修改srs流媒体服务器使webrtc支持H265(HEVC)
谷歌不支持H265，所以支持webrtc的流媒体服务器也都不支持，SRS是国内外使用量最大的流媒体服务器也不支持，怎么办？我们可以修改它使其支持。
概述
由于谷歌webRTC不支持H265，所以浏览器默认也不支持H265，但是H265比H264可以节省一半的带宽，更重要的是H265生态在国内比较成熟，如安防等很多行业芯片都支持H265编码，谷歌强推的VP9和AV1生态在国内不成熟，支持的芯片和设备比较少。
谷歌不支持H265，所以支持webrtc的流媒体服务器也都不支持，SRS是国内外使用量最大的流媒体服务器也不支持，怎么办？我们可以修改它使其支持。
修改代码
修改SRS支持webRTC的H265需要修改SDP和视频源的支持，也需要修改PLI等其他的支持，本篇文章先讲修改SDP和视频源，其他的在后面文章中讲。
SRS支持webRTC的信令是自定义的，首先就要修改SDP支持。
修改SDP支持多个编码
bool SrsMediaDesc::find_encoding_name(const std::string& encoding_name) const{
std::string lower_name(encoding_name), upper_name(encoding_name);
transform(encoding_name.begin(), encoding_name.end(), lower_name.begin(), ::tolower);
transform(encoding_name.begin(), encoding_name.end(), upper_name.begin(), ::toupper);
for (size_t i = 0; i < payload_types_.size(); ++i) {
if (payload_types_[i].encoding_name_ == std::string(lower_name.c_str()) ||
payload_types_[i].encoding_name_ == std::string(upper_name.c_str())) {
return true;
}
}
return false;
}
修改推流时视频源使其支持H265
srs_error_t SrsRtcConnection::negotiate_publish_capability(SrsRtcUserConfig* ruc, SrsRtcSourceDescription* stream_desc)
{
srs_error_t err = srs_success;
if (!stream_desc) {
return srs_error_new(ERROR_RTC_SDP_EXCHANGE, "stream description is NULL");
}
SrsRequest* req = ruc->req_;
const SrsSdp& remote_sdp = ruc->remote_sdp_;
bool nack_enabled = _srs_config->get_rtc_nack_enabled(req->vhost);
bool twcc_enabled = _srs_config->get_rtc_twcc_enabled(req->vhost);
// TODO: FIME: Should check packetization-mode=1 also.
bool has_42e01f = srs_sdp_has_h264_profile(remote_sdp, "42e01f");
for (int i = 0; i < (int)remote_sdp.media_descs_.size(); ++i) {
const SrsMediaDesc& remote_media_desc = remote_sdp.media_descs_.at(i);
SrsRtcTrackDescription* track_desc = new SrsRtcTrackDescription();
SrsAutoFree(SrsRtcTrackDescription, track_desc);
track_desc->set_direction("recvonly");
track_desc->set_mid(remote_media_desc.mid_);
// Whether feature enabled in remote extmap.
int remote_twcc_id = 0;
if (true) {
map<int, string> extmaps = remote_media_desc.get_extmaps();
for(map<int, string>::iterator it = extmaps.begin(); it != extmaps.end(); ++it) {
if (it->second == kTWCCExt) {
remote_twcc_id = it->first;
break;
}
}
}
if (twcc_enabled && remote_twcc_id) {
track_desc->add_rtp_extension_desc(remote_twcc_id, kTWCCExt);
}
if (remote_media_desc.is_audio()) {
// TODO: check opus format specific param
std::vector<SrsMediaPayloadType> payloads = remote_media_desc.find_media_with_encoding_name("opus");
if (payloads.empty()) {
return srs_error_new(ERROR_RTC_SDP_EXCHANGE, "no valid found opus payload type");
}
for (int j = 0; j < (int)payloads.size(); j++) {
const SrsMediaPayloadType& payload = payloads.at(j);
// if the payload is opus, and the encoding_param_ is channel
SrsAudioPayload* audio_payload = new SrsAudioPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_, ::atol(payload.encoding_param_.c_str()));
audio_payload->set_opus_param_desc(payload.format_specific_param_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
audio_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
audio_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->type_ = "audio";
track_desc->set_codec_payload((SrsCodecPayload*)audio_payload);
// Only choose one match opus codec.
