Raspberry Pi video out. A good source of video?

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g4bbh
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Raspberry Pi video out. A good source of video?

Post by g4bbh » Wed Apr 11, 2012 1:19 pm

With the impending delivery of the Raspberry Pi I see that it has both HDMI and composite outputs for display on a monitor or TV. I assume the coposite output can be configured for PAL or NTSC. If the video and sync quality from the composite output is good enough it may be a cheap source of video for generation of test cards, text etc.
Dick G4BBH

g4bbh
Posts: 72
Joined: Thu Mar 13, 2008 7:19 pm

Re: Raspberry Pi video out. A good source of video?

Post by g4bbh » Wed Apr 11, 2012 1:34 pm

Just found the following:-

"It can do PAL-BGHID, PAL-M, PAL-N, NTSC, NTSC_J. It just a matter of programming the TV-out hardware. We might not support all standards from the beginning though."

Dick G4BBH

G4EWJ
Posts: 719
Joined: Wed Feb 17, 2010 10:11 am

Re: Raspberry Pi video out. A good source of video?

Post by G4EWJ » Thu Apr 12, 2012 5:17 pm

It's an interesting device at a good price. Its apparent lack of fast parallel I/O may limit it for some of the things I have in mind.

Brian

g4bbh
Posts: 72
Joined: Thu Mar 13, 2008 7:19 pm

Re: Raspberry Pi video out. A good source of video?

Post by g4bbh » Thu Apr 12, 2012 9:15 pm

Brian
The RPi does have a bunch of I/O on a header. I believe they can be configured for a variety of applications, I think the 8 bit GPIO is the one. I2C could be handy too.. The expansion connector descrioption is:-
>>>>>>>>>>>>>>>
Top row, left to right:

5V0
DNC
GND
TXD
RXD
GPIO1
DNC
GPIO4
GPIO5
DNC
GPIO6
SPI_CE0_N
SPI_CE1_N

Bottom row, left to right:

3V3
SDA0
SCL0
GPIO7
DNC
GPIO0
GPIO2
GPIO3
DNC
SPI_MOSI
SPI_MISO
SPI_SCLK
DNC

Notes:

- all the UART, SPI and I2C pins can be reconfigured as GPIO if needed.
- some of the do-not-connect (DNC) pins will likely be replaced by
GPIO in a subsequent board revision.
<<<<<<<<<<<<<<

Pity the NZ version of DigiLite software is being developed on an x86 platform. The code might not port to the RPi as it is arm based. Anyway at under 30 quid and consuming very little power this little ''toy' looks as if it could be useful. The screenshots I have seen of the composite output are not bad at all and it does have the USB ports too (Digilite transmit version 1.999b???) as well as the above header. We shall find out when they get round to clearing the order list and I have one to play with.

Dick
I must be patient. I must be patient. I must be patient. I must be patient...............................

G4EWJ
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Joined: Wed Feb 17, 2010 10:11 am

Re: Raspberry Pi video out. A good source of video?

Post by G4EWJ » Wed Apr 18, 2012 9:57 am

The RPi could probably do the IQ digital filtering, but it would need to output 24 bits at 16MHz, so it doesn't look practical.

DigiLite Transmit is written in C, so it should port over quite easily with changes to the input and output routines. I wonder if it will run V4L2? Could you attach a PVR USB2 to make a compact solution?

I see they've started shipping at last.

Brian

g4bbh
Posts: 72
Joined: Thu Mar 13, 2008 7:19 pm

Re: Raspberry Pi video out. A good source of video?

Post by g4bbh » Wed Apr 18, 2012 8:11 pm

Brian
I have found a linux driver for the WinTV PVR USB2 but have yet to try it. It is in c with a makefile so will need compiling on the target machine. I will look into that later.
The limiting factor will be how fast the Raspberry Pi can transfer data. It will be abysmally slow writing to the SD card. 6MB/S on sequential write but around 2MB/S random read. Probably better with a USB hard drive. The RPi only has two USB ports but are channelled through one port at core level. Handling the WinTV and transmit paths simultaneously may be asking too much so I expect it will only be possible to play pre-recorded .mpg files via a linux version of DigiLite Transmit.
Don't hold your breath!
Dick G4BBH

M0DTS
Posts: 397
Joined: Sun Feb 24, 2008 9:03 pm

Re: Raspberry Pi video out. A good source of video?

Post by M0DTS » Thu Apr 19, 2012 6:39 pm

In Linux you can use temporary FIFO's in RAM instead of writing to a file so may be not quite as limiting speed wise.
I have a beagleboard i got last year (before the Pi was revealed.. bad timing eh! ) for the same thing, they aparrently handle the pvr usb fine, unfortunately not had time to try much with it yet.

Rob
Last edited by M0DTS on Fri Apr 20, 2012 5:52 am, edited 1 time in total.

G4EWJ
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Joined: Wed Feb 17, 2010 10:11 am

Re: Raspberry Pi video out. A good source of video?

Post by G4EWJ » Thu Apr 19, 2012 7:40 pm

That sounds promising.

Brian

Rubberfingers
Posts: 2
Joined: Mon May 07, 2012 6:56 am

Re: Raspberry Pi video out. A good source of video?

Post by Rubberfingers » Mon May 07, 2012 7:00 am

I was wondering whether the Pi is programmable at a low enough level to generate a 405 line positive video composite output for our vintage TV's

G4GUO
Posts: 629
Joined: Tue Feb 16, 2010 12:51 pm

Re: Raspberry Pi video out. A good source of video?

Post by G4GUO » Mon May 07, 2012 7:47 am

I suspect it is more a case of whether Broadcom will release the required information.
They have released some information (under duress)
http://www.element14.com/community/serv ... asheet.pdf
But not on the video part of their chip as far as I can see. Shame as it has a nice MPEG4 encoder/decoder as part of it.

You would be better off using a cheap Chinese FPGA board and a video DAC from AD.


- Charles

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