pipewire/spa/plugins/bluez5/a2dp-codec-sbc.c

/* Spa A2DP SBC codec */
/* SPDX-FileCopyrightText: Copyright © 2020 Wim Taymans */
/* SPDX-License-Identifier: MIT */

#include <unistd.h>
#include <stddef.h>
#include <errno.h>
#include <arpa/inet.h>

#include <spa/param/audio/format.h>
#include <spa/utils/string.h>

#include <sbc/sbc.h>

#include "rtp.h"
#include "media-codecs.h"

#define MAX_FRAME_COUNT 16

struct impl {
	sbc_t sbc;

	struct rtp_header *header;
	struct rtp_payload *payload;

	size_t mtu;
	int codesize;
	int max_frames;

	int min_bitpool;
	int max_bitpool;

	uint32_t enc_delay;
};

static int codec_fill_caps(const struct media_codec *codec, uint32_t flags,
		const struct spa_dict *settings, uint8_t caps[A2DP_MAX_CAPS_SIZE])
{
	static const a2dp_sbc_t a2dp_sbc = {
		.frequency =
			SBC_SAMPLING_FREQ_16000 |
			SBC_SAMPLING_FREQ_32000 |
			SBC_SAMPLING_FREQ_44100 |
			SBC_SAMPLING_FREQ_48000,
		.channel_mode =
			SBC_CHANNEL_MODE_MONO |
			SBC_CHANNEL_MODE_DUAL_CHANNEL |
			SBC_CHANNEL_MODE_STEREO |
			SBC_CHANNEL_MODE_JOINT_STEREO,
		.block_length =
			SBC_BLOCK_LENGTH_4 |
			SBC_BLOCK_LENGTH_8 |
			SBC_BLOCK_LENGTH_12 |
			SBC_BLOCK_LENGTH_16,
		.subbands =
			SBC_SUBBANDS_4 |
			SBC_SUBBANDS_8,
		.allocation_method =
			SBC_ALLOCATION_SNR |
			SBC_ALLOCATION_LOUDNESS,
		.min_bitpool = SBC_MIN_BITPOOL,
		.max_bitpool = SBC_MAX_BITPOOL,
	};

	memcpy(caps, &a2dp_sbc, sizeof(a2dp_sbc));
	return sizeof(a2dp_sbc);
}

static uint8_t default_bitpool(uint8_t freq, uint8_t mode, bool xq)
{
	/* A2DP spec v1.2 states that all SNK implementation shall handle bitrates
	 * of up to 512 kbps (~ bitpool = 86 stereo, or 2x43 dual channel at 44.1KHz
	 * or ~ bitpool = 78 stereo, or 2x39 dual channel at 48KHz). */
	switch (freq) {
	case SBC_SAMPLING_FREQ_16000:
        case SBC_SAMPLING_FREQ_32000:
		return 64;

	case SBC_SAMPLING_FREQ_44100:
		switch (mode) {
		case SBC_CHANNEL_MODE_MONO:
		case SBC_CHANNEL_MODE_DUAL_CHANNEL:
			return xq ? 43 : 32;

		case SBC_CHANNEL_MODE_STEREO:
		case SBC_CHANNEL_MODE_JOINT_STEREO:
			return xq ? 86 : 64;
		}
		return xq ? 86 : 64;
	case SBC_SAMPLING_FREQ_48000:
		switch (mode) {
		case SBC_CHANNEL_MODE_MONO:
		case SBC_CHANNEL_MODE_DUAL_CHANNEL:
			return xq ? 39 : 29;

		case SBC_CHANNEL_MODE_STEREO:
		case SBC_CHANNEL_MODE_JOINT_STEREO:
			return xq ? 78 : 58;
		}
		return xq ? 78 : 58;
	}
	return xq ? 86 : 64;
}


static const struct media_codec_config
sbc_frequencies[] = {
	{ SBC_SAMPLING_FREQ_48000, 48000, 3 },
	{ SBC_SAMPLING_FREQ_44100, 44100, 2 },
	{ SBC_SAMPLING_FREQ_32000, 32000, 1 },
	{ SBC_SAMPLING_FREQ_16000, 16000, 0 },
};

