crossdesk/src/screen_capturer/linux/screen_capturer_x11.cpp

#include "screen_capturer_x11.h"

#include <iostream>

#include "rd_log.h"

#define NV12_BUFFER_SIZE 1280 * 720 * 3 / 2
unsigned char nv12_buffer_[NV12_BUFFER_SIZE];

ScreenCapturerX11::ScreenCapturerX11() {}

ScreenCapturerX11::~ScreenCapturerX11() {
  if (inited_ && capture_thread_.joinable()) {
    capture_thread_.join();
    inited_ = false;
  }
}

int ScreenCapturerX11::Init(const int fps, cb_desktop_data cb) {
  if (cb) {
    _on_data = cb;
  }

  fps_ = fps;

  av_log_set_level(AV_LOG_QUIET);

  pFormatCtx_ = avformat_alloc_context();

  avdevice_register_all();

  // grabbing frame rate
  av_dict_set(&options_, "framerate", "30", 0);
  // show remote cursor
  av_dict_set(&options_, "capture_cursor", "0", 0);
  // Make the grabbed area follow the mouse
  // av_dict_set(&options_, "follow_mouse", "centered", 0);
  // Video frame size. The default is to capture the full screen
  // av_dict_set(&options_, "video_size", "1280x720", 0);
  std::string capture_method = "x11grab";
  ifmt_ = (AVInputFormat *)av_find_input_format(capture_method.c_str());
  if (!ifmt_) {
    LOG_ERROR("Couldn't find_input_format [{}]", capture_method.c_str());
  }

  const char *display = std::getenv("DISPLAY");
  // Grab at position 10,20
  if (display) {
    if (avformat_open_input(&pFormatCtx_, display, ifmt_, &options_) != 0) {
      LOG_ERROR("Couldn't open input stream {}", display);
      return -1;
    } else {
      LOG_INFO("Open input stream [{}]", display);
    }
  } else {
    LOG_ERROR("DISPLAY environment variable not set");
    return -1;
  }

  if (avformat_find_stream_info(pFormatCtx_, NULL) < 0) {
    LOG_ERROR("Couldn't find stream information");
    return -1;
  }

  videoindex_ = -1;
  for (i_ = 0; i_ < pFormatCtx_->nb_streams; i_++)
    if (pFormatCtx_->streams[i_]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
      videoindex_ = i_;
      break;
    }
  if (videoindex_ == -1) {
    LOG_ERROR("Didn't find a video stream");
    return -1;
  }

  pCodecParam_ = pFormatCtx_->streams[videoindex_]->codecpar;

  pCodecCtx_ = avcodec_alloc_context3(NULL);
  avcodec_parameters_to_context(pCodecCtx_, pCodecParam_);

  pCodec_ = const_cast<AVCodec *>(avcodec_find_decoder(pCodecCtx_->codec_id));
  if (pCodec_ == NULL) {
    LOG_ERROR("Codec not found");
    return -1;
  }
  if (avcodec_open2(pCodecCtx_, pCodec_, NULL) < 0) {
    LOG_ERROR("Could not open codec");
    return -1;
  }

  const int screen_w = pFormatCtx_->streams[videoindex_]->codecpar->width;
  const int screen_h = pFormatCtx_->streams[videoindex_]->codecpar->height;

  pFrame_ = av_frame_alloc();
  pFrameNv12_ = av_frame_alloc();

  pFrame_->width = screen_w;
  pFrame_->height = screen_h;
  pFrameNv12_->width = 1280;
  pFrameNv12_->height = 720;

  packet_ = (AVPacket *)av_malloc(sizeof(AVPacket));

  img_convert_ctx_ = sws_getContext(
      pFrame_->width, pFrame_->height, pCodecCtx_->pix_fmt, pFrameNv12_->width,
      pFrameNv12_->height, AV_PIX_FMT_NV12, SWS_BICUBIC, NULL, NULL, NULL);

  inited_ = true;

  return 0;
}

int ScreenCapturerX11::Destroy() {
  running_ = false;
  return 0;
}

int ScreenCapturerX11::Start() {
  running_ = true;
  capture_thread_ = std::thread([this]() {
    while (running_) {
      if (av_read_frame(pFormatCtx_, packet_) >= 0) {
        if (packet_->stream_index == videoindex_) {
          avcodec_send_packet(pCodecCtx_, packet_);
          av_packet_unref(packet_);
          got_picture_ = avcodec_receive_frame(pCodecCtx_, pFrame_);

          if (!got_picture_) {
            av_image_fill_arrays(pFrameNv12_->data, pFrameNv12_->linesize,
                                 nv12_buffer_, AV_PIX_FMT_NV12,
                                 pFrameNv12_->width, pFrameNv12_->height, 1);

            sws_scale(img_convert_ctx_, pFrame_->data, pFrame_->linesize, 0,
                      pFrame_->height, pFrameNv12_->data,
                      pFrameNv12_->linesize);

            _on_data((unsigned char *)nv12_buffer_,
                     pFrameNv12_->width * pFrameNv12_->height * 3 / 2,
                     pFrameNv12_->width, pFrameNv12_->height);
          }
        }
      }
    }
  });

  return 0;
}

int ScreenCapturerX11::Stop() {
  running_ = false;
  return 0;
}

int ScreenCapturerX11::Pause() { return 0; }

int ScreenCapturerX11::Resume() { return 0; }

void ScreenCapturerX11::OnFrame() {}

void ScreenCapturerX11::CleanUp() {}