mpd/src/inputPlugins/mp3_plugin.c

/* the Music Player Daemon (MPD)
 * (c)2003-2006 by Warren Dukes (warren.dukes@gmail.com)
 * This project's homepage is: 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "../inputPlugin.h"

#ifdef HAVE_MAD

#include "../pcm_utils.h"
#include <mad.h>

#ifdef HAVE_ID3TAG
#include <id3tag.h>
#endif

#include "../log.h"
#include "../utils.h"
#include "../replayGain.h"
#include "../tag.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>

#define FRAMES_CUSHION		2000

#define READ_BUFFER_SIZE	40960

#define DECODE_SKIP		-3
#define DECODE_BREAK		-2
#define DECODE_CONT		-1
#define DECODE_OK		0

#define MUTEFRAME_SKIP          1
#define MUTEFRAME_SEEK          2

/* the number of samples of silence the decoder inserts at start */
#define DECODERDELAY 529

/* this is stolen from mpg321! */
struct audio_dither {
	mad_fixed_t error[3];
	mad_fixed_t random;
};

static unsigned long prng(unsigned long state)
{
	return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
}

static signed long audio_linear_dither(unsigned int bits, mad_fixed_t sample,
				       struct audio_dither *dither)
{
	unsigned int scalebits;
	mad_fixed_t output, mask, random;

	enum {
		MIN = -MAD_F_ONE,
		MAX = MAD_F_ONE - 1
	};

	sample += dither->error[0] - dither->error[1] + dither->error[2];

	dither->error[2] = dither->error[1];
	dither->error[1] = dither->error[0] / 2;

	output = sample + (1L << (MAD_F_FRACBITS + 1 - bits - 1));

	scalebits = MAD_F_FRACBITS + 1 - bits;
	mask = (1L << scalebits) - 1;

	random = prng(dither->random);
	output += (random & mask) - (dither->random & mask);

	dither->random = random;

	if (output > MAX) {
		output = MAX;

		if (sample > MAX)
			sample = MAX;
	} else if (output < MIN) {
		output = MIN;

		if (sample < MIN)
			sample = MIN;
	}

	output &= ~mask;

	dither->error[0] = sample - output;

	return output >> scalebits;
}

/* end of stolen stuff from mpg321 */

/* decoder stuff is based on madlld */

#define MP3_DATA_OUTPUT_BUFFER_SIZE 4096

typedef struct _mp3DecodeData {
	struct mad_stream stream;
	struct mad_frame frame;
	struct mad_synth synth;
	mad_timer_t timer;
	unsigned char readBuffer[READ_BUFFER_SIZE];
	char outputBuffer[MP3_DATA_OUTPUT_BUFFER_SIZE];
	char *outputPtr;
	char *outputBufferEnd;
	float totalTime;
	float elapsedTime;
	int muteFrame;
	long *frameOffset;
	mad_timer_t *times;
	long highestFrame;
	long maxFrames;
	long currentFrame;
	int dropFramesAtStart;
	int dropFramesAtEnd;
	int dropSamplesAtStart;
	int dropSamplesAtEnd;
	int foundXing;
	int foundFirstFrame;
	int decodedFirstFrame;
	int flush;
	unsigned long bitRate;
	InputStream *inStream;
	struct audio_dither dither;
	enum mad_layer layer;
} mp3DecodeData;

static void initMp3DecodeData(mp3DecodeData * data, InputStream * inStream)
{
	data->outputPtr = data->outputBuffer;
	data->outputBufferEnd =
	    data->outputBuffer + MP3_DATA_OUTPUT_BUFFER_SIZE;
	data->muteFrame = 0;
	data->highestFrame = 0;
	data->maxFrames = 0;
	data->frameOffset = NULL;
	data->times = NULL;
	data->currentFrame = 0;
	data->dropFramesAtStart = 0;
	data->dropFramesAtEnd = 0;
	data->dropSamplesAtStart = 0;
	data->dropSamplesAtEnd = 0;
	data->foundXing = 0;
	data->foundFirstFrame = 0;
	data->decodedFirstFrame = 0;
	data->flush = 1;
	data->inStream = inStream;
	data->layer = 0;
	memset(&(data->dither), 0, sizeof(struct audio_dither));