static const struct media_codec_config
sbc_xq_frequencies[] = {
	{ SBC_SAMPLING_FREQ_44100, 44100, 1 },
	{ SBC_SAMPLING_FREQ_48000, 48000, 0 },
};

static const struct media_codec_config
sbc_channel_modes[] = {
	{ SBC_CHANNEL_MODE_JOINT_STEREO, 2, 3 },
	{ SBC_CHANNEL_MODE_STEREO,       2, 2 },
	{ SBC_CHANNEL_MODE_DUAL_CHANNEL, 2, 1 },
	{ SBC_CHANNEL_MODE_MONO,         1, 0 },
};

static const struct media_codec_config
sbc_xq_channel_modes[] = {
	{ SBC_CHANNEL_MODE_DUAL_CHANNEL, 2, 2 },
	{ SBC_CHANNEL_MODE_JOINT_STEREO, 2, 1 },
	{ SBC_CHANNEL_MODE_STEREO,       2, 0 },
};

static int codec_select_config(const struct media_codec *codec, uint32_t flags,
		const void *caps, size_t caps_size,
		const struct media_codec_audio_info *info,
		const struct spa_dict *settings, uint8_t config[A2DP_MAX_CAPS_SIZE])
{
	a2dp_sbc_t conf;
	int bitpool, i;
	size_t n;
	const struct media_codec_config *configs;
	bool xq = false;


	if (caps_size < sizeof(conf))
		return -EINVAL;

	xq = (spa_streq(codec->name, "sbc_xq"));

	memcpy(&conf, caps, sizeof(conf));

	if (xq) {
		configs = sbc_xq_frequencies;
		n = SPA_N_ELEMENTS(sbc_xq_frequencies);
	} else {
		configs = sbc_frequencies;
		n = SPA_N_ELEMENTS(sbc_frequencies);
	}
	if ((i = media_codec_select_config(configs, n, conf.frequency,
					  info ? info->rate : A2DP_CODEC_DEFAULT_RATE
					  )) < 0)
		return -ENOTSUP;
	conf.frequency = configs[i].config;

	if (xq) {
		configs = sbc_xq_channel_modes;
		n = SPA_N_ELEMENTS(sbc_xq_channel_modes);
	} else {
		configs = sbc_channel_modes;
		n = SPA_N_ELEMENTS(sbc_channel_modes);
	}
	if ((i = media_codec_select_config(configs, n, conf.channel_mode,
					  info ? info->channels : A2DP_CODEC_DEFAULT_CHANNELS
					  )) < 0)
		return -ENOTSUP;
	conf.channel_mode = configs[i].config;

	if (conf.block_length & SBC_BLOCK_LENGTH_16)
		conf.block_length = SBC_BLOCK_LENGTH_16;
	else if (conf.block_length & SBC_BLOCK_LENGTH_12)
		conf.block_length = SBC_BLOCK_LENGTH_12;
	else if (conf.block_length & SBC_BLOCK_LENGTH_8)
		conf.block_length = SBC_BLOCK_LENGTH_8;
	else if (conf.block_length & SBC_BLOCK_LENGTH_4)
		conf.block_length = SBC_BLOCK_LENGTH_4;
	else
		return -ENOTSUP;

	if (conf.subbands & SBC_SUBBANDS_8)
		conf.subbands = SBC_SUBBANDS_8;
	else if (conf.subbands & SBC_SUBBANDS_4)
		conf.subbands = SBC_SUBBANDS_4;
	else
		return -ENOTSUP;

	if (conf.allocation_method & SBC_ALLOCATION_LOUDNESS)
		conf.allocation_method = SBC_ALLOCATION_LOUDNESS;
	else if (conf.allocation_method & SBC_ALLOCATION_SNR)
		conf.allocation_method = SBC_ALLOCATION_SNR;
	else
		return -ENOTSUP;

	bitpool = default_bitpool(conf.frequency, conf.channel_mode, xq);

	conf.min_bitpool = SPA_MAX(SBC_MIN_BITPOOL, conf.min_bitpool);
	conf.max_bitpool = SPA_MIN(bitpool, conf.max_bitpool);
	memcpy(config, &conf, sizeof(conf));

	return sizeof(conf);
}

static int codec_caps_preference_cmp(const struct media_codec *codec, uint32_t flags, const void *caps1, size_t caps1_size,
		const void *caps2, size_t caps2_size, const struct media_codec_audio_info *info, const struct spa_dict *global_settings)
{
	a2dp_sbc_t conf1, conf2;
	a2dp_sbc_t *conf;
	int res1, res2;
	int a, b;
	bool xq = (spa_streq(codec->name, "sbc_xq"));

