fix: respect preview.max_width for video thumbnails

[ze0987]

Currently, Yazi only scales thumbnails to preview.max_height, which means that thumbnails of videos in landscape orientation are unnecessarily large.

Example:

max_width       = 600
max_height      = 900
image_quality   = 75

Before

File size: 131 kB
Image size: 1600x900
On the left is a preview in Yazi, and on the right is a generated thumbnail.

After

File size: 28 kB
Image size: 600x338

[sxyazi]

Thanks for the PR!

Could you provide some benchmarks to see how this change affects performance — separately when the video size is under max_width/max_height and when it reaches them?

[ze0987]

Sure.

max_width       = 600
max_height      = 900
image_quality   = 75

Video resolution 320x180, software

Before

  Time (mean ± σ):     253.2 ms ±   1.7 ms    [User: 194.5 ms, System: 53.8 ms]
  Range (min … max):   250.8 ms … 255.5 ms    10 runs

After

  Time (mean ± σ):     254.1 ms ±   1.6 ms    [User: 194.9 ms, System: 54.5 ms]
  Range (min … max):   251.3 ms … 256.3 ms    10 runs

Video resolution 320x180, vaapi

Before

  Time (mean ± σ):     272.6 ms ±   2.4 ms    [User: 198.1 ms, System: 68.9 ms]
  Range (min … max):   269.8 ms … 277.5 ms    10 runs

After

  Time (mean ± σ):     278.0 ms ±   2.7 ms    [User: 202.2 ms, System: 70.4 ms]
  Range (min … max):   273.3 ms … 282.8 ms    10 runs

Video resolution 1920x1080, software

Before

  Time (mean ± σ):     884.0 ms ±   2.7 ms    [User: 778.3 ms, System: 95.8 ms]
  Range (min … max):   879.6 ms … 888.7 ms    10 runs

After

  Time (mean ± σ):     843.4 ms ±   2.9 ms    [User: 744.5 ms, System: 89.7 ms]
  Range (min … max):   838.7 ms … 846.9 ms    10 runs

Video resolution 1920x1080, vaapi

Before

  Time (mean ± σ):     448.4 ms ±   3.7 ms    [User: 314.1 ms, System: 126.7 ms]
  Range (min … max):   442.9 ms … 453.8 ms    10 runs

After

  Time (mean ± σ):     388.1 ms ±   2.9 ms    [User: 268.0 ms, System: 113.2 ms]
  Range (min … max):   383.8 ms … 392.5 ms    10 runs

With this PR, thumbnails of videos smaller than preview.max_width x preview.max_height will be upscaled to preview.max_width x preview.max_height, which may or may not be a good thing.