void update_metadata_(const FLAC__StreamEncoder *encoder)
{
	FLAC__byte b[flac_max(6u, FLAC__STREAM_METADATA_SEEKPOINT_LENGTH)];
	const FLAC__StreamMetadata *metadata = &encoder->private_->streaminfo;
	const FLAC__uint64 samples = metadata->data.stream_info.total_samples;
	const uint32_t min_framesize = metadata->data.stream_info.min_framesize;
	const uint32_t max_framesize = metadata->data.stream_info.max_framesize;
	const uint32_t bps = metadata->data.stream_info.bits_per_sample;
	FLAC__StreamEncoderSeekStatus seek_status;

	FLAC__ASSERT(metadata->type == FLAC__METADATA_TYPE_STREAMINFO);

	/* All this is based on intimate knowledge of the stream header
	 * layout, but a change to the header format that would break this
	 * would also break all streams encoded in the previous format.
	 */

	/*
	 * Write MD5 signature
	 */
	{
		const uint32_t md5_offset =
			FLAC__STREAM_METADATA_HEADER_LENGTH +
			(
				FLAC__STREAM_METADATA_STREAMINFO_MIN_BLOCK_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MAX_BLOCK_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MIN_FRAME_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MAX_FRAME_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_SAMPLE_RATE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_CHANNELS_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_BITS_PER_SAMPLE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_TOTAL_SAMPLES_LEN
			) / 8;

		if((seek_status = encoder->private_->seek_callback(encoder, encoder->protected_->streaminfo_offset + md5_offset, encoder->private_->client_data)) != FLAC__STREAM_ENCODER_SEEK_STATUS_OK) {
			if(seek_status == FLAC__STREAM_ENCODER_SEEK_STATUS_ERROR)
				encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
		if(encoder->private_->write_callback(encoder, metadata->data.stream_info.md5sum, 16, 0, 0, encoder->private_->client_data) != FLAC__STREAM_ENCODER_WRITE_STATUS_OK) {
			encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
	}

	/*
	 * Write total samples
	 */
	{
		const uint32_t total_samples_byte_offset =
			FLAC__STREAM_METADATA_HEADER_LENGTH +
			(
				FLAC__STREAM_METADATA_STREAMINFO_MIN_BLOCK_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MAX_BLOCK_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MIN_FRAME_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MAX_FRAME_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_SAMPLE_RATE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_CHANNELS_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_BITS_PER_SAMPLE_LEN
				- 4
			) / 8;

		b[0] = ((FLAC__byte)(bps-1) << 4) | (FLAC__byte)((samples >> 32) & 0x0F);
		b[1] = (FLAC__byte)((samples >> 24) & 0xFF);
		b[2] = (FLAC__byte)((samples >> 16) & 0xFF);
		b[3] = (FLAC__byte)((samples >> 8) & 0xFF);
		b[4] = (FLAC__byte)(samples & 0xFF);
		if((seek_status = encoder->private_->seek_callback(encoder, encoder->protected_->streaminfo_offset + total_samples_byte_offset, encoder->private_->client_data)) != FLAC__STREAM_ENCODER_SEEK_STATUS_OK) {
			if(seek_status == FLAC__STREAM_ENCODER_SEEK_STATUS_ERROR)
				encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
		if(encoder->private_->write_callback(encoder, b, 5, 0, 0, encoder->private_->client_data) != FLAC__STREAM_ENCODER_WRITE_STATUS_OK) {
			encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
	}

	/*
	 * Write min/max framesize
	 */
	{
		const uint32_t min_framesize_offset =
			FLAC__STREAM_METADATA_HEADER_LENGTH +
			(
				FLAC__STREAM_METADATA_STREAMINFO_MIN_BLOCK_SIZE_LEN +
				FLAC__STREAM_METADATA_STREAMINFO_MAX_BLOCK_SIZE_LEN
			) / 8;

		b[0] = (FLAC__byte)((min_framesize >> 16) & 0xFF);
		b[1] = (FLAC__byte)((min_framesize >> 8) & 0xFF);
		b[2] = (FLAC__byte)(min_framesize & 0xFF);
		b[3] = (FLAC__byte)((max_framesize >> 16) & 0xFF);
		b[4] = (FLAC__byte)((max_framesize >> 8) & 0xFF);
		b[5] = (FLAC__byte)(max_framesize & 0xFF);
		if((seek_status = encoder->private_->seek_callback(encoder, encoder->protected_->streaminfo_offset + min_framesize_offset, encoder->private_->client_data)) != FLAC__STREAM_ENCODER_SEEK_STATUS_OK) {
			if(seek_status == FLAC__STREAM_ENCODER_SEEK_STATUS_ERROR)
				encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
		if(encoder->private_->write_callback(encoder, b, 6, 0, 0, encoder->private_->client_data) != FLAC__STREAM_ENCODER_WRITE_STATUS_OK) {
			encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}
	}

	/*
	 * Write seektable
	 */
	if(0 != encoder->private_->seek_table && encoder->private_->seek_table->num_points > 0 && encoder->protected_->seektable_offset > 0) {
		uint32_t i;

		FLAC__format_seektable_sort(encoder->private_->seek_table);

		FLAC__ASSERT(FLAC__format_seektable_is_legal(encoder->private_->seek_table));

		if((seek_status = encoder->private_->seek_callback(encoder, encoder->protected_->seektable_offset + FLAC__STREAM_METADATA_HEADER_LENGTH, encoder->private_->client_data)) != FLAC__STREAM_ENCODER_SEEK_STATUS_OK) {
			if(seek_status == FLAC__STREAM_ENCODER_SEEK_STATUS_ERROR)
				encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
			return;
		}

		for(i = 0; i < encoder->private_->seek_table->num_points; i++) {
			FLAC__uint64 xx;
			uint32_t x;
			xx = encoder->private_->seek_table->points[i].sample_number;
			b[7] = (FLAC__byte)xx; xx >>= 8;
			b[6] = (FLAC__byte)xx; xx >>= 8;
			b[5] = (FLAC__byte)xx; xx >>= 8;
			b[4] = (FLAC__byte)xx; xx >>= 8;
			b[3] = (FLAC__byte)xx; xx >>= 8;
			b[2] = (FLAC__byte)xx; xx >>= 8;
			b[1] = (FLAC__byte)xx; xx >>= 8;
			b[0] = (FLAC__byte)xx; xx >>= 8;
			xx = encoder->private_->seek_table->points[i].stream_offset;
			b[15] = (FLAC__byte)xx; xx >>= 8;
			b[14] = (FLAC__byte)xx; xx >>= 8;
			b[13] = (FLAC__byte)xx; xx >>= 8;
			b[12] = (FLAC__byte)xx; xx >>= 8;
			b[11] = (FLAC__byte)xx; xx >>= 8;
			b[10] = (FLAC__byte)xx; xx >>= 8;
			b[9] = (FLAC__byte)xx; xx >>= 8;
			b[8] = (FLAC__byte)xx; xx >>= 8;
			x = encoder->private_->seek_table->points[i].frame_samples;
			b[17] = (FLAC__byte)x; x >>= 8;
			b[16] = (FLAC__byte)x; x >>= 8;
			if(encoder->private_->write_callback(encoder, b, 18, 0, 0, encoder->private_->client_data) != FLAC__STREAM_ENCODER_WRITE_STATUS_OK) {
				encoder->protected_->state = FLAC__STREAM_ENCODER_CLIENT_ERROR;
				return;
			}
		}
	}
}