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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 "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "modules/video_coding/codecs/interface/common_constants.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.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;
int ParseVP8PictureID(RTPVideoHeaderVP8* vp8,
const uint8_t** data,
size_t* data_length,
size_t* parsed_bytes) {
if (*data_length == 0)
return -1;
vp8->pictureId = (**data & 0x7F);
if (**data & 0x80) {
(*data)++;
(*parsed_bytes)++;
if (--(*data_length) == 0)
return -1;
// PictureId is 15 bits
vp8->pictureId = (vp8->pictureId << 8) + **data;
}
(*data)++;
(*parsed_bytes)++;
(*data_length)--;
return 0;
}
int ParseVP8Tl0PicIdx(RTPVideoHeaderVP8* vp8,
const uint8_t** data,
size_t* data_length,
size_t* parsed_bytes) {
if (*data_length == 0)
return -1;
vp8->tl0PicIdx = **data;
(*data)++;
(*parsed_bytes)++;
(*data_length)--;
return 0;
}
int ParseVP8TIDAndKeyIdx(RTPVideoHeaderVP8* vp8,
const uint8_t** data,
size_t* data_length,
size_t* parsed_bytes,
bool has_tid,
bool has_key_idx) {
if (*data_length == 0)
return -1;
if (has_tid) {
vp8->temporalIdx = ((**data >> 6) & 0x03);
vp8->layerSync = (**data & 0x20) ? true : false; // Y bit
}
if (has_key_idx) {
vp8->keyIdx = (**data & 0x1F);
}
(*data)++;
(*parsed_bytes)++;
(*data_length)--;
return 0;
}
int ParseVP8Extension(RTPVideoHeaderVP8* vp8,
const uint8_t* data,
size_t data_length) {
RTC_DCHECK_GT(data_length, 0);
size_t parsed_bytes = 0;
// Optional X field is present.
bool has_picture_id = (*data & 0x80) ? true : false; // I bit
bool has_tl0_pic_idx = (*data & 0x40) ? true : false; // L bit
bool has_tid = (*data & 0x20) ? true : false; // T bit
bool has_key_idx = (*data & 0x10) ? true : false; // K bit
// Advance data and decrease remaining payload size.
data++;
parsed_bytes++;
data_length--;
if (has_picture_id) {
if (ParseVP8PictureID(vp8, &data, &data_length, &parsed_bytes) != 0) {
return -1;
}
}
if (has_tl0_pic_idx) {
if (ParseVP8Tl0PicIdx(vp8, &data, &data_length, &parsed_bytes) != 0) {
return -1;
}
}
if (has_tid || has_key_idx) {
if (ParseVP8TIDAndKeyIdx(vp8, &data, &data_length, &parsed_bytes, has_tid,
has_key_idx) != 0) {
return -1;
}
}
return static_cast<int>(parsed_bytes);
}
int ParseVP8FrameSize(RtpDepacketizer::ParsedPayload* parsed_payload,
const uint8_t* data,
size_t data_length) {
if (parsed_payload->frame_type != VideoFrameType::kVideoFrameKey) {
// Included in payload header for I-frames.
return 0;
}
if (data_length < 10) {
// For an I-frame we should always have the uncompressed VP8 header
// in the beginning of the partition.
return -1;
}
parsed_payload->video_header().width = ((data[7] << 8) + data[6]) & 0x3FFF;
parsed_payload->video_header().height = ((data[9] << 8) + data[8]) & 0x3FFF;
return 0;
}
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(rtc::ArrayView<const uint8_t> payload,
PayloadSizeLimits limits,
const RTPVideoHeaderVP8& hdr_info)
: hdr_(BuildHeader(hdr_info)), remaining_payload_(payload) {
limits.max_payload_len -= hdr_.size();
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;
}
// Write the VP8 payload descriptor.
