Custom video source

Custom video capture refers to the collection of a video stream from a custom source. Unlike the default video capture method, custom video capture enables you to control the capture source, and precisely adjust video attributes. You can dynamically adjust parameters such as video quality, resolution, and frame rate to adapt to various application scenarios. For example, you can capture video from high-definition cameras, and drone cameras.

Agora recommends default video capture for its stability, reliability, and ease of integration. Custom video capture offers flexibility and customization for specific video capture scenarios where default video capture does not fulfill your requirements.

Video SDK provides a custom video track method for video self-collection. You create one or more custom video tracks, join channels and publish the created video tracks in each channel. You use the self-capture module to drive the capture device, and send the captured video frames to the SDK through the video track.

The following figure shows the video data transmission process when custom video capture is implemented in a single channel or multiple channels:

• Publish to a single channel

  

• Publish to multiple channels

  

Use custom video capture in the following industries and scenarios:

Specialized video processing and enhancement

In specific gaming or virtual reality scenarios, real-time effects processing, filter handling, or other enhancement effects necessitate direct access to the original video stream. Custom video capture facilitates this, enabling seamless real-time processing and enhances the overall gaming or virtual reality experience for a more realistic outcome.

High-precision video capture

In video surveillance applications, detailed observation and analysis of scene details is necessary. Custom video capture enables higher image quality and finer control over capture to meet the requirements of video monitoring.

Capture from specific video sources

Industries such as IoT and live streaming often require the use of specific cameras, monitoring devices, or non-camera video sources, such as video capture cards or screen recording data. In such situations, default Video SDK capture may not meet your requirements, necessitating use of custom video capture.

Seamless integration with specific devices or third-party applications

In smart home or IoT applications, transmitting video from devices to users' smartphones or computers for monitoring and control may require the use of specific devices or applications for video capture. Custom video capture facilitates seamless integration of specific devices or applications with the Video SDK.

Specific video encoding formats

In certain live streaming scenarios, specific video encoding formats may be needed to meet business requirements. In such cases, Video SDK default capture might not suffice, and custom video capture is required to capture and encode videos in specific formats.

Using custom video capture offers the following advantages:

More types of video streams

Custom video capture allows the use of higher quality and a greater variety of capture devices and cameras, resulting in clearer and smoother video streams. This enhances the user viewing experience and makes the product more competitive.

More flexible video effects

Custom video capture enables you to implement richer and more personalized video effects and filters, enhancing the user experience. You can implement effects such as beautification filters and dynamic stickers.

Adaptation to diverse scenario requirements

Custom video capture helps applications better adapt to the requirements of various scenarios, such as live streaming, video conferencing, and online education. You can customize different video capture solutions based on the scenario requirements to provide a more robust application.

Ensure that you have implemented the SDK quickstart in your project.

The following figure shows the workflow you implement to capture and stream a custom video source in your app.

Take the following steps to implement this workflow:

1. Create a custom video track

   To create a custom video track and obtain the video track ID, call createCustomVideoTrack after initializing an instance of IRtcEngine. To create multiple custom video tracks, call the method multiple times.

   // For creating multiple custom video tracks, call createCustomVideoTrack multiple times
   

   int videoTrackId = m_rtcEngine->createCustomVideoTrack();
   

   m_trackVideoTrackIds[trackIndex] = videoTrackId;
   

2. Join a channel and publish the custom video track

   Call joinChannel to join a channel or joinChannelEx to join multiple channels. In the ChannelMediaOptions for each channel, set the customVideoTrackId to the video track ID you obtained. Set publishCustomVideoTrack to true to publish the specified custom video track in multiple channels.

   • Join a single channel

     ChannelMediaOptions mediaOptions;
     

     mediaOptions.clientRoleType = CLIENT_ROLE_BROADCASTER;
     

     // Publish the self-captured video stream
     

     mediaOptions.publishCustomVideoTrack = true;
     

     mediaOptions.autoSubscribeVideo = false;
     

     mediaOptions.autoSubscribeAudio = false;
     

     // Set the custom video track ID
     

     mediaOptions.customVideoTrackId = videoTrackId;
     

     // Join the channel
     

     int ret = m_rtcEngine->joinChannel(APP_TOKEN, szChannelId.data(), 0, mediaOptions);
     

   • Publish custom video to multiple channels

     int uid = 10001 + trackIndex;
     

     m_trackUids[trackIndex] = uid;
     

     m_trackConnections[trackIndex].channelId = m_strChannel.c_str();
     

     m_trackConnections[trackIndex].localUid = uid;
     

     m_trackEventHandlers[trackIndex].SetId(trackIndex + 1);
     

     m_trackEventHandlers[trackIndex].SetMsgReceiver(m_hWnd);
     

     
     

