mpd/src/decoder/MpcdecDecoderPlugin.cxx

/*
 * Copyright (C) 2003-2013 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include "MpcdecDecoderPlugin.hxx"
#include "DecoderAPI.hxx"
#include "CheckAudioFormat.hxx"
#include "TagHandler.hxx"

#include <mpc/mpcdec.h>

#include <glib.h>
#include <assert.h>
#include <unistd.h>
#include <math.h>

#undef G_LOG_DOMAIN
#define G_LOG_DOMAIN "mpcdec"

struct mpc_decoder_data {
	struct input_stream *is;
	struct decoder *decoder;
};

static mpc_int32_t
mpc_read_cb(mpc_reader *reader, void *ptr, mpc_int32_t size)
{
	struct mpc_decoder_data *data =
		(struct mpc_decoder_data *)reader->data;

	return decoder_read(data->decoder, data->is, ptr, size);
}

static mpc_bool_t
mpc_seek_cb(mpc_reader *reader, mpc_int32_t offset)
{
	struct mpc_decoder_data *data =
		(struct mpc_decoder_data *)reader->data;

	return input_stream_lock_seek(data->is, offset, SEEK_SET, nullptr);
}

static mpc_int32_t
mpc_tell_cb(mpc_reader *reader)
{
	struct mpc_decoder_data *data =
		(struct mpc_decoder_data *)reader->data;

	return (long)input_stream_get_offset(data->is);
}

static mpc_bool_t
mpc_canseek_cb(mpc_reader *reader)
{
	struct mpc_decoder_data *data =
		(struct mpc_decoder_data *)reader->data;

	return input_stream_is_seekable(data->is);
}

static mpc_int32_t
mpc_getsize_cb(mpc_reader *reader)
{
	struct mpc_decoder_data *data =
		(struct mpc_decoder_data *)reader->data;

	return input_stream_get_size(data->is);
}

/* this _looks_ performance-critical, don't de-inline -- eric */
static inline int32_t
mpc_to_mpd_sample(MPC_SAMPLE_FORMAT sample)
{
	/* only doing 16-bit audio for now */
	int32_t val;

	enum {
		bits = 24,
	};

	const int clip_min = -1 << (bits - 1);
	const int clip_max = (1 << (bits - 1)) - 1;

#ifdef MPC_FIXED_POINT
	const int shift = bits - MPC_FIXED_POINT_SCALE_SHIFT;

	if (shift < 0)
		val = sample >> -shift;
	else
		val = sample << shift;
#else
	const int float_scale = 1 << (bits - 1);

	val = sample * float_scale;
#endif

	if (val < clip_min)
		val = clip_min;
	else if (val > clip_max)
		val = clip_max;

	return val;
}

static void
mpc_to_mpd_buffer(int32_t *dest, const MPC_SAMPLE_FORMAT *src,
		  unsigned num_samples)
{
	while (num_samples-- > 0)
		*dest++ = mpc_to_mpd_sample(*src++);
}

static void
mpcdec_decode(struct decoder *mpd_decoder, struct input_stream *is)
{
	MPC_SAMPLE_FORMAT sample_buffer[MPC_DECODER_BUFFER_LENGTH];

	struct mpc_decoder_data data;
	data.is = is;
	data.decoder = mpd_decoder;

	mpc_reader reader;
	reader.read = mpc_read_cb;
	reader.seek = mpc_seek_cb;
	reader.tell = mpc_tell_cb;
	reader.get_size = mpc_getsize_cb;
	reader.canseek = mpc_canseek_cb;
	reader.data = &data;

	mpc_demux *demux = mpc_demux_init(&reader);
	if (demux == nullptr) {
		if (decoder_get_command(mpd_decoder) != DECODE_COMMAND_STOP)
			g_warning("Not a valid musepack stream");
		return;
	}

	mpc_streaminfo info;
	mpc_demux_get_info(demux, &info);