// 0
// 0 1 2 3 4 5 6 7 8
// +-+-+-+-+-+-+-+-+-+
// |X| |N|S| PART_ID |
// +-+-+-+-+-+-+-+-+-+
// X: |I|L|T|K| | (mandatory if any of the below are used)
// +-+-+-+-+-+-+-+-+-+
// I: |PictureID (16b)| (optional)
// +-+-+-+-+-+-+-+-+-+
// L: | TL0PIC_IDX | (optional)
// +-+-+-+-+-+-+-+-+-+
// T/K: |TID:Y| KEYIDX | (optional)
// +-+-+-+-+-+-+-+-+-+
RtpPacketizerVp8::RawHeader RtpPacketizerVp8::BuildHeader(
const RTPVideoHeaderVP8& header) {
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;
}
//
// VP8 format:
//
// Payload descriptor
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |X|R|N|S|PartID | (REQUIRED)
// +-+-+-+-+-+-+-+-+
// X: |I|L|T|K| RSV | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// I: | PictureID | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// L: | TL0PICIDX | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
// T/K: |TID:Y| KEYIDX | (OPTIONAL)
// +-+-+-+-+-+-+-+-+
//
// Payload header (considered part of the actual payload, sent to decoder)
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |Size0|H| VER |P|
// +-+-+-+-+-+-+-+-+
// | ... |
// + +
bool RtpDepacketizerVp8::Parse(ParsedPayload* parsed_payload,
const uint8_t* payload_data,
size_t payload_data_length) {
RTC_DCHECK(parsed_payload);
if (payload_data_length == 0) {
RTC_LOG(LS_ERROR) << "Empty payload.";
return false;
}
// Parse mandatory first byte of payload descriptor.
bool extension = (*payload_data & 0x80) ? true : false; // X bit
bool beginning_of_partition = (*payload_data & 0x10) ? true : false; // S bit
int partition_id = (*payload_data & 0x0F); // PartID field
parsed_payload->video_header().width = 0;
parsed_payload->video_header().height = 0;
parsed_payload->video_header().is_first_packet_in_frame =
beginning_of_partition && (partition_id == 0);
parsed_payload->video_header().simulcastIdx = 0;
parsed_payload->video_header().codec = kVideoCodecVP8;
auto& vp8_header = parsed_payload->video_header()
.video_type_header.emplace<RTPVideoHeaderVP8>();
vp8_header.nonReference = (*payload_data & 0x20) ? true : false; // N bit
vp8_header.partitionId = partition_id;
vp8_header.beginningOfPartition = beginning_of_partition;
vp8_header.pictureId = kNoPictureId;
vp8_header.tl0PicIdx = kNoTl0PicIdx;
vp8_header.temporalIdx = kNoTemporalIdx;
vp8_header.layerSync = false;
vp8_header.keyIdx = kNoKeyIdx;
if (partition_id > 8) {
// Weak check for corrupt payload_data: PartID MUST NOT be larger than 8.
return false;
}
// Advance payload_data and decrease remaining payload size.
payload_data++;
if (payload_data_length <= 1) {
RTC_LOG(LS_ERROR) << "Error parsing VP8 payload descriptor!";
return false;
}
payload_data_length--;
if (extension) {
const int parsed_bytes =
ParseVP8Extension(&vp8_header, payload_data, payload_data_length);
if (parsed_bytes < 0)
return false;
payload_data += parsed_bytes;
payload_data_length -= parsed_bytes;
if (payload_data_length == 0) {
RTC_LOG(LS_ERROR) << "Error parsing VP8 payload descriptor!";
return false;
}
}
// Read P bit from payload header (only at beginning of first partition).
if (beginning_of_partition && partition_id == 0) {
parsed_payload->frame_type = (*payload_data & 0x01)
? VideoFrameType::kVideoFrameDelta
: VideoFrameType::kVideoFrameKey;
} else {
parsed_payload->frame_type = VideoFrameType::kVideoFrameDelta;
}
if (ParseVP8FrameSize(parsed_payload, payload_data, payload_data_length) !=
0) {
return false;
}
parsed_payload->payload = payload_data;
parsed_payload->payload_length = payload_data_length;
return true;
}
} // namespace webrtc