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Add packet concealment for opus decoder in audiobridge
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Alexander Malaev committed Apr 2, 2024
1 parent cb6e491 commit 5b65bb2
Showing 1 changed file with 52 additions and 33 deletions.
85 changes: 52 additions & 33 deletions src/plugins/janus_audiobridge.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1698,9 +1698,9 @@ typedef struct janus_audiobridge_participant {
OpusDecoder *decoder; /* Opus decoder instance */
gboolean fec; /* Opus FEC status */
int expected_loss; /* Percentage of expected loss, to configure libopus FEC behaviour (default=0, no FEC even if negotiated) */
uint16_t expected_seq; /* Expected sequence number */
uint16_t probation; /* Used to determine new ssrc validity */
uint32_t last_timestamp; /* Last in seq timestamp */
uint16_t last_seq; /* Last sequence number */
gboolean reset; /* Whether or not the Opus context must be reset, without re-joining the room */
GThread *thread; /* Encoding thread for this participant */
gboolean mjr_active; /* Whether this participant has to be recorded to an mjr file or not */
Expand Down Expand Up @@ -2134,6 +2134,7 @@ static int janus_audiobridge_resample(int16_t *input, int input_num, int input_r
/* Jitter Buffer and queue-in settings */
#define JITTER_BUFFER_MIN_PACKETS 2
#define JITTER_BUFFER_MAX_PACKETS 40
#define JITTER_BUFFER_MAX_GAP_SIZE 20
#define JITTER_BUFFER_CHECK_USECS 1*G_USEC_PER_SEC
#define QUEUE_IN_MAX_PACKETS 4

Expand Down Expand Up @@ -6435,9 +6436,9 @@ static void *janus_audiobridge_handler(void *data) {
participant->decoder = NULL;
participant->reset = FALSE;
participant->fec = FALSE;
participant->expected_seq = 0;
participant->probation = 0;
participant->last_timestamp = 0;
participant->last_seq = 0;
janus_mutex_init(&participant->qmutex);
participant->arc = NULL;
janus_audiobridge_plainrtp_media_cleanup(&participant->plainrtp_media);
Expand Down Expand Up @@ -8547,8 +8548,9 @@ static void *janus_audiobridge_participant_thread(void *data) {
janus_audiobridge_rtp_relay_packet *mixedpkt = NULL;
janus_rtp_header *rtp = NULL;
gint64 now = janus_get_monotonic_time(), before = now;
gboolean first = TRUE, use_fec = FALSE;
gboolean first = TRUE;
int ret = 0;
int lost_packets_gap = 0;

/* Start working: check both the incoming queue (to decode and queue) and the outgoing one (to encode and send) */
while(!g_atomic_int_get(&stopping) && g_atomic_int_get(&session->destroyed) == 0) {
Expand All @@ -8572,9 +8574,53 @@ static void *janus_audiobridge_participant_thread(void *data) {
if(participant->jitter) {
ret = jitter_buffer_get(participant->jitter, &jbp, participant->codec == JANUS_AUDIOCODEC_OPUS ? 960 : 160, NULL);
jitter_buffer_tick(participant->jitter);
if(ret != JITTER_BUFFER_OK) {
/* No packet in the jitter buffer? Move on the talking detection, if needed */

if(!first && participant->codec == JANUS_AUDIOCODEC_OPUS && (ret == JITTER_BUFFER_MISSING || ret == JITTER_BUFFER_INSERTION) && lost_packets_gap <= JITTER_BUFFER_MAX_GAP_SIZE) {
lost_packets_gap += 1;

janus_mutex_unlock(&participant->qmutex);
locked = FALSE;

if(!g_atomic_int_compare_and_exchange(&participant->decoding, 0, 1)) {
/* This means we're cleaning up, so don't try to decode */
janus_audiobridge_buffer_packet_destroy(bpkt);
break;
}

int32_t output_samples;
opus_decoder_ctl(participant->decoder, OPUS_GET_LAST_PACKET_DURATION(&output_samples));

