(Full-D1) DVD 4:3 Letterbox = Lower bitrate?

If I have a widescreen (1.777) movie and don't want to convert it to Half-D1 (beacuse of its aliasing) but don't want to convert it to Full-D1 (because of its need of high bitrate), is it a good idea to letterbox this movie to still have almost the same bitrate as a SVCD?

According to my calculations letterboxing puts (PAL) 72 pixels of black bars at the top and bottom of the movie, which gives a Full-D1-movie the framesize of 720*432 (PAL). The rest of the picture is black bars and doesn't require much bitrate, right?

So if a SVCD bitrate of 2520 kbps gives almost no macroblocks (according to my eyes). And 720*432 is 12,5% larger than 480*576 (SVCD), then (1,125*2520) 2835 kbps would be enough to make a Full-D1 as macroblockless as a SVCD with 2520 kbps.

Can someone confirm this?

[Skynet107]

I would say your calculations are pretty accurate. My question is, why are you using such a low bitrate for a DVD compliant mpeg2 file? What media are you going to put this re-encoded file on? CD or DVD? And what format are you going to burn? Also you contradict your self a bit. U say that 2520 SVCD and 2835 D1 are comparable in quality vs. the bitrate, and you also say you don't want to use D1 because the need for a high bitrate.

[ronnylov]

You can also choose 704x480 instead of 720x480 to save some pixels. If you have a widesceen movie and make a SVCD of it then you'll normally also letterbox it. But it is correct that you can save some bitrate by letterboxing it instead of make it anamorphic widescreen.

If you are going to watch it on TV then you can srink it a bit more because of the hidden overscan area. Try FitCD to calclulate the resizing.

If you have a good source (like DVD) then your bitrate should be enough if you use multipass VBR encoding with a good encoder like CCE, Canopus Procoder or TMPGEnc.

Why don't you try both full D1 and half D1 (perhaps only a few minutes of each) and compare which one looks best at your given bitrate?

[flaninacupboard]

Letterboxed 720X384 would have the same aspect ratio as anamorphic 720X576.

Yes, at rates that low anamorphic is not worth it, go for letterboxed 720X384, and as suggested use multipass variable bitrate for the best quality, 100 min, 2835 average and 5000 max.

I'd rate the quality of that as "watchable"