Does half d1 alter file size at all or is it just how the bitrate is used?

[yoda313]

Ok I have about 80 50 minute flv videos that I am getting ready to convert to dvd. I want to fit 4 to a single layer dvdr. The video quality isn't fantastic but decent. I can take a hit pretty well on these.

I used the videohelp bitrate calculator and factored in 3 hours and 20 minutes (the rough estimate for 200 minutes of video give or take - each isn't exactly 50minutes but close enough).

I was planning on using format factory. Can it output in half d1? I know it can set to 720x480 but I don't know about 352x480 (ntsc of course).

Will half d1 allow for smaller file size at the same bitrate?

I guess I don't know the real purpose for half d1. These are approximate to vhs in quality.

The bitrate calculator came out with 2820kpbs for the 3 hours 20 minutes. I know the quality won't be fantastic but I'm ok with that. I just want relatively decent quality and don't want to waste dual layers on these videos. The audio on the calculator came out to 224 I think.

So should I just use regular 720x480 or half d1 at 352x480? If using half d1 means I can use a higher bitrate for the same file size I'd like that. If not I'll stick with 720x480.

FYI the original resolution is 640x480 and is 4:3.

Thanks.

Edit - no format factory doesn't do half d1 - it can do 352x240 but not 352x480. I'll check on avstodvd - I need something that has a batch mode.

Edit 2 - I just checked avstodvd and it has a half d1 option in the setting. It also has no problem opening the flv video. So if half d1 is suitable for my needs I can use avstodvd for this conversion and use its batch mode.

[jagabo]

Smaller frames, lower frame rates, and "simpler" content all let you use lower bitrates (and hence smaller files) and still achieve adequate quality. What you are doing is trading resolution to get fewer macroblock artifacts.

[yoda313]

Smaller frames, lower frame rates, and "simpler" content all let you use lower bitrates (and hence smaller files) and still achieve adequate quality. What you are doing is trading resolution to get fewer macroblock artifacts.

Thanks.

So if I were to do half d1 should I lower my bitrate below 2820? I want to target single layer size. And this will still be about 3 hours and 20 minutes or so per disc.

Also I have decided to use avstodvd after all. I forgot that I don't think format factory does chapters. Also with avstodvd not only can I output a video_ts folder I can do chapters AND basic menus. With single videos I'll often skip menus but with four on a disc I'd like to hop to the one I want with ease.

Edit - I still don't think I want to cram more than 4 50 minute videos onto a disc - I think that would be pushing it at any resolution or bitrate - for a mpeg2 dvd that is.

[jagabo]

So if I were to do half d1 should I lower my bitrate below 2820? I want to target single layer size. And this will still be about 3 hours and 20 minutes or so per disc.

The only way to get three hours and 20 minutes on a single layer DVD is to use a bitrate around 2800 kbps.

[yoda313]

@jagabo - ok so then I don't even need to worry about half d1? Or should I use half d1 to better allocate the bits I'm using to squeeze that much video on to the disc?

[jagabo]

File size = bitrate * running time

The frame size, frame rate, and nature of the video don't enter into the equation. Whether you use 720x480, 352x480, or 352x240 frames the file sizes will be the same at the same bitrate. But at a low bitrate like 2800 kbps you'll probably get a lot of macroblock artifacts at 720x480. You will get fewer macroblock artifacts (but a less sharp picture) with that bitrate if you encode at 352x480. The tradeoff is up to you -- more resolution and more macroblocks, or less resolution and less macroblocks.

[redwudz]

Try a short test encode at full D1 and 1/2 D1 settings at ~2800kb/s of a representative clip from your video and see how they look. A combination of dark areas, light areas and fast action should give you a way to compare. JMO, but starting with VHS quality, 1/2 D1 may look fairly good.

[yoda313]

The tradeoff is up to you -- more resolution and more macroblocks, or less resolution and less macroblocks.

That makes sense.

but starting with VHS quality, 1/2 D1 may look fairly good.

That is probably true.

Try a short test encode at full D1 and 1/2 D1 settings at ~2800kb/s of a representative clip from your video and see how they look.

I'll go ahead and do a full encode both ways to see. I'm not sure how to cut a flv video and keep everything intact.

[redwudz]

Let us know how it turns out. I used 1/2 D1 mostly for TV episode conversions and it worked quite well for that. But they have lower quality than VHS, depending on the VHS.