	mad_stream_init(&data->stream);
	mad_stream_options(&data->stream, MAD_OPTION_IGNORECRC);
	mad_frame_init(&data->frame);
	mad_synth_init(&data->synth);
	mad_timer_reset(&data->timer);
}

static int seekMp3InputBuffer(mp3DecodeData * data, long offset)
{
	if (seekInputStream(data->inStream, offset, SEEK_SET) < 0) {
		return -1;
	}

	mad_stream_buffer(&data->stream, data->readBuffer, 0);
	(data->stream).error = 0;

	return 0;
}

static int fillMp3InputBuffer(mp3DecodeData * data)
{
	size_t readSize;
	size_t remaining;
	size_t readed;
	unsigned char *readStart;

	if ((data->stream).next_frame != NULL) {
		remaining = (data->stream).bufend - (data->stream).next_frame;
		memmove(data->readBuffer, (data->stream).next_frame, remaining);
		readStart = (data->readBuffer) + remaining;
		readSize = READ_BUFFER_SIZE - remaining;
	} else {
		readSize = READ_BUFFER_SIZE;
		readStart = data->readBuffer, remaining = 0;
	}

	/* we've exhausted the read buffer, so give up!, these potential
	 * mp3 frames are way too big, and thus unlikely to be mp3 frames */
	if (readSize == 0)
		return -1;

	readed = readFromInputStream(data->inStream, readStart, (size_t) 1,
				     readSize);
	if (readed <= 0 && inputStreamAtEOF(data->inStream))
		return -1;
	/* sleep for a fraction of a second! */
	else if (readed <= 0) {
		readed = 0;
		my_usleep(10000);
	}

	mad_stream_buffer(&data->stream, data->readBuffer, readed + remaining);
	(data->stream).error = 0;

	return 0;
}

#ifdef HAVE_ID3TAG
static ReplayGainInfo *parseId3ReplayGainInfo(struct id3_tag *tag)
{
	int i;
	char *key;
	char *value;
	struct id3_frame *frame;
	int found = 0;
	ReplayGainInfo *replayGainInfo;

	replayGainInfo = newReplayGainInfo();

	for (i = 0; (frame = id3_tag_findframe(tag, "TXXX", i)); i++) {
		if (frame->nfields < 3)
			continue;

		key = (char *)
		    id3_ucs4_latin1duplicate(id3_field_getstring
					     (&frame->fields[1]));
		value = (char *)
		    id3_ucs4_latin1duplicate(id3_field_getstring
					     (&frame->fields[2]));

		if (strcasecmp(key, "replaygain_track_gain") == 0) {
			replayGainInfo->trackGain = atof(value);
			found = 1;
		} else if (strcasecmp(key, "replaygain_album_gain") == 0) {
			replayGainInfo->albumGain = atof(value);
			found = 1;
		} else if (strcasecmp(key, "replaygain_track_peak") == 0) {
			replayGainInfo->trackPeak = atof(value);
			found = 1;
		} else if (strcasecmp(key, "replaygain_album_peak") == 0) {
			replayGainInfo->albumPeak = atof(value);
			found = 1;
		}

		free(key);
		free(value);
	}

	if (found)
		return replayGainInfo;
	freeReplayGainInfo(replayGainInfo);
	return NULL;
}
#endif

#ifdef HAVE_ID3TAG
static void mp3_parseId3Tag(mp3DecodeData * data, signed long tagsize,
			    MpdTag ** mpdTag, ReplayGainInfo ** replayGainInfo)
{
	struct id3_tag *id3Tag = NULL;
	id3_length_t count;
	id3_byte_t const *id3_data;
	id3_byte_t *allocated = NULL;
	MpdTag *tmpMpdTag;
	ReplayGainInfo *tmpReplayGainInfo;

	count = data->stream.bufend - data->stream.this_frame;

	if (tagsize <= count) {
		id3_data = data->stream.this_frame;
		mad_stream_skip(&(data->stream), tagsize);
	} else {
		allocated = xmalloc(tagsize);
		if (!allocated)
			goto fail;

		memcpy(allocated, data->stream.this_frame, count);
		mad_stream_skip(&(data->stream), count);

		while (count < tagsize) {
			int len;