	/* Order selected configurations by preference */
	res1 = codec->select_config(codec, 0, caps1, caps1_size, info, NULL, (uint8_t *)&conf1);
	res2 = codec->select_config(codec, 0, caps2, caps2_size, info , NULL, (uint8_t *)&conf2);

#define PREFER_EXPR(expr)			\
		do {				\
			conf = &conf1; 		\
			a = (expr);		\
			conf = &conf2;		\
			b = (expr);		\
			if (a != b)		\
				return b - a;	\
		} while (0)

#define PREFER_BOOL(expr)	PREFER_EXPR((expr) ? 1 : 0)

	/* Prefer valid */
	a = (res1 > 0 && (size_t)res1 == sizeof(a2dp_sbc_t)) ? 1 : 0;
	b = (res2 > 0 && (size_t)res2 == sizeof(a2dp_sbc_t)) ? 1 : 0;
	if (!a || !b)
		return b - a;

	PREFER_BOOL(conf->frequency & (SBC_SAMPLING_FREQ_48000 | SBC_SAMPLING_FREQ_44100));

	if (xq)
		PREFER_BOOL(conf->channel_mode & SBC_CHANNEL_MODE_DUAL_CHANNEL);
	else
		PREFER_BOOL(conf->channel_mode & SBC_CHANNEL_MODE_JOINT_STEREO);

	PREFER_EXPR(conf->max_bitpool);

	return 0;

#undef PREFER_EXPR
#undef PREFER_BOOL
}

static int codec_validate_config(const struct media_codec *codec, uint32_t flags,
			const void *caps, size_t caps_size,
			struct spa_audio_info *info)
{
	const a2dp_sbc_t *conf;

	if (caps == NULL || caps_size < sizeof(*conf))
		return -EINVAL;

	conf = caps;

	spa_zero(*info);
	info->media_type = SPA_MEDIA_TYPE_audio;
	info->media_subtype = SPA_MEDIA_SUBTYPE_raw;
	info->info.raw.format = SPA_AUDIO_FORMAT_S16;

	switch (conf->frequency) {
	case SBC_SAMPLING_FREQ_16000:
		info->info.raw.rate = 16000;
		break;
	case SBC_SAMPLING_FREQ_32000:
		info->info.raw.rate = 32000;
		break;
	case SBC_SAMPLING_FREQ_44100:
		info->info.raw.rate = 44100;
		break;
	case SBC_SAMPLING_FREQ_48000:
		info->info.raw.rate = 48000;
		break;
	default:
		return -EINVAL;
        }

	switch (conf->channel_mode) {
	case SBC_CHANNEL_MODE_MONO:
		info->info.raw.channels = 1;
		info->info.raw.position[0] = SPA_AUDIO_CHANNEL_MONO;
                break;
	case SBC_CHANNEL_MODE_DUAL_CHANNEL:
	case SBC_CHANNEL_MODE_STEREO:
	case SBC_CHANNEL_MODE_JOINT_STEREO:
		info->info.raw.channels = 2;
		info->info.raw.position[0] = SPA_AUDIO_CHANNEL_FL;
		info->info.raw.position[1] = SPA_AUDIO_CHANNEL_FR;
                break;
	default:
		return -EINVAL;
        }

	switch (conf->subbands) {
	case SBC_SUBBANDS_4:
	case SBC_SUBBANDS_8:
		break;
	default:
		return -EINVAL;
	}

	switch (conf->block_length) {
	case SBC_BLOCK_LENGTH_4:
	case SBC_BLOCK_LENGTH_8:
	case SBC_BLOCK_LENGTH_12:
	case SBC_BLOCK_LENGTH_16:
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static int codec_set_bitpool(struct impl *this, int bitpool)
{
	size_t rtp_size = sizeof(struct rtp_header) + sizeof(struct rtp_payload);

