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72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
package vpx
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// https://tools.ietf.org/html/rfc6386
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import (
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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// TODO: vpx frame?
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.VP8_FRAME,
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Description: "VP8 frame",
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DecodeFn: vp8Decode,
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})
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}
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func vp8Decode(d *decode.D, _ any) any {
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var isKeyFrame bool
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versions := map[uint64]struct {
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reconstruction string
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loop string
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}{
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0: {"Bicubic", "Normal"},
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1: {"Bilinear", "Simple"},
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2: {"Bilinear", "None"},
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3: {"None", "None"},
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}
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d.FieldStruct("tag", func(d *decode.D) {
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// first_part_size is not contiguous bits
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firstPartSize0 := d.FieldU3("first_part_size0")
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d.FieldU1("show_frame")
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version := d.FieldU3("version")
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keyFrameV := d.FieldBool("frame_type", scalar.BoolToSymStr{true: "non_key_frame", false: "key_frame"})
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firstPartSize1 := d.FieldU16LE("first_part_size1")
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firstPartSize := firstPartSize0 | firstPartSize1<<3
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d.FieldValueU("first_part_size", firstPartSize)
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isKeyFrame = !keyFrameV
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if v, ok := versions[version]; ok {
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d.FieldValueStr("reconstruction", v.reconstruction)
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d.FieldValueStr("loop", v.loop)
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}
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})
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if isKeyFrame {
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d.FieldU24("start_code", d.ValidateU(0x9d012a), scalar.ActualHex)
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// width and height are not contiguous bits
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width0 := d.FieldU8("width0")
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d.FieldU2("horizontal_scale")
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width1 := d.FieldU6("width1")
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d.FieldValueU("width", width0|width1<<8)
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height0 := d.FieldU8("height0")
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d.FieldU2("vertical_scale")
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height1 := d.FieldU6("height1")
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d.FieldValueU("height", height0|height1<<8)
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}
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d.FieldRawLen("data", d.BitsLeft())
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return nil
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}
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