sbc.c

Linux的蓝牙操作工具。配合bluez-lib使用

			for (blk = 0; blk < frame->blocks; blk++)
				sbc_analyze_eight(state, frame, ch, blk);
		return frame->blocks * 8;

	default:
		return -EIO;
	}
}

/*
 * Packs the SBC frame from frame into the memory at data. At most len
 * bytes will be used, should more memory be needed an appropriate
 * error code will be returned. Returns the length of the packed frame
 * on success or a negative value on error.
 *
 * The error codes are:
 * -1 Not enough memory reserved
 * -2 Unsupported sampling rate
 * -3 Unsupported number of blocks
 * -4 Unsupported number of subbands
 * -5 Bitpool value out of bounds
 * -99 not implemented
 */

static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
{
	int produced;
	/* Will copy the header parts for CRC-8 calculation here */
	uint8_t crc_header[11] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
	int crc_pos = 0;

	/* Sampling frequency as temporary value for table lookup */
	uint8_t sf;
	uint16_t audio_sample;

	int ch, sb, blk, bit;	/* channel, subband, block and bit counters */
	int bits[2][8];		/* bits distribution */
	int levels[2][8];	/* levels are derived from that */

	u_int32_t scalefactor[2][8];	/* derived from frame->scale_factor */

	data[0] = SBC_SYNCWORD;

	if (frame->sampling_frequency == 16000) {
		data[1] = (SBC_FS_16 & 0x03) << 6;
		sf = SBC_FS_16;
	} else if (frame->sampling_frequency == 32000) {
		data[1] = (SBC_FS_32 & 0x03) << 6;
		sf = SBC_FS_32;
	} else if (frame->sampling_frequency == 44100) {
		data[1] = (SBC_FS_44 & 0x03) << 6;
		sf = SBC_FS_44;
	} else if (frame->sampling_frequency == 48000) {
		data[1] = (SBC_FS_48 & 0x03) << 6;
		sf = SBC_FS_48;
	} else
		return -2;

	switch (frame->blocks) {
	case 4:
		data[1] |= (SBC_NB_4 & 0x03) << 4;
		break;
	case 8:
		data[1] |= (SBC_NB_8 & 0x03) << 4;
		break;
	case 12:
		data[1] |= (SBC_NB_12 & 0x03) << 4;
		break;
	case 16:
		data[1] |= (SBC_NB_16 & 0x03) << 4;
		break;
	default:
		return -3;
		break;
	}

	data[1] |= (frame->channel_mode & 0x03) << 2;

	data[1] |= (frame->allocation_method & 0x01) << 1;

	switch (frame->subbands) {
	case 4:
		/* Nothing to do */
		break;
	case 8:
		data[1] |= 0x01;
		break;
	default:
		return -4;
		break;
	}

	data[2] = frame->bitpool;

	if ((frame->channel_mode == MONO || frame->channel_mode == DUAL_CHANNEL) &&
			frame->bitpool > frame->subbands << 4)
		return -5;

	if ((frame->channel_mode == STEREO || frame->channel_mode == JOINT_STEREO) &&
			frame->bitpool > frame->subbands << 5)
		return -5;

	/* Can't fill in crc yet */

	produced = 32;

	crc_header[0] = data[1];
	crc_header[1] = data[2];
	crc_pos = 16;

	for (ch = 0; ch < frame->channels; ch++) {
		for (sb = 0; sb < frame->subbands; sb++) {
			frame->scale_factor[ch][sb] = 0;
			scalefactor[ch][sb] = 2;
			for (blk = 0; blk < frame->blocks; blk++) {
				while (scalefactor[ch][sb] < fabs(frame->sb_sample_f[blk][ch][sb])) {
					frame->scale_factor[ch][sb]++;
					scalefactor[ch][sb] *= 2;
				}
			}
		}
	}

	if (frame->channel_mode == JOINT_STEREO) {
		/* like frame->sb_sample but joint stereo */
		int32_t sb_sample_j[16][2];
		/* scalefactor and scale_factor in joint case */
		u_int32_t scalefactor_j[2];
		uint8_t scale_factor_j[2];

		frame->join = 0;

		for (sb = 0; sb < frame->subbands - 1; sb++) {
			scale_factor_j[0] = 0;
			scalefactor_j[0] = 2;
			scale_factor_j[1] = 0;
			scalefactor_j[1] = 2;

			for (blk = 0; blk < frame->blocks; blk++) {
				/* Calculate joint stereo signal */
				sb_sample_j[blk][0] =
					(frame->sb_sample_f[blk][0][sb] +
						frame->sb_sample_f[blk][1][sb]) >> 1;
				sb_sample_j[blk][1] =
					(frame->sb_sample_f[blk][0][sb] -
						frame->sb_sample_f[blk][1][sb]) >> 1;

