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In RtpDepacketizerAV1 use aggregation header to detect key frames

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instead of guessing based on presence of the sequence header OBU.

Bug: webrtc:11042
Change-Id: I9a0674249feceebb07299ea965c62e87499f6baf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/161013
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29958}
This commit is contained in:
Danil Chapovalov
2019-11-28 17:38:35 +01:00
committed by Commit Bot
parent c7a3b08f07
commit 499b3b6c7e
2 changed files with 32 additions and 175 deletions
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76
modules/rtp_rtcp/source/rtp_depacketizer_av1.cc
View File

@ -26,7 +26,7 @@ namespace {
// RTP payload syntax:
// 0 1 2 3 4 5 6 7
// +-+-+-+-+-+-+-+-+
// |Z|Y| W |-|-|-|-| (REQUIRED)
// |Z|Y| W |N|-|-|-| (REQUIRED)
// +=+=+=+=+=+=+=+=+ (REPEATED W-1 times, or any times if W = 0)
// |1| |
// +-+ OBU fragment|
@ -154,7 +154,6 @@ struct ObuInfo {
// also has Sequence Header OBU.
using VectorObuInfo = absl::InlinedVector<ObuInfo, 4>;
constexpr int kObuTypeSequenceHeader = 1;
constexpr uint8_t kObuSizePresentBit = 0b0'0000'010;
bool ObuHasExtension(uint8_t obu_header) {
@ -165,10 +164,6 @@ bool ObuHasSize(uint8_t obu_header) {
return obu_header & kObuSizePresentBit;
}
int ObuType(uint8_t obu_header) {
return (obu_header & 0b0'1111'000u) >> 3;
}
bool RtpStartsWithFragment(uint8_t aggregation_header) {
return aggregation_header & 0b1000'0000u;
}
@ -178,6 +173,9 @@ bool RtpEndsWithFragment(uint8_t aggregation_header) {
int RtpNumObus(uint8_t aggregation_header) { // 0 for any number of obus.
return (aggregation_header & 0b0011'0000u) >> 4;
}
int RtpStartsNewCodedVideoSequence(uint8_t aggregation_header) {
return aggregation_header & 0b0000'1000u;
}
// Reorgonizes array of rtp payloads into array of obus:
// fills ObuInfo::data field.
@ -373,16 +371,18 @@ bool RtpDepacketizerAv1::Parse(ParsedPayload* parsed_payload,
RTC_DLOG(LS_ERROR) << "Empty rtp payload.";
return false;
}
uint8_t aggregation_header = payload_data[0];
if (RtpStartsNewCodedVideoSequence(aggregation_header) &&
RtpStartsWithFragment(aggregation_header)) {
// new coded video sequence can't start from an OBU fragment.
return false;
}
// To assemble frame, all of the rtp payload is required, including
// aggregation header.
parsed_payload->payload = payload_data;
parsed_payload->payload_length = payload_data_length;
rtc::ByteBufferReader payload(reinterpret_cast<const char*>(payload_data),
payload_data_length);
uint8_t aggregation_header;
RTC_CHECK(payload.ReadUInt8(&aggregation_header));
parsed_payload->video.codec = VideoCodecType::kVideoCodecAV1;
// These are not accurate since frame may consist of several packet aligned
// chunks of obus, but should be good enough for most cases. It might produce
@ -393,57 +393,11 @@ bool RtpDepacketizerAv1::Parse(ParsedPayload* parsed_payload,
!RtpStartsWithFragment(aggregation_header);
parsed_payload->video.is_last_packet_in_frame =
!RtpEndsWithFragment(aggregation_header);
parsed_payload->video.frame_type = VideoFrameType::kVideoFrameDelta;
// If packet starts a frame, check if it contains Sequence Header OBU.
// In that case treat it as key frame packet.
if (parsed_payload->video.is_first_packet_in_frame) {
int num_expected_obus = RtpNumObus(aggregation_header);
// The only OBU that can preceed SequenceHeader is a TemporalDelimiter OBU,
// so check no more than two OBUs while searching for SH.
for (int obu_index = 1; payload.Length() > 0 && obu_index <= 2;
++obu_index) {
uint64_t fragment_size;
// When num_expected_obus > 0, last OBU (fragment) is not preceeded by
// the size field. See W field in
// https://aomediacodec.github.io/av1-rtp-spec/#43-av1-aggregation-header
bool has_fragment_size = (obu_index != num_expected_obus);
if (has_fragment_size) {
if (!payload.ReadUVarint(&fragment_size)) {
RTC_DLOG(LS_WARNING)
<< "Failed to read OBU fragment size for OBU#" << obu_index;
return false;
}
if (fragment_size > payload.Length()) {
RTC_DLOG(LS_WARNING) << "OBU fragment size " << fragment_size
<< " exceeds remaining payload size "
<< payload.Length() << " for OBU#" << obu_index;
// Malformed input: written size is larger than remaining buffer.
return false;
}
} else {
fragment_size = payload.Length();
}
// Though it is inpractical to pass empty fragments, it is allowed.
if (fragment_size == 0) {
RTC_LOG(LS_WARNING)
<< "Weird obu of size 0 at offset "
<< (payload_data_length - payload.Length()) << ", skipping.";
continue;
}
uint8_t obu_header = *reinterpret_cast<const uint8_t*>(payload.Data());
if (ObuType(obu_header) == kObuTypeSequenceHeader) {
// TODO(bugs.webrtc.org/11042): Check frame_header OBU and/or frame OBU
// too for other conditions of the start of a new coded video sequence.
// For proper checks checking single packet might not be enough. See
// https://aomediacodec.github.io/av1-spec/av1-spec.pdf section 7.5
parsed_payload->video.frame_type = VideoFrameType::kVideoFrameKey;
break;
}
payload.Consume(fragment_size);
}
}
parsed_payload->video.frame_type =
RtpStartsNewCodedVideoSequence(aggregation_header)
? VideoFrameType::kVideoFrameKey
: VideoFrameType::kVideoFrameDelta;
return true;
}

