Skip to content

Segment accurate clipping #1410

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
mjh1 wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Segment accurate clipping #1410

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
7dcceab
Segment accurate clipping
mjh1 Jan 16, 2026
69e6549
fix
mjh1 Jan 16, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
133 changes: 4 additions & 129 deletions clients/manifest.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,8 @@ import (
"fmt"
"io"
"net/url"
"os"
"path"
"path/filepath"
"sort"
"strconv"
"strings"
"sync"
"time"
Expand Down Expand Up @@ -280,15 +277,6 @@ func GenerateAndUploadManifests(sourceManifest m3u8.MediaPlaylist, targetOSURL s
}
}

if isClip {
_, totalSegs := video.GetTotalDurationAndSegments(renditionPlaylist)
// Only add DISCONTINUITY tag if more than one segment exists in clipped playlist
if totalSegs > 1 {
renditionPlaylist.Segments[1].Discontinuity = true
renditionPlaylist.Segments[totalSegs-1].Discontinuity = true
}
}

// Write #EXT-X-ENDLIST
renditionPlaylist.Close()

Expand Down Expand Up @@ -357,124 +345,18 @@ func ClipInputManifest(requestID, sourceURL, clipTargetUrl string, startTimeUnix
return nil, fmt.Errorf("error clipping: failed to download original manifest: %w", err)
}

// Generate the absolute path URLS for segmens from the manifest's relative path
// TODO: optimize later and only get absolute path URLs for the start/end segments
sourceSegmentURLs, err := GetSourceSegmentURLs(sourceURL, origManifest)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to get segment urls: %w", err)
}

// Convert start/end time specified in UNIX time (milliseconds) to seconds wrt the first segment
startTime, endTime, err := video.ConvertUnixMillisToSeconds(requestID, origManifest.Segments[0], startTimeUnixMillis, endTimeUnixMillis)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to get start/end time offsets in seconds: %w", err)
}

// Find the segments at the clipping start/end timestamp boundaries
segs, clipsegs, err := video.ClipManifest(requestID, &origManifest, startTime, endTime)
segs, _, err := video.ClipManifest(requestID, &origManifest, startTime, endTime)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to get start/end segments: %w", err)
}

// Only the first and last segments should be clipped.
// And segs can be a single segment (if start/end times fall within the same segment)
// or it can span several segments startng from start-time and spanning to end-time
var segsToClip []*m3u8.MediaSegment
if len(segs) == 1 {
segsToClip = []*m3u8.MediaSegment{segs[0]}
} else {
segsToClip = []*m3u8.MediaSegment{segs[0], segs[len(segs)-1]}
}
// Create temp local storage dir to hold all clipping related files to upload later
clipStorageDir, err := os.MkdirTemp(os.TempDir(), "clip_stage_")
if err != nil {
return nil, fmt.Errorf("error clipping: failed to create temp clipping storage dir: %w", err)
}
defer os.RemoveAll(clipStorageDir) // nolint:errcheck

// Download start/end segments and clip
for i, v := range segsToClip {
// Create temp local file to store the segments:
clipSegmentFileName := filepath.Join(clipStorageDir, requestID+"_"+strconv.FormatUint(v.SeqId, 10)+".ts")
defer os.Remove(clipSegmentFileName)
clipSegmentFile, err := os.Create(clipSegmentFileName)
if err != nil {
return nil, err
}
defer clipSegmentFile.Close()

// Download the segment from OS and write to the temp local file
segmentURL := sourceSegmentURLs[v.SeqId].URL
dStorage := NewDStorageDownload()
err = backoff.Retry(func() error {
rc, err := GetFile(context.Background(), requestID, segmentURL.String(), dStorage)
if err != nil {
return fmt.Errorf("error clipping: failed to download segment %d: %w", v.SeqId, err)
}
defer rc.Close()

// Write the segment data to the temp local file
_, err = io.Copy(clipSegmentFile, rc)
if err != nil {
return fmt.Errorf("error clipping: failed to write segment %d: %w", v.SeqId, err)
}
return nil
}, DownloadRetryBackoff())
if err != nil {
return nil, fmt.Errorf("error clipping: failed to download or write segments to local temp storage: %w", err)
}

