25P 4k footage render out to BD interlaced only?

Gabonviper wrote on 1/22/2016, 2:15 AM

Hi,

I am trying to render concert footage I shot with the Panasonic Lumix LX100 in 4k 25P out to Blu-ray for DVDA but am having trouble retaining the excellent detail of the footage (25,000 fps progressive, 3840x2160x12, AVC).

I am using the Blu-ray 1920x1080-50i, 25 Mbps video stream template (variable bit rates 40-30-25 mbps), and the result is really blurry, and not just in panning shots but in screen shots with no or little motion. If I switch field order to progressive, DVDA will require recompression (to interlaced), as the only viable option in DVDA is MPEG-2 1920x1080-50i. (The two progressive scan options, 24.000p and 23.976p would require me to use those frame rates in rendering; I tried it and the results were even blurrier.) The AVC options make no difference here to my mind. (Correct me if I am wrong.)

What's more, the MPEG-2 interlaced render of the footage (40-30-25mbps) pales in comparison to the MP4 (AVC/AAC) Internet HD 1080p progressive render (24-20mbs) I made as far as detail is concerned, the latter being virtually as sharp as the original, at least in Best (Full) preview quality on the computer screen , at almost half the bit rate. This, to a layman such as myself, seems strange.

When I imported the MPEG-2 rendered m2v file into Vegas 13 and sharpened it and then rerendered it (this of course meant recompression), the result was better than the original render, though still not on par with the MP4 version.

One would think Blu-ray would be superior to YouTube versions, but in this case it falls short.

Is there anything I could do to retain the quality of the progressive footage?

Note:
What I could have done in the first place was shoot it in 4k 24P, and which would nicely render out to 24p using the MPEG-2 1920x1080-24p, 25 Mbps template, which DVDA has a video format setting for requiring no compression.

Two questions on 24p, though:
1) is there a marked difference between 24p and 25p to the naked eye?
2) should I choose the 23.976 option over 24p in DVDA (the frame rate in the MPEG-2 template is 23.976, which is the actual frame rate of the 24P 4k footage?)

I know this may have been addressed before, but couldn't really find answers so any help greatly appreciated. And I posted it here instead of DVDA as that forum seems much quieter than Vegas Pro and truth be told, this also deals with rendering in Vegas Pro.

Cheers
Marko

Comments

OldSmoke wrote on 1/22/2016, 7:23 AM

Try and disable resampling on all clips. This way 50i shold look and feel the same as 25p.
There are simple tricks to convert 25p to 24p by slowing it down and you wont notice the difference.

Gabonviper wrote on 1/22/2016, 7:26 AM

I had resampling disabled already. But how do you slow it down? Lower playback rate? If so, by how much? Will it still sync well with the audio (this one's 24-bit 48kHz zoom H1).
Will DVDA then accept it as 24p?
I tried rendering it with the 24p template, which DVDA accepts, and it may have come out sharper but at the expense of a lot of jitter in motion.
So what's the bag of tricks here?

Warper wrote on 1/22/2016, 8:45 AM

1) Playback rate 96% will make 25p source into 24p timeline. Project/rendering should be 24p. Resample should not hit, but still disable resample as a precaution.
You should change sudio playback rate as well to keep it in sync.
You should change video event length according to change of playback rate as slower playback will take more time and simply changing playback rate in event properties does not change event length. Simple way is to drag right side of video event up to white teeth in the upper side (it's looping/freezing last frame mark).

Alternatively you can Ctrl+drag right side of video event up to desired length, Vegas will change playback rate for video/audio accordingly.

2) I believe you can allow DVDA to simply reencode progressive material. If you make good quality of intermediate and allow 1 recompression, quality should not drop noticably. The question is if DVDA will accept 25p file. It worked for me for SD 25p, but I've never tried HD.

3) You can try 50i again, but using "interpolate fields" in deinterlacer method. It kicks in when you change the size of picture or rotate it in interlaced project (probably should not work with first progressive->interlaced transformation).

Former user wrote on 1/22/2016, 9:16 AM

Some may disagree with me, but in my experience if I try to change resolution and render to MPEG, the quality is not as good as if I would render to a lossless compression first and then render that to an mpeg.

To me Vegas does not handle downrezzing and high compression at the same time well. You could try that and see if it retains your quality.

Gabonviper wrote on 1/22/2016, 9:29 AM

Thanks Warper for your bag of tricks. I'll give them a shot and compare the results. The easiest is of course allowing DVDA to recompress 25p, which it allows but requires to be recompressed. It will be interesting to see if the result is sharper than a p to i conversion in Vegas.
Changing playback rate is trickier as I have done about a half hour of the footage already and changing the length of a clip means adjusting keyframes, reapplying stabilization (Mercalli is a nightmare to work with -very erratic) etc. And how do I adjust the playback of the audio to sync with the new frame rate? The audio is not from the camera and it just happens to sync well with 25fps.

OldSmoke wrote on 1/22/2016, 9:42 AM

Render to a 25p lossless intermediate first then change the playback rate.

Gabonviper wrote on 1/22/2016, 10:01 AM

I am sorry but what does that, "lossless intermediate", mean in practise in tge case of a 4k project?

OldSmoke wrote on 1/22/2016, 11:09 AM

Lossless would be something like Sony YUV, it's under Video for Windows but it would be a huge file.

I pesonally would use XAVC-Intra 3840x2160 25p. That will create an XAVC MXF file that isnt lossless but will still hold very well and you will visually not see any losses in quality. It is also a much smaller file compared to a Sony YUV .avi file and playback in Vegas is much better then XAVC-S.

Try and render a selction rather then the whole project.

