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%)

PR #4213 <https://github.com/Genymobile/scrcpy/pull/4213>

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",
@@ -2130,6 +2140,9 @@ 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;
@@ -2245,9 +2258,16 @@ 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");
-            return false;
+        if (opts->camera_size) {
+            if (opts->max_size) {
+                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) {
@@ -2255,6 +2275,7 @@ 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;