如何在camera2 API中使用reprocessCaptureRequest

Question

我正在嘗試將相機項目更新為Android N，因此我將舊的CameraCaptureSession移動到ReprocessableCaptureSession 。 我做到了，它工作正常，但這個新功能，我可以使用CameraDevice.TEMPLATE_ZERO_SHUTTER_LAG在我的設備模板，我可以重新處理與框架reprocessCaptureRequest 。

這是我的問題出現的地方。 因為我沒有找到任何示例，我真的不了解如何使用reprocessCaptureRequest的小文檔：

每個重新處理CaptureRequest處理從CameraCaptureSession的輸入Surface到再處理捕獲請求中包含的所有輸出Surface的一個緩沖區。 必須從從同一相機設備捕獲的一個或多個輸出圖像生成再處理輸入圖像。 應用程序可以通過queueInputImage（Image）向攝像機設備提供輸入圖像。 應用程序必須使用其中一個輸出圖像的捕獲結果來創建重新處理捕獲請求，以便攝像機設備可以使用該信息來實現最佳的再處理圖像質量。 對於僅支持1個輸出Surface的相機設備，提交具有多個輸出目標的重新處理CaptureRequest將導致CaptureFailure。

我試着看看關於google.sources中相機的CTS測試，但他們做的和我一樣。 使用倍數imageReaders，在TotalCaptureResult LinkedBlockingQueue<TotalCaptureResult>保存圖片的LinkedBlockingQueue<TotalCaptureResult> 。 后來只是打電話：

TotalCaptureResult totalCaptureResult = state.captureCallback.getTotalCaptureResult();
CaptureRequest.Builder reprocessCaptureRequest = cameraStore.state().cameraDevice.createReprocessCaptureRequest(totalCaptureResult);
reprocessCaptureRequest.addTarget(state.yuvImageReader.getSurface());
sessionStore.state().session.capture(reprocessCaptureRequest.build(), null, this.handlers.bg());

但它總是拋出一個RuntimeException： java.lang.RuntimeException: Capture failed: Reason 0 in frame 170,

我只是想知道使用ReprocessableCaptureSession的正確方法是什么，因為我已經嘗試了所有內容而且我不知道我做錯了什么。

Answer 1

最后，我找到了使我的reprocessableCaptureSession工作的解決方案。 我使用Flux架構，所以當你看到Dispatcher.dispatch(action)時不要混淆，只是把它看作回調。 所以，這是我的代碼：

首先如何創建會話：

 //Configure preview surface
     Size previewSize = previewState.previewSize;
     previewState.previewTexture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());

     ArrayList<Surface> targets = new ArrayList<>();
     for (SessionOutputTarget outputTarget : state.outputTargets) {
        Surface surface = outputTarget.getSurface();
        if (surface != null) targets.add(surface);
     }
     targets.add(previewState.previewSurface);
     CameraCharacteristics cameraCharacteristics = cameraStore.state().availableCameras.get(cameraStore.state().selectedCamera);
     Size size = CameraCharacteristicsUtil.getYuvOutputSizes(cameraCharacteristics).get(0);

     InputConfiguration inputConfiguration = new InputConfiguration(size.getWidth(),
        size.getHeight(), ImageFormat.YUV_420_888);

     CameraCaptureSession.StateCallback sessionStateCallback = new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(@NonNull CameraCaptureSession session) {
           if (sessionId != currentSessionId) {
              Timber.e("Session opened for an old open request, skipping. Current %d, Request %d", currentSessionId, sessionId);
              //performClose(session);
              return;
           }

           try {
              session.getInputSurface();
              //This call is irrelevant,
              //however session might have closed and this will throw an IllegalStateException.
              //This happens if another camera app (or this one in another PID) takes control
              //of the camera while its opening
           } catch (IllegalStateException e) {
              Timber.e("Another process took control of the camera while creating the session, aborting!");
           }

           Dispatcher.dispatchOnUi(new SessionOpenedAction(session));
        }

        @Override
        public void onConfigureFailed(@NonNull CameraCaptureSession session) {
           if (sessionId != currentSessionId) {
              Timber.e("Configure failed for an old open request, skipping. Current %d, request %d", currentSessionId, sessionId);
              return;
           }