			len = readFromInputStream(data->inStream,
						  allocated + count, (size_t) 1,
						  tagsize - count);
			if (len <= 0 && inputStreamAtEOF(data->inStream)) {
				break;
			} else if (len <= 0)
				my_usleep(10000);
			else
				count += len;
		}

		if (count != tagsize) {
			DEBUG("mp3_decode: error parsing ID3 tag\n");
			goto fail;
		}

		id3_data = allocated;
	}

	id3Tag = id3_tag_parse(id3_data, tagsize);
	if (!id3Tag)
		goto fail;

	if (mpdTag) {
		tmpMpdTag = parseId3Tag(id3Tag);
		if (tmpMpdTag) {
			if (*mpdTag)
				freeMpdTag(*mpdTag);
			*mpdTag = tmpMpdTag;
		}
	}

	if (replayGainInfo) {
		tmpReplayGainInfo = parseId3ReplayGainInfo(id3Tag);
		if (tmpReplayGainInfo) {
			if (*replayGainInfo)
				freeReplayGainInfo(*replayGainInfo);
			*replayGainInfo = tmpReplayGainInfo;
		}
	}

	id3_tag_delete(id3Tag);
fail:
	if (allocated)
		free(allocated);
}
#endif

static int decodeNextFrameHeader(mp3DecodeData * data, MpdTag ** tag,
				 ReplayGainInfo ** replayGainInfo)
{
	enum mad_layer layer;

	if ((data->stream).buffer == NULL
	    || (data->stream).error == MAD_ERROR_BUFLEN) {
		if (fillMp3InputBuffer(data) < 0) {
			return DECODE_BREAK;
		}
	}
	if (mad_header_decode(&data->frame.header, &data->stream)) {
#ifdef HAVE_ID3TAG
		if ((data->stream).error == MAD_ERROR_LOSTSYNC &&
		    (data->stream).this_frame) {
			signed long tagsize = id3_tag_query((data->stream).
							    this_frame,
							    (data->stream).
							    bufend -
							    (data->stream).
							    this_frame);

			if (tagsize > 0) {
				if (tag && !(*tag)) {
					mp3_parseId3Tag(data, tagsize, tag,
							replayGainInfo);
				} else {
					mad_stream_skip(&(data->stream),
							tagsize);
				}
				return DECODE_CONT;
			}
		}
#endif
		if (MAD_RECOVERABLE((data->stream).error)) {
			return DECODE_SKIP;
		} else {
			if ((data->stream).error == MAD_ERROR_BUFLEN)
				return DECODE_CONT;
			else {
				ERROR("unrecoverable frame level error "
				      "(%s).\n",
				      mad_stream_errorstr(&data->stream));
				data->flush = 0;
				return DECODE_BREAK;
			}
		}
	}

	layer = data->frame.header.layer;
	if (!data->layer) {
		if (layer != MAD_LAYER_II && layer != MAD_LAYER_III) {
			/* Only layer 2 and 3 have been tested to work */
			return DECODE_SKIP;
		}
		data->layer = layer;
	} else if (layer != data->layer) {
		/* Don't decode frames with a different layer than the first */
		return DECODE_SKIP;
	}

	return DECODE_OK;
}

static int decodeNextFrame(mp3DecodeData * data)
{
	if ((data->stream).buffer == NULL
	    || (data->stream).error == MAD_ERROR_BUFLEN) {
		if (fillMp3InputBuffer(data) < 0) {
			return DECODE_BREAK;
		}
	}
	if (mad_frame_decode(&data->frame, &data->stream)) {
#ifdef HAVE_ID3TAG
		if ((data->stream).error == MAD_ERROR_LOSTSYNC) {
			signed long tagsize = id3_tag_query((data->stream).
							    this_frame,
							    (data->stream).
							    bufend -
							    (data->stream).
							    this_frame);
			if (tagsize > 0) {
				mad_stream_skip(&(data->stream), tagsize);
				return DECODE_CONT;
			}
		}
#endif
		if (MAD_RECOVERABLE((data->stream).error)) {
			return DECODE_SKIP;
		} else {
			if ((data->stream).error == MAD_ERROR_BUFLEN)
				return DECODE_CONT;
			else {
				ERROR("unrecoverable frame level error "
				      "(%s).\n",
				      mad_stream_errorstr(&data->stream));
				data->flush = 0;
				return DECODE_BREAK;
			}
		}
	}

