Ideal capture resolution for analog cable?

[blade]

I've read that analog cable is only around 336*480 resolution, and that capturing at higher resolutions doesn't improve the PQ. According to what I've read, capturing analog cable at 352*480 @ 4mbit would have better quality than 720*480 @ 6mbit; because, the bits per pixel are higher with the lower resolution.

Is this true or is it just hot air?

[mdmint]

Originally Posted by blade

I've read that analog cable is only around 336*480 resolution, and that capturing at higher resolutions doesn't improve the PQ. According to what I've read, capturing analog cable at 352*480 @ 4mbit would have better quality than 720*480 @ 6mbit; because, the bits per pixel are higher with the lower resolution.

Is this true or is it just hot air?

I believe the question is mute as far as Sage and related hardware encoding is concerned. I'm relatively positive that yes you can select different recording "qualities" (I use DVD Standard as my norm) but not different recording resolutions.

[blade]

If you check the sage properties file you'll see that the different options not only change the bitrate but also the resolution that the Sage recordings are captured at. For example the DVD Standard that you are using says 720*480. The Good setting says 480*480 and the Great setting says 720*480.

I'm still a newb at all this stuff and have just started looking into tweaking my capture settings and haven't seen any recent posts on the subject. Most of the posts I found were pretty old.

I guess I'm just wondering, if you captured analog cable at 352*480 then upscale it to 1920*1080i would there be any difference in quality than if you captured at 720*480 then upscaled it to 1920*1080i?

If you capture at 720*480 does the capture card upscale the 352*480 to 720*480 as it encodes?

Of course these questions are assuming that the capture resolution is actually changed by Sage. I'm just trying to understand how the encoding works so that I can get a better feel for how to go about setting my system up to get the best quality possible without needlessly wasting drive space.

[mdmint]

Originally Posted by blade

If you check the sage properties file you'll see that the different options not only change the bitrate but also the resolution that the Sage recordings are captured at. For example the DVD Standard that you are using says 720*480. The Good setting says 480*480 and the Great setting says 720*480.

I sit corrected.

I'm still a newb at all this stuff and have just started looking into tweaking my capture settings and haven't seen any recent posts on the subject. Most of the posts I found were pretty old.

I guess I'm just wondering, if you captured analog cable at 352*480 then upscale it to 1920*1080i would there be any difference in quality than if you captured at 720*480 then upscaled it to 1920*1080i?

If you capture at 720*480 does the capture card upscale the 352*480 to 720*480 as it encodes?

Of course these questions are assuming that the capture resolution is actually changed by Sage. I'm just trying to understand how the encoding works so that I can get a better feel for how to go about setting my system up to get the best quality possible without needlessly wasting drive space.

Guess my suggestion is try various recording Q's and see how they look to you!

[blade]

Originally Posted by mdmint

Guess my suggestion is try various recording Q's and see how they look to you!

That's what I was afraid someone would say!!

[zz5]

Originally Posted by blade

I've read that analog cable is only around 336*480 resolution, and that capturing at higher resolutions doesn't improve the PQ. According to what I've read, capturing analog cable at 352*480 @ 4mbit would have better quality than 720*480 @ 6mbit; because, the bits per pixel are higher with the lower resolution.

Is this true or is it just hot air?

This is hot air. Where did you read this? Whoever wrote that has no idea what they're talking about. You want to use 720x480.

[stanger89]

Originally Posted by blade

I guess I'm just wondering, if you captured analog cable at 352*480 then upscale it to 1920*1080i would there be any difference in quality than if you captured at 720*480 then upscaled it to 1920*1080i?

It doesn't work like that, there are no pixels in an analog signal, there are only scan lines. SDTV is 480i (technically 525 interlaced scan lines with 480 with active picture info). So we're stuck with 480 as the vertical resolution, on the horizontal side, you're not actually capturing pixels, you're telling the card how often to sample the analog waveform. You could use 200 horizontal samples just as easy as 1440 or 720.

So the question is just how many samples does it take to completely capture the the information contained in each scan line. Not necessarilly and easy question to answer, if you go with 720 you're fine, since the source won't be higher than that, could you get by with less, probably, but the only way to know for sure it to try. Some cable systems are probably better than others.

[stanger89]

Originally Posted by zz5

This is hot air. Where did you read this? Whoever wrote that has no idea what they're talking about. You want to use 720x480.

Not necessarilly, 480x480 could be plenty to capture all the detail contained in the analog signal.

FWIW digital cable (at least on my system) is 528x480i, with most channels at about 1.5-2Mbps.

[zz5]

Originally Posted by stanger89

Not necessarilly, 480x480 could be plenty to capture all the detail contained in the analog signal.

FWIW digital cable (at least on my system) is 528x480i, with most channels at about 1.5-2Mbps.

If you record at 480x480 using analog cable, you will still lose some resolution. Even if the signal is a little blurry, the analog signal still has the full resolution. If you've ever tried recording at 480x480 and 720x480 and compared the outputs, you'll see what I mean. You can tell by looking at small text on the screen. The text will look wider. At 720x480, there really isn't any noticeable difference (resolution-wise) between the live signal and the recording.

[blade]

Originally Posted by zz5

This is hot air. Where did you read this? Whoever wrote that has no idea what they're talking about. You want to use 720x480.

It was from a site I found yesterday while browsing the net, I can't find the article now.

Thanks for the explanation stranger89. All the talk about bitrates, resolution, and deinterlacing can get a bit confusing to newbs like myself. I think I'm slowly starting to partially understand how some of this stuff works.

[dvd_maniac]

If you record at 480x480 using analog cable, you will still lose some resolution. Even if the signal is a little blurry, the analog signal still has the full resolution. If you've ever tried recording at 480x480 and 720x480 and compared the outputs, you'll see what I mean. You can tell by looking at small text on the screen. The text will look wider. At 720x480, there really isn't any noticeable difference (resolution-wise) between the live signal and the recording.

The reason the text looks wider is because you shrunk the horizontal resolution and left the vertical alone.

A great place to go to find out detailed info on capturing video go "HERE"

My recommendation is if you plan on transferring to DVD-R then record at either 720x480 or 352x480 and adjust the bitrate to how much you need to fit on each disc. If you plan on creating VCDs then use 352x240 w/44100 audio.
If you plan on doing ANY conversion (Divx, Xvid, MP4) then use Max Mepg-2 Quality (12mbps) as the mpeg-2 file size won't really matter...and the resulting encoded file will look MUCH better then a lower res/bitrate captured file. I shrink 1 hour episodes to 300MB and it looks great on 57" Hitachi HDTV

If you plan on leaving on hard drive until watched then delete, then just figure out how much space you have and how long shows will be on hard drive and use the appropriate quality.

Also, action and sporting events, I always use Max Quality.

[blade]

Thanks for the link dvd_maniac. Right now I'm just recording to my hard drive and deleting them as I watch them. I'm starting to toy with the idea of compressing some shows and movies to archive.

[dvd_maniac]

I'm starting to toy with the idea of compressing some shows and movies to archive.

Check out AutoGK.
On my p4 2.8 I can shrink a 5GB(Max Quality) one hour show to 300MB and see virtually no quality difference in less than 2 hours...

[zz5]

Originally Posted by dvd_maniac

The reason the text looks wider is because you shrunk the horizontal resolution and left the vertical alone. A.

No, it's not. I think you're suggesting that you think I'm watching video with everything squeezed together! The aspect ratio is still the same. 480 is not enough to capture the full horizontal resolution is what I'm saying.

Just try it and see. It's more like watching VHS, where text is thicker and hard to read if small.