break;
}
} else if (remote_media_desc.is_video() && ruc->codec_ == "av1") {
std::vector<SrsMediaPayloadType> payloads = remote_media_desc.find_media_with_encoding_name("AV1X");
if (payloads.empty()) {
return srs_error_new(ERROR_RTC_SDP_EXCHANGE, "no found valid AV1 payload type");
}
for (int j = 0; j < (int)payloads.size(); j++) {
const SrsMediaPayloadType& payload = payloads.at(j);
// Generate video payload for av1.
SrsVideoPayload* video_payload = new SrsVideoPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->type_ = "video";
track_desc->set_codec_payload((SrsCodecPayload*)video_payload);
break;
}
} else if (remote_media_desc.is_video()&&remote_media_desc.find_encoding_name("H264")) {
std::vector<SrsMediaPayloadType> payloads = remote_media_desc.find_media_with_encoding_name("H264");
if (payloads.empty()) {
return srs_error_new(ERROR_RTC_SDP_EXCHANGE, "no found valid H.264 payload type");
}
std::deque<SrsMediaPayloadType> backup_payloads;
for (int j = 0; j < (int)payloads.size(); j++) {
const SrsMediaPayloadType& payload = payloads.at(j);
if (payload.format_specific_param_.empty()) {
backup_payloads.push_front(payload);
continue;
}
H264SpecificParam h264_param;
if ((err = srs_parse_h264_fmtp(payload.format_specific_param_, h264_param)) != srs_success) {
srs_error_reset(err); continue;
}
// If not exists 42e01f, we pick up any profile such as 42001f.
bool profile_matched = (!has_42e01f || h264_param.profile_level_id == "42e01f");
// Try to pick the "best match" H.264 payload type.
if (profile_matched && h264_param.packetization_mode == "1" && h264_param.level_asymmerty_allow == "1") {
// if the playload is opus, and the encoding_param_ is channel
SrsVideoPayload* video_payload = new SrsVideoPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_);
video_payload->set_h264_param_desc(payload.format_specific_param_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->type_ = "video";
track_desc->set_codec_payload((SrsCodecPayload*)video_payload);
// Only choose first match H.264 payload type.
break;
}
backup_payloads.push_back(payload);
}
// Try my best to pick at least one media payload type.
if (!track_desc->media_ && ! backup_payloads.empty()) {
const SrsMediaPayloadType& payload = backup_payloads.front();
// if the playload is opus, and the encoding_param_ is channel
SrsVideoPayload* video_payload = new SrsVideoPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->set_codec_payload((SrsCodecPayload*)video_payload);
srs_warn("choose backup H.264 payload type=%d", payload.payload_type_);
}
// TODO: FIXME: Support RRTR?
//local_media_desc.payload_types_.back().rtcp_fb_.push_back("rrtr");
}else if (remote_media_desc.is_video()&&remote_media_desc.find_encoding_name("H265")) {
std::vector<SrsMediaPayloadType> payloads = remote_media_desc.find_media_with_encoding_name("H265");
if (payloads.empty()) {
return srs_error_new(ERROR_RTC_SDP_EXCHANGE, "no found valid H.265 payload type");
}
std::deque<SrsMediaPayloadType> backup_payloads;
for (int j = 0; j < (int)payloads.size(); j++) {
const SrsMediaPayloadType& payload = payloads.at(j);
if (payload.format_specific_param_.empty()) {
backup_payloads.push_front(payload);
continue;
}
H264SpecificParam h264_param;
if ((err = srs_parse_h264_fmtp(payload.format_specific_param_, h264_param)) != srs_success) {
srs_error_reset(err); continue;
}
// If not exists 42e01f, we pick up any profile such as 42001f.
bool profile_matched = (!has_42e01f || h264_param.profile_level_id == "42e01f");
// Try to pick the "best match" H.264 payload type.
if (profile_matched && h264_param.packetization_mode == "1" && h264_param.level_asymmerty_allow == "1") {
// if the playload is opus, and the encoding_param_ is channel
SrsVideoPayload* video_payload = new SrsVideoPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_);
video_payload->set_h264_param_desc(payload.format_specific_param_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->type_ = "video";
track_desc->set_codec_payload((SrsCodecPayload*)video_payload);
// Only choose first match H.264 payload type.