	return DECODE_OK;
}

/* xing stuff stolen from alsaplayer, and heavily modified by jat */
#define XI_MAGIC (('X' << 8) | 'i')
#define NG_MAGIC (('n' << 8) | 'g')
#define IN_MAGIC (('I' << 8) | 'n')
#define FO_MAGIC (('f' << 8) | 'o')

enum xing_magic {
	XING_MAGIC_XING, /* VBR */
	XING_MAGIC_INFO  /* CBR */
};

struct xing {
	long flags;             /* valid fields (see below) */
	unsigned long frames;   /* total number of frames */
	unsigned long bytes;    /* total number of bytes */
	unsigned char toc[100]; /* 100-point seek table */
	long scale;             /* VBR quality */
	enum xing_magic magic;  /* header magic */
};

enum {
	XING_FRAMES = 0x00000001L,
	XING_BYTES  = 0x00000002L,
	XING_TOC    = 0x00000004L,
	XING_SCALE  = 0x00000008L
};

struct lame {
	char encoder[10];   /* 9 byte encoder name/version ("LAME3.97b") */
#if 0
	/* See related comment in parse_lame() */
	float peak;         /* replaygain peak */
	float trackGain;    /* replaygain track gain */
	float albumGain;    /* replaygain album gain */
#endif
	int encoderDelay;   /* # of added samples at start of mp3 */
	int encoderPadding; /* # of added samples at end of mp3 */
};

static int parse_xing(struct xing *xing, struct mad_bitptr *ptr, int *oldbitlen)
{
	unsigned long bits;
	int bitlen;
	int bitsleft;
	int i;

	bitlen = *oldbitlen;

	if (bitlen < 16) goto fail;
	bits = mad_bit_read(ptr, 16);
	bitlen -= 16;

	if (bits == XI_MAGIC) {
		if (bitlen < 16) goto fail;
		if (mad_bit_read(ptr, 16) != NG_MAGIC) goto fail;
		bitlen -= 16;
		xing->magic = XING_MAGIC_XING;
	} else if (bits == IN_MAGIC) {
		if (bitlen < 16) goto fail;
		if (mad_bit_read(ptr, 16) != FO_MAGIC) goto fail;
		bitlen -= 16;
		xing->magic = XING_MAGIC_INFO;
	}
	else if (bits == NG_MAGIC) xing->magic = XING_MAGIC_XING;
	else if (bits == FO_MAGIC) xing->magic = XING_MAGIC_INFO;
	else goto fail;

	if (bitlen < 32) goto fail;
	xing->flags = mad_bit_read(ptr, 32);
	bitlen -= 32;

	if (xing->flags & XING_FRAMES) {
		if (bitlen < 32) goto fail;
		xing->frames = mad_bit_read(ptr, 32);
		bitlen -= 32;
	}

	if (xing->flags & XING_BYTES) {
		if (bitlen < 32) goto fail;
		xing->bytes = mad_bit_read(ptr, 32);
		bitlen -= 32;
	}

	if (xing->flags & XING_TOC) {
		if (bitlen < 800) goto fail;
		for (i = 0; i < 100; ++i) xing->toc[i] = mad_bit_read(ptr, 8);
		bitlen -= 800;
	}

	if (xing->flags & XING_SCALE) {
		if (bitlen < 32) goto fail;
		xing->scale = mad_bit_read(ptr, 32);
		bitlen -= 32;
	}

	/* Make sure we consume no less than 120 bytes (960 bits) in hopes that
	 * the LAME tag is found there, and not right after the Xing header */
	bitsleft = 960 - ((*oldbitlen) - bitlen);
	if (bitsleft < 0) goto fail;
	else if (bitsleft > 0) {
		mad_bit_read(ptr, bitsleft);
		bitlen -= bitsleft;
	}

	*oldbitlen = bitlen;

	return 1;
fail:
	xing->flags = 0;
	return 0;
}

static int parse_lame(struct lame *lame, struct mad_bitptr *ptr, int *bitlen)
{
	int i;

