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Thread: All about the audio / video connections

  1. #1
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    All about the audio / video connections

    Introduction

    The connectors are often seen as a secondary element of a home theater or audiophile. It is a big mistake because they will ensure the transfer of the signal (both image and sound) between the different elements. If their quality is poor the whole chain is affected.

    Do not hesitate to invest primarily in their price, compared with the different devices will be up 10 to 15% of the total cost.

    Analog? Digital? HDMI? YUV? coaxial? Which connector to use for better quality?

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    Digital signal and analog signal at a glance

    Digital signal and analog signal at a glance

    There are two main categories of signals passing through different connections. These analog and digital signals. Accordingly, an analog signal using an analog connection and a digital signal using digital connections. Increasingly left analog to digital place whatsoever in the field of audio or video.

    The analog signal

    The analog signal is the oldest. It contains infinite continuous values which are not limited by sampling. Although digital is becoming the analog is not about to disappear.

    In addition to its lower cost, the analogy is not subject to restrictions imposed by digital technology. It gradually ceded its place for various reasons including its high sensitivity to its environment, its degradation continues and reproducibility is more difficult.

    Whether in audio (coaxial, SPDIF) or video (HDMI, DisplayPort) leaves the analog to digital place.

    The digital signal

    The digital signal does not contain continuous values, but a signal to two amplitudes consisting of a sequence of 0 and 1. Therefore it can be copied and / or reproduced as many times as needed without loss. A parasite which can affect an analog signal will have no effect on digital.

    In short

    The analog signal is very sensitive to its environment. When it deteriorates, the correction is almost impossible. Digital is insensitive to its environment and integrates systems for correction of errors. He is however a much more important than his predecessor.

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    The video connectors

    The video connectors

    SCART (Scart)
    It is still more of the connector used every were. It can carry the video and sound but only in analogue. It does not achieve maximum quality with video equipment. It has 21 pins and allows the devices to link them (VCR and TV for example). Unfortunately all SCART connectors are not of similar quality. Some do not RGB son. The same goes for televisions. The integrated scart above do not support all RGB signal. The best is to read the documentation.


    S-Video
    The S-video connector is very present on the computer graphics cards. Conveys an analog signal. It offers high quality but lower in the composite component. The signal is decomposed into luminance and chrominance. These two signals pass through each coaxial cable of 75 ohms independent. The connectors have four pins: 1 - mass luminance, 2 - mass chroma, 3 - Luminance 4 - chrominance.


    Composite
    This is the analog connector with the worst quality. It is very common today. Luminance and chrominance are mixed. It is often found with the RCA audio connectors, red and white. It is strongly advised to use if an alternative is offered.


  4. #4
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    video connectors

    Component (Y-Cb-Cr, YUV)
    This is analog connector that provides the best results (excluding RGB). One of the cables is the luminance, the other two red and blue. It is also with the connector that you can have on very many devices an image resolution higher.


    VGA (RGB, D-SUB 15, HD-15)
    This is the most common connection on the computer graphics cards. It has 15 pins and pass the three green, blue, red and the horizontal and vertical. The signal is analog and does that image.


    DVI
    This is a digital interface that conveys the image. Used mainly in computers, however it is found on other devices. There are currently 3 types of DVI connectors:

    • DVI-A: only sends the analog signal
    • DVI-D: only transmits the digital signal
    • DVI-I: forward separately or DVI-D or DVI-A



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    HDMI connections

    HDMI
    Also known as Digital Scart. This connector is present on all new video equipment. It helps convey the image and sound. 1.3 The current standard provides a maximum transmission rate of 340Mpixels per second. In addition to the high definition video HDMI can carry an audio signal up to 8 channels uncompressed. Dolby True HD and DTS-HD Master Audio are supported with the standard 1.3.

    The HDMI connector type A has 19 pins, the type B pin 29. It enables support for high resolutions.


    DisplayPort
    Latest addition is not yet present in the different devices. Digital, it allows the transport of image and sound. Its maximum flow rate is 10.8 Gbit / s.

  6. #6
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    The audio connectors

    The audio connectors

    RCA (also known as Cinch)
    These connections transits a signal only in analogue. It is very sensitive to the external environment. Do not hesitate to invest in good quality cables to avoid any deterioration of the signal. The maximum quality stereo is obtained. Red = Right Channel, White = Left Channel.




    Coaxial
    The coaxial connector allows you to pass a digital audio signal. In practice, this allows the receiver device (often an amplifier) to make himself the decoding of the signal. Beware the new HD audio formats can not pass on this connection. Their speed is too large for the capacity of this connector (see HDMI).



    Optical (Toslink)
    The Toslink connector incorporates the same characteristics as the coaxial. Beware the new HD audio formats can not pass on this connection. Their speed is too large for the capacity of this connector (see HDMI).



    Note on the audio connectors in a home theater


    The new HD audio formats like DTS HD Master Audio HDMI connections need to be transported. Another solution is to buy a high definition player equipped with analog audio outputs. This will decode the signal and send it separately on the different audio outputs. The amplifier will then route the signal as received to the various speakers.

    To learn more about audio formats, see our guide on standards Audio (Coming soon).

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    Quality of the various cables

    Quality of the various cables

    This is a question that many of the world arises. The audio and video cables are all of equal quality? The obvious answer is no!

    This does not mean it should pay large sums of money to acquire. Two main parameters are taken into account: your level of requirement and the investment you've spent on your equipment. The third parameter concerns the type of cable and the signal that transits: analog or digital.

    In digital it is not necessary to acquire high-end connectivity if you're not a hobbyist. The standard cables are already very good results. According to our tests, HDMI no perceptible change to the human eye is visible.

    Analog is the opposite. It is strongly recommended to buy good quality cables, often gold plated. Remember that the analog signal is easily affected by its external environment. Cables with RCA or s-video you will see the difference immediately. This is not an investment unnecessary but absolutely essential. Why spend 500 euros in an amplifier if the cables degrade the signal?

    Shielding and long-distance

    Buy quality cables becomes an obligation when you want to transmit a signal over a long distance. The high-end cables are less sensitive to the distance a product entry. Analog always prefer a shielded cable.

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