	this->sbc.bitpool = SPA_CLAMP(bitpool, this->min_bitpool, this->max_bitpool);
	this->codesize = sbc_get_codesize(&this->sbc);
	this->max_frames = (this->mtu - rtp_size) / sbc_get_frame_length(&this->sbc);
	if (this->max_frames > 15)
		this->max_frames = 15;
	return this->sbc.bitpool;
}

static int codec_enum_config(const struct media_codec *codec, uint32_t flags,
		const void *caps, size_t caps_size, uint32_t id, uint32_t idx,
		struct spa_pod_builder *b, struct spa_pod **param)
{
	a2dp_sbc_t conf;
        struct spa_pod_frame f[2];
	struct spa_pod_choice *choice;
	uint32_t i = 0;
	uint32_t position[2];

	if (caps_size < sizeof(conf))
		return -EINVAL;

	memcpy(&conf, caps, sizeof(conf));

	if (idx > 0)
		return 0;

	spa_pod_builder_push_object(b, &f[0], SPA_TYPE_OBJECT_Format, id);
	spa_pod_builder_add(b,
			SPA_FORMAT_mediaType,      SPA_POD_Id(SPA_MEDIA_TYPE_audio),
			SPA_FORMAT_mediaSubtype,   SPA_POD_Id(SPA_MEDIA_SUBTYPE_raw),
			SPA_FORMAT_AUDIO_format,   SPA_POD_Id(SPA_AUDIO_FORMAT_S16),
			0);
	spa_pod_builder_prop(b, SPA_FORMAT_AUDIO_rate, 0);

	spa_pod_builder_push_choice(b, &f[1], SPA_CHOICE_None, 0);
	choice = (struct spa_pod_choice*)spa_pod_builder_frame(b, &f[1]);
	i = 0;
	if (conf.frequency & SBC_SAMPLING_FREQ_48000) {
		if (i++ == 0)
			spa_pod_builder_int(b, 48000);
		spa_pod_builder_int(b, 48000);
	}
	if (conf.frequency & SBC_SAMPLING_FREQ_44100) {
		if (i++ == 0)
			spa_pod_builder_int(b, 44100);
		spa_pod_builder_int(b, 44100);
	}
	if (conf.frequency & SBC_SAMPLING_FREQ_32000) {
		if (i++ == 0)
			spa_pod_builder_int(b, 32000);
		spa_pod_builder_int(b, 32000);
	}
	if (conf.frequency & SBC_SAMPLING_FREQ_16000) {
		if (i++ == 0)
			spa_pod_builder_int(b, 16000);
		spa_pod_builder_int(b, 16000);
	}
	if (i > 1)
		choice->body.type = SPA_CHOICE_Enum;
	spa_pod_builder_pop(b, &f[1]);

	if (conf.channel_mode & SBC_CHANNEL_MODE_MONO &&
	    conf.channel_mode & (SBC_CHANNEL_MODE_JOINT_STEREO |
		    SBC_CHANNEL_MODE_STEREO | SBC_CHANNEL_MODE_DUAL_CHANNEL)) {
		spa_pod_builder_add(b,
				SPA_FORMAT_AUDIO_channels, SPA_POD_CHOICE_RANGE_Int(2, 1, 2),
				0);
	} else if (conf.channel_mode & SBC_CHANNEL_MODE_MONO) {
		position[0] = SPA_AUDIO_CHANNEL_MONO;
		spa_pod_builder_add(b,
				SPA_FORMAT_AUDIO_channels, SPA_POD_Int(1),
				SPA_FORMAT_AUDIO_position, SPA_POD_Array(sizeof(uint32_t),
					SPA_TYPE_Id, 1, position),
				0);
	} else {
		position[0] = SPA_AUDIO_CHANNEL_FL;
		position[1] = SPA_AUDIO_CHANNEL_FR;
		spa_pod_builder_add(b,
				SPA_FORMAT_AUDIO_channels, SPA_POD_Int(2),
				SPA_FORMAT_AUDIO_position, SPA_POD_Array(sizeof(uint32_t),
					SPA_TYPE_Id, 2, position),
				0);
	}
	*param = spa_pod_builder_pop(b, &f[0]);
	return *param == NULL ? -EIO : 1;
}

static int codec_reduce_bitpool(void *data)
{
	struct impl *this = data;
	return codec_set_bitpool(this, this->sbc.bitpool - 2);
}

