01/08/2021 at 1:21 pm #19909MaxxUKParticipant
I’m working with a couple of drivers this season and a query came up the other day when looking at Gopro video footage.
I do understand from the regs that output must be MP4, 30fps (min) and 720p (min)
My question relates to the MP4 codec used :- Most later gen Gopros (certainly 7 and above, poss earlier) have the option to either encode video using H264/x264 or HEVC/x265. The advantage of the latter is that filesizes are 30% smaller for the same quality (x265 is just a more efficient codec).
However, x265/HEVC encoded footage may not play (at least initially) on older machines. All Win10 machines should support it and probably all machines (PC or Laptop) bought in the last 5 years. Even if you have an older machine, using the right player you can play x265/HEVC (VLC Player plays them as HEVC is included in the program itself).
I imagine machines used by the club to review footage from drivers would be able to playback x265/HEVC footage but some clarification would be useful.
For teams/drivers, setting your GoPro to encode with x265/HEVC means that you can get 30% more footage on your current data card than if you are currently using x264. The GoPro may say “x264/HEVC” but really it is ‘encoding’ with standard x264.
This is especially useful for longer races, specifically the 24hr races.
Roughly you’d need ‘at least’ an empty 512Gb sd card to record a full 24hr (GoPros may vary in exact bitrate recorded at)
GoPro’s also create LRV files (low resolution versions of all the MP4 video) in order to review footage on the GoPro screen and THM files which are small image thumbnails, again for review ‘on camera’. The THM files take up very little space but the LRVs take up AN ADDITIONAL 10% (as they are around 10% the size of the MP4).
Whilst you’d still need a 512Gb card for 24hrs at x265/HEVC you would ‘potentially’ get over 31hrs worth of space so being empty would not be imperative and you could also hold day/night quali on it also.
For shorter races this may allow teams using much cheaper 128Gb cards to record/store 30% more footage on the card.
Also, the above stats are for 1080p footage, which teams may prefer if using it for their own use/promotion/youtube upload.
ALSO: users may want to double-check their GoPro setting to ensure they are not using 50fps or even 60fps, as the number of frame per second influences the file sizes, a 60fps file will be (roughly) twice as large as a 30fps file.
Sorry it’s a bit technical but essentially, if you and the club can play x265/HEVC and you are looking to save space, avoid having to pay for a larger SD card, set the camera to x265 and 30fps and then whatever resolution you prefer (720p min for club use)
CORRECTION: I think the required footage needs to be 50fps (min) according to the club regs.
01/08/2021 at 1:30 pm #19919MaxxUKParticipant
- This topic was modified 1 month, 4 weeks ago by MaxxUK.
Can’t seem to edit the previous post following the addition of the CORRECTION line. Yes, 50fps is the required frame rate so users should check they are not using 60fps if sc card space is an issue as this will consume approx 20% more sd card space.
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