mpeg 4 realtime bitrates vs multipass mpeg-2 VBR

[miamicanes]

Suppose I want to use a usb2 capture device with hardware mpeg-4 to capture video from VHS source (mostly poor quality from OTA recordings over the past 20 years) that more or less preserves the tapes as they are now. The ability to burn to DVD today isn't important, but a MPEG-4 profile that's valid for a HD-DVD without re-encoding IS. A MPEG-4 profile that's compatible with common existing Divx-capable players would be nice, though.

Approximately what realtime hardware-compressed MPEG-4 bitrate would I need to use in order to end up with video quality comparable to what I'd ultimately end up with if I captured to DV or HuffyUV, then encoded it to 6000kbit/sec multipass VBR MPEG-2?

[guns1inger]

The mpeg-4 variant used on HD-DVD is in no way similar to the mpeg-4 variant used for Divx players, so you cannot kill two birds with one stone.

As a general rule, I find that to get approx the same quality from Divx/Xvid as the mpeg-2 version, I require around half the bitrate. AVC should be able to get away with around a third less again.

That said, VHS is a very noisy source, noise requires bitrate, so while you may get the same quality at 3000 kbps as you would from a 2-pass VBR at 6000 kbps for mpeg2, the quality may still not be great simply because your benchmark is too low to begin with.

[jman98]

If you see any hardware capture devices that talk about MPEG-4 encoding, they are actually talking about Divx encoding. I am not aware of any hardware capture devices at this time that are capable of what most people think of when they think of MPEG-4 encoding on the fly.

HD-DVD has special FPS (frames per second) requirements that most people tend to overlook. Any resolution of 720i/p and less requires 60 fps. You'd probably be best served to just convert your tapes to DVD. Using the high resolutions of HD-DVD would just magnify the deficiencies in the source to the point that you might consider the final product to be unwatchable. If you use the lowest resolution that HD-DVD supports, well that's identical to DVD's resolution, so you might as well just convert to DVD. It varies from person to person, but some people prefer to capture VHS tapes to 352x480 (I'm assuming based on your name that you live in the USA) over the normal DVD resolution of 720x480. 352x480 is maybe better to use if you have, say, over 2 hours of video, as the lower resolution is more forgiving of lower video bit rates than 720x480 is.

[miamicanes]

The mpeg-4 variant used on HD-DVD is in no way similar to the mpeg-4 variant used for Divx players, so you cannot kill two birds with one stone.

Oops. I didn't know that.

Is the incompatibility "real", or merely "official"? As in, mp3 audio and 50-field GOPs officially won't work on American DVD players, but discs burned with both seem to work without problems on all but the most expensive DVD players anyway (yeah, the irony...)

It's good to know that there's no assured way of killing two birds with one stone... but I'm still willing to bet that by the time the Chinese manufacturers are cranking out $199 HD-DVD players (or, god forbid, $89 "DVD+HD" frankenplayers with slightly-tweaked HD-DVD chipsets, but conventional DVD5/9 optical mechanisms geared towards HD porn authored as 720p60 HD-DVD, but stamped onto conventional dual-layer discs), MPEG-4 will just be a bucket of capabilities in an even bigger bucket of capabilities... any halfway-sane permutation of which will "just work" regardless of what the standard officially says. The Chinese are good at doing that

[guns1inger]

Totally different compression algorithms. That is not to say a HD-DVD won't play divx files - I'm sure they will - just like some DVD players will play Divx files. But you cannot author a DVD with mp3 audio or Divx files - it has to match the DVD compliant requirements. HD DVD is the same. To author HD DVD, you have to be able to create HD DVD compliant video and audio files.

If you want video you can play now and then, encode to mpeg-4 H.263 (Divx/Xvid). If you want HD DVD compliance then you need a hardware encoder that does AVC (mpeg-4 H.264) to compliant specifications. Good luck with that.

[edDV]

...
DVD5/9 optical mechanisms geared towards HD porn authored as 720p60 HD-DVD, but stamped onto conventional dual-layer discs), MPEG-4 will just be a bucket of capabilities in an even bigger bucket of capabilities... any halfway-sane permutation of which will "just work" regardless of what the standard officially says. The Chinese are good at doing that

Everyone seems to forget 1280x720/24p. If professionally shot it needs 44% the bit rate of 1920x1080/24p and 24 fps 1080p has a 20% advantage vs 29.97 fps 1080i.