好多开发者在QT环境下实现RTMP或RTSP播放时，首先考虑到的是集成VLC，集成后，却发现VLC在延迟、断网重连、稳定性等各个方面不尽人意，无法满足上线环境需求。本文以调用大牛直播SDK（官方）的Windows平台播放端SDK为例，介绍下如何在QT下实现低延迟的RTMP|RTSP播放器，废话不多说，先上图：
大牛直播SDK有MFC的demo，所以在QT上实现播放轻车熟路，如果需要多窗口播放，也可以参考转发的demo，转发的那个4窗口预览的demo做了二次封装，调用更方便。
窗体布局不再赘述，就是个普通的6窗口布局，不得不说，QT在窗体布局这块，相对MFC真的太方便了。
考虑到大多场景下，开发者有多路播放诉求，针对这种情况，我们对player做个简单的封装：
开始播放：
代码语言：javascript复制bool player_wrapper::StartPlay(const std::string& url, bool is_rtsp_tcp_mode, bool is_mute)
{
if (is_playing_)
return false;
if (!OpenPlayerHandle(url, is_rtsp_tcp_mode, is_mute))
return false;
player_api_->SetBuffer(player_handle_, 100);
player_api_->SetMute(player_handle_, is_mute ? 1 : 0);
player_api_->SetRtspAutoSwitchTcpUdp(player_handle_, true);
player_api_->SetRtspTimeout(player_handle_, 10);
player_api_->SetRenderWindow(player_handle_, render_wnd_);
player_api_->SetRenderScaleMode(player_handle_, 1);
auto ret = player_api_->StartPlay(player_handle_);
if (NT_ERC_OK != ret)
{
if (!is_recording_)
{
player_api_->Close(player_handle_);
player_handle_ = NULL;
}
return false;
}
is_playing_ = true;
return true;
}开始播放封装，调用了OpenPlayerHandle()，检查系统是不是支持特定机型硬解码，通过调用Open()接口，获取播放实例，然后进行播放前的参数设置，比如网络状态event回调、视频宽高回调、设置buffer time、RTSP的TCP-UDP模式，默认播放音量等，具体实现如下：
代码语言：javascript复制bool player_wrapper::OpenPlayerHandle(const std::string& url, bool is_rtsp_tcp_mode, bool is_mute)
{
if (player_handle_ != NULL)
return true;
if (url.empty())
return false;
bool is_support_h264_hardware_decoder_ = NT_ERC_OK == player_api_->IsSupportH264HardwareDecoder();
bool is_support_h265_hardware_decoder_ = NT_ERC_OK == player_api_->IsSupportH265HardwareDecoder();
NT_HANDLE player_handle = NULL;
Q_ASSERT(player_api_ != NULL);
if (NT_ERC_OK != player_api_->Open(&player_handle, render_wnd_, 0, NULL))
{
return false;
}
Q_ASSERT(player_handle != NULL);
player_api_->SetEventCallBack(player_handle, this, &NT_Player_SDKEventHandle);
player_api_->SetVideoSizeCallBack(player_handle, this, SP_SDKVideoSizeHandle);
player_api_->SetH264HardwareDecoder(player_handle, is_support_h264_hardware_decoder_ ? 1 : 0, 0);
player_api_->SetH265HardwareDecoder(player_handle, is_support_h265_hardware_decoder_ ? 1 : 0, 0);
player_api_->SetBuffer(player_handle, 0);
player_api_->SetFastStartup(player_handle, 1);
player_api_->SetRTSPTcpMode(player_handle, is_rtsp_tcp_mode ? 1 : 0);
player_api_->SetMute(player_handle, is_mute ? 1 : 0);
int audio_volume = 100;
player_api_->SetAudioVolume(player_handle, audio_volume);
if (NT_ERC_OK != player_api_->SetURL(player_handle, url.c_str()))
{
if (!is_recording_)
{
player_api_->Close(player_handle_);
player_handle_ = NULL;
}
return false;
}
player_handle_ = player_handle;
return true;
}停止播放：
代码语言：javascript复制void player_wrapper::StopPlay()
{
if (!is_playing_)
return;
player_api_->StopPlay(player_handle_);
if (!is_recording_)
{
player_api_->Close(player_handle_);
player_handle_ = NULL;
}
is_playing_ = false;
}Event回调：