				/* calculate scale_factor_j and scalefactor_j for joint case */
				while (scalefactor_j[0] < fabs(sb_sample_j[blk][0])) {
					scale_factor_j[0]++;
					scalefactor_j[0] *= 2;
				}
				while (scalefactor_j[1] < fabs(sb_sample_j[blk][1])) {
					scale_factor_j[1]++;
					scalefactor_j[1] *= 2;
				}
			}

			/* decide whether to join this subband */
			if ((scalefactor[0][sb] + scalefactor[1][sb]) >
					(scalefactor_j[0] + scalefactor_j[1]) ) {
				/* use joint stereo for this subband */
				frame->join |= 1 << sb;
				frame->scale_factor[0][sb] = scale_factor_j[0];
				frame->scale_factor[1][sb] = scale_factor_j[1];
				scalefactor[0][sb] = scalefactor_j[0];
				scalefactor[1][sb] = scalefactor_j[1];
				for (blk = 0; blk < frame->blocks; blk++) {
					frame->sb_sample_f[blk][0][sb] =
							sb_sample_j[blk][0];
					frame->sb_sample_f[blk][1][sb] =
							sb_sample_j[blk][1];
				}
			}
		}

		data[4] = 0;
		for (sb = 0; sb < frame->subbands - 1; sb++)
			data[4] |= ((frame->join >> sb) & 0x01) << (frame->subbands - 1 - sb);

		crc_header[crc_pos >> 3] = data[4];

		produced += frame->subbands;
		crc_pos += frame->subbands;
	}

	for (ch = 0; ch < frame->channels; ch++) {
		for (sb = 0; sb < frame->subbands; sb++) {
			data[produced >> 3] <<= 4;
			crc_header[crc_pos >> 3] <<= 4;
			data[produced >> 3] |= frame->scale_factor[ch][sb] & 0x0F;
			crc_header[crc_pos >> 3] |= frame->scale_factor[ch][sb] & 0x0F;

			produced += 4;
			crc_pos += 4;
		}
	}

	/* align the last crc byte */
	if(crc_pos % 8) 
		crc_header[crc_pos >> 3] <<= 8 - (crc_pos % 8);

	data[3] = sbc_crc8(crc_header, crc_pos);

	sbc_calculate_bits(frame, bits, sf);

	for (ch = 0; ch < frame->channels; ch++) {
		for (sb = 0; sb < frame->subbands; sb++)
			levels[ch][sb] = (1 << bits[ch][sb]) - 1;
	}

	for (blk = 0; blk < frame->blocks; blk++) {
		for (ch = 0; ch < frame->channels; ch++) {
			for (sb = 0; sb < frame->subbands; sb++) {
				if (levels[ch][sb] > 0) {
					audio_sample =
						(uint16_t) ((((frame->sb_sample_f[blk][ch][sb]*levels[ch][sb]) >>
									(frame->scale_factor[ch][sb] + 1)) +
								levels[ch][sb]) >> 1);
					audio_sample <<= 16 - bits[ch][sb];
					for (bit = 0; bit < bits[ch][sb]; bit++) {
						data[produced >> 3] <<= 1;
						if(audio_sample & 0x8000)
							data[produced >> 3] |= 0x1;
						audio_sample <<= 1;
						produced++;
					}
				}
			}
		}
	}

	/* align the last byte */
	if(produced % 8) {
		data[produced >> 3] <<= 8 - (produced % 8);
	}

	return (produced + 7) >> 3;
}

struct sbc_priv {
	int init;
	struct sbc_frame frame;
	struct sbc_decoder_state dec_state;
	struct sbc_encoder_state enc_state;
};

static void sbc_set_defaults(sbc_t *sbc, unsigned long flags)
{
	sbc->rate = 44100;
	sbc->channels = 2;
	sbc->joint = 0;
	sbc->subbands = 8;
	sbc->blocks = 16;
	sbc->bitpool = 32;
	sbc->swap = 0;
}

int sbc_init(sbc_t *sbc, unsigned long flags)
{
	if (!sbc)
		return -EIO;

	memset(sbc, 0, sizeof(sbc_t));

	sbc->priv = malloc(sizeof(struct sbc_priv));
	if (!sbc->priv)
		return -ENOMEM;

	memset(sbc->priv, 0, sizeof(struct sbc_priv));

	sbc_set_defaults(sbc, flags);

	return 0;
}

int sbc_parse(sbc_t *sbc, void *input, int input_len)
{
	return sbc_decode(sbc, input, input_len, NULL, 0, NULL);
}

int sbc_decode(sbc_t *sbc, void *input, int input_len, void *output,
		int output_len, int *written)
{
	struct sbc_priv *priv;
	char *ptr;
	int i, ch, framelen, samples;

	if (!sbc && !input)
		return -EIO;

	priv = sbc->priv;

	framelen = sbc_unpack_frame(input, &priv->frame, input_len);

