Rework rec

rec.c

@@ -13,94 +13,116 @@ struct input_event {
 	unsigned int value;
 };
 
-#define HISTSIZE 60
+/* We keep recording all the time, creating a history of BUF_HIST bytes.
+ * Once a key action has been registered, we store our history and
+ * record another BUF_POST bytes.
+ *
+ * Those exact values depend on your machine. We don't do
+ * auto-detection. */
+#define BUF_HIST (44100 / 32)
+#define BUF_POST (44100 / 2)
+
+void
+samplename(char *buf, size_t buf_len, unsigned short code, unsigned int value)
+{
+	int i;
+
+	for (i = 0; i < 10; i++)
+	{
+		snprintf(buf, buf_len, "wav-new/%02x-%d-%d.wav", code, value, i);
+		if (access(buf, R_OK) == -1)
+			return;
+	}
+
+	fprintf(stderr, "Damn, you recorded too many samples for %02x %d\n", code, value);
+	exit(EXIT_FAILURE);
+}
 
 int main(int argc, char **argv)
 {
 	struct input_event event;
 	char cmd[256];
 	char fname[256];
 	FILE *f;
-	int fd_ev, fd_snd;
-	int samples = 0;
+	int fd_snd;
 	int triggered = 0;
 	FILE *fout = NULL;
-	int head = 0;
-	int16_t hist[HISTSIZE];
-
-	if(argc < 2) {
-		fprintf(stderr, "usage: %s </dev/input/event#>\n", argv[0]);
-		exit(1);
-	}
+	int16_t hist[BUF_HIST], post[BUF_POST];
+	size_t hist_at = 0;
+
+	/* Run like:
+	 *
+	 *     $ (sleep 2; sudo stdbuf -i0 -o0 cat /dev/input/event5) | ./rec
+	 *
+	 * Begin with a sleep, so we don't catch the "Return, released"
+	 * event that started this command. */
+	fprintf(stderr, "Waiting for evdev data on stdin ...\n");
 
 	//f = popen("arecord -D plughw:1,0 -f cd -r 44100 -c 1", "r");
-	f = popen("parec --rate=44100 --format=s16le --channels=1", "r");
+	f = popen("parec --rate=44100 --format=s16le --channels=1 --latency=2", "r");
 	fd_snd = fileno(f);
 
-	fd_ev = open(argv[1], O_RDONLY);
-	if(fd_ev == -1) {
-		perror("Could not open event input");
-		exit(1);
-	}
-
 	fd_set fds;
 	while(1) {
 		FD_ZERO(&fds);
-		FD_SET(fd_ev, &fds);
+		FD_SET(STDIN_FILENO, &fds);
 		FD_SET(fd_snd, &fds);
 
 		select(16, &fds, NULL, NULL, NULL);
 
-		if(FD_ISSET(fd_ev, &fds)) {
+		if(FD_ISSET(STDIN_FILENO, &fds)) {
 
-			read(fd_ev, &event, sizeof event);
+			read(STDIN_FILENO, &event, sizeof event);
 
 			if(event.type != 1) continue;
 			if(event.value == 2) continue;
 
 			if(triggered == 0) {
-				snprintf(fname, sizeof fname, "wav-new/%02x-%d.wav", event.code, event.value);
+				samplename(fname, sizeof fname, event.code, event.value);
 				snprintf(cmd, sizeof cmd, "sox -qq -r 44100 -e signed -b 16 -c 1 -t raw - %s", fname);
 				printf("%02x %d: ", event.code, event.value);
 				fflush(stdout);
 				fout = popen(cmd, "w");
-				samples = 0;
 				triggered = 1;
 				printf("%02x %d ", event.code, event.value);
 				fflush(stdout);
 			}
 		}
 
-		if(FD_ISSET(fd_snd, &fds)) {
-			int16_t buf;
-			read(fd_snd, &buf, sizeof buf);
-
-			if(triggered) {
-				if(samples == 0) {
-					if(buf < -2000 || buf > 2000) {
-						samples = 1;
-						printf(">");
-						fflush(stdout);
-					}
-				}
-
-				if(fout && samples) {
-					fwrite(&hist[head], 1, sizeof hist[head], fout);
-					if(samples > 44000/3) {
-						fclose(fout);
-						snprintf(cmd, sizeof(cmd), "paplay %s &", fname);
-						system(cmd);
-						printf(".\n");
-						fout = NULL;
-						triggered = 0;
-					}
-				}
-
-				if(samples) samples ++;
+		if (triggered)
+		{
+			size_t history_i = 0;
+			printf(">");
+			fflush(stdout);
+
+			/* Write history. */
+			for (history_i = 0; history_i < BUF_HIST; history_i++)
+			{
+				hist_at++;
+				hist_at %= BUF_HIST;
+				fwrite(&hist[hist_at], sizeof (int16_t), 1, fout);
 			}
 
-			hist[head] = buf;
-			head = (head + 1) % HISTSIZE;
+			/* Record additional samples. */
+			fread(&post, BUF_POST, 1, f);
+			fwrite(&post, BUF_POST, 1, fout);
+
+			/* Close pipe and play back for examination. */
+			fclose(fout);
+			snprintf(cmd, sizeof(cmd), "paplay %s &", fname);
+			system(cmd);
+			printf(".\n");
+			fout = NULL;
+			triggered = 0;
+			hist_at = 0;
+		}
+
+		if(FD_ISSET(fd_snd, &fds)) {
+			/* Audio data ready to read but we haven't registered a key,
+			 * so add those two bytes to our history. */
+			read(fd_snd, &hist[hist_at], sizeof (int16_t));
+			hist_at++;
+			hist_at %= BUF_HIST;
 		}
 
 	}