Gabonviper wrote on 1/22/2016, 1:25 PM

Ok, thanks.
I'll try that. This is 2:18 hrs of foorage, so we'll see how that works out. As for the audio, someone on an LX100 FB group said that 24p is the way to go as it syncs up with the standard 48kHz sampling rate, so maybe it'll be just fine.

john_dennis wrote on 1/22/2016, 3:40 PM

I would use this straightforward method to convert 25p to 24p.

Per Bob, "[I]It really is a trivial task.[/I]"

Gabonviper wrote on 1/23/2016, 4:39 AM

Thanks for the tips. I tried the straightforward approach but I think I will just count my blessings and see if DVDA recompression produces better results than p to i rendering. In addition to my own 25p material, I also have some 25i material to fill in gaps in the footage, all perfectly synched up with the audio. Resynching it all seems like a nightmare.
But DVDA is just one dvd authoring tool. Are there any that would allow 25p without recompression? I guess there is a reason for the lack if a 25p/50p bluray template there?

PeterDuke wrote on 1/23/2016, 6:18 AM

" I will just count my blessings and see if DVDA recompression produces better results"

Good luck but I see no reason why it should. The general rule of thumb is to NEVER recompress in DVDA.

"Are there any that would allow 25p without recompression?"

The Blu-ray standard only permits a few options. The ones likely to be of interest to you are

1920x1080 50i
1920x1080 24p
1280x720 50p

There is no 25p option, so you will have to recompress to one of the above. 1920x1080 25p to 1920x1080 50i requires the least change in principle because it really only involves a flag change. There may be a tool to do that losslessly.

Gabonviper wrote on 1/23/2016, 8:26 AM

" There may be a tool to do that losslessly."

Do let me know if know of any.

I just wonder why the 1920x1080 25p or 50p option doesn't exist. I mean, 25p or 50p is more common for high-end consumer pocket cameras than 25i or 50p, right? At least as common as 24p? Does it have to do with television standards or something? In any case, what's the use of 50p or 25p if you can't really realize the camera's full potential?

Lastly, for future reference, as I intend to continue to make blurays of my concert footage for personal use (much nicer to view them on a big screen thru my home theater than on a computer screen), would you say it'd be better to shoot 24p rather than 25p?

john_dennis wrote on 1/23/2016, 12:29 PM

"[I]...would you say it'd be better to shoot 24p rather than 25p?[/I]"

When the wind is blowing hard in my face I try not to spit. For [I]Blu-ray[/I], 24p. Film makers have used that frame rate (for better or worse) for a long time.

Gabonviper wrote on 1/23/2016, 1:25 PM

Thanks. At least that makes life easier. I'll run some tests on how 24p synchs up with 48kHz audio. BTW, I ran a few comparative tests, and it appears it's better to let Vegas do the p to i conversion rather than let DVDA recompress but that was to be expected. Not a big difference but still. Thanks everybody for your help. Maybe one day 4k will no longer have to be downreszed.

OldSmoke wrote on 1/23/2016, 1:30 PM

I would have rendered a 25p file and converted it to 24p; it's just so easy and will fit on the BD without re-rendering in DVDA.

Gabonviper wrote on 1/23/2016, 2:12 PM

OldSmoke: I tried your tips on converting 25 to 24 in Vegas but that seemed like a lot of re-editing and truth be told, I probably didn't do it right.

Should playback be dropped to 0.960? I changed the ruler in the properties to absolute frames and changed playback to 0.960. When I dragged the clip, the frame count didn't change (the frame count reads in the info next to the resolution of the clip, right?).

Are you now suggesting some other way of converting a 25p render to 24p?

OldSmoke wrote on 1/23/2016, 4:24 PM

Open your existing project and render it out to 25p, I reommend XAVC-Intra. Take the newly rendered file and follow these instructions from the earlier mentioned thread and post:

There is nothing in there mentioned about playback rate.

When you render out, render to a BlueRay 24p template and for audio render to AAC. If both files have the same name but different extensions, as they should, by adding the video file to DVDA it will automatically find the audio track.

Gabonviper wrote on 1/23/2016, 4:28 PM

Thanks, I'll try that.

john_dennis wrote on 1/23/2016, 5:32 PM

"[I]...and for audio render to AAC.[/I]"

For [I]Blu-ray[/I], AAC is not a valid standard for audio. Use AC3 or LPCM (WAV).

OldSmoke wrote on 1/23/2016, 7:32 PM

+1 John, my bad.

Gabonviper wrote on 1/24/2016, 3:44 AM

Just to make sure,

My 2:18hr-project has 25i material here and there. Does that matter? Render out to 25p all the same?
Render each song out to 25p separately (the whole concert being top much for my computer to handle) and then import the XAVC-Intra files back into the project, then change clip duration for all of them etc.?
What worries me is whether I will be able to synch the audio...

Gabonviper wrote on 1/24/2016, 5:27 AM

I did the first song. The four-minute MXF file is 6.29GB (the interlaced render was 862mb). I changed project properties to 4k 16:9 24p (4096x2304; 23,976fps). The original was 3840x2160 so should I have chosen the QFHD 24p template instead (with a matching resolution)?
I matched the clip with the former frame count. Problem: the song is considerably slower in tempo, adding 10 seconds added to its length, an altogether different song really.
What am I doing wrong?

PeterDuke wrote on 1/24/2016, 6:01 AM

Yes, changing from 25 fps to 23.97 fps will increase the play time by 25/23.97 = 1.043 or 4.3%

120 beats per minute will become 115 beats per minute. 4 minutes will become 4 minutes 10 secs. You didn't do anything wrong.

If you want the exact same length then you will have to drop or interpolate frames and lose some video quality in the process. Twixtor is designed for this sort of work..