/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/modules/audio_coding/neteq/payload_splitter.h"
#include <assert.h>
#include "webrtc/modules/audio_coding/neteq/decoder_database.h"
namespace webrtc {
// The method loops through a list of packets {A, B, C, ...}. Each packet is
// split into its corresponding RED payloads, {A1, A2, ...}, which is
// temporarily held in the list |new_packets|.
// When the first packet in |packet_list| has been processed, the orignal packet
// is replaced by the new ones in |new_packets|, so that |packet_list| becomes:
// {A1, A2, ..., B, C, ...}. The method then continues with B, and C, until all
// the original packets have been replaced by their split payloads.
int PayloadSplitter::SplitRed(PacketList* packet_list) {
int ret = kOK;
PacketList::iterator it = packet_list->begin();
while (it != packet_list->end()) {
PacketList new_packets; // An empty list to store the split packets in.
Packet* red_packet = (*it);
assert(red_packet->payload);
uint8_t* payload_ptr = red_packet->payload;
// Read RED headers (according to RFC 2198):
//
// 0 1 2 3
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |F| block PT | timestamp offset | block length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Last RED header:
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |0| Block PT |
// +-+-+-+-+-+-+-+-+
bool last_block = false;
int sum_length = 0;
while (!last_block) {
Packet* new_packet = new Packet;
new_packet->header = red_packet->header;
// Check the F bit. If F == 0, this was the last block.
last_block = ((*payload_ptr & 0x80) == 0);
// Bits 1 through 7 are payload type.
new_packet->header.payloadType = payload_ptr[0] & 0x7F;
if (last_block) {
// No more header data to read.
++sum_length; // Account for RED header size of 1 byte.
new_packet->payload_length = red_packet->payload_length - sum_length;
new_packet->primary = true; // Last block is always primary.
payload_ptr += 1; // Advance to first payload byte.
} else {
// Bits 8 through 21 are timestamp offset.
int timestamp_offset = (payload_ptr[1] << 6) +
((payload_ptr[2] & 0xFC) >> 2);
new_packet->header.timestamp = red_packet->header.timestamp -
timestamp_offset;
// Bits 22 through 31 are payload length.
new_packet->payload_length = ((payload_ptr[2] & 0x03) << 8) +
payload_ptr[3];
new_packet->primary = false;
payload_ptr += 4; // Advance to next RED header.
}
sum_length += new_packet->payload_length;
sum_length += 4; // Account for RED header size of 4 bytes.
// Store in new list of packets.
new_packets.push_back(new_packet);
}
// Populate the new packets with payload data.
// |payload_ptr| now points at the first payload byte.
PacketList::iterator new_it;
for (new_it = new_packets.begin(); new_it != new_packets.end(); ++new_it) {
int payload_length = (*new_it)->payload_length;
if (payload_ptr + payload_length >
red_packet->payload + red_packet->payload_length) {
// The block lengths in the RED headers do not match the overall packet
// length. Something is corrupt. Discard this and the remaining
// payloads from this packet.
while (new_it != new_packets.end()) {
// Payload should not have been allocated yet.
assert(!(*new_it)->payload);
delete (*new_it);
new_it = new_packets.erase(new_it);
}
ret = kRedLengthMismatch;
break;
}
(*new_it)->payload = new uint8_t[payload_length];
memcpy((*new_it)->payload, payload_ptr, payload_length);
payload_ptr += payload_length;
}
// Reverse the order of the new packets, so that the primary payload is
// always first.
new_packets.reverse();
// Insert new packets into original list, before the element pointed to by
// iterator |it|.
packet_list->splice(it, new_packets, new_packets.begin(),
new_packets.end());
// Delete old packet payload.
delete [] (*it)->payload;
delete (*it);
// Remove |it| from the packet list. This operation effectively moves the
// iterator |it| to the next packet in the list. Thus, we do not have to
// increment it manually.
it = packet_list->erase(it);
}
return ret;
}
int PayloadSplitter::SplitFec(PacketList* packet_list,
DecoderDatabase* decoder_database) {
PacketList::iterator it = packet_list->begin();
// Iterate through all packets in |packet_list|.
while (it != packet_list->end()) {
Packet* packet = (*it); // Just to make the notation more intuitive.
// Get codec type for this payload.
uint8_t payload_type = packet->header.payloadType;
const DecoderDatabase::DecoderInfo* info =
decoder_database->GetDecoderInfo(payload_type);
if (!info) {
return kUnknownPayloadType;
}
// No splitting for a sync-packet.
if (packet->sync_packet) {
++it;
continue;
}
// Not an FEC packet.
