Support camera size selection using -m/--camera-ar

In addition to --camera-size to specify an explicit size, make it
possible to select the camera size automatically, respecting the maximum
size (already used for display mirroring) and an aspect ratio.

For example, "scrcpy --video-source=camera" followed by:
 - (no additional arguments)
    : mirrors at the maximum size, any a-r
 - -m1920
    : only consider valid sizes having both dimensions not above 1920
 - --camera-ar=4:3
    : only consider valid sizes having an aspect ratio of 4:3 (+/- 10%)
 - -m2048 --camera-ar=1.6
    : only consider valid sizes having both dimensions not above 2048
      and an aspect ratio of 1.6 (+/- 10%)

Co-authored-by: Simon Chan <1330321+yume-chan@users.noreply.github.com>

app/data/bash-completion/scrcpy

@@ -10,6 +10,7 @@ _scrcpy() {
         --audio-source=
         --audio-output-buffer=
         -b --video-bit-rate=
+        --camera-ar=
         --camera-id=
         --camera-facing=
         --camera-size=
@@ -153,6 +154,7 @@ _scrcpy() {
         |--audio-codec-options \
         |--audio-encoder \
         |--audio-output-buffer \
+        |--camera-ar \
         |--camera-id \
         |--camera-size \
         |--crop \

app/data/zsh-completion/_scrcpy

@@ -17,6 +17,7 @@ arguments=(
     '--audio-source=[Select the audio source]:source:(output mic)'
     '--audio-output-buffer=[Configure the size of the SDL audio output buffer (in milliseconds)]'
     {-b,--video-bit-rate=}'[Encode the video at the given bit-rate]'
+    '--camera-ar=[Select the camera size by its aspect ratio]'
     '--camera-id=[Specify the camera id to mirror]'
     '--camera-facing=[Select the device camera by its facing direction]:facing:(front back external)'
     '--camera-size=[Specify an explicit camera capture size]'

app/scrcpy.1

@@ -75,6 +75,12 @@ Encode the video at the given bit rate, expressed in bits/s. Unit suffixes are s
 
 Default is 8M (8000000).
 
+.TP
+.BI "\-\-camera\-ar " ar
+Select the camera size by its aspect ratio (+/- 10%).
+
+Possible values are "sensor" (use the camera sensor aspect ratio), "<num>:<den>" (e.g. "4:3") and "<value>" (e.g. "1.6").
+
 .TP
 .BI "\-\-camera\-id " id
 Specify the device camera id to mirror.

app/src/cli.c

@@ -87,6 +87,7 @@ enum {
     OPT_CAMERA_ID,
     OPT_CAMERA_SIZE,
     OPT_CAMERA_FACING,
+    OPT_CAMERA_AR,
 };
 
 struct sc_option {
@@ -203,6 +204,15 @@ static const struct sc_option options[] = {
         .longopt = "bit-rate",
         .argdesc = "value",
     },
+    {
+        .longopt_id = OPT_CAMERA_AR,
+        .longopt = "camera-ar",
+        .argdesc = "ar",
+        .text = "Select the camera size by its aspect ratio (+/- 10%).\n"
+                "Possible values are \"sensor\" (use the camera sensor aspect "
+                "ratio), \"<num>:<den>\" (e.g. \"4:3\") or \"<value>\" (e.g. "
+                "\"1.6\")."
+    },
     {
         .longopt_id = OPT_CAMERA_ID,
         .longopt = "camera-id",
@@ -2129,6 +2139,9 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
                     return false;
                 }
                 break;
+            case OPT_CAMERA_AR:
+                opts->camera_ar = optarg;
+                break;
             case OPT_CAMERA_ID:
                 opts->camera_id = optarg;
                 break;
@@ -2250,9 +2263,16 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             return false;
         }
 
-        if (!opts->camera_size) {
-            LOGE("Camera size must be specified by --camera-size=WIDTHxHEIGHT");
-            return false;
+        if (opts->camera_size) {
+            if (opts->camera_ar) {
+                LOGE("Could not specify both --camera-size and -m/--max-size");
+                return false;
+            }
+
+            if (opts->camera_ar) {
+                LOGE("Could not specify both --camera-size and --camera-ar");
+                return false;
+            }
         }
 
         if (opts->control) {
@@ -2260,6 +2280,7 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             opts->control = false;
         }
     } else if (opts->camera_id
+            || opts->camera_ar
             || opts->camera_facing != SC_CAMERA_FACING_ANY
             || opts->camera_size) {
         LOGE("Camera options are only available with --video-source=camera");

