JVC LS300 clarification questions

[David Andrade]

There are some things I keep reading and there doesnt seem to be a clear answer, despite visiting JVC's web site and Google. 

Is the HDMI 1.4 or 2.0? I read 1.4, but I didnt think 4k could travel over 1.4, so I assume 2.0? I also couldnt find the page that said that, so it's very possible that they were wrong. I guess this is a moot point as we know that it records 4k 60 over the HDMI, but it's odd that there is no definitive answer anywhere. 

The bitrate of the 120fps HD. What is it? I read....again.....somewhere....that it was the 50mbps. I can deal with the crop. But 50mbps seems awfully low. Again, I could be getting false information from a non-reputable site, but I can't find a definitive answer anywhere. 

One last question, which I *may* have found the answer to. When recording to 4:2:2 4k internally, it mentions the HDMI out is only HD. So....HD as in 720p? or full HD as in 1080p? 

[Anaconda_]

I'm not sure about the hdmi, but you're right. It does 4k60p so must be up to standard.

50mbps at 1920x1080 is broadcast standard, so shouldn't be low at all for your slow mo shoots. All 1080p bitrates are 50mbps or lower with this camera. 

Filming 422 4k internal allows you to output 1080p or i but I think only 25/30fps. 

[David Andrade]

25 minutes ago, Anaconda_ said:

I'm not sure about the hdmi, but you're right. It does 4k60p so must be up to standard.

50mbps at 1920x1080 is broadcast standard, so shouldn't be low at all for your slow mo shoots. All 1080p bitrates are 50mbps or lower with this camera. 

Filming 422 4k internal allows you to output 1080p or i but I think only 25/30fps. 

Thank you. 

Yeah it has have to 2.0 (hdmi) - it's the only thing that makes sense. 

Thank you for clarifying the 1080p for output. Makes sense. Still a good option if you just want to monitor 1080p (some monitors only show 1080p, anyway) or record a 1080p proxy. A little odd seeing that you can do 4k 422 externally with a higher bitrate, but still good to know it's 1080p. 

I've just heard that the lower the mbps, the lower the quality, basing it on frame per second. In other words, I've seen people divide the mbps by the fps and the amount of mbps is less because youre allotting less mbs per frame with 120 fps as opposed to 30fps. (if you cut a pizza into 120 pieces instead of 30, of course the slices (frames) will be smaller). That may not be how this works, but that seems to be a consensus online if you look around. In fact, on the sony cameras, the S&Q is considered poorer quality than just filming straight 120 fps for that exact reason, which is why I was wondering. 

[BTM_Pix]

The 120 is definitely 50mbps as and the HDMI output is max 1080p when recording 4K 4:2:2 internal as @Anaconda_ says.

The HDMI port is definitely 2.0b

The problem with JVC is they often seem to spread their documents about across a few different corporate branded sites/distributors so its a bit of a hunt to find them

http://www33.jvckenwood.com/pdfs/B5A-1634-00.pdf

http://www33.jvckenwood.com/pdfs/B5A-1634-10.pdf

http://pro.jvc.com/pro/pr/2017/nab/gyls300_inferno.html

 

[newfoundmass]

Despite owning it for two years I've never done 120 fps with it, and I don't have it near me right now, but I'm guessing the 120 fps is slowed down in camera, so 50 mbps isn't actually being used for true 120 fps but the slowed down version that plays at 24/30 fps because 50 mbps would definitely be too little for actual 120 fps video. It'd be 1/4 the quality of 30 fps at 50 mbps and 1/2 the quality of 60 fps at 50 mbps. 

[David Andrade]

27 minutes ago, newfoundmass said:

Despite owning it for two years I've never done 120 fps with it, and I don't have it near me right now, but I'm guessing the 120 fps is slowed down in camera, so 50 mbps isn't actually being used for true 120 fps but the slowed down version that plays at 24/30 fps because 50 mbps would definitely be too little for actual 120 fps video. It'd be 1/4 the quality of 30 fps at 50 mbps and 1/2 the quality of 60 fps at 50 mbps. 

First off, BTM_Pix, thank you for that. Makes me feel better about being confused. Sad to see it scattered like that. 

Secondly, thank you newfoundmass - that's what I feared. And judging by the document that BTM provided, it looks like it might be in camera, because it lists one frame rate, and then another. The least intrusive would probably be 120 to 60fps...which by your math would give us 25mpbs per second which isnt awful. Of course from there, one would have to go in and then slow it down even more in post. It's not the extra work I'm worried about or even the 46% the VSM is locked at. Now I am wondering if the final file made by the camera should be slowed down even more. 

In theory, it shouldn't matter. The shutter speed was the same no matter what, so as long as you arent REALLY compressing it when slowing it down, again, it shouldn't experience that much quality loss. Maybe a bit of a convoluted system, though. (Record high speed, import, slow down again, render out high quality) - unfortunately that makes the most sense, because 50mbps divided by 5 is only 10mbps and that is awfully low. (120 to 24fps) 

[Anaconda_]

Ah so its 50mb over 120 frames, but those 120 frames take 4 seconds to play? That's interesting. Similar to you, I recorded about 3 clips in 120 when I first got the camera and said 'meh' out loud and never did it again.

EDIT: I just did a quick test, and here's all the various info for a 120fps recording. Seems low indeed.

.

[David Andrade]

11 minutes ago, Anaconda_ said:

Ah so its 50mb over 120 frames, but those 120 frames take 4 seconds to play? That's interesting. I'm going to do a super quick test of that now... Similarly, I recorded about 3 clips in 120 when I first got the camera and said 'meh' out loud and never did it again.

