/**
 * gst_vaapi_encoder_get_buffer_with_timeout:
 * @encoder: a #GstVaapiEncoder
 * @out_codedbuf_proxy_ptr: the next coded buffer as a #GstVaapiCodedBufferProxy
 * @timeout: the number of microseconds to wait for the coded buffer, at most
 *
 * Upon successful return, *@out_codedbuf_proxy_ptr contains the next
 * coded buffer as a #GstVaapiCodedBufferProxy. The caller owns this
 * object, so gst_vaapi_coded_buffer_proxy_unref() shall be called
 * after usage. Otherwise, @GST_VAAPI_DECODER_STATUS_ERROR_NO_BUFFER
 * is returned if no coded buffer is available so far (timeout).
 *
 * The parent frame is available as a #GstVideoCodecFrame attached to
 * the user-data anchor of the output coded buffer. Ownership of the
 * frame is transferred to the coded buffer.
 *
 * Return value: a #GstVaapiEncoderStatus
 */
GstVaapiEncoderStatus
gst_vaapi_encoder_get_buffer_with_timeout (GstVaapiEncoder * encoder,
    GstVaapiCodedBufferProxy ** out_codedbuf_proxy_ptr, guint64 timeout)
{
  GstVaapiEncPicture *picture;
  GstVaapiCodedBufferProxy *codedbuf_proxy;

  codedbuf_proxy = g_async_queue_timeout_pop (encoder->codedbuf_queue, timeout);
  if (!codedbuf_proxy)
    return GST_VAAPI_ENCODER_STATUS_NO_BUFFER;

  /* Wait for completion of all operations and report any error that occurred */
  picture = gst_vaapi_coded_buffer_proxy_get_user_data (codedbuf_proxy);
  if (!gst_vaapi_surface_sync (picture->surface))
    goto error_invalid_buffer;

  gst_vaapi_coded_buffer_proxy_set_user_data (codedbuf_proxy,
      gst_video_codec_frame_ref (picture->frame),
      (GDestroyNotify) gst_video_codec_frame_unref);

  if (out_codedbuf_proxy_ptr)
    *out_codedbuf_proxy_ptr = gst_vaapi_coded_buffer_proxy_ref (codedbuf_proxy);
  gst_vaapi_coded_buffer_proxy_unref (codedbuf_proxy);
  return GST_VAAPI_ENCODER_STATUS_SUCCESS;

  /* ERRORS */
error_invalid_buffer:
  {
    GST_ERROR ("failed to encode the frame");
    gst_vaapi_coded_buffer_proxy_unref (codedbuf_proxy);
    return GST_VAAPI_ENCODER_STATUS_ERROR_INVALID_SURFACE;
  }
}
static void
gst_vaapiencode_purge (GstVaapiEncode * encode)
{
  GstVaapiCodedBufferProxy *codedbuf_proxy = NULL;
  GstVaapiEncoderStatus status;
  GstVideoCodecFrame *out_frame;

  do {
    status = gst_vaapi_encoder_get_buffer_with_timeout (encode->encoder,
        &codedbuf_proxy, 0);
    if (status == GST_VAAPI_ENCODER_STATUS_SUCCESS) {
      out_frame = gst_vaapi_coded_buffer_proxy_get_user_data (codedbuf_proxy);
      if (out_frame)
        gst_video_codec_frame_set_user_data (out_frame, NULL, NULL);

      gst_vaapi_coded_buffer_proxy_unref (codedbuf_proxy);
    }
  } while (status == GST_VAAPI_ENCODER_STATUS_SUCCESS);
}
static GstFlowReturn
gst_vaapiencode_push_frame (GstVaapiEncode * encode, gint64 timeout)
{
  GstVideoEncoder *const venc = GST_VIDEO_ENCODER_CAST (encode);
  GstVaapiEncodeClass *const klass = GST_VAAPIENCODE_GET_CLASS (encode);
  GstVideoCodecFrame *out_frame;
  GstVaapiCodedBufferProxy *codedbuf_proxy = NULL;
  GstVaapiEncoderStatus status;
  GstBuffer *out_buffer;
  GstFlowReturn ret;

  status = gst_vaapi_encoder_get_buffer_with_timeout (encode->encoder,
      &codedbuf_proxy, timeout);
  if (status == GST_VAAPI_ENCODER_STATUS_NO_BUFFER)
    return GST_VAAPI_ENCODE_FLOW_TIMEOUT;
  if (status != GST_VAAPI_ENCODER_STATUS_SUCCESS)
    goto error_get_buffer;

  out_frame = gst_vaapi_coded_buffer_proxy_get_user_data (codedbuf_proxy);
  if (!out_frame)
    goto error_get_buffer;
  gst_video_codec_frame_ref (out_frame);
  gst_video_codec_frame_set_user_data (out_frame, NULL, NULL);

  /* Update output state */
  GST_VIDEO_ENCODER_STREAM_LOCK (encode);
  if (!ensure_output_state (encode))
    goto error_output_state;
  GST_VIDEO_ENCODER_STREAM_UNLOCK (encode);

  /* Allocate and copy buffer into system memory */
  out_buffer = NULL;
  ret = klass->alloc_buffer (encode,
      GST_VAAPI_CODED_BUFFER_PROXY_BUFFER (codedbuf_proxy), &out_buffer);
  gst_vaapi_coded_buffer_proxy_replace (&codedbuf_proxy, NULL);
  if (ret != GST_FLOW_OK)
    goto error_allocate_buffer;

  gst_buffer_replace (&out_frame->output_buffer, out_buffer);
  gst_buffer_unref (out_buffer);

  GST_TRACE_OBJECT (encode, "output:%" GST_TIME_FORMAT ", size:%zu",
      GST_TIME_ARGS (out_frame->pts), gst_buffer_get_size (out_buffer));

  return gst_video_encoder_finish_frame (venc, out_frame);

  /* ERRORS */
error_get_buffer:
  {
    GST_ERROR ("failed to get encoded buffer (status %d)", status);
    if (codedbuf_proxy)
      gst_vaapi_coded_buffer_proxy_unref (codedbuf_proxy);
    return GST_FLOW_ERROR;
  }
error_allocate_buffer:
  {
    GST_ERROR ("failed to allocate encoded buffer in system memory");
    if (out_buffer)
      gst_buffer_unref (out_buffer);
    gst_video_codec_frame_unref (out_frame);
    return ret;
  }
error_output_state:
  {
    GST_ERROR ("failed to negotiate output state (status %d)", status);
    GST_VIDEO_ENCODER_STREAM_UNLOCK (encode);
    gst_video_codec_frame_unref (out_frame);
    return GST_FLOW_NOT_NEGOTIATED;
  }
}