YouTube enters the widescreen world

re: YouTube enters the widescreen world

Waethorn — Wed, 26 Nov 2008 15:08:30 GMT

"so you really believe that a full motion HD video can be broadcast as 2Mb/s?"

It depends on the source material. You can also use tricks like line-doubling with interpolation to simulate full-rez HD, and that can be done directly in the encoder....and who said it was "full motion"? It's a video conferencing system after all. It's likely much less than film framerate, as I mentioned. With network bandwidth reliability issues and overhead, 2Mb/sec can actually be too much, especially if you're using a DSL.

re: YouTube enters the widescreen world

gorath — Wed, 26 Nov 2008 15:02:36 GMT

so you really believe that a full motion HD video can be broadcast as 2Mb/s?

really?

re: YouTube enters the widescreen world

Waethorn — Wed, 26 Nov 2008 14:38:47 GMT

"Well, that's my point, compressing beyond sense"

LOL! Actually, it's not. Lossless compression is already at a ratio of 12:1, so 14:1 is hardly "beyond sense". That's such a small decrease in quality that the perceivable difference is slim to nil. MPEG compression IS based on human perception after all.

re: YouTube enters the widescreen world

gorath — Wed, 26 Nov 2008 08:41:45 GMT

"That 36Mbits on Blu-ray already looks pretty pathetic by comparison. That's a compression ratio of approximately 14:1."

Well, that's my point, compressing beyond sense.

HD is a bit of a scam, in that it pushes even bleding edge equipment to the limit, and yet they still compress it further, and further and further, ecentually reaching SD levels, but still label it as Hi-Def - It's Not.

If you're ever lucky enough to see original HD source material during filming, you might realise why calling everything that's compressed so heavily "HD" annoys me.

re: YouTube enters the widescreen world

Waethorn — Wed, 26 Nov 2008 01:09:42 GMT

"BD video uses a veriety of modern codecs, such as the ones you have listed, but still generally requires a bandwidth of 36Mb/s."

Yes, but the media isn't all that different from DVD, when compared to scale.

A typical Blu-ray disc can only hold about 2 hours of video in full HD resolution when used at the standard bitrate, just like a DVD with SD video. Blu-ray does 1080p resolution. 720p takes a fraction of the storage space. The loss in detail is likely acceptable for that usage.

Don't forget that you also have sound in there too. Blu-ray can utilize 7.1 audio with lossless compression. For an HD conferencing system, you have streaming issues you have to accomodate, and you certainly don't need multi-channel surround sound. MP3 audio can suffice for that.

I used to know the method for calculating the actual image size in bytes. It's something simple like this:

1280x720x3 (3 bytes per pixel, cuz it's 24-bit colour - there is no transparency in single-track video, so it's not 32-bit colour)

You end up with 2764800 bytes, or exactly 2700KB per image.

If you take that image and multiply it by 24 frames per second, you end up with 64800KB per second of raw video.

Per minute, it's 3888000KB per minute.

Per hour, it's 227812.5GB.

....you get the idea there.

Anyway. Raw video at 720p24 would calculate out to 506.25Mbits/sec. That's assuming that there's no network overhead (which there always is). This is a straight conversion, and purely hypothetical.

That 36Mbits on Blu-ray already looks pretty pathetic by comparison. That's a compression ratio of approximately 14:1. Numbers don't tell you everything though. Perceptual codecs work extremely well at what they do. If you just took 13 in every 14 bits out of that original data, you'd have probably the equivalent of the original TV broadcast ever made.

Ok, now this is an HD conferencing system. I'd almost bet they weren't using full-framerate video for this thing due to network constraints. Maybe 15fps if you're lucky. More than likely, half that.

re: YouTube enters the widescreen world

gorath — Wed, 26 Nov 2008 00:12:30 GMT

WOW, webguy! now that is a definite thumbs up for youtube. Major improvement.

I winder how many crappy mobile phone videos will be updated, upscaled to HD though.

re: YouTube enters the widescreen world

WebGuy3000 — Tue, 25 Nov 2008 22:16:08 GMT

Actually, the 720p encoding that Youtube is doing isn't too bad, considering. It depends on the quality of the original source, really. Some of the corporate videos I've uploaded in HD look quite amazing.

Here's one I found (Not one of my corporate videos) that really looks quite good at full screen.

www.youtube.com/watch

And yes, HD fmts (720p and 1080p) are specified as resolutions, independent of codec, data rate or compression scheme. There's a big, long, geeky discussion in there, but no one else seems particularly interested, so I'll drop it.

re: YouTube enters the widescreen world

gorath — Tue, 25 Nov 2008 21:35:50 GMT

oops, forgot to add, however, that that's a very good point about using native resolution for consumer camcorders.

re: YouTube enters the widescreen world

gorath — Tue, 25 Nov 2008 21:34:46 GMT

Waethorn, more compression is always bad.

