maemo.org - Talk
Page 2 of 2 1 2
Show 40 post(s) from this thread on one page

maemo.org - Talk (https://talk.maemo.org/index.php)
-   Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)
-   -   TV Out question (https://talk.maemo.org/showthread.php?t=52757)

quipper8 2010-05-17 14:13
Re: TV Out question
 
having plugged mine in to many hotel and friends and work tvs, i can tell you that the quality of the picture varies greatly between tvs and is more about the tv than the n900

attila77 2010-05-17 14:39
Re: TV Out question
 
Quote:
Originally Posted by acou (Post 660753)
So what's the color depth for tv-out?
The TV-out is an analog signal so the concept of color depth does not really apply.

liedekef 2010-05-17 14:55
Re: TV Out question
 
I have a tv that was "very good" some years ago when I bought it (some Philips 100hz thing), but I also find the picture too dark to be pleasant (I played around with picture settings on the tv, but it's too cumbersome). And also the sound is too silent, even when I put the volume on the N900 to 100%. On the N900 itself the thing is blasting my ears of then, but when connected to the tv, the sound is very low ...

acou 2010-05-17 20:50
Re: TV Out question
 
Quote:
Originally Posted by attila77 (Post 662527)
The TV-out is an analog signal so the concept of color depth does not really apply.
Erm, let me rephrase.

What is the value of the color depth of the (digital) video signal which is then sent to the TV via (analog) composite?

See also this abandoned thread for further clarification.

Benson 2010-05-17 23:29
Re: TV Out question
 
Quote:
Originally Posted by acou (Post 663061)
Erm, let me rephrase.

What is the value of the color depth of the (digital) video signal which is then sent to the TV via (analog) composite?

See also this abandoned thread for further clarification.
It comes straight from the framebuffer, so it starts at 16bpp (5/6/5). Whether there's any further reduction, I don't know, but keep in mind TV signals operate in non-RGB colorspaces (YUV/YIQ), so trying to track bit depths is not as meaningful as it might appear. Obviously, converting 16-bit (5/6/5) RGB to 16-bit (?/?/?) YUV will have different effects depending on the relative bit depths, and will include a loss of precision in any case.

Average Joe 2010-05-18 02:31
Re: TV Out question
 
Works great on my trusty Sony CRT (KD34-XBR960). I just bump up the brightness and contract and the picture is very acceptable imo. The cool part is using my Nokia BH-604 bluetooth stereo headset to control audio/video playback from across the room.

SpeedEvil 2010-05-19 11:07
Re: TV Out question
 
Quote:
Originally Posted by Benson (Post 663252)
It comes straight from the framebuffer, so it starts at 16bpp (5/6/5). Whether there's any further reduction, I don't know, but keep in mind TV signals operate in non-RGB colorspaces (YUV/YIQ), so trying to track bit depths is not as meaningful as it might appear. Obviously, converting 16-bit (5/6/5) RGB to 16-bit (?/?/?) YUV will have different effects depending on the relative bit depths, and will include a loss of precision in any case.
I looked at the datasheet - it's not really clear - but implies there will not be significant truncation - the inputs to the colour generator stages are all as wide as the input data.

The major loss of precision is in the chroma bandwidth. For NTSC - it's around 150 pixels across the screen of different colour.

The relevant file is http://mxr.maemo.org/fremantle/sourc...ap2/dss/venc.c
You might try playing with the 'gain' values. However - this may saturate the output.
The DAC claims 0.88V into a 75 ohm load.
I tried sticking a scope on it, but diddn't get the video output to turn on - must be doing something silly.


All times are GMT. The time now is 05:30.
Page 2 of 2 1 2
Show 40 post(s) from this thread on one page

vBulletin® Version 3.8.8