Ask questions to Compression Engineer insider "drmpeg"

[oppopioneer]

A different topic...

Is it easier for the compression engineers who put the movies on a disc to use/work with a film based movie shot on film or a movie shot entirely with a digital camera (SLR or The Red One/RED Digital Cinema) ?

[DaViD Boulet]

Originally Posted by oppopioneer

I've read on another thread that for 3D and other future bd technology regarding PQ that MPEG is prefered or is compatible with it and not VC-1. Is VC-1 going to continue to be used or be phased out?

Also, are they working on an MPEG-6 ?

Which is a superior system to use for best PQ?

I had also heard that MPEG-4/AVC had the built-in ability to compress stereoscopic using the "left minus right" to gain effeciency (why it's being used for 3D on blu-ray), but that VC-1 has no such provision for stereoscopic compression efficiency.

[4K2K]

Does encoding at a higher resolution always need a higher bitrate than encoding at a lower pixel resolution for a given picture quality with average video assuming watching with the same TV and viewing distance?

Is it possible using mpeg4 to encode 1920x1080 at low average bitrates so that even difficult to compress segments would look no worse than a lower resolution encode at the same low average bitrate (eg. by changing the block size or other compression parameters)? And that easy to encode segments at that low avg bitrate but higher res would look better than the lower res encode at the same low bitrate.

Or is it always the case that there is an optimum encoding resolution for a given average mpeg4 bitrate and that you can't encode at a higher resolution with the same bitrate to get the same quality (using the same TV and viewing distance)?

eg. at only 9 mbps (or even less) average mpeg4 bitrate, with average TV content, would it give better quality on average encoding at 1920x1080 or at a lower resolution?

I'm not advocating low mpeg4 bitrates with this post - I think they should always be high, I'm just wondering, if low bitrates had to be used on average whether you'd get better quality encoding with full 1920x1080 resolution or a lower resolution and why.

[SquidPuppet]

How many minutes of 1080p content can be safely stored on a 50g Blu-ray disc before compression will start to negatively affect the picture quality?

[DaViD Boulet]

Originally Posted by SquidPuppet

How many minutes of 1080p content can be safely stored on a 50g Blu-ray disc before compression will start to negatively affect the picture quality?

It depends on the content.

A 5 hours without much entropy might not consume as much space as 2 hours with complex motion. There are probably averages that can be talked about in general terms, but if you really want a meaningful answer it will be dependent on each unique video signal.

[SquidPuppet]

Originally Posted by DaViD Boulet

It depends on the content.

A 5 hours without much entropy might not consume as much space as 2 hours with complex motion. There are probably averages that can be talked about in general terms, but if you really want a meaningful answer it will be dependent on each unique video signal.

So 4.5 hours of sitcom with only DD 5.1 Lossy might be safe?

[DaViD Boulet]

Originally Posted by SquidPuppet

So 4.5 hours of sitcom with only DD 5.1 Lossy might be safe?

i'm not the expert, but I'd imagine that 5.1 hours of a "normal" sitcom would not be a challenge to do a high-quality AVC encode on a 50GB BD with lossy 5.1.

[SquidPuppet]

Originally Posted by DaViD Boulet

i'm not the expert, but I'd imagine that 5.1 hours of a "normal" sitcom would not be a challenge to do a high-quality AVC encode on a 50GB BD with lossy 5.1.

Thanks.

[drmpeg]

Sorry I haven't posted for so long in my own thread. I've been very busy with building new gadgets, including some ground-breaking 1080p@60 stuff.

I just happened to get hooked on "Mad Men" recently, and bought the first 3 seasons on Blu-Ray. It's a 13 episode season split on 3 discs, with 5 episodes on the first disc and 4 on the second and third discs.

The episodes are 47 minutes, so the first disc has almost 4 hours of content with DTS-HD audio. It would seem a high quality 4.5 hour encode with DD5.1 is very possible.

Ron

[4K2K]

Originally Posted by drmpeg

Sorry I haven't posted for so long in my own thread. I've been very busy with building new gadgets, including some ground-breaking 1080p@60 stuff.

Can you give us some details please?

I just happened to get hooked on "Mad Men" recently, and bought the first 3 seasons on Blu-Ray. It's a 13 episode season split on 3 discs, with 5 episodes on the first disc and 4 on the second and third discs.

The episodes are 47 minutes, so the first disc has almost 4 hours of content with DTS-HD audio. It would seem a high quality 4.5 hour encode with DD5.1 is very possible.

Ron

What if it was 4 hours of 1920x1080/50i AVC (50hz motion) which had lots of lighting effects and camera motion with lossless audio? How much quality would be lost by using 1 BD50 instead of 2 discs? What about cost differences (in encoding time and discs)?

Is there a link that gives guidelines on number of hours, of this type of content (eg. 24/25/30/50/60hz at a particular resolution) at about this complexity, needs this amount of BD50s/25s for this amount of quality?

[alehel]

I was wondering if you happen to know if anyone is using the x264 encoder for blu-ray releases yet now that it is capable of producing blu-ray compliant files.

[EDIT] nevermind. I see now that there is a list for this specific question, http://www.x264bluray.com/x264-encoded-releases

Everybody is trying to develop encoders that will go as low as possible and anything over 10 Mbps is considered high.

[Steedeel]

Guys, is this related to HD streaming and downloads? Why else would they be aiming for compression at such low bit-rates?

bit of a novice with the tech talk so please forgive me.

[drmpeg]

Originally Posted by drmpeg

Sorry I haven't posted for so long in my own thread. I've been very busy with building new gadgets, including some ground-breaking 1080p@60 stuff.

Originally Posted by 4K2K

Can you give us some details please?

It was for the recent ESPN MPEG-4 upgrade. The Motorola DSR-6100 IRD (Integrated Receiver Decoder) and transcoder is capable of converting a 1080p/60 MPEG-4 downlink to 720p/60 MPEG-2 for cable head-end distribution. The idea is that ESPN can start uplinking 1080p/60 at some point and have a premium 1080p/60 channel on cable systems that have a 1080p/60 MPEG-4 capable STB. But that same 1080p/60 uplink will continue to provide the 720p/60 MPEG-2 service through the DSR-6100.

It's a way to break the 1080p/60 logjam. Whether a premium ESPN 1080p/60 channel in marketable is debatable (discuss amongst yourselves).

http://www.tvtechnology.com/article/121492

Ron

[drmpeg]

Originally Posted by Steedeel

Guys, is this related to HD streaming and downloads? Why else would they be aiming for compression at such low bit-rates?

bit of a novice with the tech talk so please forgive me.

It's more about satellite providers like DirecTV and Echostar where bandwidth costs money. The typical HD MPEG-4 channel is encoded at around 6 Mbps.

Ron

[Steedeel]

thanks for that

Thank you for these nice and useful information

[Encoder9]

Hi. I tried searching for this but couldn't find anything. I'm new to encoding and new to Blu-ray so thank you for any help you can give me. I compressed 1080x1920 Pro Res footage into 1080x1920 MPEG-2 using Episode with their Blu-ray MPEG2 1080i60 encoder. When I import this file into Encore to burn a Blu-ray, Encore is further transcoding the file and ruining the quality. Encore does not see the file as Blu-ray compliant. Does anyone know what I need to do to make this file Blu-ray compliant so that Encore will burn it to Blu-ray as is without transcoding. My AC3 audio is working fine and has a "don't transcode" option but the video doesn't. Thanks for any help Ron.

[LisaAlix]

There is good things.

[LisaAlix]

Btw What about this?