Maker Pro
Maker Pro

BT601 / 656 PAL Video Buffer Size

J

Joe G \(Home\)

Jan 1, 1970
0
Hi All,

I wanted to calcuate the dual port ram buffer size for the following PAL
video in BT601 / 656 digital format.

625 lines per Frame, sampling at 13.5MHz and assumeing 864 samples per
line.


Is the buffer size 625 x 864 = 540,000 bytes?... Is this std for PAL
BT601?

Can you recommend any video forums or news groups?


Thanks in Advance

Joe
 
M

martin griffith

Jan 1, 1970
0
Hi All,

I wanted to calcuate the dual port ram buffer size for the following PAL
video in BT601 / 656 digital format.

625 lines per Frame, sampling at 13.5MHz and assumeing 864 samples per
line.


Is the buffer size 625 x 864 = 540,000 bytes?... Is this std for PAL
BT601?

Can you recommend any video forums or news groups?


Thanks in Advance

Joe
can you just get away with using the active samples?
from http://www.intersil.com/data/an/an9728.pdf
Active video resolutions are either 720x486 (525/60videosystems)
or720x576 (625/50videosystems).


martin
 
J

Joe G \(Home\)

Jan 1, 1970
0
Oh Yes,

Data outside the 720x576 is fixed and known, and doesn't need sampled.

TA!

Regards
Joe
 
G

Glenn Gundlach

Jan 1, 1970
0
Joe said:
Hi All,

I wanted to calcuate the dual port ram buffer size for the following PAL
video in BT601 / 656 digital format.

625 lines per Frame, sampling at 13.5MHz and assumeing 864 samples per
line.


Is the buffer size 625 x 864 = 540,000 bytes?... Is this std for PAL
BT601?

Can you recommend any video forums or news groups?


Thanks in Advance

Joe

As other have said, you don't need to sample the line and frame retrace
but you need to double the memory if you want the color. There are 2
13.5MHz streams, 1 for luma and the other multiplexed for
half-bandwidth R-Y and B-Y channels.

GG
 
M

martin griffith

Jan 1, 1970
0
Oh Yes,

Data outside the 720x576 is fixed and known, and doesn't need sampled.

TA!

Regards
Joe
Just remembered, 656 serial stuff is 10 bit, if you use just 8bit you
save some memory, and 8 bit was good enough for "broadcast quality"
for years


martin
 
J

Joe G \(Home\)

Jan 1, 1970
0
Thanks Martin and Glenn,

My goal is to use a micro (connected to a SD card or larger serial flash
mem) connected to a Averlogic dual port frame buffer (AL440) to drive a
Philips SAA7128 / SAA7120 (composite video out).

The AL440 has an 8bit sequential in and out ports that can be clocked from
the SAA7120 / SAA7128.

I am just trying to guage the memory size of the flash and AL440 for one
complete frame.

I have access to these parts from Averlogic, Philips, and SST ... so I would
like to use these.


I think I will need the to include the line and frame data as the AL440 data
is clocked in sequentually.

Unless my software counts the end of a frame and send the line and frame
info withing the code


Any other thoughts you have would be appreciated.



Regards
Joe
 
M

martin griffith

Jan 1, 1970
0
Thanks Martin and Glenn,

My goal is to use a micro (connected to a SD card or larger serial flash
mem) connected to a Averlogic dual port frame buffer (AL440) to drive a
Philips SAA7128 / SAA7120 (composite video out).

The AL440 has an 8bit sequential in and out ports that can be clocked from
the SAA7120 / SAA7128.

I am just trying to guage the memory size of the flash and AL440 for one
complete frame.

I have access to these parts from Averlogic, Philips, and SST ... so I would
like to use these.


I think I will need the to include the line and frame data as the AL440 data
is clocked in sequentually.

Unless my software counts the end of a frame and send the line and frame
info withing the code


Any other thoughts you have would be appreciated.



Regards
Joe

Hi Joe, (please dont top post)

Those dreadfull philps data sheets, I tried to figure out if the SAA
will generate sync pulses for you, and it can be used in Master mode,
I think, check section 7.4 on the 7120. But the 7120 needs a parallel
video data input, and you are using serial flash, seems a bit of a
messy way to do it,

My brain hurts, need coffee


martin
 
J

Joe G \(Home\)

Jan 1, 1970
0
martin griffith said:
Hi Joe, (please dont top post)

Those dreadfull philps data sheets, I tried to figure out if the SAA
will generate sync pulses for you, and it can be used in Master mode,
I think, check section 7.4 on the 7120. But the 7120 needs a parallel
video data input, and you are using serial flash, seems a bit of a
messy way to do it,

My brain hurts, need coffee


martin

Hi Martin,

My read up of the BT601 standard says you put the Synch pulses in the data
stream and the BT656 is the parallel interface standard.... to transport the
BT601 data.
(obviously parallel is faster than serial and needs to be 13.5MHz, and
serial would need to be 8 times this speed for 8bit).

The picture frame will be stored in memory (weather serial or parallel) and
the micro is used as the mechanism by which the video data from flash is
written to the video buffer.
The output of the video buffer is 8bit parallel transmitted to the SAA712x.


The input side of the video buffer can be slow written data and the output
side can be at full 13.5MHz.


I could use a parallel flash and a clocked CMOS 4040 to clock the address
range of the flash through the video data.... but a micro gives me the
flexibility to load the video data/memory by serial, SD card or other
methods.


Regards
Joe
 
J

Joe G \(Home\)

Jan 1, 1970
0
Glenn Gundlach said:
As other have said, you don't need to sample the line and frame retrace
but you need to double the memory if you want the color. There are 2
13.5MHz streams, 1 for luma and the other multiplexed for
half-bandwidth R-Y and B-Y channels.

GG

Thanks
I have been reading the book Video Demystified by Keith Jack

720 samples of video that are composed of Y and Cb /Cr 720x2 = 1440
byte samples per line.

I can probabaly wite code in the micro to fill in the synch and frame data
from lines 1 to 22 and 311 to 335 and 624 to 625

Regards
Joe
 
Top