pkt = g_malloc(sizeof(janus_audiobridge_rtp_relay_packet));
pkt->data = g_malloc0(OPUS_SAMPLES * (participant->stereo ? 2 : 1) * sizeof(opus_int16));
pkt->ssrc = 0;
pkt->timestamp = participant->last_timestamp + 960;
pkt->seq_number = participant->last_seq + 1;
/* This is a redundant packet, so we can't parse any extension info */
pkt->silence = FALSE;
janus_audiobridge_participant_istalking(session, participant, NULL, NULL);
pkt->length = opus_decode(participant->decoder, NULL, 0, (opus_int16 *)pkt->data, output_samples, 0);
/* Get rid of the buffered packet */
janus_audiobridge_buffer_packet_destroy(bpkt);
/* Update the details */
participant->last_seq = pkt->seq_number;
participant->last_timestamp = pkt->timestamp;
g_atomic_int_set(&participant->decoding, 0);
if(pkt->length < 0) {
JANUS_LOG(LOG_ERR, "[Opus] Ops! got an error decoding the Opus frame: %d (%s)\n", pkt->length, opus_strerror(pkt->length));
g_free(pkt->data);
g_free(pkt);
break;
}
/* Queue the decoded packet for the mixer */
janus_mutex_lock(&participant->qmutex);
locked = TRUE;
/* Do not let queue-in grow too much */
guint count = g_list_length(participant->inbuf);
if((int) count > QUEUE_IN_MAX_PACKETS) {
JANUS_LOG(LOG_WARN, "Participant queue-in contains too many packets, clearing now (count=%u)\n", count);
janus_audiobridge_participant_clear_inbuf(participant);
}
participant->inbuf = g_list_append(participant->inbuf, pkt);
} else {
/* Decode the audio packet */
bpkt = (janus_audiobridge_buffer_packet *)jbp.data;
Expand All @@ -8598,34 +8644,7 @@ static void *janus_audiobridge_participant_thread(void *data) {
break;
}
rtp = (janus_rtp_header *)buffer;
/* If this is Opus, check if there's a packet gap we should fix with FEC */
use_fec = FALSE;
if(!first && participant->codec == JANUS_AUDIOCODEC_OPUS && participant->fec) {
if(ntohs(rtp->seq_number) == (participant->expected_seq + 1)) {
/* Lost a packet here? Use FEC to recover */
use_fec = TRUE;
}
}
first = FALSE;
if(use_fec) {
/* There was a gap, try to get decode from redundant info first */
pkt = g_malloc(sizeof(janus_audiobridge_rtp_relay_packet));
pkt->data = g_malloc0(BUFFER_SAMPLES*sizeof(opus_int16));
pkt->ssrc = 0;
pkt->timestamp = participant->last_timestamp + 960; /* FIXME */
pkt->seq_number = participant->expected_seq; /* FIXME */
/* This is a redundant packet, so we can't parse any extension info */
pkt->silence = FALSE;
/* Decode the lost packet using fec=1 */
int32_t output_samples;
opus_decoder_ctl(participant->decoder, OPUS_GET_LAST_PACKET_DURATION(&output_samples));
pkt->length = opus_decode(participant->decoder, payload, plen, (opus_int16 *)pkt->data, output_samples, 1);
/* Queue the decoded redundant packet for the mixer */
janus_mutex_lock(&participant->qmutex);
participant->inbuf = g_list_append(participant->inbuf, pkt);
janus_mutex_unlock(&participant->qmutex);
/* Now we can process the next packet */
}
/* Decode the packet */
pkt = g_malloc(sizeof(janus_audiobridge_rtp_relay_packet));
pkt->data = g_malloc0(BUFFER_SAMPLES*sizeof(opus_int16));
Expand Down Expand Up @@ -8663,8 +8682,8 @@ static void *janus_audiobridge_participant_thread(void *data) {
/* Get rid of the buffered packet */
janus_audiobridge_buffer_packet_destroy(bpkt);
/* Update the details */
participant->last_seq = pkt->seq_number;
participant->last_timestamp = pkt->timestamp;
participant->expected_seq = pkt->seq_number + 1;
g_atomic_int_set(&participant->decoding, 0);
if(pkt->length < 0) {
if(participant->codec == JANUS_AUDIOCODEC_OPUS) {
Expand Down

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