webrtc/media/base/sdp_video_format_utils.h
Philipp Hancke c14a2cb9cc Add nonstandard x-google-per-layer-pli fmtp for enabling per-layer keyFrames in response to PLIs
which needs to be added to the remote codecs a=fmtp:

This also forces SimulcastCastEncoderAdapter to avoid issues with codecs that have native simulcast capability but do require synchronized keyframes.

This parameter allows for large-scale experimentation and A/B testing
whether the new behavior has advantages. It is to be considered
transitional and may be removed again in the future.

BUG=webrtc:10107

Change-Id: I81f496c987b2fed7ff3089efb746e7e89e89c033
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/333560
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41805}
2024-05-03 10:59:22 -04:00

66 lines
3.2 KiB
C++

/*
* Copyright (c) 2019 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 MEDIA_BASE_SDP_VIDEO_FORMAT_UTILS_H_
#define MEDIA_BASE_SDP_VIDEO_FORMAT_UTILS_H_
#include "absl/types/optional.h"
#include "api/video_codecs/sdp_video_format.h"
namespace webrtc {
// Generate codec parameters that will be used as answer in an SDP negotiation
// based on local supported parameters and remote offered parameters. Both
// `local_supported_params`, `remote_offered_params`, and `answer_params`
// represent sendrecv media descriptions, i.e they are a mix of both encode and
// decode capabilities. In theory, when the profile in `local_supported_params`
// represent a strict superset of the profile in `remote_offered_params`, we
// could limit the profile in `answer_params` to the profile in
// `remote_offered_params`. However, to simplify the code, each supported H264
// profile should be listed explicitly in the list of local supported codecs,
// even if they are redundant. Then each local codec in the list should be
// tested one at a time against the remote codec, and only when the profiles are
// equal should this function be called. Therefore, this function does not need
// to handle profile intersection, and the profile of `local_supported_params`
// and `remote_offered_params` must be equal before calling this function. The
// parameters that are used when negotiating are the level part of
// profile-level-id and level-asymmetry-allowed.
void H264GenerateProfileLevelIdForAnswer(
const CodecParameterMap& local_supported_params,
const CodecParameterMap& remote_offered_params,
CodecParameterMap* answer_params);
#ifdef RTC_ENABLE_H265
// Works similarly as H264GenerateProfileLevelIdForAnswer, but generates codec
// parameters that will be used as answer for H.265.
// Media configuration parameters, except level-id, must be used symmetrically.
// For level-id, the highest level indicated by the answer must not be higher
// than that indicated by the offer.
void H265GenerateProfileTierLevelForAnswer(
const CodecParameterMap& local_supported_params,
const CodecParameterMap& remote_offered_params,
CodecParameterMap* answer_params);
#endif
// Parse max frame rate from SDP FMTP line. absl::nullopt is returned if the
// field is missing or not a number.
absl::optional<int> ParseSdpForVPxMaxFrameRate(const CodecParameterMap& params);
// Parse max frame size from SDP FMTP line. absl::nullopt is returned if the
// field is missing or not a number. Please note that the value is stored in sub
// blocks but the returned value is in total number of pixels.
absl::optional<int> ParseSdpForVPxMaxFrameSize(const CodecParameterMap& params);
// Determines whether the non-standard x-google-per-layer-pli fmtp is present
// in the parameters and has a value of "1".
bool SupportsPerLayerPictureLossIndication(const CodecParameterMap& params);
} // namespace webrtc
#endif // MEDIA_BASE_SDP_VIDEO_FORMAT_UTILS_H_