static int codec_increase_bitpool(void *data)
{
	struct impl *this = data;
	return codec_set_bitpool(this, this->sbc.bitpool + 1);
}

static int codec_get_block_size(void *data)
{
	struct impl *this = data;
	return this->codesize;
}

static void *codec_init(const struct media_codec *codec, uint32_t flags,
		void *config, size_t config_len, const struct spa_audio_info *info,
		void *props, size_t mtu)
{
	struct impl *this;
	a2dp_sbc_t *conf = config;
	int res;

	this = calloc(1, sizeof(struct impl));
	if (this == NULL) {
		res = -errno;
		goto error;
	}

	sbc_init(&this->sbc, 0);
	this->sbc.endian = SBC_LE;
	this->mtu = mtu;

	if (info->media_type != SPA_MEDIA_TYPE_audio ||
	    info->media_subtype != SPA_MEDIA_SUBTYPE_raw ||
	    info->info.raw.format != SPA_AUDIO_FORMAT_S16) {
		res = -EINVAL;
		goto error;
	}

	switch (conf->frequency) {
	case SBC_SAMPLING_FREQ_16000:
		this->sbc.frequency = SBC_FREQ_16000;
		break;
	case SBC_SAMPLING_FREQ_32000:
		this->sbc.frequency = SBC_FREQ_32000;
		break;
	case SBC_SAMPLING_FREQ_44100:
		this->sbc.frequency = SBC_FREQ_44100;
		break;
	case SBC_SAMPLING_FREQ_48000:
		this->sbc.frequency = SBC_FREQ_48000;
		break;
	default:
		res = -EINVAL;
                goto error;
        }

	switch (conf->channel_mode) {
	case SBC_CHANNEL_MODE_MONO:
		this->sbc.mode = SBC_MODE_MONO;
                break;
	case SBC_CHANNEL_MODE_DUAL_CHANNEL:
		this->sbc.mode = SBC_MODE_DUAL_CHANNEL;
		break;
	case SBC_CHANNEL_MODE_STEREO:
		this->sbc.mode = SBC_MODE_STEREO;
		break;
	case SBC_CHANNEL_MODE_JOINT_STEREO:
		this->sbc.mode = SBC_MODE_JOINT_STEREO;
                break;
	default:
		res = -EINVAL;
                goto error;
        }

	switch (conf->subbands) {
	case SBC_SUBBANDS_4:
		this->sbc.subbands = SBC_SB_4;
		this->enc_delay = 37;
		break;
	case SBC_SUBBANDS_8:
		this->sbc.subbands = SBC_SB_8;
		this->enc_delay = 73;
		break;
	default:
		res = -EINVAL;
		goto error;
	}

	if (conf->allocation_method & SBC_ALLOCATION_LOUDNESS)
		this->sbc.allocation = SBC_AM_LOUDNESS;
	else
		this->sbc.allocation = SBC_AM_SNR;

	switch (conf->block_length) {
	case SBC_BLOCK_LENGTH_4:
		this->sbc.blocks = SBC_BLK_4;
		break;
	case SBC_BLOCK_LENGTH_8:
		this->sbc.blocks = SBC_BLK_8;
		break;
	case SBC_BLOCK_LENGTH_12:
		this->sbc.blocks = SBC_BLK_12;
		break;
	case SBC_BLOCK_LENGTH_16:
		this->sbc.blocks = SBC_BLK_16;
		break;
	default:
		res = -EINVAL;
		goto error;
	}

	this->min_bitpool = SPA_MAX(conf->min_bitpool, 12);
	this->max_bitpool = conf->max_bitpool;

	codec_set_bitpool(this, conf->max_bitpool);

	return this;
error:
	errno = -res;
	return NULL;
}

static void codec_deinit(void *data)
{
	struct impl *this = data;
	sbc_finish(&this->sbc);
	free(this);
}

static int codec_abr_process (void *data, size_t unsent)
{
	return -ENOTSUP;
}

static int codec_start_encode (void *data,
		void *dst, size_t dst_size, uint16_t seqnum, uint32_t timestamp)
{
	struct impl *this = data;

	this->header = (struct rtp_header *)dst;
	this->payload = SPA_PTROFF(dst, sizeof(struct rtp_header), struct rtp_payload);
	memset(this->header, 0, sizeof(struct rtp_header)+sizeof(struct rtp_payload));

