variable - constant bitrate

In the past I made the mistake of shooting interlaced video. When I rendered in HF, the footage showed jagged edges. JSBarrett gave the de-interlaced effect solution. I should have known it if I had previously watched Triem's Essential Hitfilm 7 - How to optimize troubleshoot video.
Now, in that tutorial, Triem says that he always converts his footage to a constant bitrate before editing in HF. I can understand this when one has clips from various sources (camera, gopro, smartphone), but is this conversion also necessary when  all the clips are from the same source (camera) and shot in 50p?


  • edited July 2017

    He converts to Constant framerate. If your camera is producing that already (most likely is) then no need to convert.  Latest version of Hitfilm is intended to handle Variable Frame Rate footage anyway, but no need to make it work if you can do it all up front.

    If not sure, use MediaInfo and check. It will also tell you your footages bitrate, which might indicate the sort of values you might want to use when exporting, or higher, to retain quality.

  • Sorry, my fault! I did install MediaInfo after Triem's tutorial and indeed, my framerate is 50.000 fps. 

    So framerate is important for quality when shooting the video and should be set in the camera settings
    Bitrate is important for quality when exporting the footage and should be set in the export settings.

    Finally got it. Thank you.

  • Triem23Triem23 Moderator

    Correct--constant FRAME rate, not constant BITrate.

    DSLRs, MFT, Cinema and Video cameras all shoot at a constant frame rate. Phones, tablets and screen captures grab a variable frame rate. Even though Hitfilm 2017 will take variable frame rate footage, honestly, the results aren't always correct. VFR makes things very complicated, and I'll still transcode before Hitfilm import.

    In fact, on July 4 I, like everyone else, took some fireworks footage on my phone. In theory, all my footage was 29.97 fps, but, when loaded into Hitfilm, Hitfilm thought some clips wer 24 fps, some 25 fps and some 29.97 fps. Using MediaInfo on these clips showed that some of these clips were dropping under 20 fps at points with a median frame rate of around 24/25 (remember, in theory they were ALL 29.97). Those are the clips Hitfilm was deciding were 24/25 fps.

    Constant vs. variable BITrate is a different topic. in short, variable is usually the way to go. :-)

  • @Triem23 - Thank you, left another question in the topic 'More bitrate questions'.

  • @Triem23 - changed my mind, I think my question is better put here.

    As I want a mp4 output, I have to choose the Youtube preset with the H.264 compressed for 24/25/30fps. Do I loose quality when I edit 50p footage and export to 25p? Or should I better shoot in 25p and export to 25p? Maybe the last method is quicker? I am switching from Cyberlink Powerdirector to HFilm. In Powerdirector there are a lot more export presets (full hd 50p; even full hd 120p). I suppose those presets have a certain purpose. 

    Are there more presets in HFPro than in HFExpress 2017? I only want a once and for all decent export preset. Can't forget the bad advice I followed for the last 5 years concerning the interlaced footage. 

    I set the bitrates as you suggested in the topic 'more bitrate questions'.


  • Triem23Triem23 Moderator

    Well, remember that you can always make your own export presets. My standard preset exports at a much higher data rate than the Youtube default.

    Axel did a short version tutorial of the Export Queue controls:

    I did a way too long version:

    Now--with Hitfilm, you want to export at the same frame rate you edit at. Once you go to export, Hitfilm is very literal about the number of frames on the timeline. Basically, if you edit at 50p and export 25p you'll get a slow-motion version of the first half of the edit. Hitfilm will (try to) conform footage to the timeline rate automatically on import.

    For 50p or 25p I can't say it matters which you edit in. That's a bit of a personal choice. :-) What you lose if you shoot 50p and export 25p is temporal resolution (smoothness). On the other hand, shooting 50p to export 25p is the way you want to go if you're shooting for slow motion.

  • May I ask you a last question and then I am not going to bother you again  with this item

    I am confused about the following: 

    1. I import 50p footage in HF (project settings full hd 50p)
    2. Do some editing
    3. Export with YT preset (full hd h.264 25p standard). Level 5.1
    4. Export ok and MediaInfo says the mp4 is 50p.

    How come that the preset says 25p and the final mp4 is in 50p? Is it the level 5.1 that overrules the standard setting of 25p.

  • Triem23Triem23 Moderator

    The YouTube preset that says '24/25/30p' is actually set up to take the frame rate of whatever you've told it to export. So a 50p timeline will still export as 50p.

    I said this above, but you don't want to export from Hitfilm at a different frame rate than you edited. This will absolutely mess up your final output. 

    Since you've already edited in 50p, in the export queue, right click the YouTube profile, duplicate it, rename to "YouTube 50/60p," open it up and double whatever bitrates are set for target/max. You'll probably have to change Level to 5.1. 

    Then, re-export with this profile. Go ahead and leave it 50p for now. 

  • OK, got it. Thank you.

  • Triem23Triem23 Moderator

    Yw. :) 

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