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Revise resend interval calculation to spread it out over a long latency.

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This commit is contained in:
Mike Brady
2018-05-15 12:08:01 +01:00
parent c2849b71ee
commit b9d3a036b1
3 changed files with 46 additions and 26 deletions
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player.c
+18 -13
View File
@@ -512,25 +512,30 @@ void player_put_packet(seq_t seqno, uint32_t actual_timestamp, int64_t timestamp
}
// here, we should check for missing frames
int resend_interval = (((250 * 44100) / 352) / 1000); // approximately 250 ms intervals
const int number_of_resend_attempts = 8;
int latency_based_resend_interval =
(conn->latency) / (number_of_resend_attempts * conn->max_frames_per_packet);
if (latency_based_resend_interval > resend_interval)
resend_interval = latency_based_resend_interval;
if (conn->resend_interval != resend_interval) {
debug(1, "Resend interval for latency of %" PRId64 " frames is %d frames.", conn->latency,
resend_interval);
conn->resend_interval = resend_interval;
}
if (!conn->ab_buffering) {
int j;
for (j = 1; j <= number_of_resend_attempts; j++) {
// check j times, after a short period of has elapsed, assuming 352 frames per packet
// int back_step = (((250 * 44100) / 352) / 1000) * (j); // approx 250 ms intervals
// int back_step = ((BUFFER_FRAMES-(22050/352)) / number_of_resend_attempts) * j;
int back_step = ((seq_diff(conn->ab_read, conn->ab_write,
conn->ab_read)-(22050/352)) / number_of_resend_attempts) * j;
if (back_step<(((190 * 44100) / 352) / 1000) * j) {
// debug(1,"resend request back_step %d is too small. Reset to %d.",back_step,(((190 * 44100) / 352) / 1000) * j);
back_step = (((190 * 44100) / 352) / 1000) * j;
}
int back_step = resend_interval * j;
int32_t sd = seq_diff(conn->ab_read, conn->ab_write, conn->ab_read);
int k;
for (k = -2; k <= 2; k++) {
if (back_step <
seq_diff(conn->ab_read, conn->ab_write,
conn->ab_read)) { // if it's within the range of frames in use...
int item_to_check = (conn->ab_write - back_step) & 0xffff;
if ((back_step + k) < sd) { // if it's within the range of frames in use...
int item_to_check = (conn->ab_write - back_step + k) & 0xffff;
seq_t next = item_to_check;
abuf_t *check_buf = conn->audio_buffer + BUFIDX(next);
if ((!check_buf->ready) &&
@@ -539,7 +544,7 @@ void player_put_packet(seq_t seqno, uint32_t actual_timestamp, int64_t timestamp
check_buf->resend_level = j;
if (config.disable_resend_requests == 0) {
rtp_request_resend(next, 1, conn);
if (j >= 6)
if (j >= number_of_resend_attempts - 2)
debug(2, "Resend request level #%d for packet %u in range %u to %u.", j, next,
conn->ab_read, conn->ab_write);
conn->resend_requests++;
player.h
+12 -1
View File
@@ -46,7 +46,17 @@ typedef struct audio_buffer_entry { // decoded audio packets
} abuf_t;
// default buffer size
// needs to be a power of 2 because of the way BUFIDX(seqno) works
// This eeds to be a power of 2 because of the way BUFIDX(seqno) works.
// 512 is the minimum for normal operation -- it gives 512*352/44100 or just over 4 seconds of
// buffers.
// For at least 10 seconds, you need to go to 2048.
// Resend requests will be spaced out evenly in the latency period, subject to a minimum interval of
// about 0.25 seconds.
// Each buffer occupies 352*4 bytes plus about, say, 64 bytes of overhead in various places, say
// rougly 1,500 bytes per buffer.
// Thus, 2048 buffers will occupy about 3 megabytes -- no big deal in a normal machine but maybe a
// problem in an embedded device.
