webrtc/modules/rtp_rtcp/source/rtp_format.h
Philipp Hancke acfd279a14 av1: make packetization generate more evenly sized packets
Implements a two-pass approach to packetization which creates
packets of an even size similar to RtpPacketizer::SplitAboutEqually.
This improves the bandwidth estimation.

The algorithm does a first pass with the existing packetizer, then
iterates through the resulting packet sizes and sums up the bytes left unused in each packet.
It then calculates a new maximum packet length as
  configured_max_packet_len - ((unused_bytes - packets + 1) / packets)
adjusts for the overhead and re-runs the packetization algorithm.

For example, a list of OBUs with sizes
  {1206, 1476, 1431}
currently gets packetized greedily as payload sizes
  {1200, 1200, 1200, 523}
With this change, it gets packetized as
  {1032, 1032, 1032, 1028}

This change is guarded by the field trial
  WebRTC-Video-AV1EvenPayloadSizes
which is acting as a rollout flag.

BUG=webrtc:15927

Co-authored-by: Shyam Sadhwani <shyamsadhwani@meta.com>
Change-Id: I4f0b3c27de6f06104908dd769c4dd1f34115712c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/348100
Commit-Queue: Philipp Hancke <phancke@meta.com>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42203}
2024-04-30 15:46:06 +00:00

63 lines
2 KiB
C++

/*
* 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.
*/
#ifndef MODULES_RTP_RTCP_SOURCE_RTP_FORMAT_H_
#define MODULES_RTP_RTCP_SOURCE_RTP_FORMAT_H_
#include <stdint.h>
#include <memory>
#include <vector>
#include "absl/types/optional.h"
#include "api/array_view.h"
#include "modules/rtp_rtcp/source/rtp_video_header.h"
namespace webrtc {
class RtpPacketToSend;
class RtpPacketizer {
public:
struct PayloadSizeLimits {
int max_payload_len = 1200;
int first_packet_reduction_len = 0;
int last_packet_reduction_len = 0;
// Reduction len for packet that is first & last at the same time.
int single_packet_reduction_len = 0;
};
// If type is not set, returns a raw packetizer.
static std::unique_ptr<RtpPacketizer> Create(
absl::optional<VideoCodecType> type,
rtc::ArrayView<const uint8_t> payload,
PayloadSizeLimits limits,
// Codec-specific details.
const RTPVideoHeader& rtp_video_header,
// TODO(bugs.webrtc.org/15927): remove after rollout.
bool enable_av1_even_split = false);
virtual ~RtpPacketizer() = default;
// Returns number of remaining packets to produce by the packetizer.
virtual size_t NumPackets() const = 0;
// Get the next payload with payload header.
// Write payload and set marker bit of the `packet`.
// Returns true on success, false otherwise.
virtual bool NextPacket(RtpPacketToSend* packet) = 0;
// Split payload_len into sum of integers with respect to `limits`.
// Returns empty vector on failure.
static std::vector<int> SplitAboutEqually(int payload_len,
const PayloadSizeLimits& limits);
};
} // namespace webrtc
#endif // MODULES_RTP_RTCP_SOURCE_RTP_FORMAT_H_