AV Receivers are a complicated and sometimes misunderstood component of home theater systems. It’s not incredibly clear what they do with all that bulk. Sure, there are ports all over the front and all over the back, but what are they all for? The heavy lifting here is routing sound channels to the sound system properly, so it’s clear Receivers help manage and upgrade the audio side of things. But what about the video?
AV Receivers do effect video quality. They can improve lower quality signals through video processing like up-scaling. But, they can also degrade quality by adding unnecessary video processing to signals that don't need it. The “bypass” feature will ensure that no post-processing of the signal occurs, allowing you to preserve the source quality.
It’s a classic case of unintended consequences. AV systems are designed to simplify your setup by managing the sound channels from many sources into one expensive surround sound system. But in the process they end up handling the video signals too. Manufacturers use this opportunity to add their own branded “secret sauce” to the signal in the form of extra processing of sharpness, resolution upscaling, lighting changes, etc. but, depending on the source, this can decrease quality rather than increase it.
Possible Causes of Picture Quality Degradation
Maybe you already have an AV system, or you have a new unit you’re testing out, and you’re wondering if what you’re seeing is of the highest quality possible. It’s useful, then, to discuss for a moment what forms this quality degradation can take. If your AV unit is doing any post-processing, it might be touching the image up so much that you’ll start to notice things like graininess or over-saturation.
The term “noisy” is used to describe this added graininess of an image. It starts to look like there's a sort of fog through which the video is being broadcast. The colors are still there, but more muted than they otherwise would be. The “noise” in the image takes the form of constant variations of color and light at each pixel, which may even make it look like the grains are “dancing” around, or shimmering on the screen.
What’s happening here? You have a clean signal at the source, then it goes through the AV receiver and something happens, something changes, and now it’s grainy. Without going into too much detail, the AV receiver is processing the signal to make it better, but really it’s injecting a variable that the content producer and source device aren’t expecting–they’re expecting to be sent directly to a screen.
When Post-Processing Helps
But sometimes the picture looks just fine, right? If AV post-processing made all images grainy, nobody would use it and it wouldn’t be “a thing” at all. So it’s obvious that this must be good for some people, and some videos. Really, it’s going to come down to the quality of the source. If your’e running a Roku stick or streaming Netflix from a laptop or Xbox, the signal is going to be somewhat compressed, and post-processing probably has a good shot of tightening some aspects of it up.
However, if your content source is already of the highest quality–think a 4K projector or expensive blu-ray player sending out Dolby Vision HDR content, that signal is already the best it’s going to be, and adding another variable, remixing it, is not going to go well.
Resolution Upscaling
Optimizing video quality in general is one thing, but what about resolution upscaling? After all, there’s nothing mysterious going on here–it’s easy to take a small image and simply blow it up, right? Sort of.
The core concept is simple enough, but it gets complicated when you understand that this is a process of amplification. Whatever is in the source, it’s going to get blown up and amplified during the upscale process. And as the old saying goes: “garbage in, garbage out.” A low quality signal, say a VHS or DVD of an older movie (or even some recent movies that simply weren’t shot well) may have problems with lighting, saturation, and hue that you actually don’t notice in the lower formats, but will reveal themselves when the image is upscaled.
What’s more, devices often have their own upscaling built in. Blu-ray players and TVs, along with the AV box, may all be running upscaling operations on their own, but this should be mitigated by the fact that upscaling effects the output signal which can turn off upscaling downstream. To put it clearly: if your blu-ray player upscales a 1080p signal to 4k, then your AV receiver or TV will “see” that signal coming in and know it doesn’t need to upscale it any further.
So what does “bad” upscaling look like? It’s hard to say for sure, because the upscaling on each device can be different, but the best thing you can do is figure out which of your devices is doing the upscaling (check the settings and manuals…or just Google it) and then toggle it on and off and make a call yourself which way looks better.
How Am I Supposed to Use a Receiver?
The price points and features in this category are, quite frankly, all over the place. An entry unit, like the Yamaha RX-V385, can handle 5.1 sound output and will manage 4 HDMI inputs. A similar model a few tiers up, the Yamaha RX-V685, sports 7.2 channel sound output and can manage 5 inputs and 2 outputs. It also has some creature comforts like Spotify and Airplay built in.
Unfortunately, the product description for most of this equipment focuses on the input/output ports and all the graphical and sound standards they meet. They both seem to have auto-upscaling, though they don’t come right out and say it. There are plenty of options to sort through, and if you want some help, be sure to read through our recommended AV receivers page.
If you’re trying to pick a model that will optimize your video, take into account the sources of video you have. Then, read through the comments and see if anyone is having picture with their quality, and what their setup is like. In the end, you should be ready to send it back if you get a unit that doesn’t meet your needs. But you should be able to play with any video post-processing once you’re up and running.
Takeaway
AV receivers do some things exceptionally well. They can take multiple video inputs and combine them into 1 output, providing a streamlined solution for running many devices to one screen. They also allow you to drive all those inputs to your surround sound speakers, for full immersion.
But in their pursuit of delivering you a final solution, AV receivers stumble into doing too much. Some models execute upscaling and source video processing whether you ask them to or not, and this can create video quality issues.
To make sure this doesn’t happen to you, get comfortable with the settings menu and bypass or disable that post-processing; force your Receiver to focus on the job it does best: managing inputs and outputs. Not remixing them.
