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sampleflags.go
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sampleflags.go
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package mp4
import "fmt"
// SampleFlags according to 14496-12 Sec. 8.8.3.1
type SampleFlags struct {
IsLeading byte
SampleDependsOn byte
SampleIsDependedOn byte
SampleHasRedundancy byte
SamplePaddingValue byte
SampleIsNonSync bool
SampleDegradationPriority uint16
}
func (sf SampleFlags) String() string {
return fmt.Sprintf("isLeading=%d dependsOn=%d isDependedOn=%d hasRedundancy=%d padding=%d isNonSync=%t degradationPriority=%d",
sf.IsLeading, sf.SampleDependsOn, sf.SampleIsDependedOn, sf.SampleHasRedundancy, sf.SamplePaddingValue,
sf.SampleIsNonSync, sf.SampleDegradationPriority)
}
func (sf SampleFlags) Encode() uint32 {
sfBin := uint32(sf.IsLeading)<<26 | uint32(sf.SampleDependsOn)<<24 | uint32(sf.SampleIsDependedOn)<<22
sfBin |= uint32(sf.SampleHasRedundancy)<<20 | uint32(sf.SamplePaddingValue)<<17
if sf.SampleIsNonSync {
sfBin |= 1 << 16
}
sfBin |= uint32(sf.SampleDegradationPriority)
return sfBin
}
// SyncSampleFlags - flags for I-frame or other sync sample
const SyncSampleFlags uint32 = 0x02000000
// NonSyncSampleFlags - flags for non-sync sample
const NonSyncSampleFlags uint32 = 0x00010000
// IsSyncSampleFlags - flags is set correctly for sync sample
func IsSyncSampleFlags(flags uint32) bool {
return flags&SyncSampleFlags == SyncSampleFlags
}
// SetSyncSampleFlags - return flags with syncsample pattern
func SetSyncSampleFlags(flags uint32) uint32 {
return flags & SyncSampleFlags & ^NonSyncSampleFlags
}
// SetNonSyncSampleFlags - return flags with nonsyncsample pattern
func SetNonSyncSampleFlags(flags uint32) uint32 {
return flags & ^SyncSampleFlags & NonSyncSampleFlags
}
// DecodeSampleFlags - decode a uint32 flags field
func DecodeSampleFlags(u uint32) SampleFlags {
sf := SampleFlags{
IsLeading: byte((u >> 26) & 0x3),
SampleDependsOn: byte((u >> 24) & 0x3),
SampleIsDependedOn: byte((u >> 22) & 0x3),
SampleHasRedundancy: byte((u >> 20) & 0x3),
SamplePaddingValue: byte((u >> 17) & 0x7),
SampleIsNonSync: (u>>16)&0x1 == 1,
SampleDegradationPriority: uint16(u & 0xffff),
}
return sf
}