AudioDecoder* decoder = decoder_database->GetDecoder(payload_type);
// decoder should not return NULL.
assert(decoder != NULL);
if (!decoder ||
!decoder->PacketHasFec(packet->payload, packet->payload_length)) {
++it;
continue;
}
switch (info->codec_type) {
case kDecoderOpus:
case kDecoderOpus_2ch: {
Packet* new_packet = new Packet;
new_packet->header = packet->header;
int duration = decoder->
PacketDurationRedundant(packet->payload, packet->payload_length);
new_packet->header.timestamp -= duration;
new_packet->payload = new uint8_t[packet->payload_length];
memcpy(new_packet->payload, packet->payload, packet->payload_length);
new_packet->payload_length = packet->payload_length;
new_packet->primary = false;
new_packet->waiting_time = packet->waiting_time;
new_packet->sync_packet = packet->sync_packet;
packet_list->insert(it, new_packet);
break;
}
default: {
return kFecSplitError;
}
}
++it;
}
return kOK;
}
int PayloadSplitter::CheckRedPayloads(PacketList* packet_list,
const DecoderDatabase& decoder_database) {
PacketList::iterator it = packet_list->begin();
int main_payload_type = -1;
int num_deleted_packets = 0;
while (it != packet_list->end()) {
uint8_t this_payload_type = (*it)->header.payloadType;
if (!decoder_database.IsDtmf(this_payload_type) &&
!decoder_database.IsComfortNoise(this_payload_type)) {
if (main_payload_type == -1) {
// This is the first packet in the list which is non-DTMF non-CNG.
main_payload_type = this_payload_type;
} else {
if (this_payload_type != main_payload_type) {
// We do not allow redundant payloads of a different type.
// Discard this payload.
delete [] (*it)->payload;
delete (*it);
// Remove |it| from the packet list. This operation effectively
// moves the iterator |it| to the next packet in the list. Thus, we
// do not have to increment it manually.
it = packet_list->erase(it);
++num_deleted_packets;
continue;
}
}
}
++it;
}
return num_deleted_packets;
}
int PayloadSplitter::SplitAudio(PacketList* packet_list,
const DecoderDatabase& decoder_database) {
PacketList::iterator it = packet_list->begin();
// Iterate through all packets in |packet_list|.
while (it != packet_list->end()) {
Packet* packet = (*it); // Just to make the notation more intuitive.
// Get codec type for this payload.
const DecoderDatabase::DecoderInfo* info =
decoder_database.GetDecoderInfo(packet->header.payloadType);
if (!info) {
return kUnknownPayloadType;
}
// No splitting for a sync-packet.
if (packet->sync_packet) {
++it;
continue;
}
PacketList new_packets;
switch (info->codec_type) {
case kDecoderPCMu:
case kDecoderPCMa: {
// 8 bytes per ms; 8 timestamps per ms.
SplitBySamples(packet, 8, 8, &new_packets);
break;
}
case kDecoderPCMu_2ch:
case kDecoderPCMa_2ch: {
// 2 * 8 bytes per ms; 8 timestamps per ms.
SplitBySamples(packet, 2 * 8, 8, &new_packets);
break;
}
case kDecoderG722: {
// 8 bytes per ms; 16 timestamps per ms.
SplitBySamples(packet, 8, 16, &new_packets);
break;
}
case kDecoderPCM16B: {
// 16 bytes per ms; 8 timestamps per ms.
SplitBySamples(packet, 16, 8, &new_packets);
break;
}
case kDecoderPCM16Bwb: {
// 32 bytes per ms; 16 timestamps per ms.
SplitBySamples(packet, 32, 16, &new_packets);
break;
}
case kDecoderPCM16Bswb32kHz: {
// 64 bytes per ms; 32 timestamps per ms.
SplitBySamples(packet, 64, 32, &new_packets);
break;
}
case kDecoderPCM16Bswb48kHz: {
// 96 bytes per ms; 48 timestamps per ms.
SplitBySamples(packet, 96, 48, &new_packets);
break;
}
case kDecoderPCM16B_2ch: {
// 2 * 16 bytes per ms; 8 timestamps per ms.
SplitBySamples(packet, 2 * 16, 8, &new_packets);
break;
}
case kDecoderPCM16Bwb_2ch: {
// 2 * 32 bytes per ms; 16 timestamps per ms.
SplitBySamples(packet, 2 * 32, 16, &new_packets);
break;
}
case kDecoderPCM16Bswb32kHz_2ch: {
// 2 * 64 bytes per ms; 32 timestamps per ms.
SplitBySamples(packet, 2 * 64, 32, &new_packets);
break;
}
case kDecoderPCM16Bswb48kHz_2ch: {
// 2 * 96 bytes per ms; 48 timestamps per ms.
