from video4linux list. interesting thing; old sony digital camera with video output doesn't have interlacing artifacts...
Resent-Date: 12 Jan 2000 21:02:10 -0000 Resent-Cc: recipient list not shown: ; MBOX-Line: From [email protected] Wed Jan 12 16:02:09 2000 X-Authentication-Warning: xyzzy.dsl.speakeasy.net: xyzzy owned process doing -bs Date: Wed, 12 Jan 2000 13:02:02 -0800 (PST) From: Trent Piepho <[email protected]> X-Sender: [email protected] To: [email protected] Subject: Re: Matrox Meteor II driver project? In-Reply-To: <[email protected]> Message-ID: <Pine.LNX.4.04.10001121258001.27254-100000@xyzzy.dsl.speakeasy.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Resent-Message-ID: <"ycfpf1.0.yp5.HlEVu"@lists.redhat.com> Resent-From: [email protected] Reply-To: [email protected] X-Mailing-List: <[email protected]> archive/latest/901 X-Loop: [email protected] Precedence: list Resent-Sender: [email protected] X-URL: http://www.redhat.com
On Wed, 12 Jan 2000, Alan Cox wrote:
NetWinder (www.netwinder.org) that has Philips SAA7111 shows exactly the same type of distortions (runs Linux) during capturing dynamic videos which leads me to believe it's common problem for low-cost capture boards.
Your monitor displays at 60-100hz (hopefully 72+). The incoming TV signal is 25fps and interlaced. You need to do extra bufffering and burn CPU time and memory to do good delacing, or find a card that has big buffers.
This isnt a _capture_ artefact its a viewing artefact
Sure it is. You can see interlacing artifacts just fine on still single frame captures. Take a look at http://xyzzy.dsl.speakeasy.net/~xyzzy/test.jpg, you can see the interlacing artifacts perfectly on the scrolling stock ticker on the bottom of the screen.
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Broadcast sources are interlaced. When you view a single frame on a video monitor you are really seeing two frames which are separated in time by 15 or 20 milliseconds.
If an edge moves a noticeable amount then you will have the zigzag effect. This has nothing to do with the capture, it is in the source.
One way to get rid of the effect is to capture 320x240 instead of 640x480. another is to capture 640x240 and to 'double' each of the 240 lines so that there are 480 lines.
The problem is not with capture, but with the source. This is why there is so much discussion about the quality of 720p vs 1020i on the HDTV boards ( interlaced vs progressive scan ).
i is bad...... p is good.....
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Trent Piepho wrote:
On Wed, 12 Jan 2000, Alan Cox wrote:
NetWinder (www.netwinder.org) that has Philips SAA7111 shows
exactly the
same type of distortions (runs Linux) during capturing dynamic videos which leads me to believe it's common problem for low-cost capture boards.
Your monitor displays at 60-100hz (hopefully 72+). The incoming TV signal is 25fps and interlaced. You need to do extra bufffering and burn CPU time and memory to do good delacing, or find a card that has big buffers.
This isnt a _capture_ artefact its a viewing artefact
Sure it is. You can see interlacing artifacts just fine on still single frame captures. Take a look at http://xyzzy.dsl.speakeasy.net/~xyzzy/test.jpg, you can see the interlacing artifacts perfectly on the scrolling stock ticker on the bottom of the screen.
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