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Update TransportSequenceNumberV2 extension to support fixed size

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The initial implementation forced the sender to use different sizes
of the RTP header extension depending on if a feedback request is
included or not. This can be a problem if the RTP header is pre-
allocated.
This CL changes this so that a static size of 4 bytes can be used
for the TransportSequenceNumberV2 RTP header extension. The change
in the protocol to get this to work is that
FeedbackRequest::sequence_count == 0 means that no feedback is
requested, and FeedbackRequest::sequence_count == 1 means that
feedback is requested for the current packet only.

Bug: webrtc:10262
Change-Id: Ia5134b3daf49f8a5b89f6c717894f6e055f39c8e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/125420
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26985}
This commit is contained in:
Johannes Kron
2019-03-06 09:34:13 +01:00
committed by Commit Bot
parent f441ea9429
commit 0da25a1c8e
6 changed files with 96 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
modules/rtp_rtcp/source/rtp_header_extensions.cc
View File

@ -166,10 +166,13 @@ bool TransportSequenceNumber::Write(rtc::ArrayView<uint8_t> data,
// +-+-+-+-+-+-+-+-+
//
// The bit |T| determines whether the feedback should include timing information
// or not and |seq_count| determines how many additional packets the feedback
// packet should cover.
// or not and |seq_count| determines how many packets the feedback packet should
// cover including the current packet. If |seq_count| is zero no feedback is
// requested.
constexpr RTPExtensionType TransportSequenceNumberV2::kId;
constexpr uint8_t TransportSequenceNumberV2::kValueSizeBytesWithFeedbackRequest;
constexpr uint8_t TransportSequenceNumberV2::kValueSizeBytes;
constexpr uint8_t
TransportSequenceNumberV2::kValueSizeBytesWithoutFeedbackRequest;
constexpr const char TransportSequenceNumberV2::kUri[];
constexpr uint16_t TransportSequenceNumberV2::kIncludeTimestampsBit;
@ -177,21 +180,24 @@ bool TransportSequenceNumberV2::Parse(
rtc::ArrayView<const uint8_t> data,
uint16_t* transport_sequence_number,
absl::optional<FeedbackRequest>* feedback_request) {
if (data.size() != TransportSequenceNumber::kValueSizeBytes &&
data.size() != kValueSizeBytesWithFeedbackRequest)
if (data.size() != kValueSizeBytes &&
data.size() != kValueSizeBytesWithoutFeedbackRequest)
return false;
*transport_sequence_number = ByteReader<uint16_t>::ReadBigEndian(data.data());
if (data.size() == kValueSizeBytesWithFeedbackRequest) {
*feedback_request = absl::nullopt;
if (data.size() == kValueSizeBytes) {
uint16_t feedback_request_raw =
ByteReader<uint16_t>::ReadBigEndian(data.data() + 2);
bool include_timestamps =
(feedback_request_raw & kIncludeTimestampsBit) != 0;
uint16_t sequence_count = feedback_request_raw & ~kIncludeTimestampsBit;
*feedback_request = {include_timestamps, sequence_count};
} else {
*feedback_request = absl::nullopt;
// If |sequence_count| is zero no feedback is requested.
if (sequence_count != 0) {
*feedback_request = {include_timestamps, sequence_count};
}
}
return true;
}