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a6dcdfae0c
Use TX timestamps to get accurate reading of queue length and latency on kernel + controller side. This is new kernel BT feature, so requires kernel with the necessary patches, available currently only in bluetooth-next/master branch. Enabling Poll Errqueue kernel experimental Bluetooth feature is also required for this. Use the latency information to mitigate controller issues where ISO streams are desynchronized due to tx problems or spontaneously when some packets that should have been sent are left sitting in the queue, and transmission is off by a multiple of the ISO interval. This state is visible in the latency information, so if we see streams in a group have persistently different latencies, drop packets to resynchronize them. Also make corrections if the kernel/controller queues get too long, so that we don't have too big latency there. Since BlueZ watches the same socket for errors, and TX timestamps arrive via the socket error queue, we need to set BT_POLL_ERRQUEUE in addition to SO_TIMESTAMPING so that BlueZ doesn't think TX timestamps are errors. Link: https://github.com/bluez/bluez/issues/515 Link: https://lore.kernel.org/linux-bluetooth/cover.1710440392.git.pav@iki.fi/ Link: https://lore.kernel.org/linux-bluetooth/f57e065bb571d633f811610d273711c7047af335.1712499936.git.pav@iki.fi/
49 lines
1.6 KiB
C
49 lines
1.6 KiB
C
/* Spa Bluez5 ISO I/O */
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/* SPDX-FileCopyrightText: Copyright © 2023 Pauli Virtanen */
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/* SPDX-License-Identifier: MIT */
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#ifndef SPA_BLUEZ5_ISO_IO_H
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#define SPA_BLUEZ5_ISO_IO_H
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#include <spa/utils/defs.h>
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#include <spa/support/loop.h>
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#include <spa/support/log.h>
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#include <spa/node/io.h>
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#include <spa/param/audio/format.h>
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struct spa_bt_transport;
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/**
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* ISO I/O.
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*
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* Synchronizes related writes from different streams in the same group
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* to occur at same real time instant (or not at all).
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*/
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struct spa_bt_iso_io
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{
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uint64_t now; /**< Reference time position of next packet (read-only) */
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uint64_t duration; /**< ISO interval duration in ns (read-only) */
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bool resync; /**< Resync position for next packet; (pull callback sets to
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* false when done) */
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uint32_t timestamp; /**< Packet timestamp (set by pull callback) */
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uint8_t buf[4096]; /**< Packet data (set by pull callback) */
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size_t size; /**< Packet size (set by pull callback) */
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bool need_resync; /**< Resync requested (set by pull callback) */
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struct spa_audio_info format; /**< Audio format */
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void *codec_data; /**< Codec data */
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void *user_data;
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};
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typedef void (*spa_bt_iso_io_pull_t)(struct spa_bt_iso_io *io);
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struct spa_bt_iso_io *spa_bt_iso_io_create(struct spa_bt_transport *t,
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struct spa_log *log, struct spa_loop *data_loop, struct spa_system *data_system);
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struct spa_bt_iso_io *spa_bt_iso_io_attach(struct spa_bt_iso_io *io, struct spa_bt_transport *t);
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void spa_bt_iso_io_destroy(struct spa_bt_iso_io *io);
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void spa_bt_iso_io_set_cb(struct spa_bt_iso_io *io, spa_bt_iso_io_pull_t pull, void *user_data);
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int spa_bt_iso_io_recv_errqueue(struct spa_bt_iso_io *io);
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#endif
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