blob: 633f0ae8d00dd2722a83f880b2eddaf142b3a9a0 [file] [log] [blame]
/*
* Copyright (c) 2014 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 "modules/rtp_rtcp/source/rtp_format_h264.h"
#include <string.h>
#include <memory>
#include <utility>
#include <vector>
#include "common_video/h264/h264_common.h"
#include "common_video/h264/pps_parser.h"
#include "common_video/h264/sps_parser.h"
#include "common_video/h264/sps_vui_rewriter.h"
#include "modules/include/module_common_types.h"
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/system/fallthrough.h"
#include "system_wrappers/include/metrics.h"
namespace webrtc {
namespace {
static const size_t kNalHeaderSize = 1;
static const size_t kFuAHeaderSize = 2;
static const size_t kLengthFieldSize = 2;
static const size_t kStapAHeaderSize = kNalHeaderSize + kLengthFieldSize;
static const char* kSpsValidHistogramName = "WebRTC.Video.H264.SpsValid";
enum SpsValidEvent {
kReceivedSpsPocOk = 0,
kReceivedSpsVuiOk = 1,
kReceivedSpsRewritten = 2,
kReceivedSpsParseFailure = 3,
kSentSpsPocOk = 4,
kSentSpsVuiOk = 5,
kSentSpsRewritten = 6,
kSentSpsParseFailure = 7,
kSpsRewrittenMax = 8
};
// Bit masks for FU (A and B) indicators.
enum NalDefs : uint8_t { kFBit = 0x80, kNriMask = 0x60, kTypeMask = 0x1F };
// Bit masks for FU (A and B) headers.
enum FuDefs : uint8_t { kSBit = 0x80, kEBit = 0x40, kRBit = 0x20 };
// TODO(pbos): Avoid parsing this here as well as inside the jitter buffer.
bool ParseStapAStartOffsets(const uint8_t* nalu_ptr,
size_t length_remaining,
std::vector<size_t>* offsets) {
size_t offset = 0;
while (length_remaining > 0) {
// Buffer doesn't contain room for additional nalu length.
if (length_remaining < sizeof(uint16_t))
return false;
uint16_t nalu_size = ByteReader<uint16_t>::ReadBigEndian(nalu_ptr);
nalu_ptr += sizeof(uint16_t);
length_remaining -= sizeof(uint16_t);
if (nalu_size > length_remaining)
return false;
nalu_ptr += nalu_size;
length_remaining -= nalu_size;
offsets->push_back(offset + kStapAHeaderSize);
offset += kLengthFieldSize + nalu_size;
}
return true;
}
} // namespace
RtpPacketizerH264::RtpPacketizerH264(size_t max_payload_len,
size_t last_packet_reduction_len,
H264PacketizationMode packetization_mode)
: max_payload_len_(max_payload_len),
last_packet_reduction_len_(last_packet_reduction_len),
num_packets_left_(0),
packetization_mode_(packetization_mode) {
// Guard against uninitialized memory in packetization_mode.
RTC_CHECK(packetization_mode == H264PacketizationMode::NonInterleaved ||
packetization_mode == H264PacketizationMode::SingleNalUnit);
RTC_CHECK_GT(max_payload_len, last_packet_reduction_len);
}
RtpPacketizerH264::~RtpPacketizerH264() {
}
RtpPacketizerH264::Fragment::~Fragment() = default;
RtpPacketizerH264::Fragment::Fragment(const uint8_t* buffer, size_t length)
: buffer(buffer), length(length) {}
RtpPacketizerH264::Fragment::Fragment(const Fragment& fragment)
: buffer(fragment.buffer), length(fragment.length) {}
size_t RtpPacketizerH264::SetPayloadData(
const uint8_t* payload_data,
size_t payload_size,
const RTPFragmentationHeader* fragmentation) {
RTC_DCHECK(packets_.empty());
RTC_DCHECK(input_fragments_.empty());
RTC_DCHECK(fragmentation);
for (int i = 0; i < fragmentation->fragmentationVectorSize; ++i) {
const uint8_t* buffer =
&payload_data[fragmentation->fragmentationOffset[i]];
size_t length = fragmentation->fragmentationLength[i];
bool updated_sps = false;
H264::NaluType nalu_type = H264::ParseNaluType(buffer[0]);
if (nalu_type == H264::NaluType::kSps) {
// Check if stream uses picture order count type 0, and if so rewrite it
// to enable faster decoding. Streams in that format incur additional
// delay because it allows decode order to differ from render order.
