mpd/src/decoder/DecoderAPI.cxx

/*
 * Copyright 2003-2016 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 "DecoderAPI.hxx"
#include "DecoderError.hxx"
#include "pcm/PcmConvert.hxx"
#include "AudioConfig.hxx"
#include "ReplayGainConfig.hxx"
#include "MusicChunk.hxx"
#include "MusicBuffer.hxx"
#include "MusicPipe.hxx"
#include "DecoderControl.hxx"
#include "DecoderInternal.hxx"
#include "DetachedSong.hxx"
#include "input/InputStream.hxx"
#include "util/ConstBuffer.hxx"
#include "Log.hxx"

#include <assert.h>
#include <string.h>
#include <math.h>

void
decoder_initialized(Decoder &decoder,
		    const AudioFormat audio_format,
		    bool seekable, SignedSongTime duration)
{
	DecoderControl &dc = decoder.dc;
	struct audio_format_string af_string;

	assert(dc.state == DecoderState::START);
	assert(dc.pipe != nullptr);
	assert(dc.pipe->IsEmpty());
	assert(decoder.convert == nullptr);
	assert(decoder.stream_tag == nullptr);
	assert(decoder.decoder_tag == nullptr);
	assert(!decoder.seeking);
	assert(audio_format.IsDefined());
	assert(audio_format.IsValid());

	dc.in_audio_format = audio_format;
	dc.out_audio_format = getOutputAudioFormat(audio_format);

	dc.seekable = seekable;
	dc.total_time = duration;

	FormatDebug(decoder_domain, "audio_format=%s, seekable=%s",
		    audio_format_to_string(dc.in_audio_format, &af_string),
		    seekable ? "true" : "false");

	if (dc.in_audio_format != dc.out_audio_format) {
		FormatDebug(decoder_domain, "converting to %s",
			    audio_format_to_string(dc.out_audio_format,
						   &af_string));

		decoder.convert = new PcmConvert();

		try {
			decoder.convert->Open(dc.in_audio_format,
					      dc.out_audio_format);
		} catch (...) {
			decoder.error = std::current_exception();
		}
	}

	const ScopeLock protect(dc.mutex);
	dc.state = DecoderState::DECODE;
	dc.client_cond.signal();
}

/**
 * Checks if we need an "initial seek".  If so, then the initial seek
 * is prepared, and the function returns true.
 */
gcc_pure
static bool
decoder_prepare_initial_seek(Decoder &decoder)
{
	const DecoderControl &dc = decoder.dc;
	assert(dc.pipe != nullptr);

	if (dc.state != DecoderState::DECODE)
		/* wait until the decoder has finished initialisation
		   (reading file headers etc.) before emitting the
		   virtual "SEEK" command */
		return false;

	if (decoder.initial_seek_running)
		/* initial seek has already begun - override any other
		   command */
		return true;

	if (decoder.initial_seek_pending) {
		if (!dc.seekable) {
			/* seeking is not possible */
			decoder.initial_seek_pending = false;
			return false;
		}

		if (dc.command == DecoderCommand::NONE) {
			/* begin initial seek */

			decoder.initial_seek_pending = false;
			decoder.initial_seek_running = true;
			return true;
		}

		/* skip initial seek when there's another command
		   (e.g. STOP) */

		decoder.initial_seek_pending = false;
	}

	return false;
}

/**
 * Returns the current decoder command.  May return a "virtual"
 * synthesized command, e.g. to seek to the beginning of the CUE
 * track.
 */
gcc_pure
static DecoderCommand
decoder_get_virtual_command(Decoder &decoder)
{
	if (decoder.error)
		/* an error has occurred: stop the decoder plugin */
		return DecoderCommand::STOP;

	const DecoderControl &dc = decoder.dc;
	assert(dc.pipe != nullptr);

	if (decoder_prepare_initial_seek(decoder))
		return DecoderCommand::SEEK;

	return dc.command;
}

gcc_pure
static DecoderCommand
decoder_lock_get_virtual_command(Decoder &decoder)
{
	const ScopeLock protect(decoder.dc.mutex);
	return decoder_get_virtual_command(decoder);
}

