Calculate codec processing delay on first transfer

src/a2dp-aac.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-aac.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -374,6 +374,12 @@ void *a2dp_aac_enc_thread(struct ba_transport_pcm *t_pcm) {
 						goto fail;
 					}
 
+					if (!io.initiated) {
+						/* Get the delay due to codec processing. */
+						t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+						io.initiated = true;
+					}
+
 					/* resend RTP header */
 					len -= RTP_HEADER_LEN;
 
@@ -390,14 +396,11 @@ void *a2dp_aac_enc_thread(struct ba_transport_pcm *t_pcm) {
 			}
 
 			unsigned int pcm_frames = out_args.numInSamples / info.inputChannels;
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* If the input buffer was not consumed, we have to append new data to
 			 * the existing one. Since we do not use ring buffer, we will simply
 			 * move unprocessed data to the front of our linear buffer. */

src/a2dp-aptx-hd.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-aptx-hd.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -205,15 +205,18 @@ void *a2dp_aptx_hd_enc_thread(struct ba_transport_pcm *t_pcm) {
 				goto fail;
 			}
 
+			if (!io.initiated) {
+				/* Get the delay due to codec processing. */
+				t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+				io.initiated = true;
+			}
+
 			unsigned int pcm_frames = pcm_samples / channels;
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp.ts_pcm_frames += pcm_frames;
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* reinitialize output buffer */
 			ffb_rewind(&bt);
 

src/a2dp-aptx.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-aptx.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -189,11 +189,14 @@ void *a2dp_aptx_enc_thread(struct ba_transport_pcm *t_pcm) {
 				goto fail;
 			}
 
-			/* keep data transfer at a constant bit rate */
-			asrsync_sync(&io.asrs, pcm_samples / channels);
+			if (!io.initiated) {
+				/* Get the delay due to codec processing. */
+				t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+				io.initiated = true;
+			}
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
+			/* Keep data transfer at a constant bit rate. */
+			asrsync_sync(&io.asrs, pcm_samples / channels);
 
 			/* reinitialize output buffer */
 			ffb_rewind(&bt);

src/a2dp-faststream.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-faststream.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -213,15 +213,18 @@ void *a2dp_fs_enc_thread(struct ba_transport_pcm *t_pcm) {
 				goto fail;
 			}
 
+			if (!io.initiated) {
+				/* Get the delay due to codec processing. */
+				t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+				io.initiated = true;
+			}
+
 			/* make room for new FastStream frames */
 			ffb_rewind(&bt);
 
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use
 			 * ring buffer, we will simply move unprocessed data to the front

src/a2dp-lc3plus.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-lc3plus.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -353,6 +353,12 @@ void *a2dp_lc3plus_enc_thread(struct ba_transport_pcm *t_pcm) {
 					goto fail;
 				}
 
+				if (!io.initiated) {
+					/* Get the delay due to codec processing. */
+					t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+					io.initiated = true;
+				}
+
 				/* resend RTP headers */
 				len -= rtp_headers_len;
 
@@ -370,14 +376,11 @@ void *a2dp_lc3plus_enc_thread(struct ba_transport_pcm *t_pcm) {
 
 			}
 
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use
 			 * ring buffer, we will simply move unprocessed data to the front

src/a2dp-ldac.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-ldac.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -244,6 +244,12 @@ void *a2dp_ldac_enc_thread(struct ba_transport_pcm *t_pcm) {
 					goto fail;
 				}
 
+				if (!io.initiated) {
+					/* Get the delay due to codec processing. */
+					t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+					io.initiated = true;
+				}
+
 				if (errno == EAGAIN)
 					/* The io_bt_write() call was blocking due to not enough
 					 * space in the BT socket. Set the queued_bytes to some
@@ -256,14 +262,11 @@ void *a2dp_ldac_enc_thread(struct ba_transport_pcm *t_pcm) {
 			}
 
 			unsigned int pcm_frames = pcm_samples / channels;
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 		}
 
 		/* If the input buffer was not consumed (due to codesize limit), we

src/a2dp-lhdc.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-lhdc.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  * Copyright (c) 2023      anonymix007
  *
  * This file is a part of bluez-alsa.
@@ -275,6 +275,12 @@ void *a2dp_lhdc_enc_thread(struct ba_transport_pcm *t_pcm) {
 					goto fail;
 				}
 
+				if (!io.initiated) {
+					/* Get the delay due to codec processing. */
+					t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+					io.initiated = true;
+				}
+
 				if (errno == EAGAIN)
 					/* The io_bt_write() call was blocking due to not enough
 					 * space in the BT socket. Set the queued_bytes to some
@@ -287,14 +293,11 @@ void *a2dp_lhdc_enc_thread(struct ba_transport_pcm *t_pcm) {
 			}
 
 			unsigned int pcm_frames = lhdc_pcm_samples / channels;
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 		}
 