// Locally clip (i.e re-encode + clip) those relevant segments at the specified start/end timestamps
clippedSegmentFileName := filepath.Join(clipStorageDir, requestID+"_"+strconv.FormatUint(v.SeqId, 10)+"_clip.ts")
if len(segs) == 1 {
// If start/end times fall within same segment, then clip just that single segment
duration := endTime - startTime
err = video.ClipSegment(requestID, clipSegmentFileName, clippedSegmentFileName, clipsegs[0].ClipOffsetSecs, clipsegs[0].ClipOffsetSecs+duration)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to clip segment %d: %w", v.SeqId, err)
}
} else {
// If start/end times fall within different segments, then clip segment from start-time to end of segment
// or clip from beginning of segment to end-time.
if i == 0 {
err = video.ClipSegment(requestID, clipSegmentFileName, clippedSegmentFileName, clipsegs[0].ClipOffsetSecs, -1)
} else {
err = video.ClipSegment(requestID, clipSegmentFileName, clippedSegmentFileName, -1, clipsegs[1].ClipOffsetSecs)
}
if err != nil {
return nil, fmt.Errorf("error clipping: failed to clip segment %d: %w", v.SeqId, err)
}
}

// Upload clipped segment to OS
clippedSegmentFile, err := os.Open(clippedSegmentFileName)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to open clipped segment %d: %w", v.SeqId, err)
}
defer clippedSegmentFile.Close() // nolint:errcheck

clippedSegmentOSFilename := "clip_" + strconv.FormatUint(v.SeqId, 10) + ".ts"
err = UploadToOSURL(clipTargetUrl, clippedSegmentOSFilename, clippedSegmentFile, MaxCopyFileDuration)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to upload clipped segment %d: %w", v.SeqId, err)
}

// Get duration of clipped segment(s) to use in the clipped manifest
p := video.Probe{}
clipSegProbe, err := p.ProbeFile(requestID, clippedSegmentFileName)
if err != nil {
return nil, fmt.Errorf("error clipping: failed to probe file: %w", err)
}
vidTrack, err := clipSegProbe.GetTrack(video.TrackTypeVideo)
if err != nil {
return nil, fmt.Errorf("error clipping: unknown duration of clipped segment: %w", err)
}
// Overwrite segs with new uri/duration. Note that these are pointers
// so the start/end segments in original segs slice are directly modified
v.Duration = vidTrack.DurationSec
v.URI = clippedSegmentOSFilename
}

// Generate the new clipped manifest
clippedPlaylist, err := CreateClippedPlaylist(origManifest, segs)
if err != nil {
Expand Down Expand Up @@ -514,24 +396,17 @@ func CreateClippedPlaylist(origManifest m3u8.MediaPlaylist, segs []*m3u8.MediaSe
return nil, fmt.Errorf("error clipping: failed to create clipped media playlist: %w", err)
}
var t time.Time
for i, s := range segs {
for _, s := range segs {
if s == nil {
break
}

// TODO/HACK: Currently all segments between the start/end segments will always
// TODO/HACK: Currently all segments will always
// be in the same place from root folder. Find a smarter way to handle this later.
if i != 0 && i != (len(segs)-1) {
s.URI = "../" + s.URI
}
s.URI = "../" + s.URI
// Remove PROGRAM-DATE-TIME tag from all segments so that player doesn't
// run into seek issues or display incorrect times on playhead
s.ProgramDateTime = t
// Add a DISCONTINUITY tag to let hls players know about different encoding between
// segments. But don't do this if there's a single segment in the clipped manifest
if i-1 == 0 || (totalSegs > 2 && i == totalSegs-1) {
s.Discontinuity = true
}

// Add segment to clipped manifest
err := clippedPlaylist.AppendSegment(s)
Expand Down
6 changes: 2 additions & 4 deletions clients/manifest_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -256,13 +256,11 @@ func TestCompliantClippedManifest(t *testing.T) {
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-TARGETDURATION:15
#EXTINF:10.000,blah0
source/0.ts
#EXT-X-DISCONTINUITY
../source/0.ts
#EXTINF:15.000,blah1
../source/1.ts
#EXT-X-DISCONTINUITY
#EXTINF:10.000,blah2
source/2.ts
../source/2.ts
#EXT-X-ENDLIST
`

Expand Down
Loading