BD to BD5 which resolution

[longtom]

Any experience if it is better to go with 720p instead of 1080p for a BD5?
Is the picture better with 720p than 1080p? (because of less compression?)

:thanks:

[Ghitulescu]

The only one that can decide if the quality is ok, good, bad etc. is you.

The quality depends on: original quality (FullHD 1080p quality, as one sees in the advertising, is just advertising), codec, bitrate and frame size: whereas the second and the latter are set by the target (player, TV) and the third by the space:duration ratio.

[rotty]

Any experience if it is better to go with 720p instead of 1080p for a BD5?
Is the picture better with 720p than 1080p? (because of less compression?)

:thanks:

Hi Longtom

just been having a look thought the posts and saw your great question, like Ghitulescu said, really its a "heads I win, tails you loose". Something has to go.

You/me and every body else on here are all obviously well into our HD disks and yet we are looking for ways to degrade them.

Well if its a movie you like then dont do it, give it what it deserves, put it on a BD25, and if you have to re-encode then at least its far less compression than 5G, BD Rebuilder does a blinding job, PLUS no dilemma.

[Capsbackup]

IMHO, and my 2¢, :p
I always keep the original resolution, and I can't tell the difference from the original on my 50" 1080P Samsung Plasma.
I generally use BD5 for movies up to 2 hours, BD9 for 2.5 to 3 hours long or for full movie backups with total time of 2.5 to 3.5 hours long.
If I really like the movie and it has many extras, 4+ hours, and I want to keep HD audio, I use BD25.
I have yet to be disappointed in the results from BD-RB for this! :)

[Sharc]

I usually go for 720p on BD5 given the fact that many of the commercial BDs appear to be low pass filtered, means the effective resolution is about 720p only anyway.
One may do a simple downscale / upscale comparison test to check if details would be lost when going for 720p.

[jdobbs]

I usually go for 720p on BD5 given the fact that many of the commercial BDs appear to be low pass filtered, means the effective resolution is about 720p only anyway.
One may do a simple downscale / upscale comparison test to check if details would be lost when going for 720p. Interestingly the differences between 720p and 1080p is really hard to see anyway on most HD systems.

[Ghitulescu]

Interestingly the differences between 720p and 1080p is really hard to see anyway on most HD systems.

It's mostly because most available materials were shot in 720p then upscaled to 1080p for distribution. On the other hand it's much easier to write an algorithm for 1.5x than for ~1.8x (PAL SD->HD) so it can be cheaper to implement also in the cheapest TV sets. Sometimes the optical resolution of a film doesn't allow a 2k scan. Of course you have the FullHD in terms of pixels but not in terms of distinct visual points.

[Video Dude]

If you choose to downscale to 720p, does Blu-ray keep the source 1080p framerate or is it doubled like broadcast 720p? Would a 1080p 24fps movie be encoded at 720p 24fps?

[jdobbs]

If you choose to downscale to 720p, does Blu-ray keep the source 1080p framerate or is it doubled like broadcast 720p? Would a 1080p 24fps movie be encoded at 720p 24fps? Yes, a 1080p/24 would be reecoded to 720p/24. Same for 23.976. The exceptions would be sources that are 1080i/29.97 and 1080i/25. They have to be deinterlaced and converted to 59.94p and 50p. There is no support for 29.97i or 25i in a 720 format.

Hmmm... Now that I think about it, I believe I've been upsizing the fields and doubling the framerate to keep it compatible on 29.97/25i -- when it may make more sense to just double it with pulldown flags now that pulldown is supported in X264. I'll have to give that a try.

[jfcarbel]

I have read that if you are viewing your HD content at more then 12-13 feet away then your eyes cannot pick up the minute details that 1080 provides, so in that case 720p vs 1080p would make no difference.

Sorry, I do forget where I read this. But someone was asking this question in regards to whether getting a 720p older Plasma TV would make a difference vs the newer 1080p ones. And that is when the journalist answered that it depends and viewing distance from screen would make the determination.

I am curious though in how much of a percentage of reduction in file size does one achieve when going from 1080p to 720p. Is it close to a 50% reduction?

[MvB]

I have read that if you are viewing your HD content at more then 12-13 feet away then your eyes cannot pick up the minute details that 1080 provides, so in that case 720p vs 1080p would make no difference.


I have a 50'' plasma and i'm watching from about 9-10 ft away. There you see a subtile difference between 1080p and 720p. If you're 12-13 ft away i would say you cannot distinguish. What the heck, with my 42'' plasma i wasn't able to differentiate between 720p and 1080p from 9 ft away.

[jdobbs]

I have a 50'' plasma and i'm watching from about 9-10 ft away. There you see a subtile difference between 1080p and 720p. If you're 12-13 ft away i would say you cannot distinguish. What the heck, with my 42'' plasma i wasn't able to differentiate between 720p and 1080p from 9 ft away. Subtitles are a little different -- because they are resized by TSMUXER rather than AVISYNTH and X264.

[Ghitulescu]

I have read that if you are viewing your HD content at more then 12-13 feet away then your eyes cannot pick up the minute details that 1080 provides, so in that case 720p vs 1080p would make no difference.

Sorry, I do forget where I read this. But someone was asking this question in regards to whether getting a 720p older Plasma TV would make a difference vs the newer 1080p ones. And that is when the journalist answered that it depends and viewing distance from screen would make the determination.