	/* Unlike the xing header, the lame tag has a fixed length.  Fail if
	 * not all 36 bytes (288 bits) are there. */
	if (*bitlen < 288) return 0;

	for (i = 0; i < 9; i++) lame->encoder[i] = (char)mad_bit_read(ptr, 8);
	lame->encoder[9] = '\0';

	/* This is technically incorrect, since the encoder might not be lame.
	 * But there's no other way to determine if this is a lame tag, and we
	 * wouldn't want to go reading a tag that's not there. */
	if (strncmp(lame->encoder, "LAME", 4) != 0) return 0;

#if 0
	/* Apparently lame versions <3.97b1 do not calculate replaygain.  I'm
	 * using lame 3.97b2, and while it does calculate replaygain, it's
	 * setting the values to 0.  Using --replaygain-(fast|accurate) doesn't
	 * make any difference.  Leaving this code unused until we have a way
	 * of testing it. -- jat */

	mad_bit_read(ptr, 16);

	mad_bit_read(ptr, 32); /* peak */

	mad_bit_read(ptr, 6); /* header */
	bits = mad_bit_read(ptr, 1); /* sign bit */
	lame->trackGain = mad_bit_read(ptr, 9); /* gain*10 */
	lame->trackGain = (bits ? -lame->trackGain : lame->trackGain) / 10;

	mad_bit_read(ptr, 6); /* header */
	bits = mad_bit_read(ptr, 1); /* sign bit */
	lame->albumGain = mad_bit_read(ptr, 9); /* gain*10 */
	lame->albumGain = (bits ? -lame->albumGain : lame->albumGain) / 10;

	mad_bit_read(ptr, 16);
#else
	mad_bit_read(ptr, 96);
#endif

	lame->encoderDelay = mad_bit_read(ptr, 12);
	lame->encoderPadding = mad_bit_read(ptr, 12);

	mad_bit_read(ptr, 96);

	*bitlen -= 288;

	return 1;
}

static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
                            MpdTag ** tag, ReplayGainInfo ** replayGainInfo)
{
	struct xing xing;
	struct lame lame;
	struct mad_bitptr ptr;
	int bitlen;
	int ret;

	/* stfu gcc */
	memset(&xing, 0, sizeof(struct xing));
	xing.flags = 0;

	while (1) {
		while ((ret = decodeNextFrameHeader(data, tag, replayGainInfo)) == DECODE_CONT &&
		       (!dc || !dc->stop));
		if (ret == DECODE_BREAK || (dc && dc->stop)) return -1;
		if (ret == DECODE_SKIP) continue;

		while ((ret = decodeNextFrame(data)) == DECODE_CONT &&
		       (!dc || !dc->stop));
		if (ret == DECODE_BREAK || (dc && dc->stop)) return -1;
		if (ret == DECODE_OK) break;
	}

	ptr = data->stream.anc_ptr;
	bitlen = data->stream.anc_bitlen;

	/*
	 * Attempt to calulcate the length of the song from filesize
	 */
	{
		size_t offset = data->inStream->offset;
		mad_timer_t duration = data->frame.header.duration;
		float frameTime = ((float)mad_timer_count(duration,
		                   MAD_UNITS_MILLISECONDS)) / 1000;

		if (data->stream.this_frame != NULL)
			offset -= data->stream.bufend - data->stream.this_frame;
		else
			offset -= data->stream.bufend - data->stream.buffer;

		if (data->inStream->size >= offset) {
			data->totalTime = ((data->inStream->size - offset) *
			                   8.0) / (data->frame).header.bitrate;
			data->maxFrames = data->totalTime / frameTime +
			                  FRAMES_CUSHION;
		} else {
			data->maxFrames = FRAMES_CUSHION;
			data->totalTime = 0;
		}
	}
	/*
	 * if an xing tag exists, use that!
	 */
	if (parse_xing(&xing, &ptr, &bitlen)) {
		data->foundXing = 1;
		data->muteFrame = MUTEFRAME_SKIP;

		if (parse_lame(&lame, &ptr, &bitlen)) {
			data->dropSamplesAtStart = lame.encoderDelay + DECODERDELAY;
			data->dropSamplesAtEnd = lame.encoderPadding;
		}

		if ((xing.flags & XING_FRAMES) && xing.frames) {
			mad_timer_t duration = data->frame.header.duration;
			mad_timer_multiply(&duration, xing.frames);
			data->totalTime = ((float)mad_timer_count(duration, MAD_UNITS_MILLISECONDS)) / 1000;
			data->maxFrames = xing.frames;
		}
	} 