DecoderCommand
decoder_get_command(Decoder &decoder)
{
	return decoder_lock_get_virtual_command(decoder);
}

void
decoder_command_finished(Decoder &decoder)
{
	DecoderControl &dc = decoder.dc;

	const ScopeLock protect(dc.mutex);

	assert(dc.command != DecoderCommand::NONE ||
	       decoder.initial_seek_running);
	assert(dc.command != DecoderCommand::SEEK ||
	       decoder.initial_seek_running ||
	       dc.seek_error || decoder.seeking);
	assert(dc.pipe != nullptr);

	if (decoder.initial_seek_running) {
		assert(!decoder.seeking);
		assert(decoder.chunk == nullptr);
		assert(dc.pipe->IsEmpty());

		decoder.initial_seek_running = false;
		decoder.timestamp = dc.start_time.ToDoubleS();
		return;
	}

	if (decoder.seeking) {
		decoder.seeking = false;

		/* delete frames from the old song position */

		if (decoder.chunk != nullptr) {
			dc.buffer->Return(decoder.chunk);
			decoder.chunk = nullptr;
		}

		dc.pipe->Clear(*dc.buffer);

		decoder.timestamp = dc.seek_time.ToDoubleS();
	}

	dc.command = DecoderCommand::NONE;
	dc.client_cond.signal();
}

SongTime
decoder_seek_time(Decoder &decoder)
{
	const DecoderControl &dc = decoder.dc;

	assert(dc.pipe != nullptr);

	if (decoder.initial_seek_running)
		return dc.start_time;

	assert(dc.command == DecoderCommand::SEEK);

	decoder.seeking = true;

	return dc.seek_time;
}

uint64_t
decoder_seek_where_frame(Decoder &decoder)
{
	const DecoderControl &dc = decoder.dc;

	return decoder_seek_time(decoder).ToScale<uint64_t>(dc.in_audio_format.sample_rate);
}

void decoder_seek_error(Decoder & decoder)
{
	DecoderControl &dc = decoder.dc;

	assert(dc.pipe != nullptr);

	if (decoder.initial_seek_running) {
		/* d'oh, we can't seek to the sub-song start position,
		   what now? - no idea, ignoring the problem for now. */
		decoder.initial_seek_running = false;
		return;
	}

	assert(dc.command == DecoderCommand::SEEK);

	dc.seek_error = true;
	decoder.seeking = false;

	decoder_command_finished(decoder);
}

InputStreamPtr
decoder_open_uri(Decoder &decoder, const char *uri)
{
	assert(decoder.dc.state == DecoderState::START ||
	       decoder.dc.state == DecoderState::DECODE);

	DecoderControl &dc = decoder.dc;
	Mutex &mutex = dc.mutex;
	Cond &cond = dc.cond;

	auto is = InputStream::Open(uri, mutex, cond);

	const ScopeLock lock(mutex);
	while (true) {
		is->Update();
		if (is->IsReady())
			return is;

		if (dc.command == DecoderCommand::STOP)
			throw StopDecoder();

		cond.wait(mutex);
	}
}

/**
 * Should be read operation be cancelled?  That is the case when the
 * player thread has sent a command such as "STOP".
 */
gcc_pure
static inline bool
decoder_check_cancel_read(const Decoder *decoder)
{
	if (decoder == nullptr)
		return false;

	if (decoder->error)
		/* this translates to DecoderCommand::STOP */
		return true;

	const DecoderControl &dc = decoder->dc;
	if (dc.command == DecoderCommand::NONE)
		return false;

	/* ignore the SEEK command during initialization, the plugin
	   should handle that after it has initialized successfully */
	if (dc.command == DecoderCommand::SEEK &&
	    (dc.state == DecoderState::START || decoder->seeking ||
	     decoder->initial_seek_running))
		return false;

	return true;
}

size_t
decoder_read(Decoder *decoder,
	     InputStream &is,
	     void *buffer, size_t length)
try {
	/* XXX don't allow decoder==nullptr */

	assert(decoder == nullptr ||
	       decoder->dc.state == DecoderState::START ||
	       decoder->dc.state == DecoderState::DECODE);
	assert(buffer != nullptr);

	if (length == 0)
		return 0;

