Support recording to MKV

Implement recording to Matroska files.

The format to use is determined by the option -F/--record-format if set,
or by the file extension (".mp4" or ".mkv").

app/src/main.c

@@ -7,11 +7,13 @@
 
 #include "config.h"
 #include "log.h"
+#include "recorder.h"
 
 struct args {
     const char *serial;
     const char *crop;
     const char *record_filename;
+    enum recorder_format record_format;
     SDL_bool fullscreen;
     SDL_bool help;
     SDL_bool version;
@@ -42,6 +44,9 @@ static void usage(const char *arg0) {
         "    -f, --fullscreen\n"
         "        Start in fullscreen.\n"
         "\n"
+        "    -F, --record-format\n"
+        "        Force recording format (either mp4 or mkv).\n"
+        "\n"
         "    -h, --help\n"
         "        Print this help.\n"
         "\n"
@@ -57,6 +62,8 @@ static void usage(const char *arg0) {
         "\n"
         "    -r, --record file.mp4\n"
         "        Record screen to file.\n"
+        "        The format is determined by the -F/--record-format option if\n"
+        "        set, or by the file extension (.mp4 or .mkv).\n"
         "\n"
         "    -s, --serial\n"
         "        The device serial number. Mandatory only if several devices\n"
@@ -208,6 +215,36 @@ static SDL_bool parse_port(char *optarg, Uint16 *port) {
     return SDL_TRUE;
 }
 
+static SDL_bool
+parse_record_format(const char *optarg, enum recorder_format *format) {
+    if (!strcmp(optarg, "mp4")) {
+        *format = RECORDER_FORMAT_MP4;
+        return SDL_TRUE;
+    }
+    if (!strcmp(optarg, "mkv")) {
+        *format = RECORDER_FORMAT_MKV;
+        return SDL_TRUE;
+    }
+    LOGE("Unsupported format: %s (expected mp4 or mkv)", optarg);
+    return SDL_FALSE;
+}
+
+static enum recorder_format
+guess_record_format(const char *filename) {
+    size_t len = strlen(filename);
+    if (len < 4) {
+        return 0;
+    }
+    const char *ext = &filename[len - 4];
+    if (!strcmp(ext, ".mp4")) {
+        return RECORDER_FORMAT_MP4;
+    }
+    if (!strcmp(ext, ".mkv")) {
+        return RECORDER_FORMAT_MKV;
+    }
+    return 0;
+}
+
 static SDL_bool parse_args(struct args *args, int argc, char *argv[]) {
     static const struct option long_options[] = {
         {"always-on-top", no_argument,       NULL, 'T'},
@@ -218,13 +255,14 @@ static SDL_bool parse_args(struct args *args, int argc, char *argv[]) {
         {"max-size",      required_argument, NULL, 'm'},
         {"port",          required_argument, NULL, 'p'},
         {"record",        required_argument, NULL, 'r'},
+        {"record-format", required_argument, NULL, 'f'},
         {"serial",        required_argument, NULL, 's'},
         {"show-touches",  no_argument,       NULL, 't'},
         {"version",       no_argument,       NULL, 'v'},
         {NULL,            0,                 NULL, 0  },
     };
     int c;
-    while ((c = getopt_long(argc, argv, "b:c:fhm:p:r:s:tTv", long_options, NULL)) != -1) {
+    while ((c = getopt_long(argc, argv, "b:c:fF:hm:p:r:s:tTv", long_options, NULL)) != -1) {
         switch (c) {
             case 'b':
                 if (!parse_bit_rate(optarg, &args->bit_rate)) {
@@ -237,6 +275,11 @@ static SDL_bool parse_args(struct args *args, int argc, char *argv[]) {
             case 'f':
                 args->fullscreen = SDL_TRUE;
                 break;
+            case 'F':
+                if (!parse_record_format(optarg, &args->record_format)) {
+                    return SDL_FALSE;
+                }
+                break;
             case 'h':
                 args->help = SDL_TRUE;
                 break;
@@ -276,6 +319,21 @@ static SDL_bool parse_args(struct args *args, int argc, char *argv[]) {
         LOGE("Unexpected additional argument: %s", argv[index]);
         return SDL_FALSE;
     }
+
+    if (args->record_format && !args->record_filename) {
+        LOGE("Record format specified without recording");
+        return SDL_FALSE;
+    }
+
+    if (args->record_filename && !args->record_format) {
+        args->record_format = guess_record_format(args->record_filename);
+        if (!args->record_format) {
+            LOGE("No format specified for \"%s\" (try with -F mkv)",
+                 args->record_filename);
+            return SDL_FALSE;
+        }
+    }
+
     return SDL_TRUE;
 }
 
@@ -290,6 +348,7 @@ int main(int argc, char *argv[]) {
         .serial = NULL,
         .crop = NULL,
         .record_filename = NULL,
+        .record_format = 0,
         .help = SDL_FALSE,
         .version = SDL_FALSE,
         .show_touches = SDL_FALSE,
@@ -329,6 +388,7 @@ int main(int argc, char *argv[]) {
         .crop = args.crop,
         .port = args.port,
         .record_filename = args.record_filename,
+        .record_format = args.record_format,
         .max_size = args.max_size,
         .bit_rate = args.bit_rate,
         .show_touches = args.show_touches,