Seems like a 640×480 colour video should be more complex than a stereo signal audio.
In: Technology
The video signal is a complex high frequency signal, it contains the picture synchronization for analog TVs, the black and white information as well as the color information. Its all rolled into one signal. That’s why it’s called a composite signal. It was originally transferred through high quality BNC cabling and (barely) fits through the cheap cinch cables that became the de facto standard.
Audio evolved from mono audio which only used one cable. The transmission was not usually encoded in a high frequency scheme. It was just a baseband signal and equipment did not have to decode it in any way which was cost-saving. When stereo was added, I.e. a second channel, there was a lot of existing equipment that would have been confused by an additional channel stacked on top of the existing simple signal. It was easier to just use the mono connection for mono equipment and add another cable for the second channel.
Surprising things happened when analog surround sound was added. There were complex encodings like e.g. quadrophonic vinyls that contained a high frequency four channel audio signal on the vinyl. Also there were several other analog surround formats that were somewhat backwards compatible to existing stereo equipment.
Some links:
https://en.m.wikipedia.org/wiki/Composite_video
https://en.m.wikipedia.org/wiki/Stereophonic_sound
https://en.m.wikipedia.org/wiki/Quadraphonic_sound
https://en.m.wikipedia.org/wiki/Dolby_Pro_Logic
It doesn’t have anything to do with the amount of data. The left and right audio channels are split at the source, so they each have a separate wire. The entire video signal goes down one line. When that single video channel isn’t enough (it’s really more for a cleaner picture than because of the amount of data), you need a component cable, which splits out the brightness and color in to their own separate lines.
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Cost. The audio signals are analog signals being sent along separate 2-conductor cables so that whatever device is receiving the signal doesn’t need to do anything to split the two audio streams.
Speakers are usually placed at different corners of the room for good acoustics. While 1 was enough for the video
The connectors are just that, connectors. How many you need depends on what type of signal is sent through the cables. For example there are several video signal standards that use three or even five RCA connectors. But it have become common to combine these signals into one composite signal as this is easier. This is how the signal is sent over the air so TVs already have hardware to decode it into separate signals. But even over the air the sound signals is sent as two separate signals so there is no hardware to reduce it down to one connector. Although several such standards does exist and when CDs and digital music became common it became very common to have a single digital audio connector instead of two or more connectors. For example many DVD players only required you to connect the yellow RCA connector to your TV and the orange RCA connector to your digital stereo.
Put simply, digital audio can actually be transmitted over a single coaxial (cables with RCA connectors on the end are generally coaxial cables) and even fiber optics. Once that digital signal runs through digital to analog (D/A) converter, then you’re just running analog electricity, which needs to remain in two separate circuits from there to the speaker. The sound information is actually a slight voltage change on the wire and not actual data. if you were to push both audio channels into a single wire, the signals would blend into a summed monophonic signal.
Note: You don’t listen to digital sound, ever. Every single device that produces sound is producing it from an analog source. Even bluetooth ear buds convert the data to analog before pumping it to the speakers. the D/A converter is inside the ear bud.
In fact the only way that stereo even came into existence was when someone had the brilliant idea of doubling the audio circuitry to provide audio for each ear. Even inside the amplifier, there are two discreet channels all the way out to the speaker outputs. Does that clarify?
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