	ScopeLock lock(is.mutex);

	while (true) {
		if (decoder_check_cancel_read(decoder))
			return 0;

		if (is.IsAvailable())
			break;

		is.cond.wait(is.mutex);
	}

	size_t nbytes = is.Read(buffer, length);
	assert(nbytes > 0 || is.IsEOF());

	return nbytes;
} catch (const std::runtime_error &e) {
	if (decoder != nullptr)
		decoder->error = std::current_exception();
	else
		LogError(e);
	return 0;
}

bool
decoder_read_full(Decoder *decoder, InputStream &is,
		  void *_buffer, size_t size)
{
	uint8_t *buffer = (uint8_t *)_buffer;

	while (size > 0) {
		size_t nbytes = decoder_read(decoder, is, buffer, size);
		if (nbytes == 0)
			return false;

		buffer += nbytes;
		size -= nbytes;
	}

	return true;
}

bool
decoder_skip(Decoder *decoder, InputStream &is, size_t size)
{
	while (size > 0) {
		char buffer[1024];
		size_t nbytes = decoder_read(decoder, is, buffer,
					     std::min(sizeof(buffer), size));
		if (nbytes == 0)
			return false;

		size -= nbytes;
	}

	return true;
}

void
decoder_timestamp(Decoder &decoder, double t)
{
	assert(t >= 0);

	decoder.timestamp = t;
}

/**
 * Sends a #tag as-is to the music pipe.  Flushes the current chunk
 * (decoder.chunk) if there is one.
 */
static DecoderCommand
do_send_tag(Decoder &decoder, const Tag &tag)
{
	MusicChunk *chunk;

	if (decoder.chunk != nullptr) {
		/* there is a partial chunk - flush it, we want the
		   tag in a new chunk */
		decoder.FlushChunk();
	}

	assert(decoder.chunk == nullptr);

	chunk = decoder.GetChunk();
	if (chunk == nullptr) {
		assert(decoder.dc.command != DecoderCommand::NONE);
		return decoder.dc.command;
	}

	chunk->tag = new Tag(tag);
	return DecoderCommand::NONE;
}

static bool
update_stream_tag(Decoder &decoder, InputStream *is)
{
	Tag *tag;

	tag = is != nullptr
		? is->LockReadTag()
		: nullptr;
	if (tag == nullptr) {
		tag = decoder.song_tag;
		if (tag == nullptr)
			return false;

		/* no stream tag present - submit the song tag
		   instead */
	} else
		/* discard the song tag; we don't need it */
		delete decoder.song_tag;

	decoder.song_tag = nullptr;

	delete decoder.stream_tag;
	decoder.stream_tag = tag;
	return true;
}

DecoderCommand
decoder_data(Decoder &decoder,
	     InputStream *is,
	     const void *data, size_t length,
	     uint16_t kbit_rate)
{
	DecoderControl &dc = decoder.dc;

	assert(dc.state == DecoderState::DECODE);
	assert(dc.pipe != nullptr);
	assert(length % dc.in_audio_format.GetFrameSize() == 0);

	DecoderCommand cmd = decoder_lock_get_virtual_command(decoder);

	if (cmd == DecoderCommand::STOP || cmd == DecoderCommand::SEEK ||
	    length == 0)
		return cmd;

	assert(!decoder.initial_seek_pending);
	assert(!decoder.initial_seek_running);

	/* send stream tags */

	if (update_stream_tag(decoder, is)) {
		if (decoder.decoder_tag != nullptr) {
			/* merge with tag from decoder plugin */
			Tag *tag = Tag::Merge(*decoder.decoder_tag,
					      *decoder.stream_tag);
			cmd = do_send_tag(decoder, *tag);
			delete tag;
		} else
			/* send only the stream tag */
			cmd = do_send_tag(decoder, *decoder.stream_tag);

		if (cmd != DecoderCommand::NONE)
			return cmd;
	}

	if (decoder.convert != nullptr) {
		assert(dc.in_audio_format != dc.out_audio_format);

