Jump to content

X-T3 hevc video codec rate distortion / quality issues


Recommended Posts

Obviously I don't have documentation for Fuji internal configuration of its video encoders for X-T3, but looking at a reference h.265 implementation manual, it seems rate distortion is a parameter used to increase compression at the cost of video frame rate distortion - namely jumpy video.


I find that 60fps 4K DCI 10bit 4:2:0 hevc long gop max bitrate is unusable because it is way too jumpy; 50 fps 4K DCI 10bit 4:2:0 hevc long gop max bitrate almost tolerable but does not look professional when object moving side to side with even moderate speed look like you selected the wrong shutter agle (I didn't) or it is dropping frames (I don't think it is). Even at 23.976 or 24 or 25 I still notice it sometimes - which doesn't make sense since the available bit rate is so much higher at the lower frame rates.

I tried asking Fuji and they said they looked at the video (and they were engineers not tier one help desk) and said they would have another group get back to me but have had no response for several months.

My guess is that the rate distortion quality setting is too aggressive. I have not tried external recording 10 bit 4:2:2 - maybe someone can confirm that the behavior disappears if the camera is not actually recording just passing through? I am especially interested in 4K DCI 10 bit 4:2:2 external 50 frames per second (I plan to post to 25fps - but as mentioned I notice this in all frame rates).

It is frustrating that they got so close to perfect value priced high quality cinema camera except for this behavior.

I am attaching a link to a small clip where you can see the traffic is jumpy left to right but not into camera - presumably these exercise different limits of the encoder - one causing rate distortion to fit within the bit rate available.

On the other hand it could also be that the Fuji engineers just left the parameter at a default setting (28?) that does a very bad job and could have set it lower and still fit within the bit rate available. But I am just guessing since I don't have access to any of the Fuji codec docs or parameters used :(

Does the Medium Format camera have same issues for 4K DCI video? At all frame rates?

Attached via link are two very short examples - but it doesn't matter if camera is on tripod, handheld, etc - always this jumpy motion for lateral movement.




Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Similar Content

  • Posts

    • I found this forum in a link from another Fuji forum so I'm glad to be here.  Regarding Ken, he's a strong, unique personality and part of his identity is to rattle the pots and pans. He's a quirky, intelligent person who has opinions, like we all do. His presentation can be extremely off putting, but he's worth listening to when deciding on a new Fuji.  I agree with others here who say it's best to rent a new camera if possible, and compare to one's own knowledge base and shooting preferences. 
    • Hello GO I thought Ken raised a few valid points and others which were fit for the floor mounted circular filing cabinet. But they were his points as he saw them so good for him. But irrespective of his views and his 4/10 rating, I bought an X-H2S and have to say that it is an exceptional camera. It is so fast, the subject detection system is phenominal and the EVF is in a different league to any of my FujiFilm cameras. I have it side by side with my beloved X-H1, a camera that was hewn from rock, and whilst it doesn't quite have that same 'feel' of indestructability, it is superbly made and tactile wise, a level above the X-H1. What I mean by that is the controls are well damped and responsive, the shutter button is less touch sensitive (ie doesn't fire at the lightest touch), and the control wheels, whilst not clickeable, are precise. The joystick is not as well positioned as the X-H1 but as I have only had the camera for two days, it will improve as my  muscle/brain memory kicks in. The extended grip is as good as, if not better than, the X-H1 and though still early days, I found the 100-400mm nicer to hold and use when on the X-H2S with or without either of the TC's. As for the charger, never got one with my X-T4 and yes it is tight of FujiFilm but I am glad that they spent the money on the sensor and the overall package. It shouldn't and didn't put me off but I see where he is coming from. PSAM is not a big deal for me, its on all my Sony's and on mylovely little X-S10 so it came natural to me. The C1-7 modes are just superb and if I had to trade the conventional dials just for this feature then I would...almost, as I still love the manual control nature of my other FujiFilm's. To be able to dial in my favourite settings and recall them at the click of a dial (and lock it should I wish) is fantastic and instant. I have a Delkin Black 150 Gb CFExpress card as well as a SanDisk Extreme SD Card. Never had a CF before, it makes the SD card seem pedestrian and even when on high speed bursts it clears the buffer immediately. I enjoyed Ken's review but I beg to differ with his conclusions and thoughts. As for muddy twixt the X-T4, I am not sure where he got that from but IQ is exactly the same as my X-T4 and X-S10 using all my FujiFilm lenses ......but many more images are 100% in focus and processed 4 x quicker than any other body. It is a cracking camera.      
    • Thank you ! No i got the point 👍. Will do more research in to that 
    • The f-stop is not changing, which is the ratio stays the same. Constant aperture is really constant f-ratio., which means effective or virtual ratio. A truly manual constant aperture lens operates differently than by-the-wire lenses, which is why the older ones are so large, they have to maintain that ratio over their range. Newer lenses do it differently which is why they are referred to as having virtual constant ratios. Btw, that Canon approach is pretty limited. Try that trick on a wterfall and you will see the waterfall change from falling water to shaving cream.
    • My lense is 16-80 f4. So its constant aperture. When i zoom the aperture isnt changing!
  • Create New...