// The mechanism used is to rewrite (edit or add) the SPS's VUI to contain
// restrictions on the maximum number of reordered pictures. This reduces
// latency significantly, though it still adds about a frame of latency to
// decoding.
// Note that we do this rewriting both here (send side, in order to
// protect legacy receive clients) and below in
// RtpDepacketizerH264::ParseSingleNalu (receive side, in orderer to
// protect us from unknown or legacy send clients).
absl::optional<SpsParser::SpsState> sps;
std::unique_ptr<rtc::Buffer> output_buffer(new rtc::Buffer());
// Add the type header to the output buffer first, so that the rewriter
// can append modified payload on top of that.
output_buffer->AppendData(buffer[0]);
SpsVuiRewriter::ParseResult result = SpsVuiRewriter::ParseAndRewriteSps(
buffer + H264::kNaluTypeSize, length - H264::kNaluTypeSize, &sps,
output_buffer.get());
switch (result) {
case SpsVuiRewriter::ParseResult::kVuiRewritten:
input_fragments_.push_back(
Fragment(output_buffer->data(), output_buffer->size()));
input_fragments_.rbegin()->tmp_buffer = std::move(output_buffer);
updated_sps = true;
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kSentSpsRewritten,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kPocOk:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kSentSpsPocOk,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kVuiOk:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kSentSpsVuiOk,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kFailure:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kSentSpsParseFailure,
SpsValidEvent::kSpsRewrittenMax);
break;
}
}
if (!updated_sps)
input_fragments_.push_back(Fragment(buffer, length));
}
if (!GeneratePackets()) {
// If failed to generate all the packets, discard already generated
// packets in case the caller would ignore return value and still try to
// call NextPacket().
num_packets_left_ = 0;
while (!packets_.empty()) {
packets_.pop();
}
return 0;
}
return num_packets_left_;
}
bool RtpPacketizerH264::GeneratePackets() {
for (size_t i = 0; i < input_fragments_.size();) {
switch (packetization_mode_) {
case H264PacketizationMode::SingleNalUnit:
if (!PacketizeSingleNalu(i))
return false;
++i;
break;
case H264PacketizationMode::NonInterleaved:
size_t fragment_len = input_fragments_[i].length;
if (i + 1 == input_fragments_.size()) {
// Pretend that last fragment is larger instead of making last packet
// smaller.
fragment_len += last_packet_reduction_len_;
}
if (fragment_len > max_payload_len_) {
PacketizeFuA(i);
++i;
} else {
i = PacketizeStapA(i);
}
break;
}
}
return true;
}
void RtpPacketizerH264::PacketizeFuA(size_t fragment_index) {
// Fragment payload into packets (FU-A).
// Strip out the original header and leave room for the FU-A header.
const Fragment& fragment = input_fragments_[fragment_index];
bool is_last_fragment = fragment_index + 1 == input_fragments_.size();
size_t payload_left = fragment.length - kNalHeaderSize;
size_t offset = kNalHeaderSize;
size_t per_packet_capacity = max_payload_len_ - kFuAHeaderSize;
// Instead of making the last packet smaller we pretend that all packets are
// of the same size but we write additional virtual payload to the last
// packet.
size_t extra_len = is_last_fragment ? last_packet_reduction_len_ : 0;
// Integer divisions with rounding up. Minimal number of packets to fit all
// payload and virtual payload.
size_t num_packets = (payload_left + extra_len + (per_packet_capacity - 1)) /
per_packet_capacity;
// Bytes per packet. Average rounded down.
size_t payload_per_packet = (payload_left + extra_len) / num_packets;
// We make several first packets to be 1 bytes smaller than the rest.
// i.e 14 bytes splitted in 4 packets would be 3+3+4+4.
size_t num_larger_packets = (payload_left + extra_len) % num_packets;
num_packets_left_ += num_packets;
while (payload_left > 0) {
// Increase payload per packet at the right time.
if (num_packets == num_larger_packets)
++payload_per_packet;
size_t packet_length = payload_per_packet;
if (payload_left <= packet_length) { // Last portion of the payload
packet_length = payload_left;
// One additional packet may be used for extensions in the last packet.
