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mirror of https://github.com/wader/fq.git synced 2024-11-26 10:33:53 +03:00
fq/format/av1/av1_obu.go
Mattias Wadman 2fc0a71a47 decode: Refactor scalar usage
Move scalar into own package.
Split scalar code into decode related scalar code (that reads etc) and
scalar code that just transform the scalar value.
Use a scalar.Mapper interface instead of just a function.
Make mappers, assert and validat impement the interface.
2021-12-02 17:39:26 +01:00

91 lines
2.0 KiB
Go

package av1
import (
"github.com/wader/fq/format"
"github.com/wader/fq/format/registry"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/scalar"
)
func init() {
registry.MustRegister(decode.Format{
Name: format.AV1_OBU,
Description: "AV1 Open Bitstream Unit",
DecodeFn: obuDecode,
})
}
//nolint:revive
const (
OBU_SEQUENCE_HEADER = 1
OBU_TEMPORAL_DELIMITER = 2
OBU_FRAME_HEADER = 3
OBU_TILE_GROUP = 4
OBU_METADATA = 5
OBU_FRAME = 6
OBU_REDUNDANT_FRAME_HEADER = 7
OBU_TILE_LIST = 8
OBU_PADDING = 15
)
var obuTypeNames = scalar.UToSymStr{
OBU_SEQUENCE_HEADER: "OBU_SEQUENCE_HEADER",
OBU_TEMPORAL_DELIMITER: "OBU_TEMPORAL_DELIMITER",
OBU_FRAME_HEADER: "OBU_FRAME_HEADER",
OBU_TILE_GROUP: "OBU_TILE_GROUP",
OBU_METADATA: "OBU_METADATA",
OBU_FRAME: "OBU_FRAME",
OBU_REDUNDANT_FRAME_HEADER: "OBU_REDUNDANT_FRAME_HEADER",
OBU_TILE_LIST: "OBU_TILE_LIST",
OBU_PADDING: "OBU_PADDING",
}
func decodeLeb128(d *decode.D) uint64 {
var v uint64
for i := 0; i < 8; i++ {
b := d.U8()
v = v | (b&0x7f)<<(i*7)
if b&0x80 == 0 {
break
}
}
return v
}
func obuDecode(d *decode.D, in interface{}) interface{} {
var obuType uint64
var obuSize int64
hasExtension := false
hasSizeField := false
d.FieldStruct("header", func(d *decode.D) {
d.FieldU1("forbidden_bit")
obuType = d.FieldU4("type", obuTypeNames)
hasExtension = d.FieldBool("extension_flag")
hasSizeField = d.FieldBool("has_size_field")
d.FieldU1("reserved_1bit")
if hasExtension {
d.FieldU3("temporal_id")
d.FieldU2("spatial_id")
d.FieldU3("extension_header_reserved_3bits")
}
})
if hasSizeField {
obuSize = int64(d.FieldUFn("size", decodeLeb128))
} else {
obuSize = d.BitsLeft() / 8
if hasExtension {
obuSize--
}
}
_ = obuType
if d.BitsLeft() > 0 {
d.FieldRawLen("data", obuSize*8)
}
return nil
}