What is your absolute LOWEST bitrate for DVDR??

[MaX_NormaL]

Just curious as to how low it is safe to go, I know it depends on length/size of movie etc but would like to know what is the lowest?

I have gone down to AVG 3000 (VBR) in CCE on a 3 hour film and they both were cool. One was Black and White and the other was animation though, I think I may have got poorer results if it had been a proper film. Like Apocolypse Now Redux. Do you think it's possible to do that length of an action film onto one DVDR?

TIA. :P

[Marco33]

I've done 2 movies over 3 hours long, Casino & The Godfather. I would consider the quality slightly better than VHS. This is on a 43" widescreen tv.

I think 3 hours is the topper. Can't wait to try Godfather II, 3 hours 20 min.

[Ndb;-))]

You could use as low as 1500 VBR with Half D1 (near SVCD res) or CIF (VCD res) and get better than VHS quality.

These would give you about 6 hours to play with

Dunno about on a 43" widescreen TV though

Ndb)

[SaSi]

Bitrate can go as low as you feel like it. However, as it becomes lower, quality can deteriorate. Quality will not deteriorate if image content can be encoded in fewer bits. If the movie does not have many action scenes, then a lower bitrate will not have a negative effect on quality.

It is motion that requires bitrate. Imaging the movie being 1 hour of a still picture. It would actually require a single jpeg image. Of course, it's not and since it is difficult to determine scene changes and action scenes vs still scenes, Variable Bit Rate encoding was "invented". Both CCE and Tmpgenc can encode in VBR mode. Another option is to encode in constant quality mode. This means you select a quality setting (how much content you are willing to sacrifice) and let the encoder try it's best. Only drawback, you can't determine the final size. You can guess, but any guess is as good as a guess. You can try and err and retry, and that's an approach people can take.

Now to a rule of thumb. If the movie is in nominal DVD resolution (720/575 for PAL and 720x480 for NTSC) you can go for an average of 4,500kbps without any noticeable loss in quality. However, the "rule" cancel's out itself, as NTSC has fewer scan lines and therefore requires a bit less bits, isn't it?

If you are in squeezing mode, cut the resolution in half. This will result in information becoming a quarter of the original. This means that you can almost go to a quarter of the bitrate without again any noticeable loss in quality. However, remember that this refers to the quarter size image. By cutting resolution you have already lost information.

However, the eye will be most annoyed by blocky artifacts (low bitrate) than less lines. In high-squeeze mode, I would recommend a VBR of 2500 with a max of 4000kbps. Remember to lower the minimum bitrate to 500 or even less (no more than 200), so that you don't waste bitrate.

For Tmpgenc, I have found that if you increase the Motion Search Precision to Highest quality, you get better picture for a given bitrate. Compression time however increases. Also, DC Component precision should be set to 9. Setting it to 8 hurts quality but does not return much bits. A value of 10 will increase quality a bit and have a 2-3% overhead in bitrate.

Another controversial issue relates to interlace. I have found that Tmpgenc compresses progressive movies much better (20-30% better as a matter of fact). If you can spare a separate de-interlace phase, you can gain.

Another reason to go for a de-interlace phase is clipping black stripes from a widescreen movie. If you do such clipping in Virualdub as well as de-interlace, Tmpgenc will compress much better (and can restore the frame size to the full frame while encoding).

Last, but not least, in squeeze mode you should squeeze audio by as much. Don't waste 224kbps for it. Go to MPEG-2 Layer II at 64kbps. Sound will be good and audio stream size will be minimal.

[furball6969]

I go as low as VCD bitrate/resolution (1150000 bps) for some TV show caps. Obviously not for anything that warrants high quality settings.

[gcutler]

I've done some encoding at 2000000BPS and when a talking head it is fine, but even a quick turn of a head or a brisk handshake can show noticable pixelation. While not action, there are enough everyday occurrances that occur at fast speed,making low encoding rates less attractive.