Raspberry Pi Forums

I recently bought a composite cable so I can see the output of my Raspberry Pi 3 on my PC, with VLC, and this is what I see: The question is: what do I blame for the image quality issues?
1. The Pi's composite output?
2. The composite cable?
3. The USB capture device? (ID 05e1:0408 Syntek Semiconductor Co., Ltd STK1160 Video Capture Device)

Hmm... I'll try the output on my TV and find out if the capture device is to blame. I hope it will be that simple.

Composite output is low resolution. It is designed to work on an old standard definition TV. That's (barely) adequate for watching non-HD videos.

The best output on the Pi is the HDMI, which can easily handle HD video and a bit higher. Ideally you plug the Pi directly into a monitor.

Perhaps you can find a USB HDMI capture device for your PC?

Otherwise try one of the VNC options (I can't remember which is the best to use on a Pi), or perhaps stream the video over a network from the Pi to your PC.

kneekoo wrote: ↑

Fri Dec 22, 2017 4:43 am

I recently bought a composite cable so I can see the output of my Raspberry Pi 3 on my PC, with VLC, and this is what I see:
vlcsnap-2017-12-21-20h58m53s568.jpg

The question is: what do I blame for the image quality issues?
1. The Pi's composite output?
2. The composite cable?
3. The USB capture device? (ID 05e1:0408 Syntek Semiconductor Co., Ltd STK1160 Video Capture Device)

Hmm... I'll try the output on my TV and find out if the capture device is to blame. I hope it will be that simple.

In my experience, what you see (color bleeding) is about what I would expect from a CRT monitor if you feed it composite video, and use such a "high" resolution.
There is a reason why homecomputers tended to use no more than 40 characters per line.

Why do you think the use of composite was abandoned for computer displays.

If the photo above is the output of the video capture device then that is as good as can be expected. Consider it good if you can read the text at all. Direct to a TV won't be much better. Composite on an LCD TV will be a bit better than to a CRT TV.
Composite does not do well, and was never intended to be used with text or static images from computers.

When television was being invented, 575 lines of black-and-white was considered high definition.
Then they decided they wanted colour! All in the same bandwidth!
So they modulated the extra information onto a carrier inside the 5MHz, and hoped it wouldn't disturb people with monochrome tellies.
To make it less disagreeable they made the carrier an odd harmonic of the line frequency so that any interference would cancel on alternate lines, then moved it a bit more so it would not be static

You could, of course, turn down the colour on your monitor, except that you monitor probably hasn't got that nob

Burngate wrote: ↑

Fri Dec 22, 2017 7:17 pm

When television was being invented, 575 lines of black-and-white was considered high definition.

With standard definition being about 30 lines on the very first tellies and later (the first TV I remember watching) 405 lines.

Thanks everyone for your feedback. I didn't get to test it today so I'll just add a few more details. I bought the composite cable mostly for travel purposes, in case I find myself in a place with RCA inputs only. But having the Pi's display on my PC (in a window) is quite useful, regardless of the type of session (text or graphical). I didn't know what to expect, but I expected the picture to look normal.

To make it crystal-clear, here's my setup:
Raspberry Pi 3 -> composite cable -> USB capture device (on another PC) -> VLC (Open Capture Device)

As for my screenshot, it's Raspbian lite. I didn't need a GUI so I didn't want to waste resources with the full desktop, not to mention the useless wearing of the microSD card to update the required packages for the graphical environment and all the software for it - so no VNC/TeamViewer/etc.

My monitor has 2 HDMI inputs but no picture-in-picture feature, so I can only get one A/V source at a time. Is there another way to get a nice quality image from the Pi?

Oh, and on another microSD card, with PIXEL, I switched the sound from HDMI to Analog but I got no sound from the Pi. I turned up the volume everywhere: VLC, the USB capture device, and my Pi, but no sound. So I'll really have to test it on my TV. Or is there some config.txt directive I should set? The audio is set to Auto in raspi-config, and Raspbian is fully updated.

Here's how it looks. The movies looked reasonable with deinterlacing enabled in VLC but the rest of the desktop looks fuzzy. And I don't know why sometimes Kodi doesn't cover the whole screen while playing back the movies. Oh well, that's entirely out of the scope of this thread. I will obviously be unable to make screenshots with my tests on the TV, but I'll let you know if I get a decent picture and maybe sound.

Cheers!

The composite audio/video output works great on an LCD TV, so the blame is my video capture device and/or its driver. While the video could be better (though it's nearly pixel-perfect), the audio is much better than I expected - no issues at all.

Merry Christmas!