 		/* If the input buffer was not consumed (due to codesize limit), we

src/a2dp-mpeg.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-mpeg.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -294,6 +294,12 @@ void *a2dp_mp3_enc_thread(struct ba_transport_pcm *t_pcm) {
 					goto fail;
 				}
 
+				if (!io.initiated) {
+					/* Get the delay due to codec processing. */
+					t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+					io.initiated = true;
+				}
+
 				/* account written payload only */
 				len -= RTP_HEADER_LEN + sizeof(*rtp_mpeg_audio_header);
 
@@ -309,14 +315,11 @@ void *a2dp_mp3_enc_thread(struct ba_transport_pcm *t_pcm) {
 
 		}
 
-		/* keep data transfer at a constant bit rate */
+		/* Keep data transfer at a constant bit rate. */
 		asrsync_sync(&io.asrs, pcm_frames);
 		/* move forward RTP timestamp clock */
 		rtp_state_update(&rtp, pcm_frames);
 
-		/* update busy delay (encoding overhead) */
-		t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 		/* If the input buffer was not consumed (due to frame alignment), we
 		 * have to append new data to the existing one. Since we do not use
 		 * ring buffer, we will simply move unprocessed data to the front

src/a2dp-opus.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-opus.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -230,14 +230,17 @@ void *a2dp_opus_enc_thread(struct ba_transport_pcm *t_pcm) {
 				goto fail;
 			}
 
-			/* keep data transfer at a constant bit rate */
+			if (!io.initiated) {
+				/* Get the delay due to codec processing. */
+				t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+				io.initiated = true;
+			}
+
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, opus_frame_pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, opus_frame_pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* If the input buffer was not consumed (due to encoder frame
 			 * constraint), we have to append new data to the existing one.
 			 * Since we do not use ring buffer, we will simply move data

src/a2dp-sbc.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - a2dp-sbc.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -259,14 +259,22 @@ void *a2dp_sbc_enc_thread(struct ba_transport_pcm *t_pcm) {
 				goto fail;
 			}
 
-			/* keep data transfer at a constant bit rate */
+			if (!io.initiated) {
+				/* Get the codec processing delay, which is a time spent in the
+				 * processing loop between reading PCM data and writing the first
+				 * encoded SBC frame. Subsequently encoded frames do not contribute
+				 * to the delay, because (assuming no underruns) since the first
+				 * frame is written, the BT sink can start decoding and playing
+				 * audio in a continuous fashion. */
+				t_pcm->processing_delay_dms = asrsync_get_dms_since_last_sync(&io.asrs);
+				io.initiated = true;
+			}
+
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, pcm_frames);
 			/* move forward RTP timestamp clock */
 			rtp_state_update(&rtp, pcm_frames);
 
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
-
 			/* If the input buffer was not consumed (due to codesize limit), we
 			 * have to append new data to the existing one. Since we do not use
 			 * ring buffer, we will simply move unprocessed data to the front

src/io.c

@@ -347,6 +347,7 @@ ssize_t io_poll_and_read_pcm(
 		case BA_TRANSPORT_PCM_SIGNAL_OPEN:
 		case BA_TRANSPORT_PCM_SIGNAL_RESUME:
 			io->asrs.frames = 0;
+			io->initiated = false;
 			io->timeout = -1;
 			goto repoll;
 		case BA_TRANSPORT_PCM_SIGNAL_CLOSE:

src/io.h

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - io.h
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -16,6 +16,7 @@
 # include <config.h>
 #endif
 
+#include <stdbool.h>
 #include <sys/types.h>
 
 #include "ba-transport-pcm.h"
@@ -30,6 +31,8 @@
 struct io_poll {
 	/* transfer bit rate synchronization */
 	struct asrsync asrs;
+	/* transfer has been initiated */
+	bool initiated;
 	/* keep-alive and sync timeout */
 	int timeout;
 };

src/sco-cvsd.c

@@ -1,6 +1,6 @@
 /*
  * BlueALSA - sco-cvsd.c
- * Copyright (c) 2016-2024 Arkadiusz Bokowy
+ * Copyright (c) 2016-2025 Arkadiusz Bokowy
  *
  * This file is a part of bluez-alsa.
  *
@@ -76,10 +76,8 @@ void *sco_cvsd_enc_thread(struct ba_transport_pcm *t_pcm) {
 			input += mtu_samples;
 			input_samples -= mtu_samples;
 
-			/* keep data transfer at a constant bit rate */
+			/* Keep data transfer at a constant bit rate. */
 			asrsync_sync(&io.asrs, mtu_samples);
-			/* update busy delay (encoding overhead) */
-			t_pcm->processing_delay_dms = asrsync_get_busy_usec(&io.asrs) / 100;
 
 		}