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What are H.264 bitrate requirements for high frame rate (48, 50, 60 fps) 4K / UHD?
  • neokooneokoo

    What is the bitrate (and/or other codec specifications) necessary for lifelike motion in HFR 4K and UHD video, when shooting on cameras that use H.264 codec?

    For example, GH5 offers [4K/8bit/150M/60p] Long GOP setting. At 150Mbps, can it be trusted that motion will always be captured and reproduced well? Or could there be problems like stuttering or macroblocking, especially when there are lots of details in the image?

  • 3 Replies sorted by
  • Vitaliy_KiselevVitaliy_Kiselev

    The more details and the faster the motion - the more bitrate is necessary. And even this can not save the day, as encoder decides how to use bitrate and can do it in strange ways.

    Lifelike motion also greatly depends on shutter speed and camera motion :-)

  • bannedindvbannedindv

    You could help yourself by recording outboard prores or dnxhd using an atomos product (if there is 4k60p output on hdmi working now)...

  • neokooneokoo

    Thanks @Vitaliy_Kiselev and @bannedindv

    Recently announced Atomos Ninja Inferno with its 4K 60fps ProRes support seems like a good option for critical 60fps work.

    It is interesting to see these ProRes specs for 10-bit 4:2:2 3840x2160 intraframe 60p (from Apple ProRes whitepaper, June 2014):

    ProRes 422: 1178 Mbps (147 MByte/second), 530 GByte/hour  (1 h 50 min per terabyte)

    ProRes 422 HQ: 1768 Mbps (221 MByte/second),  795 GByte/hour (1 h 15 min per terabyte)

    ...in comparison to 8-bit 4:2:0 3840x2160 interframe 60p H.264 on GH5:

    4K/8bit/150M/60p: 150 Mbps (19 MByte/second), 68 GByte/hour (14 hours per terabyte)

    My main interest is using HFR for documentary, so internal 60fps codec in GH5 is very tempting for practical reasons. But like always with long GOP H.264, scenes with almost-random detail and motion, such as snowfall, water etc. are a cause for concern.

    Hopefully as GH5 becomes available, users of 4K 60p settings can report some experiences in this area :)

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