Especially in the case of HD video footage, where the original uncompressed filesize is absolutely huge. To get that down to a 2Mb stream requires massive amounts of data to be removed.

BD video uses a veriety of modern codecs, such as the ones you have listed, but still generally requires a bandwidth of 36Mb/s.

That's a long, long long loooooong way off SD bandwidth.

re: YouTube enters the widescreen world

Waethorn — Tue, 25 Nov 2008 20:26:01 GMT

"For example, I was talking with a friend of mine who installs video conferencing systems recently. He was telling me about a new HD conferencing system they'd just installed in a largely rural area. I thought this was an insane as it was impressive, so I asked him how much bandwidth something like that uses.

2Mb/s. two megabits per fricking second?

When I pointed out that it couldn't possibly be HD, as even SD DVD video is generally 4.8Mb/s, and can go as high as 9.8"

"High Definition" has no specification for what kind of bandwidth you use. The only "specification" is that it's displayed in a particular resolution, usually 1280x720 or 1920x1080, interlaced or progressive.

In actuality, the resulting quality depends on the codec. DVD's use MPEG-2. HD-DVD's and Blu-ray discs use MPEG-4, AVC/H.264 (MPEG-4 Part 10), and/or VC-1. Satellite systems (even HD ones) frequently use MPEG-2 for the most part, but are [very] slowly moving to MPEG-4 because they can compress the stream down to SD bandwidth levels while maintaining HD resolutions. Ditto for digital cable systems. The bandwidth used is dependent on the carrier, and will be designed for the medium.

Your argument is moot anyway. It's like saying you need a WMA file (or AAC if you will) at the same bandwidth as an MP3 to achieve the same quality, which is totally false. Newer codecs are more efficient, and they can squeeze a higher quality signal into less bits than older codecs can.

....

I'm thinking this is going to be good for those new ultra-cheap consumer HD camcorders, such as the Flip Mino HD. You'll be able to use the native resolution from them instead of having to downsample to 4:3 SD.

re: YouTube enters the widescreen world

gorath — Tue, 25 Nov 2008 18:45:01 GMT

Thanks for the heads up, webguy, but I checked that HD link you posted, and whilst it is a monumental improvement over normal youtube videos, it is still compressed to buggery.

As a side note, I think the whole "HD" term is bandied around far to often, in a meaningless way these days.

For example, I was talking with a friend of mine who installs video conferencing systems recently. He was telling me about a new HD conferencing system they'd just installed in a largely rural area. I thought this was an insane as it was impressive, so I asked him how much bandwidth something like that uses.

2Mb/s. two megabits per fricking second?

When I pointed out that it couldn't possibly be HD, as even SD DVD video is generally 4.8Mb/s, and can go as high as 9.8, he replied,

"well, yeah, but it really is almost as good as a dvd"

Bearing in mind that this was on a mahoosive display I can only imagine how bad a 2Mb video would have looked.

It turns out that the camera takes 720p images, then they downscale the image and drastically compress it, compress the audio, and then decompress and upscale at the other end.

HD my ***!

re: YouTube enters the widescreen world

gorath — Tue, 25 Nov 2008 18:29:32 GMT

@Webguy:

"you get an actual 1280x72 HD video. "

WOW, now that IS widescreen indeed! :p

re: YouTube enters the widescreen world

WebGuy3000 — Tue, 25 Nov 2008 16:05:48 GMT

This is actually great news for those of us who are putting widescreen content on YT. They've been quietly adding ways to get better video quality up there.

Did you know that there are at least four different versions of any Youtube video available if you know the secret handshakes?

As a public service, I hereby present Webguy's Guide to Youtube video versions:

YouTube (crappy) default - just go to any video and you get this:

Video: Sorenson H.263 (Flash), 320 x 180 (scaled up to 480x270)

Audio: MPEG Layer 3, Mono, 22.050 kHz

YouTube "High Quality" - Click the "watch in high quality" link

below the video (if available) and you get:

Video: Sorenson H.263 (Flash), 480 x 270

Audio: MPEG Layer 3, MONO, 44.100 kHz

YouTube "High Quality stereo" (aka ipod version)

Append "&fmt-18" (without the quotes) after the URL and you get h.264 encoded video with stereo sound:

Video: H.264, 480

Audio: AAC, Stereo (L R), 44.100 kHz

YouTube Hi-Definition (who knew?)

Append "&fmt-22" (without the quotes) after the URL and (if the video submitter actually uploaded an HD video in the first place) you get an actual 1280x72 HD video. (Of course you have click the full screen icon below the video to see the difference, but it is impressive.)

Video: H.264, 1280 x 720

Audio: AAC, Stereo (L R), 44.100 kHz

Of course, all the above only work on fairly recent videos where appropriately hi-res source was uploaded in the first place. Also note that some of this may have changed with the latest updates - this was as of yesterday.

An example of a 720p video can be seen here:

www.youtube.com/watch

(be sure to go full screen, note the crispness of the text