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/*
* Copyright (c) 2011 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_vp8.h"
#include <stdint.h>
#include <string.h> // memcpy
#include <vector>
#include "api/array_view.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "modules/video_coding/codecs/interface/common_constants.h"
#include "modules/video_coding/codecs/vp8/include/vp8_globals.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
constexpr int kXBit = 0x80;
constexpr int kNBit = 0x20;
constexpr int kSBit = 0x10;
constexpr int kKeyIdxField = 0x1F;
constexpr int kIBit = 0x80;
constexpr int kLBit = 0x40;
constexpr int kTBit = 0x20;
constexpr int kKBit = 0x10;
constexpr int kYBit = 0x20;
bool ValidateHeader(const RTPVideoHeaderVP8& hdr_info) {
if (hdr_info.pictureId != kNoPictureId) {
RTC_DCHECK_GE(hdr_info.pictureId, 0);
RTC_DCHECK_LE(hdr_info.pictureId, 0x7FFF);
}
if (hdr_info.tl0PicIdx != kNoTl0PicIdx) {
RTC_DCHECK_GE(hdr_info.tl0PicIdx, 0);
RTC_DCHECK_LE(hdr_info.tl0PicIdx, 0xFF);
}
if (hdr_info.temporalIdx != kNoTemporalIdx) {
RTC_DCHECK_GE(hdr_info.temporalIdx, 0);
RTC_DCHECK_LE(hdr_info.temporalIdx, 3);
} else {
RTC_DCHECK(!hdr_info.layerSync);
}
if (hdr_info.keyIdx != kNoKeyIdx) {
RTC_DCHECK_GE(hdr_info.keyIdx, 0);
RTC_DCHECK_LE(hdr_info.keyIdx, 0x1F);
}
return true;
}
} // namespace
RtpPacketizerVp8::RtpPacketizerVp8(ArrayView<const uint8_t> payload,
PayloadSizeLimits limits,
const RTPVideoHeaderVP8& hdr_info)
: hdr_(BuildHeader(hdr_info)), remaining_payload_(payload) {
limits.max_payload_len -= hdr_.size();
if (!payload.empty()) {
payload_sizes_ = SplitAboutEqually(payload.size(), limits);
}
current_packet_ = payload_sizes_.begin();
}
RtpPacketizerVp8::~RtpPacketizerVp8() = default;
size_t RtpPacketizerVp8::NumPackets() const {
return payload_sizes_.end() - current_packet_;
}
bool RtpPacketizerVp8::NextPacket(RtpPacketToSend* packet) {
RTC_DCHECK(packet);
if (current_packet_ == payload_sizes_.end()) {
return false;
}
size_t packet_payload_len = *current_packet_;
++current_packet_;
uint8_t* buffer = packet->AllocatePayload(hdr_.size() + packet_payload_len);
RTC_CHECK(buffer);
memcpy(buffer, hdr_.data(), hdr_.size());
memcpy(buffer + hdr_.size(), remaining_payload_.data(), packet_payload_len);
remaining_payload_ = remaining_payload_.subview(packet_payload_len);
hdr_[0] &= (~kSBit); // Clear 'Start of partition' bit.
packet->SetMarker(current_packet_ == payload_sizes_.end());
return true;
}
RtpPacketizerVp8::RawHeader RtpPacketizerVp8::BuildHeader(
const RTPVideoHeaderVP8& header) {
// VP8 payload descriptor
// https://datatracker.ietf.org/doc/html/rfc7741#section-4.2
//
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |X|R|N|S|R| PID | (REQUIRED)
// +-+-+-+-+-+-+-+-+
// X: |I|L|T|K| RSV | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// I: |M| PictureID | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// | PictureID |
// +-+-+-+-+-+-+-+-+
// L: | TL0PICIDX | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// T/K: |TID|Y| KEYIDX | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
RTC_DCHECK(ValidateHeader(header));
RawHeader result;
bool tid_present = header.temporalIdx != kNoTemporalIdx;
bool keyid_present = header.keyIdx != kNoKeyIdx;
bool tl0_pid_present = header.tl0PicIdx != kNoTl0PicIdx;
bool pid_present = header.pictureId != kNoPictureId;
uint8_t x_field = 0;
if (pid_present)
x_field |= kIBit;
if (tl0_pid_present)
x_field |= kLBit;
if (tid_present)
x_field |= kTBit;
if (keyid_present)
x_field |= kKBit;
uint8_t flags = 0;
if (x_field != 0)
flags |= kXBit;
if (header.nonReference)
flags |= kNBit;
// Create header as first packet in the frame. NextPacket() will clear it
// after first use.
flags |= kSBit;
result.push_back(flags);
if (x_field == 0) {
return result;
}
result.push_back(x_field);
if (pid_present) {
const uint16_t pic_id = static_cast<uint16_t>(header.pictureId);
result.push_back(0x80 | ((pic_id >> 8) & 0x7F));
result.push_back(pic_id & 0xFF);
}
if (tl0_pid_present) {
result.push_back(header.tl0PicIdx);
}
if (tid_present || keyid_present) {
uint8_t data_field = 0;
if (tid_present) {
data_field |= header.temporalIdx << 6;
if (header.layerSync)
data_field |= kYBit;
}
if (keyid_present) {
data_field |= (header.keyIdx & kKeyIdxField);
}
result.push_back(data_field);
}
return result;
}
} // namespace webrtc
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