app/src/options.c

@@ -13,6 +13,7 @@ const struct scrcpy_options scrcpy_options_default = {
     .audio_encoder = NULL,
     .camera_id = NULL,
     .camera_size = NULL,
+    .camera_ar = NULL,
     .log_level = SC_LOG_LEVEL_INFO,
     .video_codec = SC_CODEC_H264,
     .audio_codec = SC_CODEC_OPUS,

app/src/options.h

@@ -132,6 +132,7 @@ struct scrcpy_options {
     const char *audio_encoder;
     const char *camera_id;
     const char *camera_size;
+    const char *camera_ar;
     enum sc_log_level log_level;
     enum sc_codec video_codec;
     enum sc_codec audio_codec;

app/src/scrcpy.c

@@ -375,6 +375,7 @@ scrcpy(struct scrcpy_options *options) {
         .audio_encoder = options->audio_encoder,
         .camera_id = options->camera_id,
         .camera_size = options->camera_size,
+        .camera_ar = options->camera_ar,
         .force_adb_forward = options->force_adb_forward,
         .power_off_on_close = options->power_off_on_close,
         .clipboard_autosync = options->clipboard_autosync,

app/src/server.c

@@ -77,6 +77,7 @@ sc_server_params_destroy(struct sc_server_params *params) {
     free((char *) params->audio_encoder);
     free((char *) params->tcpip_dst);
     free((char *) params->camera_id);
+    free((char *) params->camera_ar);
 }
 
 static bool
@@ -105,6 +106,7 @@ sc_server_params_copy(struct sc_server_params *dst,
     COPY(audio_encoder);
     COPY(tcpip_dst);
     COPY(camera_id);
+    COPY(camera_ar);
 #undef COPY
 
     return true;
@@ -303,6 +305,9 @@ execute_server(struct sc_server *server,
         ADD_PARAM("camera_facing=%s",
             sc_server_get_camera_facing_name(params->camera_facing));
     }
+    if (params->camera_ar) {
+        ADD_PARAM("camera_ar=%s", params->camera_ar);
+    }
     if (params->show_touches) {
         ADD_PARAM("show_touches=true");
     }

app/src/server.h

@@ -36,6 +36,7 @@ struct sc_server_params {
     const char *audio_encoder;
     const char *camera_id;
     const char *camera_size;
+    const char *camera_ar;
     struct sc_port_range port_range;
     uint32_t tunnel_host;
     uint16_t tunnel_port;

server/src/main/java/com/genymobile/scrcpy/CameraAspectRatio.java

@@ -0,0 +1,37 @@
+package com.genymobile.scrcpy;
+
+public class CameraAspectRatio {
+    private static final float SENSOR = -1;
+
+    private float ar;
+
+    private CameraAspectRatio(float ar) {
+        this.ar = ar;
+    }
+
+    public static CameraAspectRatio fromFloat(float ar) {
+        if (ar < 0) {
+            throw new IllegalArgumentException("Invalid aspect ratio: " + ar);
+        }
+        return new CameraAspectRatio(ar);
+    }
+
+    public static CameraAspectRatio fromFraction(int w, int h) {
+        if (w <= 0 || h <= 0) {
+            throw new IllegalArgumentException("Invalid aspect ratio: " + w + ":" + h);
+        }
+        return new CameraAspectRatio((float) w / h);
+    }
+
+    public static CameraAspectRatio sensorAspectRatio() {
+        return new CameraAspectRatio(SENSOR);
+    }
+
+    public boolean isSensor() {
+        return ar == SENSOR;
+    }
+
+    public float getAspectRatio() {
+        return ar;
+    }
+}

server/src/main/java/com/genymobile/scrcpy/CameraCapture.java

@@ -4,6 +4,7 @@ import com.genymobile.scrcpy.wrappers.ServiceManager;
 
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
+import android.graphics.Rect;
 import android.hardware.camera2.CameraAccessException;
 import android.hardware.camera2.CameraCaptureSession;
 import android.hardware.camera2.CameraCharacteristics;
@@ -13,6 +14,8 @@ import android.hardware.camera2.CaptureFailure;
 import android.hardware.camera2.CaptureRequest;
 import android.hardware.camera2.params.OutputConfiguration;
 import android.hardware.camera2.params.SessionConfiguration;
+import android.hardware.camera2.params.StreamConfigurationMap;
+import android.media.MediaCodec;
 import android.os.Build;
 import android.os.Handler;
 import android.os.HandlerThread;
@@ -20,34 +23,25 @@ import android.view.Surface;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Stream;
 