I am curious though in how much of a percentage of reduction in file size does one achieve when going from 1080p to 720p. Is it close to a 50% reduction?

I have a 50'' plasma and i'm watching from about 9-10 ft away. There you see a subtile difference between 1080p and 720p. If you're 12-13 ft away i would say you cannot distinguish. What the heck, with my 42'' plasma i wasn't able to differentiate between 720p and 1080p from 9 ft away.

The visual acuity of the normal human eye is 1". Using trigonometry one can calculate the distance knowing the panel size or viceversa.

However, most tests I've seen in magazines are simply not tests, but just false marketing issues: a proper comparison of 720p with 1080p requires a native 720 panel and a native 1080 panel (normally they use a native 1080 panel only, so 720p is disadvantaged by upscaling), a native material (720 or 1080, very difficult in the past, as videocameras were 720p and the only source of 1080p was the film, which was not scanned at 720p, today there are 1080p cameras - I mean cameras that can really discern 1080 points) and players that can output the native resolution (very few in the past).

One of the best quality Blurays I have (non-animated), the UK edition of Planet Earth, was shot in 720p (I saw the camcorders :), a BBC subcontractor confirmed this), yet the visual quality exceeds all the 2k-scanned movies (even Anniversary or Collectors' editions) I saw. It's not all pixels.

[Groucho2004]

One of the best quality Blurays I have (non-animated), the UK edition of Planet Earth, was shot in 720p (I saw the camcorders :), a BBC subcontractor confirmed this), yet the visual quality exceeds all the 2k-scanned movies (even Anniversary or Collectors' editions) I saw. It's not all pixels.

Very good point - and you should put the last sentence in your signature. :)

[Video Dude]

I don't have a PC Blu-ray drive yet, but if I did I would likely do BD5 720p backups.

Could someone tell me the average time it would take to do a 2 hour movie on an Intel Core 2 Q6600 (2.40 GHz Quad Processor) using the default setings for a BD5 720p backup?

[longtom]

I don't have a PC Blu-ray drive yet, but if I did I would likely do BD5 720p backups.

Could someone tell me the average time it would take to do a 2 hour movie on an Intel Core 2 Q6600 (2.40 GHz Quad Processor) using the default setings for a BD5 720p backup?

too long :cool:

[jdobbs]

I don't have a PC Blu-ray drive yet, but if I did I would likely do BD5 720p backups.

Could someone tell me the average time it would take to do a 2 hour movie on an Intel Core 2 Q6600 (2.40 GHz Quad Processor) using the default setings for a BD5 720p backup?

I don't have your setup, but I'd imagine around 6-7 hours or so for a full 1080p backup. I'd guess that you'll get close to 1:1 on the first pass and somewhere around 10fps on the second pass. So cut that down to what 720p would take... I don't know, maybe 4-5 hours?

I have a Phenom II X4 945 overclocked to 3.3Ghz and I just finished a movie that was 1h 32m in 1080p using 2-pass High Quality to a BD-5 and it took 2.5hrs.

[laserfan]

I don't have a PC Blu-ray drive yet, but if I did I would likely do BD5 720p backups.

Could someone tell me the average time it would take to do a 2 hour movie on an Intel Core 2 Q6600 (2.40 GHz Quad Processor) using the default setings for a BD5 720p backup?Easy answer: "overnight". Or as longtom implied, "too long" (to wait for)...

[Video Dude]

Hmmm... Now that I think about it, I believe I've been upsizing the fields and doubling the framerate to keep it compatible on 29.97/25i -- when it may make more sense to just double it with pulldown flags now that pulldown is supported in X264. I'll have to give that a try.
jdobbs, did you decide to implement this?

[jdobbs]

jdobbs, did you decide to implement this? I couldn't get it to work.

[jdobbs]

Any experience if it is better to go with 720p instead of 1080p for a BD5?
Is the picture better with 720p than 1080p? (because of less compression?)

:thanks: Well... it's not as cut-and-dry as that. When you go to 720p you are also doubling the framerate, so even though you are encoding fewer pixels, you are also encoding more pictures.


I personally have used 1080 on my DVD-5 encodes in the past. But, honestly, with DVD-9 discs now at less than 60 cents each -- I rarely use DVD-5 anymore. Here's (http://www.meritline.com/titan-dvd-plus-r-dual-layer-dl-8x-white-inkjet-hub-printable---p-47503.aspx) an example. I got 100 of these and have had no issues. I typically do my movie-only backups to DVD-9 and full backups to BD-25 (they're hanging in at a little over $1 per disc).

[Sharc]

Well... it's not as cut-and-dry as that. When you go to 720p you are also doubling the framerate, so even though you are encoding fewer pixels, you are also encoding more pictures.

Why doubling the framerate for 720p?
Framerate doubling would only have to be applied for interlaced 25 fps or 29.97 fps 1080i sources. Most blu-ray sources are 23.976 or 24 fps progressive, which can be scaled to 720p at same framerate.
Am I wrong?

[jdobbs]

Why doubling the framerate for 720p?
Framerate doubling would only have to be applied for interlaced 25 fps or 29.97 fps 1080i sources. Most blu-ray sources are 23.976 or 24 fps progressive, which can be scaled to 720p at same framerate.
Am I wrong? You are correct. I should have clarified that frame doubling is only true on 29.97 and 25fps sources.