I'll report back with my findings.

Please do! Thank you for doing so! 

Yeah, like I said, unless you can determine something else that makes sense, I think 120 to 60fps makes the most sense. Which doesnt get us super slow motion, but the hope is that slowing it down in the computer won't ruin it much worse than what was done in camera. 

I'll keep an eye out  

 

EDIT: Thanks for the update!! Hmmmm.....

[David Andrade]

14 minutes ago, Anaconda_ said:

Ah so its 50mb over 120 frames, but those 120 frames take 4 seconds to play? That's interesting. Similar to you, I recorded about 3 clips in 120 when I first got the camera and said 'meh' out loud and never did it again.

EDIT: I just did a quick test, and here's all the various info for a 120fps recording. Seems low indeed.

.

Just for clarity, which option did you end up choosing? I just want to make sure we're all on the same page haha 

 

[newfoundmass]

It's 50 mbps over 29.97 fps. The camera has a buffer, so before it compresses it and writes it to the card it is processed so that 120 fps is played in a 29.97 fps file at four times the length. That all happens before any compression occurs, so it's not really 120 fps @ 50 mbps. True 120 fps at 50 mbps would be way too little. 

2 hours ago, Anaconda_ said:

I just did a quick test, and here's all the various info for a 120fps recording. Seems low indeed.

.

This is actually reasonable; variable bit rate only uses the max bit rate when it needs to. Because your clip likely has very little motion and movement, it didn't need to use all 50 mbps for it all to achieve the best quality and could do so instead at an average of 33 mbps, saving you space on your card. 

[webrunner5]

People that own a Canon C100 would KILL for 50mbps! the Codec on one is 24Mbps and it looks pretty damn good.

[newfoundmass]

It's nice to have as much data as possible to work with, but it's one of those things that people have gotten hung up on. It was inevitable with the digital video revolution as technology allowed us to work with footage in ways we weren't able to 20 years ago when I was a 13 year kid learning from the people at the local production company. 

It's a good thing, obviously, but at the same time people rely on it so much that they kinda forget that you don't NEED it to achieve good results. @webrunner5 is right, look at the C100. 

[David Andrade]

10 hours ago, newfoundmass said:

It's nice to have as much data as possible to work with, but it's one of those things that people have gotten hung up on. It was inevitable with the digital video revolution as technology allowed us to work with footage in ways we weren't able to 20 years ago when I was a 13 year kid learning from the people at the local production company. 

It's a good thing, obviously, but at the same time people rely on it so much that they kinda forget that you don't NEED it to achieve good results. @webrunner5 is right, look at the C100. 

You guys aren't wrong. Thanks for putting things into perspective. Also, the Sony FS100. Actually, this most recent part of the discussion makes me even more interested in the LS300 as opposed to something like the GH5. 10 bit on the Panasonic, sure. 400mbps, sure. But an entirely different form factor, smaller sensor and no VSM. Add the XLR interface on the GH5 and the prices are basically the same. It's becoming more and more clear why this camera is considered by some to be a "hidden gem" 

[David Andrade]

15 hours ago, newfoundmass said:

It's 50 mbps over 29.97 fps. The camera has a buffer, so before it compresses it and writes it to the card it is processed so that 120 fps is played in a 29.97 fps file at four times the length. That all happens before any compression occurs, so it's not really 120 fps @ 50 mbps. True 120 fps at 50 mbps would be way too little. 

newfoundmass, my head is still sort of spinning from this. I understand after referencing that screenshot what you're saying, at first. It's the last sentence that loses me. So, as we said before, it's compressing the 120fps into 30fps in camera - which is what you're referring to? 

And this is actually great news, right? As you said, if we had straight 120fps, the bitrate would (potentially) be much lower. 

[Anaconda_]

On 6/18/2018 at 8:56 PM, David Andrade said:

Just for clarity, which option did you end up choosing? I just want to make sure we're all on the same page haha 

  

Sorry, I missed this. My sample above was 120/60p 50M.

22 hours ago, David Andrade said:

But an entirely different form factor, smaller sensor and no VSM. Add the XLR interface on the GH5 and the prices are basically the same.

Form factor and XLRs are basically why I chose the LS300, I upgraded from a Canon XF100, so to me it was the same size and shape, but with a much better sensor and many more lens options. 

 

[David Andrade]

56 minutes ago, Anaconda_ said:

Sorry, I missed this. My sample above was 120/60p 50M.

Form factor and XLRs are basically why I chose the LS300, I upgraded from a Canon XF100, so to me it was the same size and shape, but with a much better sensor and many more lens options. 

 

Thank you! And yeah, that makes sense. I would have done the same. 31.3mbps isn't that bad. And I am sure if whatever you filmed had more action, the bit rate would go up from there. I think I've justified this camera enough to myself to go out and purchase one now haha

[webrunner5]

It is a really hard camera to not buy now that the prices have dropped. Just the form factor along is worth it. JVC has always had a pretty output on their cameras.  I think you are making a good decision. If you don't like it I doubt you would loose much money on selling it. But I think it will get the job done for you.

[newfoundmass]

On 6/19/2018 at 8:46 AM, David Andrade said:

newfoundmass, my head is still sort of spinning from this. I understand after referencing that screenshot what you're saying, at first. It's the last sentence that loses me. So, as we said before, it's compressing the 120fps into 30fps in camera - which is what you're referring to? 

And this is actually great news, right? As you said, if we had straight 120fps, the bitrate would (potentially) be much lower. 

Conformed might be a better word than compress, but yes.

[David Andrade]

1 hour ago, newfoundmass said:

Conformed might be a better word than compress, but yes.

ha! Agreed!