Initial commit

pkg/h264/ps/pps.go

@@ -0,0 +1,127 @@
+package ps
+
+import (
+	"errors"
+	"github.com/AlexxIT/go2rtc/pkg/h264/golomb"
+)
+
+const PPSHeader = 0x68
+
+// https://www.itu.int/rec/T-REC-H.264
+// 7.3.2.2 Picture parameter set RBSP syntax
+
+type PPS struct{}
+
+func (p *PPS) Marshal() []byte {
+	w := golomb.NewWriter()
+
+	// this is typical PPS for most H264 cameras
+	w.WriteByte(PPSHeader)
+	w.WriteUEGolomb(0) // pic_parameter_set_id
+	w.WriteUEGolomb(0) // seq_parameter_set_id
+	w.WriteBit(1)      // entropy_coding_mode_flag
+	w.WriteBit(0)      // bottom_field_pic_order_in_frame_present_flag
+	w.WriteUEGolomb(0) // num_slice_groups_minus1
+	w.WriteUEGolomb(0) // num_ref_idx_l0_default_active_minus1
+	w.WriteUEGolomb(0) // num_ref_idx_l1_default_active_minus1
+	w.WriteBit(0)      // weighted_pred_flag
+	w.WriteBits(0, 2)  // weighted_bipred_idc
+	w.WriteSEGolomb(0) // pic_init_qp_minus26
+	w.WriteSEGolomb(0) // pic_init_qs_minus26
+	w.WriteSEGolomb(0) // chroma_qp_index_offset
+	w.WriteBit(1)      // deblocking_filter_control_present_flag
+	w.WriteBit(0)      // constrained_intra_pred_flag
+	w.WriteBit(0)      // redundant_pic_cnt_present_flag
+
+	w.WriteBit(1) // rbsp_trailing_bits()
+
+	return w.Bytes()
+}
+
+func (p *PPS) Unmarshal(data []byte) (err error) {
+	r := golomb.NewReader(data)
+
+	var b byte
+	var u uint
+
+	if b, err = r.ReadByte(); err != nil {
+		return
+	}
+	if b&0x1F != 8 {
+		err = errors.New("not PPS data")
+		return
+	}
+
+	// pic_parameter_set_id
+	if u, err = r.ReadUEGolomb(); err != nil {
+		return
+	}
+	// seq_parameter_set_id
+	if u, err = r.ReadUEGolomb(); err != nil {
+		return
+	}
+	// entropy_coding_mode_flag
+	if b, err = r.ReadBit(); err != nil {
+		return
+	}
+	// bottom_field_pic_order_in_frame_present_flag
+	if b, err = r.ReadBit(); err != nil {
+		return
+	}
+
+	// num_slice_groups_minus1
+	if u, err = r.ReadUEGolomb(); err != nil {
+		return
+	}
+	if u > 0 {
+		//panic("not implemented")
+		return nil
+	}
+
+	// num_ref_idx_l0_default_active_minus1
+	if _, err = r.ReadUEGolomb(); err != nil {
+		return
+	}
+	// num_ref_idx_l1_default_active_minus1
+	if _, err = r.ReadUEGolomb(); err != nil {
+		return
+	}
+	// weighted_pred_flag
+	if _, err = r.ReadBit(); err != nil {
+		return
+	}
+	// weighted_bipred_idc
+	if _, err = r.ReadBits(2); err != nil {
+		return
+	}
+	// pic_init_qp_minus26
+	if _, err = r.ReadSEGolomb(); err != nil {
+		return
+	}
+	// pic_init_qs_minus26
+	if _, err = r.ReadSEGolomb(); err != nil {
+		return
+	}
+	// chroma_qp_index_offset
+	if _, err = r.ReadSEGolomb(); err != nil {
+		return
+	}
+	// deblocking_filter_control_present_flag
+	if _, err = r.ReadBit(); err != nil {
+		return
+	}
+	// constrained_intra_pred_flag
+	if _, err = r.ReadBit(); err != nil {
+		return
+	}
+	// redundant_pic_cnt_present_flag
+	if _, err = r.ReadBit(); err != nil {
+		return
+	}
+
+	if !r.End() {
+		//panic("not implemented")
+	}
+
+	return
+}