AMD's UVD2-based XvBA Finally Does Something On Linux

[tuxdriver]

There's youtube HD, pirate HD, and bluray HD, in rising quality & descending amount order. The first two are most volumous, and also play just on practically any cpu.

Guess HD means different things to you two.

You forgot camera HD (1080p @ 60fps) . Camera HD stresses your CPU even harder than BluRay HD.

Here's a low bitrate L4.2 camera clip that is a pain in the ass to decode with a Dual Core CPU:

http://ckworks.sakura.ne.jp/data/xacti_hd2000_dogsample20090207_1_mp4.zip

[curaga]

@tuxdriver: true. My own dual struggled somewhat. But since when is 24Mbps considered low bitrate :P

[tuxdriver]

But since when is 24Mbps considered low bitrate :P

Very low for camera HD standards. Good quality camera video starts at 40Mbps

[curaga]

One has to wonder what the heck do the cams do with it.

Bitrate should scale about directly to the square root of pixels; since dvd-resolution (720x576) looks good at 1 mbps (xvid), full hd should be enough with 2.23 mbps (sqrt((1920*1080)/(720*576))). Especially with a better codec.

[Jimbo]

why?

2 - 4 mbps should work very well, but obviously if you want the top quality to post processing, video production... 20 - 40 mbps is the way to go in HD content.

[Kano]

@curaga

Where does your sqrt come from? Basically you have got factor 5 more pixels and i do NOT consider 1 mbps for xvid as good, that maybe begins with 1.5. h264 can look good with lower bitrates too - youtube has about 4 mpbs average for 1080p, but as commerical apps do not use x264 as encoder vc1 is very widespread and h264 with other encoders usually needs a higher bitrate too. the chips in a camera have to encode in realtime so thats less efficient by definition - to optimize bitrate you often use multipass, thats impossible for recording.

Basically it would be often possible to reduce the bitrate to the half using a more efficient encoder but do you really want to spend that much time on a movie that you only want to watch? Today you just buy a new hd when needed

[Jimbo]

I think the key, is that your camera can record video to something very near to raw quality, so 40 mbps should be fine. Then you have the option to post-process it to the Mbps you want, and the codec you want, because the source has near raw quality. In the way you think video professionals can not post process at all.

[Kano]

RAW would be even for 1080p,24 fps,16 bit color nearly 800 mbps. So even 40 is already compressed by factor 20

[Jimbo]

I know what is RAW , i mean in SNR terms (near raw quality).

[curaga]

It comes from subjective tests at doom9, IIRC.

Basically it would be often possible to reduce the bitrate to the half using a more efficient encoder but do you really want to spend that much time on a movie that you only want to watch?

Maybe one wants to share, or store for a longer time.

I really think 40 mbps is overkill, even for a single pass & bad encoder as in the cams. If one needs perfect quality before processing, just use something lossless.
I wonder if any cam can shoot straight png frames, plus separate audio. Would take less processing than H.264 encoding, but more space.