	GError *error = nullptr;
	struct audio_format audio_format;
	if (!audio_format_init_checked(&audio_format, info.sample_freq,
				       SAMPLE_FORMAT_S24_P32,
				       info.channels, &error)) {
		g_warning("%s", error->message);
		g_error_free(error);
		mpc_demux_exit(demux);
		return;
	}

	struct replay_gain_info replay_gain_info;
	replay_gain_info_init(&replay_gain_info);
	replay_gain_info.tuples[REPLAY_GAIN_ALBUM].gain = MPC_OLD_GAIN_REF  - (info.gain_album  / 256.);
	replay_gain_info.tuples[REPLAY_GAIN_ALBUM].peak = pow(10, info.peak_album / 256. / 20) / 32767;
	replay_gain_info.tuples[REPLAY_GAIN_TRACK].gain = MPC_OLD_GAIN_REF  - (info.gain_title  / 256.);
	replay_gain_info.tuples[REPLAY_GAIN_TRACK].peak = pow(10, info.peak_title / 256. / 20) / 32767;

	decoder_replay_gain(mpd_decoder, &replay_gain_info);

	decoder_initialized(mpd_decoder, &audio_format,
			    input_stream_is_seekable(is),
			    mpc_streaminfo_get_length(&info));

	enum decoder_command cmd = DECODE_COMMAND_NONE;
	do {
		if (cmd == DECODE_COMMAND_SEEK) {
			mpc_int64_t where = decoder_seek_where(mpd_decoder) *
				audio_format.sample_rate;
			bool success;

			success = mpc_demux_seek_sample(demux, where)
				== MPC_STATUS_OK;
			if (success)
				decoder_command_finished(mpd_decoder);
			else
				decoder_seek_error(mpd_decoder);
		}

		mpc_uint32_t vbr_update_bits = 0;

		mpc_frame_info frame;
		frame.buffer = (MPC_SAMPLE_FORMAT *)sample_buffer;
		mpc_status status = mpc_demux_decode(demux, &frame);
		if (status != MPC_STATUS_OK) {
			g_warning("Failed to decode sample");
			break;
		}

		if (frame.bits == -1)
			break;

		mpc_uint32_t ret = frame.samples;
		ret *= info.channels;

		int32_t chunk[G_N_ELEMENTS(sample_buffer)];
		mpc_to_mpd_buffer(chunk, sample_buffer, ret);

		long bit_rate = vbr_update_bits * audio_format.sample_rate
			/ 1152 / 1000;

		cmd = decoder_data(mpd_decoder, is,
				   chunk, ret * sizeof(chunk[0]),
				   bit_rate);
	} while (cmd != DECODE_COMMAND_STOP);

	mpc_demux_exit(demux);
}

static float
mpcdec_get_file_duration(struct input_stream *is)
{
	struct mpc_decoder_data data;
	data.is = is;
	data.decoder = nullptr;

	mpc_reader reader;
	reader.read = mpc_read_cb;
	reader.seek = mpc_seek_cb;
	reader.tell = mpc_tell_cb;
	reader.get_size = mpc_getsize_cb;
	reader.canseek = mpc_canseek_cb;
	reader.data = &data;

	mpc_demux *demux = mpc_demux_init(&reader);
	if (demux == nullptr)
		return -1;

	mpc_streaminfo info;
	mpc_demux_get_info(demux, &info);
	mpc_demux_exit(demux);

	return mpc_streaminfo_get_length(&info);
}

static bool
mpcdec_scan_stream(struct input_stream *is,
		   const struct tag_handler *handler, void *handler_ctx)
{
	float total_time = mpcdec_get_file_duration(is);

	if (total_time < 0)
		return false;

	tag_handler_invoke_duration(handler, handler_ctx, total_time);
	return true;
}

static const char *const mpcdec_suffixes[] = { "mpc", nullptr };

const struct decoder_plugin mpcdec_decoder_plugin = {
	"mpcdec",
	nullptr,
	nullptr,
	mpcdec_decode,
	nullptr,
	nullptr,
	mpcdec_scan_stream,
	nullptr,
	mpcdec_suffixes,
	nullptr,
};