Poor resolution and flickering of still image renders

Pete
Pete Posts: 38

Hi,

I'm noting a very poor resolution of images that are rendered, even at high bitrates. 

I'm also noting an odd flickering of rendered images.

https://youtu.be/_r6jc2iSfbE

My project is simple - a single image on the timeline, followed by a video clip, followed by an image.

This is the image I am using - Dropbox - original image

 

There are some oddities in the render. This is a screengrab from Window Media Player, showing the first frame. The quality of the image is as I would expect, no issue here.

Dropbox - frame 1 in WMP

After that, subsequent frames show a significant decrease in quality. This is even apparent in the scaled down images embedded into this post, note the artifacts in the shadows under the shelves.

You can show the same thing by pausing the Youtube video and rewinding to the first frame.

Dropbox - frame 2 in WMP

 

Then, if you playback the video render, you will note flickering of the still image in the render. This is a CBR render at 50mbps, 59.94 fps.

Dropbox - Video CBR [341mb]

I tried the same render at VBR, 50mbps, 59.94fps

Dropbox - Video VBR [251mb]

In the middle of the video there is a video clip. When transitioning from the still image to the video clip during playback, you will note the first frame of the video clip also suffers from the decrease in quality

Dropbox - First video frame

 

Thereafter, subsequent video frames get an increase in quality (in particular pay attention to the detail on the center rock)

Dropbox - Subsequent video frames

 

My export settings are as follows for CBR, VBR is as below both target and max bitrate set to 50:

Width: 1920

Height: 1080

Scale Mode: Keep Aspect Ratio

Frame Rate: 59.94

Aspect Ratio: Square Pixels

Profile: Main

Level: 5.0

Encoding: CBR

Bitrate: 50.000 mbps

Comments

  • Pete
    Pete Posts: 38

    This looks quite similar to the artifacts I was seeing in HF2

    http://hitfilm.com/forum/discussion/comment/24056/

    But I realise that thread has zero useful content now...

  • NormanPCN
    NormanPCN Posts: 4,082 Enthusiast

    I downloaded the VBR 50 video and I do not see any flickering on the still. Where should I be looking. Also, the first couple of frames on the stream are similar quality.

    I was primarily using VLC to examine, but I brought the video into Hitfilm and Vegas for a close look.

    A lot of media players use the video driver playback engine and the driver playback engines normally default to enabling various video "enhancement" effects. The results of those, may be what you are seeing. I know AMD drivers have by default always enabled such features in the past.

  • Pete
    Pete Posts: 38
    edited November 2015

    Thanks for taking a look @NormanPCN. Did you see any artifacts on the Youtube video?

    I tried playback on different devices and I see the same thing on all of them. It's apparent on the bottom right corner of the screen, you should see the shadow flickering and on the top right, the compression artifacts come and go.

  • Aladdin4d
    Aladdin4d Posts: 2,481 Enthusiast
    edited November 2015

     I haven't taken the time to go in depth like NormanPCN has but I do see what you're talking about in the Youtube video. I don't know what's causing it but it's definitely not random it's happening in timed pulses.

    EDIT: I'm with NormanPCN on the VBR 50 video - No flickering at all and nothing obviously wrong with the first stream frames. CBR 50 coming up next 

    EDIT 2: CBR 50 video definitely has the rhythmic pulse or flicker and as I said before about the Youtube video it isn't random

  • NormanPCN
    NormanPCN Posts: 4,082 Enthusiast

    No, I did not look at the Youtube version. The reason being we users have no control over the Youtube re-encode of our upload. Their encodes are very low bitrate.

    The video I downloaded was 60p and I do not know the exact particulars about what Youtube does with 60p. Supposedly they (can) keep the 60p. I do know 60p does not get twice the bitrate of 30p so the source material needs to get good compression relatively speaking to keep the same quality as 30p would get.

    So for me I look at the source file only. If the source is good but the Youtube encode is not so good, then what can we do if we uploaded within proper constraints? e.g. frame size, progressive and framerate within specified bounds. I mean, giving Youtube something "better" than the "good" is not somehow going make the Youtube re-encode come out better.

  • Pete
    Pete Posts: 38

     Thanks for the confirmation @Aladding4d

    @NormanPCN - yeah sure, the YouTube  embed is simply an easy way to demonstrate the problem. YouTube supports 60fps at 4K. They recommend 12mbps for 1080p60fps.

    Regardless of whether it's apparent in the CBR or VNR renders, the issue is apparent if the video is uploaded to YouTube, which is an important platform for delivering media.

  • Pete
    Pete Posts: 38

    Here's an interesting observation, I uploaded to YouTube directly from HF4:

    And this upload is one I rendered first, then uploaded via the web:

     

    I can see the flickering in the second one, but not the first

  • Marcin
    Marcin Posts: 128 Just Starting Out

    So it seems that the flickering is caused by YT re-encoding, as direct YT export is uploaded in a form, that do not need re-encoding.

  • Poya
    Poya Posts: 1

    I have noticed the exact same behavior. Exporting H.264 causes this odd throbbing / flickering, however a direct upload to YouTube looks fine. I tried all sorts of combinations of bitrate (both fixed and variable) and other settings but the results had the same artifacts.

    I'm wondering if the Export to YouTube option goes through the same rendering pipeline as H.264 and if so what the exact underlying settings are so we can try and replicate those settings.

This discussion has been closed.