Re: [HDTV-in-SFbay] Cozi Sherlock Holmes Postage Stamp aspect continues.
- The pixel (sample) aspect ratio can be calculated like this (from
section 6.3.3 of the MPEG-2 specification I linked to):
sample aspect ratio = display aspect ratio * horizontal size / vertical size
So for 1920x1080 at 16:9 it would be:
(9/16) * (1920/1080) = 1 (square pixels)
For 704x480 at 16:9 it would be:
(9/16) * (704/480) = 0.825 (non-square pixels).
The typical way to test aspect ratios is to use a test pattern
with circles. Any distortion can be easily seen. Here's a
few bitstreams I created with a hardware MPEG-2 encoder.
1) 720x480 at 16:9, just like Cozi is sending except 720 wide instead of 704
2) 544x480 at 16:9, just to see how the decoder handles it. 544 wide is a
valid MPEG-2 resolution.
3) 720x480 at 4:3 with a display extension for 16:9. Again, just to see
how the decoder handles it. A compliant decoder should display a
16:9 image even though the aspect ratio is signaled as 4:3. Most
(but not all) versions of VLC will do the correct thing.
All clips are about a minute long and about 144 Megabytes. Audio
is silent. Have fun!
On 2/28/2013 10:00 PM, Stephen H. Fischer wrote:
I was able to download the documents. There is not sufficient time remaining in my life to understand much.
I am wondering if this guess is ~ correct,
That the pixel shapes for the following resolutions is about the same:
1920x1080 (16:9 program on 16:9 display)
1280x720 (16:9 program on 16:9 display)
704x480 (16:9 program on 16:9 display)
704x480 (4:3 program on 4:3 display)
> For some reason, the aspect ratio of non-square pixel
> formats like 704x480 is very difficult for folks to understand.
I think I am in that class, but then "string theory" is just as far beyond me.
You do say non square, does that mean that the first two are square?
I do have an idea of the "big bang" down very hot.
Looking at your pictures I think that they were not helpful to me was because they did not show the additional black bands I am seeing.
I was looking at a screen that is fixed in size with an additional black band and your pictures were wider than each other with out the additional black band.
The document parts I scanned clearly show 704x480 in places. So that was not just stations guessing at a V and H.
Finding two streams marked 704x480 (4:3) in addition to COZI's 704x480 (16:9) was a surprise.
I now have a Magnum, P.I. Which the OP first complained about.
It looks exactly like Sherlock Holmes does on Fusion with original ratio selected, an additional BLACK band on both sides. Selecting 16:9 Fixed produces a normal picture. MyHD and VLC Media Player also show a normal picture.
So this problem is understood, an programming error in the tuner!
- Hi,Fusion with "16:9 Fixed" showed all three clips at full width on my 16:9 screenWhen I switched to "Original Ratio" 3) had the BLACK bands added to each side and the circles were not round.My new 6 - Million Dollar Man Eyes could not really tell any difference with "16:9 Fixed" between the three.If you have a FTP for uploads, send me a PM with password, I captured an interesting KGO test pattern long ago. (3/6/2006) It's 39 MB in size.
mailto:a_nani_mouse@...SHF----- Original Message -----From: Ron EconomosSent: Friday, March 01, 2013 4:49 PMSubject: Re: [HDTV-in-SFbay] Cozi Sherlock Holmes Postage Stamp aspect continues.