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TOPIC: Converting HEVC from GoPro and iPhone with Handbrake

Converting HEVC from GoPro and iPhone with Handbrake 4 months, 1 week ago #166802

  • hugly
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  • 4 months, 1 week ago
Lightworks doesn't support h.265/HEVC codec (High Efficiency Video Coding) as import format yet (V14.1).
Footage recorded in this format must to be converted prior to import in Lightworks.

GoPro recommend Handbrake to transcode their HEVC recordings and explain how to, here:

gopro.com/help/articles/how_to/how-to-convert-gopro-hevc-videos-to-h-264-using-handbrake

The format created by Handbrake, AVC, isn't best possible choice for intermediates in terms of quality and editing performance, but Handbrake is well known, easy to use and available on all supported platforms. I’m sure Handbrake will be used and, it’s suitable to convert HEVC recordings from other devices as well (e.g. iPhone 8 ).

From my point of view, they recommend meaningful settings, in general (see link above).
For editing with Lightworks I'd like to add the following points:

1. Downscale the footage to the export resolution planned to use with Lightworks, e.g. to 720p when using the Free version. There's no benefit in terms of quality when using higher resolutions, as of now (V14.1), but there are drawbacks in editing performance.

2. Shorten the keyframe interval in Handbrake to 60 for 720p (30 for HD, 15 for UHD) to increase editing performance by adding this line to "Extra Options:" in "Video” tab of Handbrake:
keyint=60

3. Users of the Pro version might wish converting to higher resolution than 720p. AVC is a comparably demanding codec, so it might be necessary, especially with 4K/UHD, to use internal proxies to improve editing performance.

4. For recordings in variable frame rate mode (webcams, mobile phones, e.a.) select a frame rate explicitly, instead of using "Same as Source" in “Video” tab of Handbrake.

5. Before converting a large number of videos, make a few tests with different settings to see what looks and works best on your machine and under your viewing conditions.
It's better to travel well than to arrive...
Last Edit: 4 months ago by hugly.

Re: Converting HEVC from GoPro and iPhone with Handbrake 4 months ago #167594

  • hugly
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Off topic: Those who are familiar with FFmpeg and like the comparably small file sizes created by AVC/h.264, but prefer using uncompressed PCM audio instead of compressed formats created by Handbrake, might wish to make some tests with the command line below using x.264 encoder library:

ffmpeg -i "<INPUT>" -vsync cfr -pix_fmt yuv420p -vf scale=-1:720 -g 60 -c:v  libx264 -preset fast -crf 20 -c:a pcm_s16le -ar 48000 -f mov -y -threads 4 "<OUTPUT>.MOV"


Parameters to adjust explained:
-vf scale=-1:720
Scales to 720 vertical pixels and keeps aspect ratio.
Set as needed. To keep original dimensions set to -1:-1 (or remove).
- g 60
Sets keyframe interval (GOP) to 60 frames.
My recommendation: 60 for 720p and below, 30 for HD, 15 for UHD/4K.
-crf 20
Sets Constant Rate Factor (very specific to x.264 encoder, basically a mixture between bitrate and quantizer settings, trying to keep quality constant). It influences overall quality and bitrate/file size (and also encoding speed, to some extent).
Recommendations: 16-20 for SD, 18-24 for HD and 22-28 for UHD/4K - the lower the better.
-preset fast
Sets various internal parameters which influence encoding speed and quality (mainly blocking/banding artifacts caused by motion prediction/estimation).
Recommendations: "very fast" or "ultrafast" for testing, "faster", "fast", "medium", or "slow" for conversion - the slower the better (beyond preset "slow" it's kind of placebo, in my view). Personally, I use preset slow on a regular basis, with very good results.

Please note: Both, "CRF" and "Preset" settings influence quality, but they don't target the same x264 encoder parameters. As long as B-frames and P-frames are created (GOP >1) you can't compensate (completely) by increasing CRF (bitrate) for artifacts created by too fast encoder preset. In other words CRF 2 and preset ultrafast will blow up file size dramatically with lightning fast encoding, but it won't look nice.
It's better to travel well than to arrive...
Last Edit: 2 months ago by hugly.

Re: Converting HEVC from GoPro and iPhone with Handbrake 4 months ago #167830

  • hugly
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As an example, Handbrake settings explained earlier summarized in screenshots showing Handbrake V1.07 with 1080p29.97 source video:

Red: Mandatory
Green: Recommended - modify if you know what you're doing
Yellow: Adjust to meet your needs


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Please note: Quality "crf 20" and encoder preset "medium" with 1080p sources will create high quality at reasonable encoding speed and file size for most practical purposes. Nonetheless, there might be critical footage (e.g. animation, grainy film scans, fine color gradients) which might need different settings and even encoder tunes. Testing different settings with the footage used is always a good idea.

For a explanation of basic parameters and recommendations how to use them, please see the post above.
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It's better to travel well than to arrive...
Last Edit: 3 months, 3 weeks ago by hugly.
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