D1 vs Half D1

[timmyp]

Hello,

I'm backing up a couple movies to one DVDR and I have a question about resolution.

In TMPGEnc, on the final screen of the wizard, there is a resolution option that i can set to 352x480 (Half D1, right?) or 720x480. This option changes its default automatically, it appears, based on what bitrate I select to encode with. The lower bitrates seem to automatically switch to the 352x480 resolution.

Can someone please explain when I would want to use D1 vs Half D1 or point me to a site/thread that explains this in some detail?

Thank you.

[Faceman101]

I've never encountered TMPGEnc changing resolution based on bitrate.

Either way, think of Half D1 as SVCD. It's very similar and even the Chinese have their own format using it (CVD). I'm sure searching the forums for "half D1 or CVD" will come up with alot of info and threads.

[timmyp]

Thanks for the reply.

I have read through several threads on this subject and have a general understanding of what it is.

I still feel my question is not fully answered, though. Maybe it's a TMPGEnc issue, because I see several threads that talk about reduced overall file size when using Half D1 (1/2 the data to encode), but when I switch this option back and forth in the TMPGEnc wizard, it does not change the projected bitrate.

I guess my bottom-line question is: If both these movies are fitting onto one DVDR at a bitrate of 3000 Constant Quality, is there any reason I should be looking at using Half D1?

Thanks again,

Tim

[adam]

Your filesize is determined solely by your bitrate, so the file will be the same size regardless of what resolution you use. But the higher your resolution, the more pixels you are using to represent the same image. This means a much sharper image, but if you don't have enough bitrate then there will be quality degragation. So if you lower your bitrate beyond a certain point, you are actually better dropping the resolution as well. 3mbits is kinda a close call. You are getting to the point where you won't have enough bitrate to sustain full D-1 resolution, but for a compressible source you should still be fine. I would try encoding a test clip using each resolution and see whch looks better to you.

[timmyp]

Thanks for the reply.. I will go ahead and do a little test to see which looks better to me and then go from there.

Thanks again.

[FulciLives]

When using half D1 you can get very acceptable quality at a much lower bitrate than using full D1.

For instance the same high quality source recorded at full D1 3000kbps would look like CRAP but that same source recorded at half D1 3000kbps will actually look pretty decent.

The trick here is the lack of resolution in half D1 is actually not very noticeable on a standard TV and it requires less bitrate than full D1

That is why half D1 can look better than full D1 at low resolutions.

I sometimes record TV captures at half D1 and I've found that usually 3500kbps (give or takes) gives really good results though some people will go as low as 2500kpbs

You might want to try 2-pass VBR with a 3000AVG and a low of 2000 and a high of 5000

Anyway if you have to encode this stuff at 3000kbps then definately go half D1

- John "FulciLives" Coleman

[Vejita-sama]

I use 1/2 D1 for all my VHS/LD backups (capture, encode, author) normally with a bitrate of ~4000kbit/s. I think this really gives the best results. The only draw back is that for DVD backups anamorphic discs are only supported at D1, so you unless your standalone supports xDVD, you have to letterbox (for std TV) or leave as widescreen (for widescreen TVs) the video. Ie. it won't play correctly on all tvs.

[indolikaa]

I use 1/2 D1 regularly for satellite television recordings and CVD for VHS/Beta transfers. No complaints or compatibility issues.

[SatStorm]

1/2 D1 is a good alternative as a target framesize when your source is VHS/SVHS or Live TV in general. Analogue grabb from satellite / cable feeds also can be used for this framesize with excellent results.
If now you have a very good source (like LD or a good Satellilte transmission) and State Of the Art Cables and Hardware (forget low / mid cost solutions) you might gain better results a bit higher, but no so good to excuse a full D1 encoding. This is somehow a debate and it is based to many parameters, you can't even imagine that take place...

For DVD Backups, or direct DVB -s/-c/-t stuff (possible with the correct hardware), the use of D1 is a better choice most of the time if quality is what matters. If filesize is important, the alternative of 1/2 D1 may be really the best way. Smaller framesize, less bitrate is needed for perfect mpeg 2 results...

[timmyp]

Thank you all again for the many responses.

What I'm doing is backing up the kids DVD's and want to place 2 movies on each DVDR (thus, the lower bitrates)... Super quality isn't a huge issue (the kids sure as heck aren't going to notice, LOL), but I'd like it to be decent.

Did some testing with half and full D1 and I think that I do like the half D1 for this situation. With full D1 I get a little pixelation or jaggies (?) in the high-motion scenes. Don't seem to experience that with half D1.

It looks good to me, anyways!

Thanks again all,

Tim

[mfsav]

Just a specification
The SVCD format is NOT Half D1 (or D2)
it is 480/576 or 480/480

The D2 is 352/576 or 352/480
The DVD standard allows only D1 or D2 format.

Using the D2 format at "low" bandwith like 2.5Mbps allow to have wery low pixellation or artifacts
BUT
it costs in terms of sharpness of the picture.

In the site there is an interesting article on how to create a DVD with SVCD format files.

Ciao,
Mf

[indolikaa]

The DVD standard allows only D1 or D2 format.

I believe that may be incorrect...

Allowable picture resolutions are:
MPEG-2, 525/60 (NTSC): 720x480, 704x480, 352x480, 352x240
MPEG-2, 625/50 (PAL): 720x576, 704x576, 352x576, 352x288
MPEG-1, 525/60 (NTSC): 352x240
MPEG-1, 625/50 (PAL): 352x288

.indolikaa.