	if (!data->maxFrames) return -1;

	data->frameOffset = xmalloc(sizeof(long) * data->maxFrames);
	data->times = xmalloc(sizeof(mad_timer_t) * data->maxFrames);

	return 0;
}

static void mp3DecodeDataFinalize(mp3DecodeData * data)
{
	mad_synth_finish(&data->synth);
	mad_frame_finish(&data->frame);
	mad_stream_finish(&data->stream);

	if (data->frameOffset) free(data->frameOffset);
	if (data->times) free(data->times);
}

/* this is primarily used for getting total time for tags */
static int getMp3TotalTime(char *file)
{
	InputStream inStream;
	mp3DecodeData data;
	int ret;

	if (openInputStream(&inStream, file) < 0)
		return -1;
	initMp3DecodeData(&data, &inStream);
	if (decodeFirstFrame(&data, NULL, NULL, NULL) < 0)
		ret = -1;
	else
		ret = data.totalTime + 0.5;
	mp3DecodeDataFinalize(&data);
	closeInputStream(&inStream);

	return ret;
}

static int openMp3FromInputStream(InputStream * inStream, mp3DecodeData * data,
				  DecoderControl * dc, MpdTag ** tag,
				  ReplayGainInfo ** replayGainInfo)
{
	initMp3DecodeData(data, inStream);
	*tag = NULL;
	if (decodeFirstFrame(data, dc, tag, replayGainInfo) < 0) {
		mp3DecodeDataFinalize(data);
		if (tag && *tag)
			freeMpdTag(*tag);
		return -1;
	}

	return 0;
}

static int mp3Read(mp3DecodeData * data, OutputBuffer * cb, DecoderControl * dc,
		   ReplayGainInfo ** replayGainInfo)
{
	int samplesPerFrame;
	int samplesLeft;
	int i;
	int ret;
	int skip;

	if (data->currentFrame >= data->highestFrame) {
		mad_timer_add(&data->timer, (data->frame).header.duration);
		data->bitRate = (data->frame).header.bitrate;
		if (data->currentFrame >= data->maxFrames) {
			data->currentFrame = data->maxFrames - 1;
		} else {
			data->highestFrame++;
		}
		data->frameOffset[data->currentFrame] = data->inStream->offset;
		if (data->stream.this_frame != NULL) {
			data->frameOffset[data->currentFrame] -=
			    data->stream.bufend - data->stream.this_frame;
		} else {
			data->frameOffset[data->currentFrame] -=
			    data->stream.bufend - data->stream.buffer;
		}
		data->times[data->currentFrame] = data->timer;
	} else {
		data->timer = data->times[data->currentFrame];
	}
	data->currentFrame++;
	data->elapsedTime =
	    ((float)mad_timer_count(data->timer, MAD_UNITS_MILLISECONDS)) /
	    1000;

	switch (data->muteFrame) {
	case MUTEFRAME_SKIP:
		data->muteFrame = 0;
		break;
	case MUTEFRAME_SEEK:
		if (dc->seekWhere <= data->elapsedTime) {
			data->outputPtr = data->outputBuffer;
			clearOutputBuffer(cb);
			data->muteFrame = 0;
			dc->seek = 0;
		}
		break;
	default:
		mad_synth_frame(&data->synth, &data->frame);

		if (!data->foundFirstFrame) {
			samplesPerFrame = (data->synth).pcm.length;
			data->dropFramesAtStart = data->dropSamplesAtStart / samplesPerFrame;
			data->dropFramesAtEnd = data->dropSamplesAtEnd / samplesPerFrame;
			data->dropSamplesAtStart = data->dropSamplesAtStart % samplesPerFrame;
			data->dropSamplesAtEnd = data->dropSamplesAtEnd % samplesPerFrame;
			data->foundFirstFrame = 1;
		}

		if (data->dropFramesAtStart > 0) {
			data->dropFramesAtStart--;
			break;
		} else if ((data->dropFramesAtEnd > 0) && 
		           (data->currentFrame == (data->maxFrames + 1 - data->dropFramesAtEnd))) {
			/* stop decoding, effectively dropping all remaining
			 * frames */
			return DECODE_BREAK;
		}