代码语言：javascript复制extern "C" NT_VOID NT_CALLBACK NT_Player_SDKEventHandle(NT_HANDLE handle, NT_PVOID user_data,
NT_UINT32 event_id,
NT_INT64 param1,
NT_INT64 param2,
NT_UINT64 param3,
NT_PCSTR param4,
NT_PCSTR param5,
NT_PVOID param6)
{
if (user_data == NULL)
return;
auto wrapper = reinterpret_cast<player_wrapper*>(user_data);
if (wrapper == NULL)
return;
wrapper->OnPlayerStatus(event_id, param1);
}void player_wrapper::OnPlayerStatus(NT_UINT32 event_id, NT_INT64 param1)
{
if (player_handle_ == NULL)
return;
if (!is_playing_ && !is_recording_)
{
return;
}
if (NT_SP_E_EVENT_ID_RTSP_STATUS_CODE == event_id)
{
int status_code = (int)param1;
if (401 == status_code)
{
//HandleVerification();
}
return;
}
if (NT_SP_E_EVENT_ID_CONNECTING == event_id
|| NT_SP_E_EVENT_ID_CONNECTION_FAILED == event_id
|| NT_SP_E_EVENT_ID_CONNECTED == event_id
|| NT_SP_E_EVENT_ID_DISCONNECTED == event_id
|| NT_SP_E_EVENT_ID_NO_MEDIADATA_RECEIVED == event_id)
{
if (NT_SP_E_EVENT_ID_CONNECTING == event_id)
{
OutputDebugStringA("connection status: connectingrn");
}
else if (NT_SP_E_EVENT_ID_CONNECTION_FAILED == event_id)
{
OutputDebugStringA("connection status: connection failedrn");
}
else if (NT_SP_E_EVENT_ID_CONNECTED == event_id)
{
OutputDebugStringA("connection status: connectedrn");
}
else if (NT_SP_E_EVENT_ID_DISCONNECTED == event_id)
{
OutputDebugStringA("connection status: disconnectedrn");
}
else if (NT_SP_E_EVENT_ID_NO_MEDIADATA_RECEIVED == event_id)
{
OutputDebugStringA("connection status: no mediadata receivedrn");
}
}
std::unique_lock<std::recursive_mutex> lock(player_handle_mutex_);
player_status_ = event_id;
}调用封装后的播放接口，记得多实例播放环境下，Init()和UnInit()接口仅需要调用一次，测试URL可自行设置。
代码语言：javascript复制void frmMain::startplay()
{
for (int i = 0; i < widgets.size(); i)
{
if (!plays[i])
{
plays[i] = std::make_shared<player_wrapper>(&player_api_, (HWND)NULL,
(HWND)widgets.at(i)->winId());
}
auto& play = plays[i];
if (!play->IsPlaying())
{
QString play_url = "rtsp://admin:admin123456@192.168.0.121:554/cam/realmonitor?channel=1&subtype=0";
if (!play->StartPlay(play_url.toStdString(), true, false))
{
QMessageBox::information(NULL, "播放失败!", play_url);
}
}
}
}void frmMain::stopplay()
{
for (int i = 0; i < widgets.size(); i)
{
if (!plays[i])
{
plays[i] = std::make_shared<player_wrapper>(&player_api_, (HWND)NULL,
(HWND)widgets.at(i)->winId());
}
auto& play = plays[i];
if (play->IsPlaying())
{
play->StopPlay();
}
widgets.at(i)->setText(QString("通道 %1").arg(i 1));
widgets.at(i)->update();
}
}窗体大小发生改变时：
代码语言：javascript复制void frmMain::resizeEvent(QResizeEvent* event)
{
for (int i = 0; i < widgets.size(); i)
{
if (!plays[i])
{
plays[i] = std::make_shared<player_wrapper>(&player_api_, (HWND)NULL,
(HWND)widgets.at(i)->winId());
}
auto& play = plays[i];
if (play->IsPlaying())
{
play->OnWindowSize(widgets.at(i)->width(), widgets.at(i)->height());
}
}
}以上是QT环境下集成个低延迟的RTMP、RTSP播放的基本流程，感兴趣的开发者可酌情参考。相对MFC，QT环境下在实现更酷炫和实用的逻辑显然体验更好一些。
