On 05.03.2018 07:53, Luiz Augusto von Dentz wrote:
Hi George,
On Sun, Mar 4, 2018 at 11:56 PM, Georg Chini <[email protected]> wrote:
The rewrite of the thread function does not change functionality much,
most of it is only cleanup, minor bug fixing and documentation work.
This patch also changes the send buffer size for a2dp sink to avoid lags
after temporary connection drops, following the proof-of-concept patch
posted by Dmitry Kalyanov.
Bug-Link: https://bugs.freedesktop.org/show_bug.cgi?id=58746
---
src/modules/bluetooth/module-bluez5-device.c | 271 ++++++++++++++++++---------
1 file changed, 178 insertions(+), 93 deletions(-)
diff --git a/src/modules/bluetooth/module-bluez5-device.c
b/src/modules/bluetooth/module-bluez5-device.c
index 7970dda7..7e5f8900 100644
--- a/src/modules/bluetooth/module-bluez5-device.c
+++ b/src/modules/bluetooth/module-bluez5-device.c
@@ -56,7 +56,6 @@ PA_MODULE_LOAD_ONCE(false);
PA_MODULE_USAGE("path=<device object path>"
"autodetect_mtu=<boolean>");
-#define MAX_PLAYBACK_CATCH_UP_USEC (100 * PA_USEC_PER_MSEC)
#define FIXED_LATENCY_PLAYBACK_A2DP (25 * PA_USEC_PER_MSEC)
#define FIXED_LATENCY_PLAYBACK_SCO (125 * PA_USEC_PER_MSEC)
#define FIXED_LATENCY_RECORD_A2DP (25 * PA_USEC_PER_MSEC)
@@ -660,6 +659,34 @@ static int a2dp_process_push(struct userdata *u) {
return ret;
}
+static void update_buffer_size(struct userdata *u) {
+ int old_bufsize;
+ socklen_t len = sizeof(int);
+ int ret;
+
+ ret = getsockopt(u->stream_fd, SOL_SOCKET, SO_SNDBUF, &old_bufsize, &len);
+ if (ret == -1) {
+ pa_log_warn("Changing bluetooth buffer size: Failed to
getsockopt(SO_SNDBUF): %s", pa_cstrerror(errno));
+ } else {
+ int new_bufsize;
+
+ /* Set send buffer size as small as possible. The minimum value is
1024 according to the
+ * socket man page. The data is written to the socket in chunks of
write_buffer_size,
+ * so there should at least be room for two chunks in the buffer.
Generally, write_buf_size
+ * is larger than 512. If not, use the next multiple of
write_block_size which is larger
+ * than 1024. */
+ new_bufsize = 2 * u->write_block_size;
+ if (new_bufsize < 1024)
+ new_bufsize = (1024 / u->write_block_size + 1) *
u->write_block_size;
+
+ ret = setsockopt(u->stream_fd, SOL_SOCKET, SO_SNDBUF, &new_bufsize,
len);
+ if (ret == -1)
+ pa_log_warn("Changing bluetooth buffer size: Failed to change from %d
to %d: %s", old_bufsize, new_bufsize, pa_cstrerror(errno));
+ else
+ pa_log_info("Changing bluetooth buffer size: Changed from %d to
%d", old_bufsize, new_bufsize);
+ }
+}
+
Not sure why you are doing getsockopt beforehand if you just use it to
print, perhaps you should check if any change should be done.
Yes, you are right, I will use it to see if a change is needed.
btw the
bluetoothd actually attempts to set a proper buffer size base on the
MTU size:
https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/profiles/audio/avdtp.c#n838
That does not seem to happen on my system. The buffer size is equal
to the default value found in /proc/sys/net/core/wmem_default (around
212 kB) and the same obviously seems to be true for other people,
otherwise they would not see lags.
The socket is packet based so we have to be careful if it end up
writing more than the MTU size the socket will reject the message,
perhaps we should set the buffer size in terms of ms, like buffer at
most 200ms, though bluetoothd cannot calculate that as it has no idea
what codec is in use, so it must be done in PA anyway.
We are currently writing to the buffer in chunks of write_block_size,
which is calculated from the MTU. Therefore I think using twice
the block size should be the correct choice.
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