		if (data->inStream->metaTitle) {
			MpdTag *tag = newMpdTag();
			if (data->inStream->metaName) {
				addItemToMpdTag(tag,
						TAG_ITEM_NAME,
						data->inStream->metaName);
			}
			addItemToMpdTag(tag, TAG_ITEM_TITLE,
					data->inStream->metaTitle);
			free(data->inStream->metaTitle);
			data->inStream->metaTitle = NULL;
			copyMpdTagToOutputBuffer(cb, tag);
			freeMpdTag(tag);
		}

		samplesLeft = (data->synth).pcm.length;

		for (i = 0; i < (data->synth).pcm.length; i++) {
			mpd_sint16 *sample;

			samplesLeft--;

			if (!data->decodedFirstFrame &&
			    (i < data->dropSamplesAtStart)) {
				continue;
			} else if (data->dropSamplesAtEnd &&
			           (data->currentFrame == (data->maxFrames - data->dropFramesAtEnd)) &&
				   (samplesLeft < data->dropSamplesAtEnd)) {
				/* stop decoding, effectively dropping
				 * all remaining samples */
				return DECODE_BREAK;
			}

			sample = (mpd_sint16 *) data->outputPtr;
			*sample = (mpd_sint16) audio_linear_dither(16,
								   (data->synth).pcm.samples[0][i],
								   &(data->dither));
			data->outputPtr += 2;

			if (MAD_NCHANNELS(&(data->frame).header) == 2) {
				sample = (mpd_sint16 *) data->outputPtr;
				*sample = (mpd_sint16) audio_linear_dither(16,
									   (data->synth).pcm.samples[1][i],
									   &(data->dither));
				data->outputPtr += 2;
			}

			if (data->outputPtr >= data->outputBufferEnd) {
				long ret;
				ret = sendDataToOutputBuffer(cb,
							     data->inStream,
							     dc,
							     data->inStream->seekable,
							     data->outputBuffer,
							     data->outputPtr - data->outputBuffer,
							     data->elapsedTime,
							     data->bitRate / 1000,
							     (replayGainInfo != NULL) ? *replayGainInfo : NULL);
				if (ret == OUTPUT_BUFFER_DC_STOP) {
					data->flush = 0;
					return DECODE_BREAK;
				}

				data->outputPtr = data->outputBuffer;

				if (ret == OUTPUT_BUFFER_DC_SEEK)
					break;
			}
		}

		data->decodedFirstFrame = 1;

		if (dc->seek && data->inStream->seekable) {
			long i = 0;
			data->muteFrame = MUTEFRAME_SEEK;
			while (i < data->highestFrame && dc->seekWhere >
			       ((float)mad_timer_count(data->times[i],
						       MAD_UNITS_MILLISECONDS))
			       / 1000) {
				i++;
			}
			if (i < data->highestFrame) {
				if (seekMp3InputBuffer(data,
						       data->frameOffset[i]) ==
				    0) {
					data->outputPtr = data->outputBuffer;
					clearOutputBuffer(cb);
					data->currentFrame = i;
				} else
					dc->seekError = 1;
				data->muteFrame = 0;
				dc->seek = 0;
			}
		} else if (dc->seek && !data->inStream->seekable) {
			dc->seek = 0;
			dc->seekError = 1;
		}
	}

	while (1) {
		skip = 0;
		while ((ret =
			decodeNextFrameHeader(data, NULL,
					      replayGainInfo)) == DECODE_CONT
		       && !dc->stop) ;
		if (ret == DECODE_BREAK || dc->stop || dc->seek)
			break;
		else if (ret == DECODE_SKIP)
			skip = 1;
		if (!data->muteFrame) {
			while ((ret = decodeNextFrame(data)) == DECODE_CONT &&
			       !dc->stop && !dc->seek) ;
			if (ret == DECODE_BREAK || dc->stop || dc->seek)
				break;
		}
		if (!skip && ret == DECODE_OK)
			break;
	}

	if (dc->stop)
		return DECODE_BREAK;

	return ret;
}

static void initAudioFormatFromMp3DecodeData(mp3DecodeData * data,
					     AudioFormat * af)
{
	af->bits = 16;
	af->sampleRate = (data->frame).header.samplerate;
	af->channels = MAD_NCHANNELS(&(data->frame).header);
}

