Fix VP9 decoding on iOS

codecs/vp9/bits.go

@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package vp9
+
+import "errors"
+
+var errNotEnoughBits = errors.New("not enough bits")
+
+func hasSpace(buf []byte, pos int, n int) error {
+	if n > ((len(buf) * 8) - pos) {
+		return errNotEnoughBits
+	}
+	return nil
+}
+
+func readFlag(buf []byte, pos *int) (bool, error) {
+	err := hasSpace(buf, *pos, 1)
+	if err != nil {
+		return false, err
+	}
+
+	return readFlagUnsafe(buf, pos), nil
+}
+
+func readFlagUnsafe(buf []byte, pos *int) bool {
+	b := (buf[*pos>>0x03] >> (7 - (*pos & 0x07))) & 0x01
+	*pos++
+	return b == 1
+}
+
+func readBits(buf []byte, pos *int, n int) (uint64, error) {
+	err := hasSpace(buf, *pos, n)
+	if err != nil {
+		return 0, err
+	}
+
+	return readBitsUnsafe(buf, pos, n), nil
+}
+
+func readBitsUnsafe(buf []byte, pos *int, n int) uint64 {
+	res := 8 - (*pos & 0x07)
+	if n < res {
+		v := uint64((buf[*pos>>0x03] >> (res - n)) & (1<<n - 1))
+		*pos += n
+		return v
+	}
+
+	v := uint64(buf[*pos>>0x03] & (1<<res - 1))
+	*pos += res
+	n -= res
+
+	for n >= 8 {
+		v = (v << 8) | uint64(buf[*pos>>0x03])
+		*pos += 8
+		n -= 8
+	}
+
+	if n > 0 {
+		v = (v << n) | uint64(buf[*pos>>0x03]>>(8-n))
+		*pos += n
+	}
+
+	return v
+}

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
+}

codecs/vp9/header_test.go

@@ -0,0 +1,85 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package vp9
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestHeaderUnmarshal(t *testing.T) {
+	cases := []struct {
+		name   string
+		byts   []byte
+		sh     Header
+		width  uint16
+		height uint16
+	}{
+		{
+			"chrome webrtc",
+			[]byte{
+				0x82, 0x49, 0x83, 0x42, 0x00, 0x77, 0xf0, 0x32,
+				0x34, 0x30, 0x38, 0x24, 0x1c, 0x19, 0x40, 0x18,
+				0x03, 0x40, 0x5f, 0xb4,
+			},
+			Header{
+				ShowFrame: true,
+				ColorConfig: &HeaderColorConfig{
+					BitDepth:     8,
+					SubsamplingX: true,
+					SubsamplingY: true,
+				},
+				FrameSize: &HeaderFrameSize{
+					FrameWidthMinus1:  1919,
+					FrameHeightMinus1: 803,
+				},
+			},
+			1920,
+			804,
+		},
+		{
+			"vp9 sample",
+			[]byte{
+				0x82, 0x49, 0x83, 0x42, 0x40, 0xef, 0xf0, 0x86,
+				0xf4, 0x04, 0x21, 0xa0, 0xe0, 0x00, 0x30, 0x70,
+				0x00, 0x00, 0x00, 0x01,
+			},
+			Header{
+				ShowFrame: true,
+				ColorConfig: &HeaderColorConfig{
+					BitDepth:     8,
+					ColorSpace:   2,
+					SubsamplingX: true,
+					SubsamplingY: true,
+				},
+				FrameSize: &HeaderFrameSize{
+					FrameWidthMinus1:  3839,
+					FrameHeightMinus1: 2159,
+				},
+			},
+			3840,
+			2160,
+		},
+	}
+
+	for _, ca := range cases {
+		t.Run(ca.name, func(t *testing.T) {
+			var sh Header
+			err := sh.Unmarshal(ca.byts)
+			if err != nil {
+				t.Fatal("unexpected error")
+			}
+
+			if !reflect.DeepEqual(ca.sh, sh) {
+				t.Fatalf("expected %#+v, got %#+v", ca.sh, sh)
+			}
+			if ca.width != sh.Width() {
+				t.Fatalf("unexpected width")
+			}
+			if ca.height != sh.Height() {
+				t.Fatalf("unexpected height")
+			}
+		})
+	}
+}