131
modules/rtp_rtcp/source/rtp_depacketizer_av1_unittest.cc
View File

@ -19,12 +19,9 @@ namespace {
using ::testing::ElementsAre;
// Signals number of the OBU (fragments) in the packet.
constexpr uint8_t kObuCountAny = 0b0000'0000;
constexpr uint8_t kObuCountOne = 0b0001'0000;
constexpr uint8_t kObuCountTwo = 0b0010'0000;
constexpr uint8_t kObuCountOne = 0b00'01'0000;
constexpr uint8_t kObuHeaderSequenceHeader = 0b0'0001'000;
constexpr uint8_t kObuHeaderTemporalDelimiter = 0b0'0010'000;
constexpr uint8_t kObuHeaderFrame = 0b0'0110'000;
constexpr uint8_t kObuHeaderHasSize = 0b0'0000'010;
@ -73,131 +70,37 @@ TEST(RtpDepacketizerAv1Test, ParseTreatsNoWillContinueFlagAsEndOfFrame) {
EXPECT_TRUE(parsed.video.is_last_packet_in_frame);
}
TEST(RtpDepacketizerAv1Test, ParseTreatsStartOfSequenceHeaderAsKeyFrame) {
const uint8_t packet[] = {kObuCountOne, kObuHeaderSequenceHeader};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.is_first_packet_in_frame);
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test, ParseTreatsNotStartOfFrameAsDeltaFrame) {
const uint8_t packet[] = {
(uint8_t{1} << 7) | kObuCountOne,
// Byte that look like start of sequence header, but since it is not start
// of an OBU, it is actually not a start of sequence header.
kObuHeaderSequenceHeader};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_FALSE(parsed.video.is_first_packet_in_frame);
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameDelta);
}
TEST(RtpDepacketizerAv1Test,
ParseTreatsStartOfFrameWithoutSequenceHeaderAsDeltaFrame) {
const uint8_t packet[] = {kObuCountOne, kObuHeaderFrame};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.is_first_packet_in_frame);
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameDelta);
}
TEST(RtpDepacketizerAv1Test, ParseFindsSequenceHeaderBehindFragmentSize1) {
const uint8_t packet[] = {kObuCountAny,
1, // size of the next fragment
ParseUsesNewCodedVideoSequenceBitAsKeyFrameIndidcator) {
const uint8_t packet[] = {(uint8_t{1} << 3) | kObuCountOne,
kObuHeaderSequenceHeader};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test, ParseFindsSequenceHeaderBehindFragmentSize2) {
const uint8_t packet[] = {kObuCountTwo,
2, // size of the next fragment
kObuHeaderSequenceHeader,
42, // SH payload.
kObuHeaderFrame};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.is_first_packet_in_frame);
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test,
ParseFindsSequenceHeaderBehindMultiByteFragmentSize) {
const uint8_t packet[] = {kObuCountTwo,
0b1000'0101, // leb128 encoded value of 5
0b1000'0000, // using 3 bytes
0b0000'0000, // to encode the value.
kObuHeaderSequenceHeader,
8, // 4 bytes of SH payload.
0,
0,
0,
kObuHeaderFrame};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test, ParseFindsSequenceHeaderBehindTemporalDelimiter) {
const uint8_t packet[] = {kObuCountTwo,
1, // size of the next fragment
kObuHeaderTemporalDelimiter,
kObuHeaderSequenceHeader,
8, // 4 bytes of SH payload.
0,
0,
0};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test,
ParseFindsSequenceHeaderBehindTemporalDelimiterAndSize) {
const uint8_t packet[] = {kObuCountAny,
1, // size of the next fragment
kObuHeaderTemporalDelimiter,
5, // size of the next fragment
kObuHeaderSequenceHeader,
8, // 4 bytes of SH payload.
0,
0,
0,
1, // size of the next fragment
kObuHeaderFrame};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameKey);
}
TEST(RtpDepacketizerAv1Test, ParseSkipsEmptyFragments) {
static_assert(kObuHeaderSequenceHeader == 8, "");
const uint8_t packet[] = {kObuCountAny,
0, // size of the next fragment
8, // size of the next fragment that look like SH
kObuHeaderFrame,
1,
2,
3,
4,
5,
6,
7};
ParseUsesUnsetNewCodedVideoSequenceBitAsDeltaFrameIndidcator) {
const uint8_t packet[] = {(uint8_t{0} << 3) | kObuCountOne,
kObuHeaderSequenceHeader};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
ASSERT_TRUE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
EXPECT_TRUE(parsed.video.is_first_packet_in_frame);
EXPECT_TRUE(parsed.video.frame_type == VideoFrameType::kVideoFrameDelta);
}
TEST(RtpDepacketizerAv1Test,
ParseRejectsPacketWithNewCVSAndContinuationFlagsBothSet) {
const uint8_t packet[] = {0b10'00'1000 | kObuCountOne,
kObuHeaderSequenceHeader};
RtpDepacketizerAv1 depacketizer;
RtpDepacketizer::ParsedPayload parsed;
EXPECT_FALSE(depacketizer.Parse(&parsed, packet, sizeof(packet)));
}
TEST(RtpDepacketizerAv1Test, AssembleFrameSetsOBUPayloadSizeWhenAbsent) {
const uint8_t payload1[] = {0b00'01'0000, // aggregation header
0b0'0110'000, // / Frame