media/base/sdp_video_format_utils.h

/*
 *  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 <optional>

#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. std::nullopt is returned if the
// field is missing or not a number.
std::optional<int> ParseSdpForVPxMaxFrameRate(const CodecParameterMap& params);

// Parse max frame size from SDP FMTP line. std::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.
std::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_