break;
}
backup_payloads.push_back(payload);
}
// Try my best to pick at least one media payload type.
if (!track_desc->media_ && ! backup_payloads.empty()) {
const SrsMediaPayloadType& payload = backup_payloads.front();
// if the playload is opus, and the encoding_param_ is channel
SrsVideoPayload* video_payload = new SrsVideoPayload(payload.payload_type_, payload.encoding_name_, payload.clock_rate_);
// TODO: FIXME: Only support some transport algorithms.
for (int k = 0; k < (int)payload.rtcp_fb_.size(); ++k) {
const string& rtcp_fb = payload.rtcp_fb_.at(k);
if (nack_enabled) {
if (rtcp_fb == "nack" || rtcp_fb == "nack pli") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
if (twcc_enabled && remote_twcc_id) {
if (rtcp_fb == "transport-cc") {
video_payload->rtcp_fbs_.push_back(rtcp_fb);
}
}
}
track_desc->set_codec_payload((SrsCodecPayload*)video_payload);
srs_warn("choose backup H.265 payload type=%d", payload.payload_type_);
}
// TODO: FIXME: Support RRTR?
//local_media_desc.payload_types_.back().rtcp_fb_.push_back("rrtr");
}
// TODO: FIXME: use one parse payload from sdp.
track_desc->create_auxiliary_payload(remote_media_desc.find_media_with_encoding_name("red"));
track_desc->create_auxiliary_payload(remote_media_desc.find_media_with_encoding_name("rtx"));
track_desc->create_auxiliary_payload(remote_media_desc.find_media_with_encoding_name("ulpfec"));
std::string track_id;
for (int j = 0; j < (int)remote_media_desc.ssrc_infos_.size(); ++j) {
const SrsSSRCInfo& ssrc_info = remote_media_desc.ssrc_infos_.at(j);
// ssrc have same track id, will be description in the same track description.
if(track_id != ssrc_info.msid_tracker_) {
SrsRtcTrackDescription* track_desc_copy = track_desc->copy();
track_desc_copy->ssrc_ = ssrc_info.ssrc_;
track_desc_copy->id_ = ssrc_info.msid_tracker_;
track_desc_copy->msid_ = ssrc_info.msid_;
if (remote_media_desc.is_audio() && !stream_desc->audio_track_desc_) {
stream_desc->audio_track_desc_ = track_desc_copy;
} else if (remote_media_desc.is_video()) {
stream_desc->video_track_descs_.push_back(track_desc_copy);
}
}
track_id = ssrc_info.msid_tracker_;
}
// set track fec_ssrc and rtx_ssrc
for (int j = 0; j < (int)remote_media_desc.ssrc_groups_.size(); ++j) {
const SrsSSRCGroup& ssrc_group = remote_media_desc.ssrc_groups_.at(j);
SrsRtcTrackDescription* track_desc = stream_desc->find_track_description_by_ssrc(ssrc_group.ssrcs_[0]);
if (!track_desc) {
continue;
}
if (ssrc_group.semantic_ == "FID") {
track_desc->set_rtx_ssrc(ssrc_group.ssrcs_[1]);
} else if (ssrc_group.semantic_ == "FEC") {
track_desc->set_fec_ssrc(ssrc_group.ssrcs_[1]);
}
}
}
return err;
}
这样SRS信令就可以支持H265
客户端测试
使用yangwebrtc可以进行测试，yangwebrtc已经支持webrtc的H265
详见用yangwebrtc搭建低延迟并节省一半码率的H265的webrtc应用_m0_56595685的博客-CSDN博客
https://blog.csdn.net/m0_56595685/article/details/121880362
下载源代码
GitHub - metartc/srs-webrtc265https://github.com/metartc/srs-webrtc265
srs-webrtc265: 支持webrtc的H265(hevc)的srs版本
git clone https://github.com/metartc/srs-webrtc265.git
或者
git clone https://gitee.com/metartc/srs-webrtc265.git
编译：
./configure
make
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