SplitBySamples(packet, 2 * 96, 48, &new_packets);
break;
}
case kDecoderPCM16B_5ch: {
// 5 * 16 bytes per ms; 8 timestamps per ms.
SplitBySamples(packet, 5 * 16, 8, &new_packets);
break;
}
case kDecoderILBC: {
int bytes_per_frame;
int timestamps_per_frame;
if (packet->payload_length >= 950) {
return kTooLargePayload;
} else if (packet->payload_length % 38 == 0) {
// 20 ms frames.
bytes_per_frame = 38;
timestamps_per_frame = 160;
} else if (packet->payload_length % 50 == 0) {
// 30 ms frames.
bytes_per_frame = 50;
timestamps_per_frame = 240;
} else {
return kFrameSplitError;
}
int ret = SplitByFrames(packet, bytes_per_frame, timestamps_per_frame,
&new_packets);
if (ret < 0) {
return ret;
} else if (ret == kNoSplit) {
// Do not split at all. Simply advance to the next packet in the list.
++it;
// We do not have any new packets to insert, and should not delete the
// old one. Skip the code after the switch case, and jump straight to
// the next packet in the while loop.
continue;
}
break;
}
default: {
// Do not split at all. Simply advance to the next packet in the list.
++it;
// We do not have any new packets to insert, and should not delete the
// old one. Skip the code after the switch case, and jump straight to
// the next packet in the while loop.
continue;
}
}
// Insert new packets into original list, before the element pointed to by
// iterator |it|.
packet_list->splice(it, new_packets, new_packets.begin(),
new_packets.end());
// Delete old packet payload.
delete [] (*it)->payload;
delete (*it);
// Remove |it| from the packet list. This operation effectively moves the
// iterator |it| to the next packet in the list. Thus, we do not have to
// increment it manually.
it = packet_list->erase(it);
}
return kOK;
}
void PayloadSplitter::SplitBySamples(const Packet* packet,
int bytes_per_ms,
int timestamps_per_ms,
PacketList* new_packets) {
assert(packet);
assert(new_packets);
int split_size_bytes = packet->payload_length;
// Find a "chunk size" >= 20 ms and < 40 ms.
int min_chunk_size = bytes_per_ms * 20;
// Reduce the split size by half as long as |split_size_bytes| is at least
// twice the minimum chunk size (so that the resulting size is at least as
// large as the minimum chunk size).
while (split_size_bytes >= 2 * min_chunk_size) {
split_size_bytes >>= 1;
}
int timestamps_per_chunk =
split_size_bytes * timestamps_per_ms / bytes_per_ms;
uint32_t timestamp = packet->header.timestamp;
uint8_t* payload_ptr = packet->payload;
int len = packet->payload_length;
while (len >= (2 * split_size_bytes)) {
Packet* new_packet = new Packet;
new_packet->payload_length = split_size_bytes;
new_packet->header = packet->header;
new_packet->header.timestamp = timestamp;
timestamp += timestamps_per_chunk;
new_packet->primary = packet->primary;
new_packet->payload = new uint8_t[split_size_bytes];
memcpy(new_packet->payload, payload_ptr, split_size_bytes);
payload_ptr += split_size_bytes;
new_packets->push_back(new_packet);
len -= split_size_bytes;
}
if (len > 0) {
Packet* new_packet = new Packet;
new_packet->payload_length = len;
new_packet->header = packet->header;
new_packet->header.timestamp = timestamp;
new_packet->primary = packet->primary;
new_packet->payload = new uint8_t[len];
memcpy(new_packet->payload, payload_ptr, len);
new_packets->push_back(new_packet);
}
}
int PayloadSplitter::SplitByFrames(const Packet* packet,
int bytes_per_frame,
int timestamps_per_frame,
PacketList* new_packets) {
if (packet->payload_length % bytes_per_frame != 0) {
return kFrameSplitError;
}
int num_frames = packet->payload_length / bytes_per_frame;
if (num_frames == 1) {
// Special case. Do not split the payload.
return kNoSplit;
}
uint32_t timestamp = packet->header.timestamp;
uint8_t* payload_ptr = packet->payload;
int len = packet->payload_length;
while (len > 0) {
assert(len >= bytes_per_frame);
Packet* new_packet = new Packet;
new_packet->payload_length = bytes_per_frame;
new_packet->header = packet->header;
new_packet->header.timestamp = timestamp;
timestamp += timestamps_per_frame;
new_packet->primary = packet->primary;
new_packet->payload = new uint8_t[bytes_per_frame];
memcpy(new_packet->payload, payload_ptr, bytes_per_frame);
payload_ptr += bytes_per_frame;
new_packets->push_back(new_packet);
len -= bytes_per_frame;
}
return kOK;
}
} // namespace webrtc