[jagabo]

Half d1 at 2800 kbps from a good source should look better than VHS.

[davexnet]

I've found the settings in Hcenc, Lumgain and AQ can help in low bit-rate situations.
The default setting in AVStoDVD which uses AQ 1, LG 1 - so perhaps it's worth giving a try with AQ=2 (and/or LG=2), for example
and seeing if it helps.

[yoda313]

Well after a bit of user error on my first side by side test I redid the test and got the right outputs.

Visual checking on the full d1 and half d1 did not turn up any dramatic differences. HOWEVER one difference was in encoding time. The same file using quenc constant bit rate at 2800kpbs for a 50 minute video came in at 25 minutes and a full d1 at the same bitrate same length came out to 32 minutes. I was not doing any additional background actions during either encode.

I figure even if there weren't any visual gains by doing half d1 shaving seven minutes off a single video encode is surely worth using it. And since there would be no discernable loss or gain there is no reason not to use half d1 - IT IS FULLY DVD COMPATIBLE right? This is supported on regular settop players right? Though my most likely target player will be either my xbox 360 or ps3 but I probably will use regular plain old dvd players too - I'd hate to encode 80 videos and only be able to play them on my game consoles.

Thanks everyone for your help.

OH and both test encodes came out to 1.09gb without a menu for half d1 and full d1 so yes it doesn't affect file size output - now I can see that for myself after being explained the theory - thanks.

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Oh and also I needed to drop my target bitrate to 2740 to fit in a basic menu template - I did set the menu wizard in avstodvd to its lowest setting of 3000. I'm sure the 60kpbs loss will be minimal for this project - I was hoping for 2800 but I came at 102% on the output over 4450mb from the avstodvd projected output. I want to be under that number so I can simply drop the video_ts folder in imgburn and burn after the encode. I don't want to pop em in dvd shrink if I don't have to - one less step.

[redwudz]

1/2 D1 is part of the DVD spec, so should be fully compatible. (I would still test one on a set top player, just in case. ) I've dropped the bitrate a little below 2000Kb/s and still had decent quality, so you should be fine. I didn't see your audio format mentioned, but AC3, even two channel stereo format, is a good choice.

[yoda313]

@redwudz - thanks.

It only took just over an hour and a half to encode the four videos.

FYI audio was ac3 at 224kpbs - sorry to neglect that.

It seems just fine. I burnt it and it plays well in my xbox 360 and to be sure I tested it in my vcr/dvd combo panasonic player and loaded just fine. The half d1 looks good. It doesn't look overly soft or otherwise weak. And the quick encoding time with quenc and cbr 1 pass means I can whip through this in no time.

Which is good considering my 80 videos I'm gonna do take up nearly 20gigs of space

Only downside I can see using avstodvd for the whole project is I need to rename my files before beginning the project. I couldn't tell how to rename them in the menu wizard. I'm sure there is a way but it was not plainly obvious. I know renaming the file (getting rid of some header info to get to just the video number and name) will work.

Thanks everyone. I can finally get this project under way in the most efficient manner with decent results - plus I'm glad I don't need to waste dual layers on relatively sub par video quality. I can save those for more precious 2+ hours vhs caps and for high def avchd needs

Thanks again.

[yoda313]

Just an fyi I finished my 80 set conversion this afternoon. I could have done it a little sooner but I did shut off the pc during the night sometimes and I wasn't always able to start a new batch right after the previous batch. But all in all it worked out well.

Thanks for all the help. The video quality is as good as I could expect for budgeting to a single layer instead of dual layer. But doing 4 on a disc let me save discs (though some I did 3 on a disc to keep the collection in order).

I'm gonna be doing some more batch conversions. I figure I'll use this technique on the lesser quality captures and internet video downloads.

Thanks again (and this freed up 20gbs of flvs! - fyi I did not burn a backup of the original flv files nor copy to a harddrive - I figure the quality wasn't good enough to justify the waste of discs or disc space - but I do have useable copies on dvd now that i can play in any player).

Edit - I think I will take the time to do a full defrag of my capture drive - it probably really needs it since that was the drive I had the original files on and the same drive that I had the video_ts folders outputted to - so those are deleted now and is probably a lot more fragmented now - fyi sata internal drive.