 public class CameraCapture extends SurfaceCapture {
 
-    public static class CameraSelection {
-        private String explicitCameraId;
-        private CameraFacing cameraFacing;
-
-        public CameraSelection(String explicitCameraId, CameraFacing cameraFacing) {
-            this.explicitCameraId = explicitCameraId;
-            this.cameraFacing = cameraFacing;
-        }
-
-        boolean hasId() {
-            return explicitCameraId != null;
-        }
-
-        boolean hasProperties() {
-            return cameraFacing != null;
-        }
-    }
-
-    private final CameraSelection cameraSelection;
+    private final String explicitCameraId;
+    private final CameraFacing cameraFacing;
     private final Size explicitSize;
+    private int maxSize;
+    private final CameraAspectRatio aspectRatio;
+
+    private String cameraId;
+    private Size size;
 
     private HandlerThread cameraThread;
     private Handler cameraHandler;
@@ -56,9 +50,12 @@ public class CameraCapture extends SurfaceCapture {
 
     private final AtomicBoolean disconnected = new AtomicBoolean();
 
-    public CameraCapture(CameraSelection cameraSelection, Size explicitSize) {
-        this.cameraSelection = cameraSelection;
+    public CameraCapture(String explicitCameraId, CameraFacing cameraFacing, Size explicitSize, int maxSize, CameraAspectRatio aspectRatio) {
+        this.explicitCameraId = explicitCameraId;
+        this.cameraFacing = cameraFacing;
         this.explicitSize = explicitSize;
+        this.maxSize = maxSize;
+        this.aspectRatio = aspectRatio;
     }
 
     @Override
@@ -69,11 +66,16 @@ public class CameraCapture extends SurfaceCapture {
         cameraExecutor = new HandlerExecutor(cameraHandler);
 
         try {
-            String cameraId = selectCamera(cameraSelection);
+            cameraId = selectCamera(explicitCameraId, cameraFacing);
             if (cameraId == null) {
                 throw new IOException("No matching camera found");
             }
 
+            size = selectSize(cameraId, explicitSize, maxSize, aspectRatio);
+            if (size == null) {
+                throw new IOException("Could not select camera size");
+            }
+
             Ln.i("Using camera '" + cameraId + "'");
             cameraDevice = openCamera(cameraId);
         } catch (CameraAccessException | InterruptedException e) {
@@ -81,15 +83,15 @@ public class CameraCapture extends SurfaceCapture {
         }
     }
 
-    private String selectCamera(CameraSelection cameraSelection) throws CameraAccessException {
-        if (cameraSelection.hasId()) {
-            return cameraSelection.explicitCameraId;
+    private static String selectCamera(String explicitCameraId, CameraFacing cameraFacing) throws CameraAccessException {
+        if (explicitCameraId != null) {
+            return explicitCameraId;
         }
 
         CameraManager cameraManager = ServiceManager.getCameraManager();
 
         String[] cameraIds = cameraManager.getCameraIdList();
-        if (!cameraSelection.hasProperties()) {
+        if (cameraFacing == null) {
             // Use the first one
             return cameraIds.length > 0 ? cameraIds[0] : null;
         }
@@ -97,21 +99,66 @@ public class CameraCapture extends SurfaceCapture {
         for (String cameraId : cameraIds) {
             CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
 
-            if (cameraSelection.cameraFacing != null) {
-                int facing = characteristics.get(CameraCharacteristics.LENS_FACING);
-                if (cameraSelection.cameraFacing.value() != facing) {
-                    // Does not match
-                    continue;
-                }
+            int facing = characteristics.get(CameraCharacteristics.LENS_FACING);
+            if (cameraFacing.value() == facing) {
+                return cameraId;
             }
+        }
 
-            return cameraId;
+        // Not found
+        return null;
+    }
+
+    @TargetApi(Build.VERSION_CODES.N)
+    private static Size selectSize(String cameraId, Size explicitSize, int maxSize, CameraAspectRatio aspectRatio) throws CameraAccessException {
+        if (explicitSize != null) {
+            return explicitSize;
+        }
+
+        CameraManager cameraManager = ServiceManager.getCameraManager();
+        CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
+
+        StreamConfigurationMap configs = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
+        android.util.Size[] sizes = configs.getOutputSizes(MediaCodec.class);
+        Stream<android.util.Size> stream = Arrays.stream(sizes);
+        if (maxSize > 0) {
+            stream = stream.filter(it -> it.getWidth() <= maxSize && it.getHeight() <= maxSize);
+        }
+
+        Float targetAspectRatio = resolveAspectRatio(aspectRatio, characteristics);
+        if (targetAspectRatio != null) {
+            stream = stream.filter(it -> {
+                float ar = ((float) it.getWidth() / it.getHeight());
+                float arRatio = ar / targetAspectRatio;
+                // Accept if the aspect ratio is the target aspect ratio + or - 10%
+                return arRatio >= 0.9f && arRatio <= 1.1f;
+            });
+        }
+
+        Optional<android.util.Size> selected = stream.min(
+                Comparator.comparing(android.util.Size::getWidth).thenComparing(android.util.Size::getHeight).reversed());
+        if (selected.isPresent()) {
+            android.util.Size size = selected.get();
+            return new Size(size.getWidth(), size.getHeight());
         }
 
