v7.1.8
This commit is contained in:
429Enjoyer
@@ -0,0 +1,247 @@
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package backend
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import (
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"encoding/hex"
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"fmt"
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"io"
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"os"
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"strings"
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"github.com/Eyevinn/mp4ff/mp4"
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)
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func decryptWithMP4FF(keySpecs []string, inputPath, outputPath string) error {
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key, keysByKID, strictKIDMode, err := parseMP4FFKeySpecs(keySpecs)
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if err != nil {
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return err
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}
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inFile, err := os.Open(inputPath)
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if err != nil {
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return fmt.Errorf("failed to open encrypted MP4: %w", err)
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}
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defer inFile.Close()
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outFile, err := os.Create(outputPath)
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if err != nil {
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return fmt.Errorf("failed to create decrypted MP4: %w", err)
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}
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outClosed := false
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defer func() {
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if !outClosed {
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_ = outFile.Close()
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}
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}()
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if err := decryptMP4FFFileWithKeyMap(inFile, nil, outFile, key, keysByKID, strictKIDMode); err != nil {
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_ = outFile.Close()
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outClosed = true
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_ = os.Remove(outputPath)
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return fmt.Errorf("mp4ff decryption failed: %w", err)
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}
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if err := outFile.Close(); err != nil {
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outClosed = true
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_ = os.Remove(outputPath)
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return fmt.Errorf("failed to finalize decrypted MP4: %w", err)
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}
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outClosed = true
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return nil
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}
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func parseMP4FFKeySpecs(keySpecs []string) (key []byte, keysByKID map[string][]byte, strictKIDMode bool, err error) {
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normalizedSpecs := make([]string, 0, len(keySpecs))
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seenSpecs := make(map[string]struct{}, len(keySpecs))
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for _, spec := range keySpecs {
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normalized, err := normalizeMP4FFKeySpec(spec)
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if err != nil {
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return nil, nil, false, err
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}
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if normalized == "" {
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continue
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}
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if _, ok := seenSpecs[normalized]; ok {
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continue
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}
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seenSpecs[normalized] = struct{}{}
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normalizedSpecs = append(normalizedSpecs, normalized)
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}
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if len(normalizedSpecs) == 0 {
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return nil, nil, false, fmt.Errorf("no mp4ff key specs provided")
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}
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hasKIDPair := false
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hasLegacyKey := false
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for _, spec := range normalizedSpecs {
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if strings.Contains(spec, ":") {
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hasKIDPair = true
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} else {
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hasLegacyKey = true
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}
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}
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if hasKIDPair && hasLegacyKey {
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return nil, nil, false, fmt.Errorf("cannot mix legacy key and kid:key key format")
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}
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if !hasKIDPair {
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if len(normalizedSpecs) != 1 {
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return nil, nil, false, fmt.Errorf("multiple legacy keys are not supported")
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}
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key, err = mp4.UnpackKey(normalizedSpecs[0])
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if err != nil {
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return nil, nil, false, fmt.Errorf("unpacking key: %w", err)
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}
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return key, nil, false, nil
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}
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keysByKID = make(map[string][]byte, len(normalizedSpecs))
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for _, spec := range normalizedSpecs {
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parts := strings.SplitN(spec, ":", 2)
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if len(parts) != 2 || strings.TrimSpace(parts[0]) == "" || strings.TrimSpace(parts[1]) == "" {
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return nil, nil, false, fmt.Errorf("bad kid:key format %q", spec)
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}
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kid, err := mp4.UnpackKey(strings.TrimSpace(parts[0]))
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if err != nil {
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return nil, nil, false, fmt.Errorf("unpacking kid: %w", err)
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}
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kidHex := hex.EncodeToString(kid)
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if _, exists := keysByKID[kidHex]; exists {
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return nil, nil, false, fmt.Errorf("duplicate kid %s", kidHex)
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}
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parsedKey, err := mp4.UnpackKey(strings.TrimSpace(parts[1]))
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if err != nil {
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return nil, nil, false, fmt.Errorf("unpacking key for kid %s: %w", kidHex, err)
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}
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keysByKID[kidHex] = parsedKey
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}
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return nil, keysByKID, true, nil
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}
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func normalizeMP4FFKeySpec(spec string) (string, error) {
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spec = strings.TrimSpace(spec)
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if spec == "" || !strings.Contains(spec, ":") {
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return spec, nil
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}
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parts := strings.SplitN(spec, ":", 2)
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left := strings.TrimSpace(parts[0])
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right := strings.TrimSpace(parts[1])
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if left == "" || right == "" {
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return "", fmt.Errorf("bad key spec %q", spec)
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}
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if _, err := mp4.UnpackKey(left); err == nil {
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return left + ":" + right, nil
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}
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if !isDecimalString(left) {
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return "", fmt.Errorf("bad kid in key spec %q", spec)
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}
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if _, err := mp4.UnpackKey(right); err != nil {
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return "", fmt.Errorf("bad key spec %q: %w", spec, err)
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}
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return right, nil
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}
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func isDecimalString(value string) bool {
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if value == "" {
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return false
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}
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for _, ch := range value {
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if ch < '0' || ch > '9' {
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return false
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}
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}
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return true
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}
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func decryptMP4FFFileWithKeyMap(r, initR io.Reader, w io.Writer, key []byte, keysByKID map[string][]byte, strictKIDMode bool) error {
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inMp4, err := mp4.DecodeFile(r)
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if err != nil {
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return err
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}
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if !inMp4.IsFragmented() {
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return fmt.Errorf("file not fragmented. Not supported")
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}
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init := inMp4.Init
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if inMp4.Init == nil {
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if initR == nil {
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return fmt.Errorf("no init segment file and no init part of file")
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}
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initSegment, err := mp4.DecodeFile(initR)
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if err != nil {
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return fmt.Errorf("could not decode init file: %w", err)
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}
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init = initSegment.Init
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}
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decryptInfo, err := mp4.DecryptInit(init)
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if err != nil {
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return err
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}
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if inMp4.Init != nil {
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if err := inMp4.Init.Encode(w); err != nil {
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return err
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}
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}
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for _, segment := range inMp4.Segments {
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if inMp4.Init == nil {
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if err := segment.ParseSenc(init); err != nil {
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return fmt.Errorf("parseSenc: %w", err)
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}
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}
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if err := decryptMP4FFSegmentWithSparseSenc(segment, decryptInfo, key, keysByKID, strictKIDMode); err != nil {
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return fmt.Errorf("decryptSegment: %w", err)
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}
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if err := segment.Encode(w); err != nil {
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return err
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}
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}
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return nil
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}
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func decryptMP4FFSegmentWithSparseSenc(segment *mp4.MediaSegment, decryptInfo mp4.DecryptInfo, key []byte, keysByKID map[string][]byte, strictKIDMode bool) error {
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for _, fragment := range segment.Fragments {
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if !mp4FragmentContainsSenc(fragment) {
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continue
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}
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if err := mp4.DecryptFragmentWithKeys(fragment, decryptInfo, key, keysByKID, strictKIDMode); err != nil {
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return err
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}
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}
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if len(segment.Sidxs) > 0 {
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segment.Sidx = nil
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segment.Sidxs = nil
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}
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return nil
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}
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func mp4FragmentContainsSenc(fragment *mp4.Fragment) bool {
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if fragment == nil || fragment.Moof == nil {
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return false
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}
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for _, traf := range fragment.Moof.Trafs {
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if traf == nil {
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continue
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}
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hasSenc, _ := traf.ContainsSencBox()
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if hasSenc {
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return true
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}
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}
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return false
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}
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