// Together with last payload packet there may be at most 2 of them.
RTC_DCHECK_LE(num_packets, 2);
if (num_packets == 2) {
// Whole payload fits in the first num_packets-1 packets but extra
// packet is used for virtual payload. Leave at least one byte of data
// for the last packet.
--packet_length;
}
}
RTC_CHECK_GT(packet_length, 0);
packets_.push(PacketUnit(Fragment(fragment.buffer + offset, packet_length),
offset - kNalHeaderSize == 0,
payload_left == packet_length, false,
fragment.buffer[0]));
offset += packet_length;
payload_left -= packet_length;
--num_packets;
}
RTC_CHECK_EQ(0, payload_left);
}
size_t RtpPacketizerH264::PacketizeStapA(size_t fragment_index) {
// Aggregate fragments into one packet (STAP-A).
size_t payload_size_left = max_payload_len_;
int aggregated_fragments = 0;
size_t fragment_headers_length = 0;
const Fragment* fragment = &input_fragments_[fragment_index];
RTC_CHECK_GE(payload_size_left, fragment->length);
++num_packets_left_;
while (payload_size_left >= fragment->length + fragment_headers_length &&
(fragment_index + 1 < input_fragments_.size() ||
payload_size_left >= fragment->length + fragment_headers_length +
last_packet_reduction_len_)) {
RTC_CHECK_GT(fragment->length, 0);
packets_.push(PacketUnit(*fragment, aggregated_fragments == 0, false, true,
fragment->buffer[0]));
payload_size_left -= fragment->length;
payload_size_left -= fragment_headers_length;
fragment_headers_length = kLengthFieldSize;
// If we are going to try to aggregate more fragments into this packet
// we need to add the STAP-A NALU header and a length field for the first
// NALU of this packet.
if (aggregated_fragments == 0)
fragment_headers_length += kNalHeaderSize + kLengthFieldSize;
++aggregated_fragments;
// Next fragment.
++fragment_index;
if (fragment_index == input_fragments_.size())
break;
fragment = &input_fragments_[fragment_index];
}
RTC_CHECK_GT(aggregated_fragments, 0);
packets_.back().last_fragment = true;
return fragment_index;
}
bool RtpPacketizerH264::PacketizeSingleNalu(size_t fragment_index) {
// Add a single NALU to the queue, no aggregation.
size_t payload_size_left = max_payload_len_;
if (fragment_index + 1 == input_fragments_.size())
payload_size_left -= last_packet_reduction_len_;
const Fragment* fragment = &input_fragments_[fragment_index];
if (payload_size_left < fragment->length) {
RTC_LOG(LS_ERROR) << "Failed to fit a fragment to packet in SingleNalu "
"packetization mode. Payload size left "
<< payload_size_left << ", fragment length "
<< fragment->length << ", packet capacity "
<< max_payload_len_;
return false;
}
RTC_CHECK_GT(fragment->length, 0u);
packets_.push(PacketUnit(*fragment, true /* first */, true /* last */,
false /* aggregated */, fragment->buffer[0]));
++num_packets_left_;
return true;
}
bool RtpPacketizerH264::NextPacket(RtpPacketToSend* rtp_packet) {
RTC_DCHECK(rtp_packet);
if (packets_.empty()) {
return false;
}
PacketUnit packet = packets_.front();
if (packet.first_fragment && packet.last_fragment) {
// Single NAL unit packet.
size_t bytes_to_send = packet.source_fragment.length;
uint8_t* buffer = rtp_packet->AllocatePayload(bytes_to_send);
memcpy(buffer, packet.source_fragment.buffer, bytes_to_send);
packets_.pop();
input_fragments_.pop_front();
} else if (packet.aggregated) {
RTC_CHECK(H264PacketizationMode::NonInterleaved == packetization_mode_);
bool is_last_packet = num_packets_left_ == 1;
NextAggregatePacket(rtp_packet, is_last_packet);
} else {
RTC_CHECK(H264PacketizationMode::NonInterleaved == packetization_mode_);
NextFragmentPacket(rtp_packet);
}
RTC_DCHECK_LE(rtp_packet->payload_size(), max_payload_len_);
if (packets_.empty()) {
RTC_DCHECK_LE(rtp_packet->payload_size(),
max_payload_len_ - last_packet_reduction_len_);
}
rtp_packet->SetMarker(packets_.empty());
--num_packets_left_;
return true;
}
void RtpPacketizerH264::NextAggregatePacket(RtpPacketToSend* rtp_packet,
bool last) {
uint8_t* buffer = rtp_packet->AllocatePayload(
last ? max_payload_len_ - last_packet_reduction_len_ : max_payload_len_);
RTC_DCHECK(buffer);
PacketUnit* packet = &packets_.front();
RTC_CHECK(packet->first_fragment);
// STAP-A NALU header.
