Always keep CVSD read buffer bigger than read MTU

Read less data than the SCO MTU might cause issues with prompt SCO
buffer flushing, which in turn might cause audio issues.

Fixes #510

configure.ac

@@ -3,7 +3,7 @@
 
 AC_PREREQ([2.60])
 AC_INIT([BlueALSA],
-	[m4_normalize(esyscmd([test -d .git && git describe || echo v3.1.0]))],
+	[m4_normalize(esyscmd([test -d .git && git describe --always --dirty || echo v3.1.0]))],
 	[[email protected]], [bluez-alsa], [https://github.com/Arkq/bluez-alsa])
 AM_INIT_AUTOMAKE([foreign subdir-objects -Wall -Werror])
 

src/a2dp-aac.c

@@ -404,14 +404,15 @@ static void *a2dp_aac_dec_thread(struct ba_transport_thread *th) {
 		}
 
 		if (ffb_len_in(&latm) < rtp_latm_len) {
-			debug("Resizing LATM buffer: %zd -> %zd", latm.size, latm.size + t->mtu_read);
-			size_t prev_len = ffb_len_out(&latm);
-			ffb_init_uint8_t(&latm, latm.nmemb + t->mtu_read);
-			ffb_seek(&latm, prev_len);
+			debug("Resizing LATM buffer: %zd -> %zd", latm.nmemb, latm.nmemb + t->mtu_read);
+			if (ffb_init_uint8_t(&latm, latm.nmemb + t->mtu_read) == -1)
+				error("Couldn't resize LATM buffer: %s", strerror(errno));
 		}
 
-		memcpy(latm.tail, rtp_latm, rtp_latm_len);
-		ffb_seek(&latm, rtp_latm_len);
+		if (ffb_len_in(&latm) >= rtp_latm_len) {
+			memcpy(latm.tail, rtp_latm, rtp_latm_len);
+			ffb_seek(&latm, rtp_latm_len);
+		}
 
 		if (markbit_quirk != 1 && !rtp_header->markbit) {
 			debug("Fragmented RTP packet [%u]: LATM len: %zd", rtp_seq_number, rtp_latm_len);

src/sco.c

@@ -286,10 +286,13 @@ static void *sco_cvsd_dec_thread(struct ba_transport_thread *th) {
 	struct ba_transport_pcm *pcm = &t->sco.mic_pcm;
 	struct io_poll io = { .timeout = -1 };
 
+	const size_t mtu_samples = t->mtu_read / sizeof(int16_t);
+	const size_t mtu_samples_multiplier = 2;
+
 	ffb_t buffer = { 0 };
 	pthread_cleanup_push(PTHREAD_CLEANUP(ffb_free), &buffer);
 
-	if (ffb_init_int16_t(&buffer, t->mtu_read) == -1) {
+	if (ffb_init_int16_t(&buffer, mtu_samples * mtu_samples_multiplier) == -1) {
 		error("Couldn't create data buffers: %s", strerror(errno));
 		goto fail_ffb;
 	}
@@ -303,6 +306,13 @@ static void *sco_cvsd_dec_thread(struct ba_transport_thread *th) {
 		else if (len == 0)
 			goto exit;
 
+		if ((size_t)len == buffer.nmemb * buffer.size) {
+			debug("Resizing CVSD read buffer: %zd -> %zd",
+					buffer.nmemb * buffer.size, buffer.nmemb * buffer.size * 2);
+			if (ffb_init_int16_t(&buffer, buffer.nmemb * 2) == -1)
+				error("Couldn't resize CVSD read buffer: %s", strerror(errno));
+		}
+
 		if (!ba_transport_pcm_is_active(pcm))
 			continue;
 

src/shared/ffb.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - ffb.c
- * Copyright (c) 2016-2020 Arkadiusz Bokowy
+ * Copyright (c) 2016-2021 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -26,7 +26,10 @@ int ffb_init(ffb_t *ffb, size_t nmemb, size_t size) {
 	if ((ptr = realloc(ffb->data, nmemb * size)) == NULL)
 		return -1;
 
-	ffb->data = ffb->tail = ptr;
+	size_t len = ffb_blen_out(ffb);
+
+	ffb->data = ptr;
+	ffb->tail = (uint8_t *)ptr + len;
 	ffb->nmemb = nmemb;
 	ffb->size = size;
 

test/test-utils.c

@@ -183,7 +183,7 @@ START_TEST(test_difftimespec) {
 
 } END_TEST
 
-START_TEST(test_fifo_buffer) {
+START_TEST(test_ffb) {
 
 	ffb_t ffb_u8 = { 0 };
 	ffb_t ffb_16 = { 0 };
@@ -241,6 +241,29 @@ START_TEST(test_fifo_buffer) {
 
 } END_TEST
 
+START_TEST(test_ffb_resize) {
+
+	const char *data = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+	const size_t data_len = strlen(data);
+
+	ffb_t ffb = { 0 };
+	ck_assert_int_eq(ffb_init_uint8_t(&ffb, 64), 0);
+
+	memcpy(ffb.data, data, data_len);
+	ffb_seek(&ffb, data_len);
+
+	ck_assert_int_eq(ffb_len_out(&ffb), data_len);
+	ck_assert_int_eq(ffb_len_in(&ffb), 64 - data_len);
+	ck_assert_int_eq(memcmp(ffb.data, data, data_len), 0);
+
+	ck_assert_int_eq(ffb_init_uint8_t(&ffb, 128), 0);
+
+	ck_assert_int_eq(ffb_len_out(&ffb), data_len);
+	ck_assert_int_eq(ffb_len_in(&ffb), 128 - data_len);
+	ck_assert_int_eq(memcmp(ffb.data, data, data_len), 0);
+
+} END_TEST
+
 int main(void) {
 
 	Suite *s = suite_create(__FILE__);
@@ -255,7 +278,9 @@ int main(void) {
 	tcase_add_test(tc, test_g_variant_sanitize_object_path);
 	tcase_add_test(tc, test_batostr_);
 	tcase_add_test(tc, test_difftimespec);
-	tcase_add_test(tc, test_fifo_buffer);
+
+	tcase_add_test(tc, test_ffb);
+	tcase_add_test(tc, test_ffb_resize);
 
 	srunner_run_all(sr, CK_ENV);
 	int nf = srunner_ntests_failed(sr);