     // For publishing custom video tracks in multiple channels, set ChannelMediaOptions multiple times and call joinChannelEx multiple times
     

     ChannelMediaOptions mediaOptions;
     

     mediaOptions.clientRoleType = CLIENT_ROLE_BROADCASTER;
     

     // Publish the self-captured video stream
     

     mediaOptions.publishCustomVideoTrack = true;
     

     mediaOptions.autoSubscribeVideo = false;
     

     mediaOptions.autoSubscribeAudio = false;
     

     // Set the custom video track ID
     

     mediaOptions.customVideoTrackId = videoTrackId;
     

     // Join multiple channels
     

     int ret = m_rtcEngine->joinChannelEx(APP_TOKEN, m_trackConnections[trackIndex], mediaOptions, &m_trackEventHandlers[trackIndex]);
     

3. Implement self-capture module

   Agora provides the YUVReader.cpp and YUVReader.h demo projects that show you how to read YUV format video data from a local file. In a production environment, create a custom video module for your device using Video SDK based on your business requirements.

   // Use the custom YUVReader class to continuously read YUV-format video data in the YUVReader thread and pass the data to the OnYUVRead callback for further processing
   

   m_yuvReaderHandlers[trackIndex].Setup(m_rtcEngine, m_mediaEngine.get(), videoTrackId);
   

   m_yuvReaders[trackIndex].start(std::bind(&MultiVideoSourceTracksYUVReaderHander::OnYUVRead, m_yuvReaderHandlers[trackIndex], std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4));
   

4. Push video data to the SDK

   Call pushVideoFrame to push the captured video frames through the video track to Video SDK. Ensure that the videoTrackId matches the track ID you specified when joining the channel. Customize parameters like pixel format, data type, and timestamp in the VideoFrame.

   Information

   To ensure audio-video synchronization, set the timestamp parameter of VideoFrame to the system's Monotonic Time. Use getCurrentMonotonicTimeInMs to obtain the current Monotonic Time.

   void MultiVideoSourceTracksYUVReaderHander::OnYUVRead(int width, int height,
   

   unsigned char* buffer,
   

   int size) {
   

   if (m_mediaEngine == nullptr || m_rtcEngine == nullptr) {
   

   return;
   

   }
   

   
   

   // Set the video pixel format to I420
   

   m_videoFrame.format = agora::media::base::VIDEO_PIXEL_I420;
   

   // Set the video data type to raw data
   

   m_videoFrame.type = agora::media::base::ExternalVideoFrame::
   

   VIDEO_BUFFER_TYPE::VIDEO_BUFFER_RAW_DATA;
   

   // Pass the width, height, and buffer of the captured YUV video data to videoFrame
   

   m_videoFrame.height = height;
   

   m_videoFrame.stride = width;
   

   m_videoFrame.buffer = buffer;
   

   // Get the current Monotonic Time from the SDK and assign it to the timestamp parameter of videoFrame
   

   m_videoFrame.timestamp = m_rtcEngine->getCurrentMonotonicTimeInMs();
   

   // Push the video frame to the SDK
   

   m_mediaEngine->pushVideoFrame(&m_videoFrame, m_videoTrackId);
   

   }
   
   Information

   The sample code demonstrates converting YUV format to raw video data in I420 format. Agora video self-capture supports pushing external video frames in other formats; refer to VIDEO_PIXEL_FORMAT.

   Information

   If the captured custom video format is Texture and remote users experience flickering or distortion in the captured video, it is recommended to first duplicate the video data and then send both the original and duplicated video data back to the Video SDK. This helps eliminate anomalies during internal data encoding processes.

5. Destroy custom video tracks

   To stop custom video capture and destroy the video track, call destroyCustomVideoTrack. To destroy multiple video tracks, call the method for each track.

   // Stop self-captured video data
   

   m_yuvReaders[trackIndex].stop();
   

   m_yuvReaderHandlers[trackIndex].Release();
   

   // Destroy the custom video track
   

   m_rtcEngine->destroyCustomVideoTrack(m_trackVideoTrackIds[trackIndex]);
   

   // Leave the channel
   

   m_rtcEngine->leaveChannelEx(m_trackConnections[trackIndex]);
   

To implement custom video rendering in your app, refer to the following steps:

1. Set up onCaptureVideoFrame or onRenderVideoFrame callback to obtain the video data to be played.
2. Implement video rendering and playback yourself.

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

Agora provides the following open-source sample projects for your reference. Download the project or view the source code for a more detailed example.

• MultiVideoSourceTracks: Video self-capture
• CustomVideoCapture: Custom video rendering

• createCustomVideoTrack
• destroyCustomVideoTrack
• getCurrentMonotonicTimeInMs
• joinChannelEx
• pushVideoFrame
• onCaptureVideoFrame
• onRenderVideoFrame