	if (!priv->init) {
		sbc_decoder_init(&priv->dec_state, &priv->frame);
		priv->init = 1;

		sbc->rate = priv->frame.sampling_frequency;
		sbc->channels = priv->frame.channels;
		sbc->subbands = priv->frame.subbands;
		sbc->blocks = priv->frame.blocks;
		sbc->bitpool = priv->frame.bitpool;

		priv->frame.codesize = sbc_get_codesize(sbc);
		priv->frame.length = sbc_get_frame_length(sbc);
	}

	if (!output)
		return framelen;

	if (written)
		*written = 0;

	samples = sbc_synthesize_audio(&priv->dec_state, &priv->frame);

	ptr = output;

	if (output_len < samples * priv->frame.channels * 2)
		samples = output_len / (priv->frame.channels * 2);

	for (i = 0; i < samples; i++) {
		for (ch = 0; ch < priv->frame.channels; ch++) {
			int16_t s;
			s = priv->frame.pcm_sample[ch][i];

			if (sbc->swap) {
				*ptr++ = (s & 0xff00) >> 8;
				*ptr++ = (s & 0x00ff);
			} else {
				*ptr++ = (s & 0x00ff);
				*ptr++ = (s & 0xff00) >> 8;
			}
		}
	}

	if (written)
		*written = samples * priv->frame.channels * 2;

	return framelen;
}

int sbc_encode(sbc_t *sbc, void *input, int input_len, void *output,
		int output_len, int *written)
{
	struct sbc_priv *priv;
	char *ptr;
	int i, ch, framelen, samples;

	if (!sbc && !input)
		return -EIO;

	priv = sbc->priv;

	if (written)
		*written = 0;

	if (!priv->init) {
		priv->frame.sampling_frequency = sbc->rate;
		priv->frame.channels = sbc->channels;

		if (sbc->channels > 1) {
			if (sbc->joint)
				priv->frame.channel_mode = JOINT_STEREO;
			else
				priv->frame.channel_mode = STEREO;
		} else
			priv->frame.channel_mode = MONO;

		priv->frame.allocation_method = sbc->allocation;
		priv->frame.subbands = sbc->subbands;
		priv->frame.blocks = sbc->blocks;
		priv->frame.bitpool = sbc->bitpool;
		priv->frame.codesize = sbc_get_codesize(sbc);
		priv->frame.length = sbc_get_frame_length(sbc);

		sbc_encoder_init(&priv->enc_state, &priv->frame);
		priv->init = 1;
	}

	/* input must be large enough to encode a complete frame */
	if (input_len < priv->frame.codesize)
		return 0;

	/* output must be large enough to receive the encoded frame */
	if (!output || output_len < priv->frame.length)
		return -ENOSPC;

	ptr = input;

	for (i = 0; i < priv->frame.subbands * priv->frame.blocks; i++) {
		for (ch = 0; ch < sbc->channels; ch++) {
			int16_t s;

			if (sbc->swap)
				s = (ptr[0] & 0xff) << 8 | (ptr[1] & 0xff);
			else
				s = (ptr[0] & 0xff) | (ptr[1] & 0xff) << 8;
			ptr += 2;
			priv->frame.pcm_sample[ch][i] = s;
		}
	}

	samples = sbc_analyze_audio(&priv->enc_state, &priv->frame);

	framelen = sbc_pack_frame(output, &priv->frame, output_len);

	if (written)
		*written = framelen;

	return samples * sbc->channels * 2;
}

void sbc_finish(sbc_t *sbc)
{
	if (!sbc)
		return;

	if (sbc->priv)
		free(sbc->priv);

	memset(sbc, 0, sizeof(sbc_t));
}

int sbc_get_frame_length(sbc_t *sbc)
{
	int ret;

	ret = 4 + (4 * sbc->subbands * sbc->channels) / 8;

	/* This term is not always evenly divide so we round it up */
	if (sbc->channels == 1)
		ret += ((sbc->blocks * sbc->channels * sbc->bitpool) + 7) / 8;
	else
		ret += (((sbc->joint ? sbc->subbands : 0) + sbc->blocks * sbc->bitpool)
			+ 7) / 8;

	return ret;
}

int sbc_get_frame_duration(sbc_t *sbc)
{
	return (1000000 * sbc->blocks * sbc->subbands) / sbc->rate;
}

int sbc_get_codesize(sbc_t *sbc)
{
	return sbc->subbands * sbc->blocks * sbc->channels * 2;
}

int sbc_reinit(sbc_t *sbc, unsigned long flags)
{
	struct sbc_priv *priv;

	if (!sbc || !sbc->priv)
		return -EIO;

	priv = sbc->priv;

	if (priv->init == 1)
		memset(sbc->priv, 0, sizeof(struct sbc_priv));

	sbc_set_defaults(sbc, flags);

	return 0;
}