	this->payload->frame_count = 0;
	this->header->v = 2;
	this->header->pt = 96;
	this->header->sequence_number = htons(seqnum);
	this->header->timestamp = htonl(timestamp);
	this->header->ssrc = htonl(1);
	return sizeof(struct rtp_header) + sizeof(struct rtp_payload);
}

static int codec_encode(void *data,
		const void *src, size_t src_size,
		void *dst, size_t dst_size,
		size_t *dst_out, int *need_flush)
{
	struct impl *this = data;
	int res;

	res = sbc_encode(&this->sbc, src, src_size,
			dst, dst_size, (ssize_t*)dst_out);
	if (SPA_UNLIKELY(res < 0))
		return -EINVAL;
	spa_assert(res == this->codesize);

	this->payload->frame_count += res / this->codesize;
	*need_flush = (this->payload->frame_count >= this->max_frames) ? NEED_FLUSH_ALL : NEED_FLUSH_NO;
	return res;
}

static int codec_start_decode (void *data,
		const void *src, size_t src_size, uint16_t *seqnum, uint32_t *timestamp)
{
	const struct rtp_header *header = src;
	size_t header_size = sizeof(struct rtp_header) + sizeof(struct rtp_payload);

	if (src_size <= header_size)
		return -EINVAL;

	if (seqnum)
		*seqnum = ntohs(header->sequence_number);
	if (timestamp)
		*timestamp = ntohl(header->timestamp);
	return header_size;
}

static int codec_decode(void *data,
		const void *src, size_t src_size,
		void *dst, size_t dst_size,
		size_t *dst_out)
{
	struct impl *this = data;
	int res;

	res = sbc_decode(&this->sbc, src, src_size,
			dst, dst_size, dst_out);

	return res;
}

static void codec_get_delay(void *data, uint32_t *encoder, uint32_t *decoder)
{
	struct impl *this = data;

	if (encoder)
		*encoder = this->enc_delay;
	if (decoder)
		*decoder = 0;
}

const struct media_codec a2dp_codec_sbc = {
	.id = SPA_BLUETOOTH_AUDIO_CODEC_SBC,
	.kind = MEDIA_CODEC_A2DP,
	.codec_id = A2DP_CODEC_SBC,
	.name = "sbc",
	.description = "SBC",
	.fill_caps = codec_fill_caps,
	.select_config = codec_select_config,
	.enum_config = codec_enum_config,
	.validate_config = codec_validate_config,
	.caps_preference_cmp = codec_caps_preference_cmp,
	.init = codec_init,
	.deinit = codec_deinit,
	.get_block_size = codec_get_block_size,
	.abr_process = codec_abr_process,
	.start_encode = codec_start_encode,
	.encode = codec_encode,
	.start_decode = codec_start_decode,
	.decode = codec_decode,
	.reduce_bitpool = codec_reduce_bitpool,
	.increase_bitpool = codec_increase_bitpool,
	.get_delay = codec_get_delay,
};

const struct media_codec a2dp_codec_sbc_xq = {
	.id = SPA_BLUETOOTH_AUDIO_CODEC_SBC_XQ,
	.kind = MEDIA_CODEC_A2DP,
	.codec_id = A2DP_CODEC_SBC,
	.name = "sbc_xq",
	.description = "SBC-XQ",
	.endpoint_name = "sbc",
	.fill_caps = NULL,
	.select_config = codec_select_config,
	.enum_config = codec_enum_config,
	.validate_config = codec_validate_config,
	.caps_preference_cmp = codec_caps_preference_cmp,
	.init = codec_init,
	.deinit = codec_deinit,
	.get_block_size = codec_get_block_size,
	.abr_process = codec_abr_process,
	.start_encode = codec_start_encode,
	.encode = codec_encode,
	.start_decode = codec_start_decode,
	.decode = codec_decode,
	.reduce_bitpool = codec_reduce_bitpool,
	.increase_bitpool = codec_increase_bitpool,
	.get_delay = codec_get_delay,
};

MEDIA_CODEC_EXPORT_DEF(
	"sbc",
	&a2dp_codec_sbc,
	&a2dp_codec_sbc_xq
);