		try {
			auto result = decoder.convert->Convert({data, length});
			data = result.data;
			length = result.size;
		} catch (const std::runtime_error &e) {
			/* the PCM conversion has failed - stop
			   playback, since we have no better way to
			   bail out */
			decoder.error = std::current_exception();
			return DecoderCommand::STOP;
		}
	} else {
		assert(dc.in_audio_format == dc.out_audio_format);
	}

	while (length > 0) {
		MusicChunk *chunk;
		bool full;

		chunk = decoder.GetChunk();
		if (chunk == nullptr) {
			assert(dc.command != DecoderCommand::NONE);
			return dc.command;
		}

		const auto dest =
			chunk->Write(dc.out_audio_format,
				     SongTime::FromS(decoder.timestamp) -
				     dc.song->GetStartTime(),
				     kbit_rate);
		if (dest.IsEmpty()) {
			/* the chunk is full, flush it */
			decoder.FlushChunk();
			continue;
		}

		const size_t nbytes = std::min(dest.size, length);

		/* copy the buffer */

		memcpy(dest.data, data, nbytes);

		/* expand the music pipe chunk */

		full = chunk->Expand(dc.out_audio_format, nbytes);
		if (full) {
			/* the chunk is full, flush it */
			decoder.FlushChunk();
		}

		data = (const uint8_t *)data + nbytes;
		length -= nbytes;

		decoder.timestamp += (double)nbytes /
			dc.out_audio_format.GetTimeToSize();

		if (dc.end_time.IsPositive() &&
		    decoder.timestamp >= dc.end_time.ToDoubleS())
			/* the end of this range has been reached:
			   stop decoding */
			return DecoderCommand::STOP;
	}

	return DecoderCommand::NONE;
}

DecoderCommand
decoder_tag(Decoder &decoder, InputStream *is,
	    Tag &&tag)
{
	gcc_unused const DecoderControl &dc = decoder.dc;
	DecoderCommand cmd;

	assert(dc.state == DecoderState::DECODE);
	assert(dc.pipe != nullptr);

	/* save the tag */

	delete decoder.decoder_tag;
	decoder.decoder_tag = new Tag(std::move(tag));

	/* check for a new stream tag */

	update_stream_tag(decoder, is);

	/* check if we're seeking */

	if (decoder_prepare_initial_seek(decoder))
		/* during initial seek, no music chunk must be created
		   until seeking is finished; skip the rest of the
		   function here */
		return DecoderCommand::SEEK;

	/* send tag to music pipe */

	if (decoder.stream_tag != nullptr) {
		/* merge with tag from input stream */
		Tag *merged;

		merged = Tag::Merge(*decoder.stream_tag,
				    *decoder.decoder_tag);
		cmd = do_send_tag(decoder, *merged);
		delete merged;
	} else
		/* send only the decoder tag */
		cmd = do_send_tag(decoder, *decoder.decoder_tag);

	return cmd;
}

void
decoder_replay_gain(Decoder &decoder,
		    const ReplayGainInfo *replay_gain_info)
{
	if (replay_gain_info != nullptr) {
		static unsigned serial;
		if (++serial == 0)
			serial = 1;

		if (REPLAY_GAIN_OFF != replay_gain_mode) {
			ReplayGainMode rgm = replay_gain_mode;
			if (rgm != REPLAY_GAIN_ALBUM)
				rgm = REPLAY_GAIN_TRACK;

			const auto &tuple = replay_gain_info->tuples[rgm];
			const auto scale =
				tuple.CalculateScale(replay_gain_preamp,
						     replay_gain_missing_preamp,
						     replay_gain_limit);
			decoder.dc.replay_gain_db = 20.0 * log10f(scale);
		}

		decoder.replay_gain_info = *replay_gain_info;
		decoder.replay_gain_serial = serial;

		if (decoder.chunk != nullptr) {
			/* flush the current chunk because the new
			   replay gain values affect the following
			   samples */
			decoder.FlushChunk();
		}
	} else
		decoder.replay_gain_serial = 0;
}

void
decoder_mixramp(Decoder &decoder, MixRampInfo &&mix_ramp)
{
	DecoderControl &dc = decoder.dc;

	dc.SetMixRamp(std::move(mix_ramp));
}