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server/vendor/github.com/pion/rtp/codecs/vp9/header.go

@@ -0,0 +1,221 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+// Package vp9 contains a VP9 header parser.
+package vp9
+
+import (
+	"errors"
+)
+
+var (
+	errInvalidFrameMarker  = errors.New("invalid frame marker")
+	errWrongFrameSyncByte0 = errors.New("wrong frame_sync_byte_0")
+	errWrongFrameSyncByte1 = errors.New("wrong frame_sync_byte_1")
+	errWrongFrameSyncByte2 = errors.New("wrong frame_sync_byte_2")
+)
+
+// HeaderColorConfig is the color_config member of an header.
+type HeaderColorConfig struct {
+	TenOrTwelveBit bool
+	BitDepth       uint8
+	ColorSpace     uint8
+	ColorRange     bool
+	SubsamplingX   bool
+	SubsamplingY   bool
+}
+
+func (c *HeaderColorConfig) unmarshal(profile uint8, buf []byte, pos *int) error {
+	if profile >= 2 {
+		var err error
+		c.TenOrTwelveBit, err = readFlag(buf, pos)
+		if err != nil {
+			return err
+		}
+
+		if c.TenOrTwelveBit {
+			c.BitDepth = 12
+		} else {
+			c.BitDepth = 10
+		}
+	} else {
+		c.BitDepth = 8
+	}
+
+	tmp, err := readBits(buf, pos, 3)
+	if err != nil {
+		return err
+	}
+	c.ColorSpace = uint8(tmp)
+
+	if c.ColorSpace != 7 {
+		var err error
+		c.ColorRange, err = readFlag(buf, pos)
+		if err != nil {
+			return err
+		}
+
+		if profile == 1 || profile == 3 {
+			err := hasSpace(buf, *pos, 3)
+			if err != nil {
+				return err
+			}
+
+			c.SubsamplingX = readFlagUnsafe(buf, pos)
+			c.SubsamplingY = readFlagUnsafe(buf, pos)
+			*pos++
+		} else {
+			c.SubsamplingX = true
+			c.SubsamplingY = true
+		}
+	} else {
+		c.ColorRange = true
+
+		if profile == 1 || profile == 3 {
+			c.SubsamplingX = false
+			c.SubsamplingY = false
+
+			err := hasSpace(buf, *pos, 1)
+			if err != nil {
+				return err
+			}
+			*pos++
+		}
+	}
+
+	return nil
+}
+
+// HeaderFrameSize is the frame_size member of an header.
+type HeaderFrameSize struct {
+	FrameWidthMinus1  uint16
+	FrameHeightMinus1 uint16
+}
+
+func (s *HeaderFrameSize) unmarshal(buf []byte, pos *int) error {
+	err := hasSpace(buf, *pos, 32)
+	if err != nil {
+		return err
+	}
+
+	s.FrameWidthMinus1 = uint16(readBitsUnsafe(buf, pos, 16))
+	s.FrameHeightMinus1 = uint16(readBitsUnsafe(buf, pos, 16))
+	return nil
+}
+
+// Header is a VP9 Frame header.
+// Specification:
+// https://storage.googleapis.com/downloads.webmproject.org/docs/vp9/vp9-bitstream-specification-v0.6-20160331-draft.pdf
+type Header struct {
+	Profile            uint8
+	ShowExistingFrame  bool
+	FrameToShowMapIdx  uint8
+	NonKeyFrame        bool
+	ShowFrame          bool
+	ErrorResilientMode bool
+	ColorConfig        *HeaderColorConfig
+	FrameSize          *HeaderFrameSize
+}
+
+// Unmarshal decodes a Header.
+func (h *Header) Unmarshal(buf []byte) error {
+	pos := 0
+
+	err := hasSpace(buf, pos, 4)
+	if err != nil {
+		return err
+	}
+
+	frameMarker := readBitsUnsafe(buf, &pos, 2)
+	if frameMarker != 2 {
+		return errInvalidFrameMarker
+	}
+
+	profileLowBit := uint8(readBitsUnsafe(buf, &pos, 1))
+	profileHighBit := uint8(readBitsUnsafe(buf, &pos, 1))
+	h.Profile = profileHighBit<<1 + profileLowBit
+
+	if h.Profile == 3 {
+		err = hasSpace(buf, pos, 1)
+		if err != nil {
+			return err
+		}
+		pos++
+	}
+
+	h.ShowExistingFrame, err = readFlag(buf, &pos)
+	if err != nil {
+		return err
+	}
+
+	if h.ShowExistingFrame {
+		var tmp uint64
+		tmp, err = readBits(buf, &pos, 3)
+		if err != nil {
+			return err
+		}
+		h.FrameToShowMapIdx = uint8(tmp)
+		return nil
+	}
+
+	err = hasSpace(buf, pos, 3)
+	if err != nil {
+		return err
+	}
+
+	h.NonKeyFrame = readFlagUnsafe(buf, &pos)
+	h.ShowFrame = readFlagUnsafe(buf, &pos)
+	h.ErrorResilientMode = readFlagUnsafe(buf, &pos)
+
+	if !h.NonKeyFrame {
+		err := hasSpace(buf, pos, 24)
+		if err != nil {
+			return err
+		}
+
+		frameSyncByte0 := uint8(readBitsUnsafe(buf, &pos, 8))
+		if frameSyncByte0 != 0x49 {
+			return errWrongFrameSyncByte0
+		}
+
+		frameSyncByte1 := uint8(readBitsUnsafe(buf, &pos, 8))
+		if frameSyncByte1 != 0x83 {
+			return errWrongFrameSyncByte1
+		}
+
+		frameSyncByte2 := uint8(readBitsUnsafe(buf, &pos, 8))
+		if frameSyncByte2 != 0x42 {
+			return errWrongFrameSyncByte2
+		}
+
+		h.ColorConfig = &HeaderColorConfig{}
+		err = h.ColorConfig.unmarshal(h.Profile, buf, &pos)
+		if err != nil {
+			return err
+		}
+
+		h.FrameSize = &HeaderFrameSize{}
+		err = h.FrameSize.unmarshal(buf, &pos)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Width returns the video width.
+func (h Header) Width() uint16 {
+	if h.FrameSize == nil {
+		return 0
+	}
+	return h.FrameSize.FrameWidthMinus1 + 1
+}
+
+// Height returns the video height.
+func (h Header) Height() uint16 {
+	if h.FrameSize == nil {
+		return 0
+	}
+	return h.FrameSize.FrameHeightMinus1 + 1
+}