buffer[0] = (packet->header & (kFBit | kNriMask)) | H264::NaluType::kStapA;
size_t index = kNalHeaderSize;
bool is_last_fragment = packet->last_fragment;
while (packet->aggregated) {
const Fragment& fragment = packet->source_fragment;
// Add NAL unit length field.
ByteWriter<uint16_t>::WriteBigEndian(&buffer[index], fragment.length);
index += kLengthFieldSize;
// Add NAL unit.
memcpy(&buffer[index], fragment.buffer, fragment.length);
index += fragment.length;
packets_.pop();
input_fragments_.pop_front();
if (is_last_fragment)
break;
packet = &packets_.front();
is_last_fragment = packet->last_fragment;
}
RTC_CHECK(is_last_fragment);
rtp_packet->SetPayloadSize(index);
}
void RtpPacketizerH264::NextFragmentPacket(RtpPacketToSend* rtp_packet) {
PacketUnit* packet = &packets_.front();
// NAL unit fragmented over multiple packets (FU-A).
// We do not send original NALU header, so it will be replaced by the
// FU indicator header of the first packet.
uint8_t fu_indicator =
(packet->header & (kFBit | kNriMask)) | H264::NaluType::kFuA;
uint8_t fu_header = 0;
// S | E | R | 5 bit type.
fu_header |= (packet->first_fragment ? kSBit : 0);
fu_header |= (packet->last_fragment ? kEBit : 0);
uint8_t type = packet->header & kTypeMask;
fu_header |= type;
const Fragment& fragment = packet->source_fragment;
uint8_t* buffer =
rtp_packet->AllocatePayload(kFuAHeaderSize + fragment.length);
buffer[0] = fu_indicator;
buffer[1] = fu_header;
memcpy(buffer + kFuAHeaderSize, fragment.buffer, fragment.length);
if (packet->last_fragment)
input_fragments_.pop_front();
packets_.pop();
}
std::string RtpPacketizerH264::ToString() {
return "RtpPacketizerH264";
}
RtpDepacketizerH264::RtpDepacketizerH264() : offset_(0), length_(0) {}
RtpDepacketizerH264::~RtpDepacketizerH264() {}
bool RtpDepacketizerH264::Parse(ParsedPayload* parsed_payload,
const uint8_t* payload_data,
size_t payload_data_length) {
RTC_CHECK(parsed_payload != nullptr);
if (payload_data_length == 0) {
RTC_LOG(LS_ERROR) << "Empty payload.";
return false;
}
offset_ = 0;
length_ = payload_data_length;
modified_buffer_.reset();
uint8_t nal_type = payload_data[0] & kTypeMask;
parsed_payload->type.Video.codecHeader.H264.nalus_length = 0;
if (nal_type == H264::NaluType::kFuA) {
// Fragmented NAL units (FU-A).
if (!ParseFuaNalu(parsed_payload, payload_data))
return false;
} else {
// We handle STAP-A and single NALU's the same way here. The jitter buffer
// will depacketize the STAP-A into NAL units later.
// TODO(sprang): Parse STAP-A offsets here and store in fragmentation vec.
if (!ProcessStapAOrSingleNalu(parsed_payload, payload_data))
return false;
}
const uint8_t* payload =
modified_buffer_ ? modified_buffer_->data() : payload_data;
parsed_payload->payload = payload + offset_;
parsed_payload->payload_length = length_;
return true;
}
bool RtpDepacketizerH264::ProcessStapAOrSingleNalu(
ParsedPayload* parsed_payload,
const uint8_t* payload_data) {
parsed_payload->type.Video.width = 0;
parsed_payload->type.Video.height = 0;
parsed_payload->type.Video.codec = kVideoCodecH264;
parsed_payload->type.Video.is_first_packet_in_frame = true;
RTPVideoHeaderH264* h264_header =
&parsed_payload->type.Video.codecHeader.H264;
const uint8_t* nalu_start = payload_data + kNalHeaderSize;
const size_t nalu_length = length_ - kNalHeaderSize;
uint8_t nal_type = payload_data[0] & kTypeMask;
std::vector<size_t> nalu_start_offsets;
if (nal_type == H264::NaluType::kStapA) {
// Skip the StapA header (StapA NAL type + length).
