FAQs: Audio | HDMI Codec

FAQs: Audio of Codec

Why does it not work to stream to YouTube when switching audio input from HDMI to Line-in?

When you switch the audio input from HDMI to Line-in, the encoding algorithm used for streaming is not automatically adjusted, resulting in pending audio. Rebooting the device after the switch is necessary to reset the encoding algorithm and ensure that the audio is properly streamed to YouTube. This issue could be related to the audio encoding settings not properly switching when the input source is changed, thereby requiring a reboot to apply the changes.

Why are there so much noises with Aux Audio?

The presence of noise when using an auxiliary audio (Aux) connection can often be attributed to a few different factors:
  1. Interference: Noise can occur due to interference from other electronic devices or poor shielding of the audio cables. Using a shielded cable and keeping it away from other electronic devices can help reduce interference.
  2. Poor connection: If the auxiliary cable is not properly connected or if there are loose connections, it can lead to noise. Ensuring a secure and proper connection can help minimize noise.
  3. Ground loops: Ground loops can cause buzzing or humming noise in audio systems. Using a ground loop isolator can help mitigate this issue.
And it's strongly recommended to use a standard 3.5mm audio connector with two black circles and keeping the volume below 80, this is to ensure compatibility and optimal audio quality, especially for GK72 & Pro Encoder Series, MC30 Encoder Series, and TV30 Codec Series. Using the correct connector ensures that the audio is properly transmitted, and keeping the volume below 80 may prevent distortion and potential noise issues.
In summary, to minimize noise with an Aux audio connection, it's important to use a quality cable, ensure a secure connection, and address any issues related to interference or ground loops. Additionally, following the recommended connector type and volume level can contribute to better audio quality and reduced noise.

What's Audio Mix?

Audio mix refers to the process of combining multiple audio sources or tracks into a single audio output. When combining audio from HDMI and 3.5mm Line-In sources, it typically involves blending or mixing the audio signals from these sources into a single composite audio stream.

For example, in a multimedia or audiovisual setup, such as a presentation or video conference, you may want to combine the audio from a video source connected via HDMI with another audio input from a separate device using a 3.5mm Line-In connection. This could be achieved by using an EXVIST HDMI video encoder with the latest firmware released around December 2023. For more information, please refer to Available Models of Audio Mix.

What's Active Audio?

Active audio typically refers to audio components or devices that require external power to operate. In the context of audio equipment,  "active" generally refers to devices that contain built-in amplification or signal processing capabilities, which necessitate an external power source to function. This includes powered speakers, amplifiers, mixers with built-in preamps, and active audio interfaces.

What's Passive Audio?

Passive audio typically refers to a type of audio signal or system that does not require external power or an active amplifier. In the context of speakers, a passive speaker does not have a built-in amplifier and relies on an external power source, such as a separate amplifier, to drive the audio signal and produce sound.

How should we select codec type of audio?

AAC (Advanced Audio Coding) is a widely supported audio format that is ideal for live broadcasting due to its high-quality sound and efficient compression. It is commonly used for streaming audio and video content over the internet.

G.711U is a standard audio codec commonly used in video surveillance systems. It provides high-quality audio with low latency, making it suitable for real-time monitoring and recording in surveillance applications.

When setting audio for live broadcasting, you should select AAC as the audio format to ensure high-quality sound and efficient streaming. For video surveillance, G.711U is the preferred choice to ensure clear and reliable audio for monitoring and recording purposes.

What's Soundtrack

The difference between stereo, dual channel and mono

Assuming that the waveforms of the left and right channels of the dual channel are the same, there is no stereoscopic effect, and the effect is the same as that of the single channel. (That is to say, the two channels are not necessarily stereo.) When the waveforms of the left and right channels of the two channels are exactly the same, artificially creating a certain phase difference can create a wide sound field, making it three-dimensional, and artificially creating phase difference It is fixed, so this kind of stereo is called pseudo stereo. True stereo is two waveforms with completely different channels, each with a different phase difference every moment.
After understanding these principles, many novice problems can be easily solved.

Is the recording in stereo or mono?

Since a microphone can only record two sound channels with exactly the same waveform, there is no difference between single and double sound recording. The only difference is that the available capacity for recording into a dual-channel hard disk becomes smaller.

How to record in stereo?

Use a stereo microphone, or use two microphones to pick up the sound in different positions.

Should I add a mono effector or a two-channel effector?

A dual-channel effector is equivalent to two effectors working. If a mono effector is connected to the stereo, there is no side effect. Generally, the effector that affects the phase will not have a mono plug-in. For example, you are in the MONO of WAVES. You can't find the delay plugin supertap 2-Tap Mod. It doesn't matter what is monophonic.

What software can be used to eliminate the vocals in the song?

As mentioned in the previous theory, vocal cancellation is achieved through phase cancellation, so no software can really eliminate vocals, and the poor quality of the accompaniment is inevitable. Not only the vocals are canceled, but also because of the BASS and The phase difference of the drum is very small, and it is also cancelled out, so the anechoic accompaniment must be compensated for low frequency.

Why does the vocals I recorded have a very obvious muffled sound?

The walls of the room without sound absorption will cause the reflected sound and the direct sound to have a certain degree of acoustic cancellation, especially the position where the microphone is pointing, that is, the position behind the singer. Avoiding offset is a problem that must be paid attention to in recording.

Why does the audio get interrupted when streaming MP4 videos stored on a USB flash drive?

Yes, audio interruptions when streaming MP4 videos from a USB flash drive can be linked to your audio settings. If the audio in the MP4 file is at a sample rate of 44.1 kHz, it's important to ensure that your audio settings reflect this sampling rate, set to 44100 Hz. Adjusting this may help resolve the interruptions.

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