Ultimate compressibility-enhancing technique?

[TheBluefox]

Divx Xvid and GK experts, would appreciate ur input on this.. :)

1- Compress the DVD movie with Divx/Xvid at full quality (q=2)at FULL vertical resolution (never mind having horizontal rez > 100%) with light/medium de-noising using the default H.263 quantization, not MPEG-2.

2- Open the resulting full-quality Divx video, select a desired resolution and run a compressibilty check

3- Encode (re-compress) the full quality divx video file using 2-pass encoding at 45%-60% compressibilty

I found this technique to boost the quality/size ratio of my encodes.

Converting from MPEG-2 to a Divx/Xvid with H.263 quantization at q=2 smoothes the video while keeping details relatively sharp. This contributes to greater compressibility.

I suppose MPEG-4 compression is, by itself, a great denoiser :)

Would really appreciate your testing/feedback on this..

Thanks

[twist3d]

Just my 2c:
Re-encoding already encoded material is always bad idea.
Think of dvd source, it's already compressed mpeg-2 video, then re-encoded to mpeg-4. Your method is like ripping an already lossy atrac-compressed audio file from minidisc, encoding it with lame --alt-preset insane and then re-encoding it to smaller size with ogg/mpeg-4 aac and saying it sounds great.
Use proper filtering when encoding the first time.

[CWR03]

Since blank DVD media is so cheap now, I typically encode so three movies fit on a DVD-ROM. I see no good reason to worry or work over finding maximum compressability for backups. I maintain cropped video width, even if vertical zoom is over 100%, and as long as the movie is under two hours it's virtually indistinguishable from the original.

[TheBluefox]

Exactly.. I am now thinking beyond CD-sized encodes. The first new consideration is, as you said, the fall in DVD-ROM prices. Also, I am keeping my eye on HD grade DivX players.

That said, I am encoding my DVDs at FULL resolution, i.e. 480 vertical for NTSC or 576 vertical for PAL (minus cropping)with the corresponding width dictated by the aspect ratio... Yes, I am going beyond 100% horizontal because I believe that doing the resize with Avisynth is far superior in terms of quality than doing it during playback. HD grade players will support a resolution of 1200 x 480 anyway.

Now, since the encoded frame is large, I do not need to go beyond 45% compressibilty, since the video will need to be stretched by a smaller amount than a 720 x 300 frame, and therefore, blocking/ringing will be less visible.

Encode size is about 800-900MB per hour (including AC3 audio)

I guess there are as many encoding styles and preferences as there are users, which is quite interesting I believe :)

[jsquare]

I was doing something similar, but in my case a 1-pass encode with Q=3 at 1:1 AR(thus keeping V resolution after cropping), and then fixing the AR with MPEG4 Modifier.
The quality is great but only Nero Showtime shows the correct AR, and my DVP642 refuses to play it. I'll will try your method and see what's happens.