static int mp3_decode(OutputBuffer * cb, DecoderControl * dc,
		      InputStream * inStream)
{
	mp3DecodeData data;
	MpdTag *tag = NULL;
	ReplayGainInfo *replayGainInfo = NULL;

	if (openMp3FromInputStream(inStream, &data, dc, &tag, &replayGainInfo) <
	    0) {
		closeInputStream(inStream);
		if (!dc->stop) {
			ERROR
			    ("Input does not appear to be a mp3 bit stream.\n");
			return -1;
		} else {
			dc->state = DECODE_STATE_STOP;
			dc->stop = 0;
		}
		return 0;
	}

	initAudioFormatFromMp3DecodeData(&data, &(dc->audioFormat));
	getOutputAudioFormat(&(dc->audioFormat), &(cb->audioFormat));

	dc->totalTime = data.totalTime;

	if (inStream->metaTitle) {
		if (tag)
			freeMpdTag(tag);
		tag = newMpdTag();
		addItemToMpdTag(tag, TAG_ITEM_TITLE, inStream->metaTitle);
		free(inStream->metaTitle);
		inStream->metaTitle = NULL;
		if (inStream->metaName) {
			addItemToMpdTag(tag, TAG_ITEM_NAME, inStream->metaName);
		}
		copyMpdTagToOutputBuffer(cb, tag);
		freeMpdTag(tag);
	} else if (tag) {
		if (inStream->metaName) {
			clearItemsFromMpdTag(tag, TAG_ITEM_NAME);
			addItemToMpdTag(tag, TAG_ITEM_NAME, inStream->metaName);
		}
		copyMpdTagToOutputBuffer(cb, tag);
		freeMpdTag(tag);
	} else if (inStream->metaName) {
		tag = newMpdTag();
		if (inStream->metaName) {
			addItemToMpdTag(tag, TAG_ITEM_NAME, inStream->metaName);
		}
		copyMpdTagToOutputBuffer(cb, tag);
		freeMpdTag(tag);
	}

	dc->state = DECODE_STATE_DECODE;

	while (mp3Read(&data, cb, dc, &replayGainInfo) != DECODE_BREAK) ;
	/* send last little bit if not dc->stop */
	if (!dc->stop && data.outputPtr != data.outputBuffer && data.flush) {
		sendDataToOutputBuffer(cb, NULL, dc,
				       data.inStream->seekable,
				       data.outputBuffer,
				       data.outputPtr - data.outputBuffer,
				       data.elapsedTime, data.bitRate / 1000,
				       replayGainInfo);
	}

	if (replayGainInfo)
		freeReplayGainInfo(replayGainInfo);

	closeInputStream(inStream);

	if (dc->seek && data.muteFrame == MUTEFRAME_SEEK) {
		clearOutputBuffer(cb);
		dc->seek = 0;
	}

	flushOutputBuffer(cb);
	mp3DecodeDataFinalize(&data);

	if (dc->stop) {
		dc->state = DECODE_STATE_STOP;
		dc->stop = 0;
	} else
		dc->state = DECODE_STATE_STOP;

	return 0;
}

static MpdTag *mp3_tagDup(char *file)
{
	MpdTag *ret = NULL;
	int time;

	ret = id3Dup(file);

	time = getMp3TotalTime(file);

	if (time >= 0) {
		if (!ret)
			ret = newMpdTag();
		ret->time = time;
	} else {
		DEBUG("mp3_tagDup: Failed to get total song time from: %s\n",
		      file);
	}

	return ret;
}

static char *mp3_suffixes[] = { "mp3", "mp2", NULL };
static char *mp3_mimeTypes[] = { "audio/mpeg", NULL };

InputPlugin mp3Plugin = {
	"mp3",
	NULL,
	NULL,
	NULL,
	mp3_decode,
	NULL,
	mp3_tagDup,
	INPUT_PLUGIN_STREAM_FILE | INPUT_PLUGIN_STREAM_URL,
	mp3_suffixes,
	mp3_mimeTypes
};
#else

InputPlugin mp3Plugin = {
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	0,
	NULL,
	NULL
};

#endif