if (length_ <= kStapAHeaderSize) {
RTC_LOG(LS_ERROR) << "StapA header truncated.";
return false;
}
if (!ParseStapAStartOffsets(nalu_start, nalu_length, &nalu_start_offsets)) {
RTC_LOG(LS_ERROR) << "StapA packet with incorrect NALU packet lengths.";
return false;
}
h264_header->packetization_type = kH264StapA;
nal_type = payload_data[kStapAHeaderSize] & kTypeMask;
} else {
h264_header->packetization_type = kH264SingleNalu;
nalu_start_offsets.push_back(0);
}
h264_header->nalu_type = nal_type;
parsed_payload->frame_type = kVideoFrameDelta;
nalu_start_offsets.push_back(length_ + kLengthFieldSize); // End offset.
for (size_t i = 0; i < nalu_start_offsets.size() - 1; ++i) {
size_t start_offset = nalu_start_offsets[i];
// End offset is actually start offset for next unit, excluding length field
// so remove that from this units length.
size_t end_offset = nalu_start_offsets[i + 1] - kLengthFieldSize;
if (end_offset - start_offset < H264::kNaluTypeSize) {
RTC_LOG(LS_ERROR) << "STAP-A packet too short";
return false;
}
NaluInfo nalu;
nalu.type = payload_data[start_offset] & kTypeMask;
nalu.sps_id = -1;
nalu.pps_id = -1;
start_offset += H264::kNaluTypeSize;
switch (nalu.type) {
case H264::NaluType::kSps: {
// Check if VUI is present in SPS and if it needs to be modified to
// avoid
// excessive decoder latency.
// Copy any previous data first (likely just the first header).
std::unique_ptr<rtc::Buffer> output_buffer(new rtc::Buffer());
if (start_offset)
output_buffer->AppendData(payload_data, start_offset);
absl::optional<SpsParser::SpsState> sps;
SpsVuiRewriter::ParseResult result = SpsVuiRewriter::ParseAndRewriteSps(
&payload_data[start_offset], end_offset - start_offset, &sps,
output_buffer.get());
switch (result) {
case SpsVuiRewriter::ParseResult::kVuiRewritten:
if (modified_buffer_) {
RTC_LOG(LS_WARNING)
<< "More than one H264 SPS NAL units needing "
"rewriting found within a single STAP-A packet. "
"Keeping the first and rewriting the last.";
}
// Rewrite length field to new SPS size.
if (h264_header->packetization_type == kH264StapA) {
size_t length_field_offset =
start_offset - (H264::kNaluTypeSize + kLengthFieldSize);
// Stap-A Length includes payload data and type header.
size_t rewritten_size =
output_buffer->size() - start_offset + H264::kNaluTypeSize;
ByteWriter<uint16_t>::WriteBigEndian(
&(*output_buffer)[length_field_offset], rewritten_size);
}
// Append rest of packet.
