hamza
Posts: 76
Joined: Fri Apr 03, 2015 7:16 pm

RCA or 35 mm output bad image quality

Sat May 30, 2015 10:11 am

hi

the image or video signal quality of RCA or 35 mm output is too bad ,so, does raspberry pi intrested to develop the quality of this signal??

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26442
Joined: Sat Jul 30, 2011 7:41 pm

Re: RCA or 35 mm output bad image quality

Sat May 30, 2015 10:22 am

The Composite out is done by the SoC so cannot really be changed without a HW change. The 3.5m audio is known to be fairly low quality - thats because of the cheap cost of the board, its not poassible to have a very high quality DAC on board and keep within the price budget.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

User avatar
DougieLawson
Posts: 38883
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: RCA or 35 mm output bad image quality

Sat May 30, 2015 10:31 am

What do you expect from a 576i display resolution?

It's going to be fuzzy, it's going to have ugly artifacts on desktop objects, that's the nature of analog displays.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All non-medical doctors are on my foes list.

User avatar
Burngate
Posts: 6290
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: RCA or 35 mm output bad image quality

Sat May 30, 2015 11:46 am

It's not just that there's only 576 lines, or that it's interlaced.
It's also that the colour information is inextricably mixed into the luminance. (That's why s-vhs could be somewhat better - they were kept separate)

For that reason, if the signal-path were to be redesigned so that they came out of the SoC on separate pins, the end result would be better.
Even more improvement could be seen if the R, G, B signals came out seperately. And keeping it all in the digital domain would be perfect.

Oh - hang on - we've already got that!

Return to “Beginners”