         // Not found
         return null;
     }
 
+    private static Float resolveAspectRatio(CameraAspectRatio ratio, CameraCharacteristics characteristics) {
+        if (ratio == null) {
+            return null;
+        }
+
+        if (ratio.isSensor()) {
+            Rect activeSize = characteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);
+            return (float) activeSize.width() / activeSize.height();
+        }
+
+        return ratio.getAspectRatio();
+    }
+
     @Override
     public void start(Surface surface) throws IOException {
         try {
@@ -137,12 +184,23 @@ public class CameraCapture extends SurfaceCapture {
 
     @Override
     public Size getSize() {
-        return explicitSize;
+        return size;
     }
 
     @Override
-    public boolean setMaxSize(int size) {
-        return false;
+    public boolean setMaxSize(int maxSize) {
+        if (explicitSize != null) {
+            return false;
+        }
+
+        this.maxSize = maxSize;
+        try {
+            size = selectSize(cameraId, null, maxSize, aspectRatio);
+            return true;
+        } catch (CameraAccessException e) {
+            Ln.w("Could not select camera size", e);
+            return false;
+        }
     }
 
     @SuppressLint("MissingPermission")

server/src/main/java/com/genymobile/scrcpy/Options.java

@@ -27,6 +27,7 @@ public class Options {
     private String cameraId;
     private Size cameraSize;
     private CameraFacing cameraFacing;
+    private CameraAspectRatio cameraAspectRatio;
     private boolean showTouches;
     private boolean stayAwake;
     private List<CodecOption> videoCodecOptions;
@@ -131,6 +132,10 @@ public class Options {
         return cameraFacing;
     }
 
+    public CameraAspectRatio getCameraAspectRatio() {
+        return cameraAspectRatio;
+    }
+
     public boolean getShowTouches() {
         return showTouches;
     }
@@ -374,6 +379,11 @@ public class Options {
                         options.cameraFacing = facing;
                     }
                     break;
+                case "camera_ar":
+                    if (!value.isEmpty()) {
+                        options.cameraAspectRatio = parseCameraAspectRatio(value);
+                    }
+                    break;
                 case "send_device_meta":
                     options.sendDeviceMeta = Boolean.parseBoolean(value);
                     break;
@@ -427,4 +437,20 @@ public class Options {
         int height = Integer.parseInt(tokens[1]);
         return new Size(width, height);
     }
+
+    private static CameraAspectRatio parseCameraAspectRatio(String ar) {
+        if ("sensor".equals(ar)) {
+            return CameraAspectRatio.sensorAspectRatio();
+        }
+
+        String[] tokens = ar.split(":");
+        if (tokens.length == 2) {
+            int w = Integer.parseInt(tokens[0]);
+            int h = Integer.parseInt(tokens[1]);
+            return CameraAspectRatio.fromFraction(w, h);
+        }
+
+        float floatAr = Float.parseFloat(tokens[0]);
+        return CameraAspectRatio.fromFloat(floatAr);
+    }
 }

server/src/main/java/com/genymobile/scrcpy/Server.java

@@ -138,9 +138,8 @@ public final class Server {
                 if (options.getVideoSource() == VideoSource.DISPLAY) {
                     surfaceCapture = new ScreenCapture(device);
                 } else {
-                    CameraCapture.CameraSelection cameraSelection = new CameraCapture.CameraSelection(options.getCameraId(),
-                            options.getCameraFacing());
-                    surfaceCapture = new CameraCapture(cameraSelection, options.getCameraSize());
+                    surfaceCapture = new CameraCapture(options.getCameraId(), options.getCameraFacing(), options.getCameraSize(),
+                            options.getMaxSize(), options.getCameraAspectRatio());
                 }
                 SurfaceEncoder surfaceEncoder = new SurfaceEncoder(surfaceCapture, videoStreamer, options.getVideoBitRate(), options.getMaxFps(),
                         options.getVideoCodecOptions(), options.getVideoEncoder(), options.getDownsizeOnError());