#define BUFFER_FRAMES 1024
typedef struct {
@@ -57,6 +67,7 @@ typedef struct {
typedef struct {
int connection_number; // for debug ID purposes, nothing else...
int resend_interval; // this is really just for debugging
int AirPlayVersion; // zero if not an AirPlay session. Used to help calculate latency
int64_t latency; // the actual latency used for this play session
int64_t minimum_latency; // set if an a=min-latency: line appears in the ANNOUNCE message; zero
shairport.c
+16 -12
View File
@@ -274,7 +274,7 @@ int parse_options(int argc, char **argv) {
optind = j;
optCon = poptGetContext(NULL, optind, (const char **)argv, optionsTable, 0);
if (optCon==NULL)
if (optCon == NULL)
die("Can not get a secondary popt context.");
poptSetOtherOptionHelp(optCon, "[OPTIONS]* ");
@@ -321,7 +321,7 @@ int parse_options(int argc, char **argv) {
}
poptFreeContext(optCon);
if ((daemonisewith) && (daemonisewithout))
die("Select either daemonize_with_pid_file or daemonize_without_pid_file -- you have selected "
"both!");
@@ -892,7 +892,7 @@ int parse_options(int argc, char **argv) {
optind = j;
optCon = poptGetContext(NULL, optind, (const char **)argv, optionsTable, 0);
if (optCon==NULL)
if (optCon == NULL)
die("Can not get a popt context.");
poptSetOtherOptionHelp(optCon, "[OPTIONS]* ");
@@ -1052,13 +1052,13 @@ void shairport_startup_complete(void) {
}
}
const char *pid_file_proc(char* fn,size_t max_length) {
const char *pid_file_proc(char *fn, size_t max_length) {
if (fn) {
snprintf(fn, max_length, "%s/%s.pid", config.computed_piddir,
daemon_pid_file_ident ? daemon_pid_file_ident : "unknown");
// debug(1,"fn \"%s\".",fn);
} else {
debug(1,"the sise of the buffer for the PID file path is zero.");
debug(1, "the sise of the buffer for the PID file path is zero.");
}
return fn;
}
@@ -1358,12 +1358,16 @@ int main(int argc, char **argv) {
// audio_backend_latency_offset instead.
if (config.userSuppliedLatency) {
inform("The fixed latency setting is deprecated, as Shairport Sync can now get the correct "
"latency from the source.");
inform("Please remove this setting and use the relevant audio_backend_latency_offset setting, "
"if necessary, to compensate for delays elsewhere.");
if ((config.userSuppliedLatency!=0) && ((config.userSuppliedLatency<4410) || (config.userSuppliedLatency>BUFFER_FRAMES*352-22050)))
die("An out-of-range fixed latency has been specified. It must be between 4410 and %d (at 44100 frames per second).",BUFFER_FRAMES*352-22050);
inform("The fixed latency setting is deprecated, as Shairport Sync gets the correct "
"latency automatically from the source.");
inform("Use the audio_backend_latency_offset_in_seconds setting "
"instead to compensate for timing issues.");
if ((config.userSuppliedLatency != 0) &&
((config.userSuppliedLatency < 4410) ||
(config.userSuppliedLatency > BUFFER_FRAMES * 352 - 22050)))
die("An out-of-range fixed latency has been specified. It must be between 4410 and %d (at "
"44100 frames per second).",
BUFFER_FRAMES * 352 - 22050);
}
/* print out version */
@@ -1380,7 +1384,7 @@ int main(int argc, char **argv) {
/* Print out options */
debug(1, "statistics_requester status is %d.", config.statistics_requested);
debug(1, "daemon status is %d.", config.daemonise);
debug(1, "deamon pid file is \"%s\".", pid_file_proc(pid_file_path_string,4096));
debug(1, "deamon pid file is \"%s\".", pid_file_proc(pid_file_path_string, 4096));
debug(1, "rtsp listening port is %d.", config.port);
debug(1, "udp base port is %d.", config.udp_port_base);
debug(1, "udp port range is %d.", config.udp_port_range);