           Timber.e("Failed to configure the session");
           Dispatcher.dispatchOnUi(new SessionFailedAction(session, new IllegalStateException("onConfigureFailed")));
        }
     };

     if (state.outputMode == OutputMode.PHOTO) {
        cameraState.cameraDevice.createReprocessableCaptureSession(inputConfiguration, targets, sessionStateCallback, handlers.bg());
     } else if (state.outputMode == OutputMode.VIDEO) {
        cameraState.cameraDevice.createCaptureSession(targets, sessionStateCallback, handlers.bg());
     }

  } catch (IllegalStateException | IllegalArgumentException e) {
     Timber.e(e, "Something went wrong trying to start the session");
  } catch (CameraAccessException e) {
     //Camera will throw CameraAccessException if another we try to open / close the
     //session very fast.
     Timber.e("Failed to access camera, it was closed");
  }

使用4個曲面創建的照片會話（預覽，YUV（輸入），JPEG和RAW）。 之后，我配置了我的imageWriter：

   Dispatcher.subscribe(Dispatcher.VERY_HIGH_PRIORITY, SessionOpenedAction.class)
     .filter(a -> isInPhotoMode())
     .subscribe(action -> {
           PhotoState newState = new PhotoState(state());
           newState.zslImageWriter = ImageWriter.newInstance(action.session.getInputSurface(), MAX_REPROCESS_IMAGES);
           setState(newState);
     });

好的，現在我們已經創建了ImageWriter和會話。 不，我們通過重復請求開始流式傳輸：

         CaptureRequest.Builder captureRequestBuilder =
            cameraStore.state().cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_ZERO_SHUTTER_LAG);

         captureRequestBuilder.addTarget(previewStore.state().previewSurface);
         captureRequestBuilder.addTarget(photoStore.state().yuvImageReader.getSurface());
         state.session.setRepeatingRequest(captureRequestBuilder.build(), state.zslCaptureCallback, handlers.bg());

為了不添加大量代碼，只需說zslCaptureCallback是一個自定義回調，它在LinkedBlockingQueue<TotalCaptureRequest>保存X最后的TotalCaptureRequests。 另外，我對yuvImageReader（輸入一個）執行相同的操作，將最后的X個圖像保存在隊列中。

最后這是我的“拍照”方法：

try {
        //Retrieve the last image stored by the zslImageReader
        Image image = zslImageReaderListener.getImage();
        //Retrieve the last totalCaptureResult from the zslCaptureCallback and create a reprocessableCaptureRequest with it
        TotalCaptureResult captureResult = sessionStore.state().zslCaptureCallback.getCaptureResult(image.getTimestamp());
        CaptureRequest.Builder captureRequest = cameraStore.state().cameraDevice.createReprocessCaptureRequest(captureResult);
        //Add the desired target and values to the captureRequest
        captureRequest.addTarget(state().jpegImageReader.getSurface());
        //Queued back to ImageWriter for future consumption.
        state.zslImageWriter.queueInputImage(image);
        //Drain all the unused and queued CapturedResult from the CaptureCallback
        sessionStore.state().zslCaptureCallback.drain();
        //Capture the desired frame
        CaptureRequest futureCaptureResult = captureRequest.build();
        sessionStore.state().session.capture(futureCaptureResult, new CameraCaptureSession.CaptureCallback() {
           @Override
           public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                          @NonNull CaptureRequest request,
                                          @NonNull TotalCaptureResult result) {
              Dispatcher.dispatchOnUi(new PhotoStatusChangedAction(PhotoState.Status.SUCCESS));
           }

           @Override
           public void onCaptureFailed(@NonNull CameraCaptureSession session,
                                       @NonNull CaptureRequest request,
                                       @NonNull CaptureFailure failure) {
              super.onCaptureFailed(session, request, failure);
              Exception captureFailedException = new RuntimeException(
                 String.format("Capture failed: Reason %s in frame %d, was image captured? -> %s",
                    failure.getReason(),
                    failure.getFrameNumber(),
                    failure.wasImageCaptured()));
              Timber.e(captureFailedException, "Cannot take mediaType, capture failed!");

              Dispatcher.dispatchOnUi(new PhotoStatusChangedAction(PhotoState.Status.ERROR, captureFailedException));
           }
        }, this.handlers.bg());

        //Capture did not blow up, we are taking the photo now.
        newState.status = PhotoState.Status.TAKING;

     } catch (CameraAccessException | InterruptedException| IllegalStateException | IllegalArgumentException | SecurityException e) {
        Timber.e(e, "Cannot take picture, capture error!");
        newState.status = PhotoState.Status.ERROR;
     }