feat(gateway): repair native Apollo provider path

gateway/apollo_audio_fec.go

@@ -0,0 +1,144 @@
+package gateway
+
+const (
+	apolloAudioDataShards    = 4
+	apolloAudioParityShards  = 2
+	apolloAudioTotalShards   = apolloAudioDataShards + apolloAudioParityShards
+	apolloAudioMaximumBlocks = 4
+)
+
+type apolloAudioFECBlock struct {
+	base      uint16
+	timestamp uint32
+	ssrc      uint32
+	haveFEC   bool
+	size      int
+	shards    [apolloAudioTotalShards][]byte
+	received  [apolloAudioTotalShards]bool
+	count     int
+}
+
+type apolloAudioAssembler struct {
+	blocks map[uint16]*apolloAudioFECBlock
+}
+
+func (a *apolloAudioAssembler) Add(codec *apolloMediaCodec, shard apolloAudioShard) ([][]byte, error) {
+	if codec == nil || len(shard.payload) == 0 || len(shard.payload) > 1408 || len(shard.payload)%16 != 0 {
+		return nil, errApolloMedia
+	}
+	if a.blocks == nil {
+		a.blocks = make(map[uint16]*apolloAudioFECBlock)
+	}
+	base := shard.base
+	if base&3 != 0 {
+		return nil, errApolloMedia
+	}
+	block := a.blocks[base]
+	if block == nil {
+		if len(a.blocks) >= apolloAudioMaximumBlocks {
+			return nil, errApolloMedia
+		}
+		block = &apolloAudioFECBlock{base: base}
+		a.blocks[base] = block
+	}
+	if block.size == 0 {
+		block.size = len(shard.payload)
+	} else if block.size != len(shard.payload) {
+		return nil, errApolloMedia
+	}
+	index := 0
+	if shard.parity {
+		if shard.parityIndex >= apolloAudioParityShards {
+			return nil, errApolloMedia
+		}
+		index = apolloAudioDataShards + int(shard.parityIndex)
+		if block.haveFEC && (block.timestamp != shard.timestamp || block.ssrc != shard.ssrc) {
+			return nil, errApolloMedia
+		}
+		block.timestamp, block.ssrc, block.haveFEC = shard.timestamp, shard.ssrc, true
+	} else {
+		index = int(uint16(shard.sequence - base))
+		if index >= apolloAudioDataShards {
+			return nil, errApolloMedia
+		}
+		if block.haveFEC && (shard.timestamp != block.timestamp+uint32(index*5) || shard.ssrc != block.ssrc) {
+			return nil, errApolloMedia
+		}
+	}
+	if block.received[index] {
+		return nil, errApolloMedia
+	}
+	block.shards[index] = append([]byte(nil), shard.payload...)
+	block.received[index] = true
+	block.count++
+	if block.count < apolloAudioDataShards {
+		return nil, nil
+	}
+	if err := reconstructApolloAudioBlock(block); err != nil {
+		return nil, err
+	}
+	output := make([][]byte, apolloAudioDataShards)
+	for index := range output {
+		payload, err := codec.openApolloAudioCipher(base+uint16(index), block.shards[index])
+		if err != nil {
+			return nil, err
+		}
+		output[index] = payload
+	}
+	delete(a.blocks, base)
+	return output, nil
+}
+
+func reconstructApolloAudioBlock(block *apolloAudioFECBlock) error {
+	if block == nil || block.count < apolloAudioDataShards || block.size == 0 {
+		return errApolloMedia
+	}
+	missing := false
+	for index := 0; index < apolloAudioDataShards; index++ {
+		if !block.received[index] {
+			missing = true
+			block.shards[index] = make([]byte, block.size)
+		}
+	}
+	if !missing {
+		return nil
+	}
+	if !block.haveFEC {
+		return errApolloMedia
+	}
+	rows := make([][]byte, 0, apolloAudioDataShards)
+	shards := make([][]byte, 0, apolloAudioDataShards)
+	for index, received := range block.received {
+		if !received {
+			continue
+		}
+		rows = append(rows, apolloAudioFECRow(index))
+		shards = append(shards, block.shards[index])
+		if len(rows) == apolloAudioDataShards {
+			break
+		}
+	}
+	inverse, ok := apolloGFInvert(rows)
+	if !ok {
+		return errApolloMedia
+	}
+	for index := 0; index < apolloAudioDataShards; index++ {
+		if block.received[index] {
+			continue
+		}
+		for source, coefficient := range inverse[index] {
+			apolloGFAXPY(block.shards[index], shards[source], coefficient)
+		}
+	}
+	return nil
+}
+
+func apolloAudioFECRow(index int) []byte {
+	if index < apolloAudioDataShards {
+		row := make([]byte, apolloAudioDataShards)
+		row[index] = 1
+		return row
+	}
+	parity := [8]byte{0x77, 0x40, 0x38, 0x0e, 0xc7, 0xa7, 0x0d, 0x6c}
+	return append([]byte(nil), parity[(index-apolloAudioDataShards)*apolloAudioDataShards:(index-apolloAudioDataShards+1)*apolloAudioDataShards]...)
+}