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/*
GoToSocial
Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package media
import (
"bytes"
"fmt"
"image"
"image/color"
"image/draw"
"image/jpeg"
"io"
"os"
"github.com/abema/go-mp4"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/log"
)
var thumbFill = color.RGBA{42, 43, 47, 0} // the color to fill video thumbnails with
func decodeVideo(r io.Reader, contentType string) (*mediaMeta, error) {
// We'll need a readseeker to decode the video. We can get a readseeker
// without burning too much mem by first copying the reader into a temp file.
// First create the file in the temporary directory...
tempFile, err := os.CreateTemp(os.TempDir(), "gotosocial-")
if err != nil {
return nil, fmt.Errorf("could not create temporary file while decoding video: %w", err)
}
tempFileName := tempFile.Name()
// Make sure to clean up the temporary file when we're done with it
defer func() {
if err := tempFile.Close(); err != nil {
log.Errorf("could not close file %s: %s", tempFileName, err)
}
if err := os.Remove(tempFileName); err != nil {
log.Errorf("could not remove file %s: %s", tempFileName, err)
}
}()
// Now copy the entire reader we've been provided into the
// temporary file; we won't use the reader again after this.
if _, err := io.Copy(tempFile, r); err != nil {
return nil, fmt.Errorf("could not copy video reader into temporary file %s: %w", tempFileName, err)
}
var (
width int
height int
duration float32
framerate float32
bitrate uint64
)
// probe the video file to extract useful metadata from it; for methodology, see:
// https://github.com/abema/go-mp4/blob/7d8e5a7c5e644e0394261b0cf72fef79ce246d31/mp4tool/probe/probe.go#L85-L154
info, err := mp4.Probe(tempFile)
if err != nil {
return nil, fmt.Errorf("could not probe temporary video file %s: %w", tempFileName, err)
}
for _, tr := range info.Tracks {
if tr.AVC == nil {
continue
}
if w := int(tr.AVC.Width); w > width {
width = w
}
if h := int(tr.AVC.Height); h > height {
height = h
}
if br := tr.Samples.GetBitrate(tr.Timescale); br > bitrate {
bitrate = br
} else if br := info.Segments.GetBitrate(tr.TrackID, tr.Timescale); br > bitrate {
bitrate = br
}
if d := float32(tr.Duration) / float32(tr.Timescale); d > duration {
duration = d
framerate = float32(len(tr.Samples)) / duration
}
}
var errs gtserror.MultiError
if width == 0 {
errs = append(errs, "video width could not be discovered")
}
if height == 0 {
errs = append(errs, "video height could not be discovered")
}
if duration == 0 {
errs = append(errs, "video duration could not be discovered")
}
if framerate == 0 {
errs = append(errs, "video framerate could not be discovered")
}
if bitrate == 0 {
errs = append(errs, "video bitrate could not be discovered")
}
if errs != nil {
return nil, errs.Combine()
}
return &mediaMeta{
width: width,
height: height,
duration: duration,
framerate: framerate,
bitrate: bitrate,
size: height * width,
aspect: float32(width) / float32(height),
}, nil
}
func deriveThumbnailFromVideo(height int, width int) (*mediaMeta, error) {
// create a rectangle with the same dimensions as the video
img := image.NewRGBA(image.Rect(0, 0, width, height))
// fill the rectangle with our desired fill color
draw.Draw(img, img.Bounds(), &image.Uniform{thumbFill}, image.Point{}, draw.Src)
// we can get away with using extremely poor quality for this monocolor thumbnail
out := &bytes.Buffer{}
if err := jpeg.Encode(out, img, &jpeg.Options{Quality: 1}); err != nil {
return nil, fmt.Errorf("error encoding video thumbnail: %w", err)
}
return &mediaMeta{
width: width,
height: height,
size: width * height,
aspect: float32(width) / float32(height),
small: out.Bytes(),
}, nil
}
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