computer the d/l file, with no audio until I tried VLC. I also tried sharing from the Wyze app to the family who were not able to hear it, either.
There is no recording on the memory card - seems the advanced, local Storage, setting for Record Events Only did not record to the card. I have changed to Continuous recording and will check it later.
When I used the app to download, it downloaded. After trying to (unsuccessfully) hear the audio using the 'droid app, I copied to my computer and had the same issue with media player. When I shared it from the Event itself, same result.
Is there a way to reset the codec used in the Wyze app?