output_buffer->AppendData(
&payload_data[end_offset],
nalu_length + kNalHeaderSize - end_offset);
modified_buffer_ = std::move(output_buffer);
length_ = modified_buffer_->size();
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kReceivedSpsRewritten,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kPocOk:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kReceivedSpsPocOk,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kVuiOk:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kReceivedSpsVuiOk,
SpsValidEvent::kSpsRewrittenMax);
break;
case SpsVuiRewriter::ParseResult::kFailure:
RTC_HISTOGRAM_ENUMERATION(kSpsValidHistogramName,
SpsValidEvent::kReceivedSpsParseFailure,
SpsValidEvent::kSpsRewrittenMax);
break;
}
if (sps) {
parsed_payload->type.Video.width = sps->width;
parsed_payload->type.Video.height = sps->height;
nalu.sps_id = sps->id;
} else {
RTC_LOG(LS_WARNING) << "Failed to parse SPS id from SPS slice.";
}
parsed_payload->frame_type = kVideoFrameKey;
break;
}
case H264::NaluType::kPps: {
uint32_t pps_id;
uint32_t sps_id;
if (PpsParser::ParsePpsIds(&payload_data[start_offset],
end_offset - start_offset, &pps_id,
&sps_id)) {
nalu.pps_id = pps_id;
nalu.sps_id = sps_id;
} else {
RTC_LOG(LS_WARNING)
<< "Failed to parse PPS id and SPS id from PPS slice.";
}
break;
}
case H264::NaluType::kIdr:
parsed_payload->frame_type = kVideoFrameKey;
RTC_FALLTHROUGH();
case H264::NaluType::kSlice: {
absl::optional<uint32_t> pps_id = PpsParser::ParsePpsIdFromSlice(
&payload_data[start_offset], end_offset - start_offset);
if (pps_id) {
nalu.pps_id = *pps_id;
} else {
RTC_LOG(LS_WARNING) << "Failed to parse PPS id from slice of type: "
<< static_cast<int>(nalu.type);
}
break;
}
// Slices below don't contain SPS or PPS ids.
case H264::NaluType::kAud:
case H264::NaluType::kEndOfSequence:
case H264::NaluType::kEndOfStream:
case H264::NaluType::kFiller:
case H264::NaluType::kSei:
break;
case H264::NaluType::kStapA:
case H264::NaluType::kFuA:
RTC_LOG(LS_WARNING) << "Unexpected STAP-A or FU-A received.";
return false;
}
RTPVideoHeaderH264* h264 = &parsed_payload->type.Video.codecHeader.H264;
if (h264->nalus_length == kMaxNalusPerPacket) {
RTC_LOG(LS_WARNING)
<< "Received packet containing more than " << kMaxNalusPerPacket
<< " NAL units. Will not keep track sps and pps ids for all of them.";
} else {
h264->nalus[h264->nalus_length++] = nalu;
}
}
return true;
}
bool RtpDepacketizerH264::ParseFuaNalu(
RtpDepacketizer::ParsedPayload* parsed_payload,
const uint8_t* payload_data) {
if (length_ < kFuAHeaderSize) {
RTC_LOG(LS_ERROR) << "FU-A NAL units truncated.";
return false;
}
uint8_t fnri = payload_data[0] & (kFBit | kNriMask);
uint8_t original_nal_type = payload_data[1] & kTypeMask;
bool first_fragment = (payload_data[1] & kSBit) > 0;
NaluInfo nalu;
nalu.type = original_nal_type;
nalu.sps_id = -1;
nalu.pps_id = -1;
if (first_fragment) {
offset_ = 0;
length_ -= kNalHeaderSize;
absl::optional<uint32_t> pps_id = PpsParser::ParsePpsIdFromSlice(
payload_data + 2 * kNalHeaderSize, length_ - kNalHeaderSize);
if (pps_id) {
nalu.pps_id = *pps_id;
} else {
RTC_LOG(LS_WARNING)
<< "Failed to parse PPS from first fragment of FU-A NAL "
"unit with original type: "
<< static_cast<int>(nalu.type);
}
uint8_t original_nal_header = fnri | original_nal_type;
modified_buffer_.reset(new rtc::Buffer());
modified_buffer_->AppendData(payload_data + kNalHeaderSize, length_);
(*modified_buffer_)[0] = original_nal_header;
} else {
offset_ = kFuAHeaderSize;
length_ -= kFuAHeaderSize;
}
if (original_nal_type == H264::NaluType::kIdr) {
parsed_payload->frame_type = kVideoFrameKey;
} else {
parsed_payload->frame_type = kVideoFrameDelta;
}
parsed_payload->type.Video.width = 0;
parsed_payload->type.Video.height = 0;
parsed_payload->type.Video.codec = kVideoCodecH264;
parsed_payload->type.Video.is_first_packet_in_frame = first_fragment;
RTPVideoHeaderH264* h264 = &parsed_payload->type.Video.codecHeader.H264;
h264->packetization_type = kH264FuA;
h264->nalu_type = original_nal_type;
if (first_fragment) {
h264->nalus[h264->nalus_length] = nalu;
h264->nalus_length = 1;
}
return true;
}
} // namespace webrtc