Pixelation Issue On Scene Transitions?

GrumpyOutdoors
GrumpyOutdoors Posts: 3 Just Starting Out*

Hello everyone, I'm hoping someone could try and problem solve an issue I'm having. Between video scenes I'm getting pretty bad pixelation for a second or two before it returns to a bareable resolution.

It seems to be worse if I'm switching between different cameras (say footage from my phone cutting to footage from my camera) but I may well be using incorrect settings for projects or on export.

Some examples of what I mean:

Wildlife Trust: Phyllis Currie Nature Reserve [5th August 2022] - YouTube (1:58 on transition between duck to footpath)

North Weald to Stansted: Walk & Wildcamp - YouTube (1:39, a particularly bad example of pixelation in the next few scenes - but it's bad throughout the entire video.)

I think it is probably being caused by swapping between two different cameras with different codecs and slightly different fps (my camcorder records at 50fps and I set the video settings to that, but record in 60fps in other cameras.) If anyone could look and help me work it out that would be awesome, thank you.

Comments

  • NormanPCN
    NormanPCN Posts: 4,367 Expert
    edited November 8

    You have not given useful enough information to help you. If your car has the check engine light on, you would not take a picture of that and show it to a mechanic and ask for help fixing the check engine light. You give them the car and let them figure it out. Well, giving us your full project is not really going to happen, so we need information, details, about exactly what you have and have done. Like a mechanic might be interested in what make of car you have, Toyota, Ford or Chevy, we would like to know exactly what version of Hitfilm you are using.

    Some good minimal basics Hitfilm Version, Operating system, project settings (frame size and frame rate). If an export related issue, as likely here, then exactly how you exported and at what settings.

    --

    First never, but never, judge video quality by Youtube results. You judge your export from Hitfilm. Youtube re-encodes everything you upload and you have no control over that.

    So my first question would be on the pixelation. Do you see it in playback in Hitfilm. Probably not. Do you see it in the Hitfilm export, or do you see it only on the Youtube result.

    I am going to make some assumptions here. I will assume your are using the Free version of Hitfilm. The current version or very recent version. I will assume you are running on Windows. I am going to assume you exported using the Hitfilm Youtube 1080 export preset. It seems from your post, and the Youtube result, that your project settings are 1080p50.

    The Free version of Hitfilm uses the operating system AVC encoder. AVC is a specific format of video. This so that they(FxHome) lose less money on each free license activated. This encoder has issues where it can pixelate in circumstances for a brief period and then recover. The only cure for this is to raise the export bitrate.

    You should also note that your video is 50p and the Hitfilm Youtube 1080 preset says it is setup for 24-30p. Higher frame rates want higher bitrates. Now the Hitfilm preset is quite conservative with bitrate so it can probably work for a lot of high frame rate video. Your content shown does not really use/need high frame rate, the motion is pretty slow, so it can get away with relatively lower bitrates.

    "The only cure for this is to raise the export bitrate."

    Here I am referencing using the Hitfilm 'MP4' export. What bitrate? There is no actual answer to that. There is no ideal bitrate. Different content has different needs and different encoders have different needs. Frame size and frame rate all factor in what bitrates can work. It comes down to experience with your content and the software/encoder(s) you are using. You see some pixelation/blur in the export, that is not in the video content, so you need to increase export bitrate. A decent rule is to bump it by 50%. A jump of that amount should give very visual changes in the result. If that is not enough then bump it again. Again you are comparing editor playback to the export result.

    Don't want to mess with that? You can just export a high quality Cineform file (large file) from Hitfilm and upload that to Youtube. Hitfilm 'MOV' offers the Cineform codec.

  • GrumpyOutdoors
    GrumpyOutdoors Posts: 3 Just Starting Out*
    Thank you Norman.

    I would have given more information on settings but I usually delete the files off the PC after I've uploaded. I just didn't want to repeat the same mistakes if it's potentially being caused in camera.

    Turns out I have actually been using the Hitfilm Express version without me realising, I think I had both on the computer at the same time a while back and I must have removed the wrong version. I've rectified that now. The computer itself is unlikely to be the issue as it's pretty new (GPU is a GTX 3080.)

    The settings that I have been using are "1080p Full HD @50fps", with 'Square Pixels.' To be totally honest I don't think I've ever touched the export settings as I presumed the 1080 template I started off with upon beginning a new project was enough information. I'll try CineForm in the future.

    I'm looking at the 'Full' version of it now though and it's telling me I need to pay for half the features that were available for free on previous versions, lol. Which is a little frustrating since I've probably already spent £60 on bits and pieces for it.
  • NormanPCN
    NormanPCN Posts: 4,367 Expert

    The last version, or two?, of Hitfilm Express started using the Window operating system AVC encoder. So same potential issues as current. Older than those versions, Express used the same encoder as the paid licenses.

    The old Hitfilm Express and the current Free Hitfilm are considered different software and they install separately. Both Express and current Hitfilm version can coexist on same machine without conflict.

  • Gelqone
    Gelqone PolandPosts: 156 Enthusiast

    Try rising the bitrate at the export.

  • GrumpyOutdoors
    GrumpyOutdoors Posts: 3 Just Starting Out*

    Is there a way of doing this manually or should I just play about with presets?

    I just tried Cineform option but the file size was huge and not really workable for uploading.

  • NormanPCN
    NormanPCN Posts: 4,367 Expert

    You create your own preset, or just duplicate an existing one. Like duplicate the Youtube 1080 preset you have been using and edit the duplicate, renaming it as well.

    Then while editing the preset you will see the options for average and max bitrate (on Hitfilm 'MP4' preset types). Adjust those as necessary.

    You can make your new preset the default if you like. If you create a new preset you choose the Hitfilm 'MP4' option. That is the preset for AVC video encodes which can give you your smallest result video file.

    Here is an FxHome tutorial on all things on exporting.


  • Triem23
    Triem23 Posts: 20,276 Power User

    A note or two on Export Bitrate.

    In general, VBR (Variable Bit Rate) is considered better than Constant Bit Rate (CBR). With CBR, if you set (example) 35mbps everything will stay 35mbps. Depending on your material, this might be wasteful. A typical tutorial or talking head interview form good examples. In both these cases large areas of the frame remain static and the encoder doesn't need that data. VBR will "downshift" to use less data on static frames and use more data with lots of motion. General wisdom holds in VBR encoding to set the "Max" bitrate between 150-200% of the "Target" bitrate.

    Try a target of 35mbps and a Max of 55mbps for 1080p output.