[paraslash.git] / mp3_afh.c

/*
 * Copyright (C) 2003-2007 Andre Noll <maan@systemlinux.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, USA.
 */

/** \file mp3_afh.c para_server's mp3 audio format handler */

/*
 * This file is based in part on mp3tech.c and mp3tech.h, Copyright (C)
 * 2000-2001 Cedric Tefft <cedric@earthling.net>, which in turn is based
 * in part on
 *
 *      * MP3Info 0.5 by Ricardo Cerqueira <rmc@rccn.net>
 *      * MP3Stat 0.9 by Ed Sweetman <safemode@voicenet.com> and
 *                       Johannes Overmann <overmann@iname.com>
 */

#include "server.h"
#include "error.h"
#include "fd.h"
#include "string.h"

/** \cond some defines and structs which are only used in this file */

/*
 * MIN_CONSEC_GOOD_FRAMES defines how many consecutive valid MP3 frames we need
 * to see before we decide we are looking at a real MP3 file
 */
#define MIN_CONSEC_GOOD_FRAMES 4
#define FRAME_HEADER_SIZE 4
#define MIN_FRAME_SIZE 21

struct mp3header {
        unsigned long sync;
        unsigned int version;
        unsigned int layer;
        unsigned int crc;
        unsigned int bitrate;
        unsigned int freq;
        unsigned int padding;
        unsigned int mode;
        unsigned int copyright;
        unsigned int original;
        unsigned int emphasis;
};

struct id3tag {
        char title[31];
        char artist[31];
        char album[31];
        char year[5];
        char comment[31];
};

struct mp3info {
        struct mp3header header;
        int id3_isvalid;
        struct id3tag id3;
        int vbr;
};

/** \endcond */
static const int frequencies[3][4] = {
        {22050,24000,16000,50000}, /* MPEG 2.0 */
        {44100,48000,32000,50000}, /* MPEG 1.0 */
        {11025,12000,8000,50000} /* MPEG 2.5 */
};

static const int mp3info_bitrate[2][3][14] = {
{ /* MPEG 2.0 */
        {32,48,56,64,80,96,112,128,144,160,176,192,224,256}, /* layer 1 */
        {8,16,24,32,40,48,56,64,80,96,112,128,144,160}, /* layer 2 */
        {8,16,24,32,40,48,56,64,80,96,112,128,144,160} /* layer 3 */
},

{ /* MPEG 1.0 */
        {32,64,96,128,160,192,224,256,288,320,352,384,416,448}, /* layer 1 */
        {32,48,56,64,80,96,112,128,160,192,224,256,320,384}, /* layer 2 */
        {32,40,48,56,64,80,96,112,128,160,192,224,256,320} /* layer 3 */
}
};

static const int frame_size_index[] = {24000, 72000, 72000};
static const char *mode_text[] = {"stereo", "joint stereo", "dual channel", "mono", "invalid"};

static struct mp3info mp3;

static int header_frequency(struct mp3header *h)
{
        if (h->version > 2 || h->freq > 3)
                return -E_HEADER_FREQ;
        return frequencies[h->version][h->freq];
}

static const char *header_mode(struct mp3header *h)
{
        if (h->mode > 4)
                h->mode = 4; /* invalid */
        return mode_text[h->mode];
}

static int header_channels(struct mp3header *h)
{
        if (h->mode > 3)
                return 0;
        if (h->mode < 3)
                return 2;
        return 1;
}

static int header_bitrate(struct mp3header *h)
{
        if (h->layer > 3 || h->bitrate > 14)
                return -E_HEADER_BITRATE;
        return mp3info_bitrate[h->version & 1][3 - h->layer][h->bitrate - 1];
}

static int frame_length(struct mp3header *header)
{
        int hb, hf = header_frequency(header);

        if (hf < 0)
                return hf;
        hb = header_bitrate(header);
        if (hb < 0)
                return hb;
        if (header->sync != 0xFFE || header->layer > 3)
                return -E_FRAME;
        return frame_size_index[3 - header->layer] *
                ((header->version & 1) + 1) * hb / hf
                + header->padding;
}

static void write_info_str(struct audio_format_info *afi)
{
        int v = mp3.id3_isvalid;

        snprintf(afi->info_string, MMD_INFO_SIZE,
                "audio_file_info1:%lu x %lums, %u kbit/s (%cbr) %i KHz %s\n"
                "audio_file_info2:%s, by %s\n"
                "audio_file_info3:A: %s, Y: %s, C: %s\n",
                afi->chunks_total,
                tv2ms(&afi->chunk_tv),
                afi->bitrate,
                mp3.vbr? 'v' : 'c',
                afi->frequency / 1000,
                header_mode(&mp3.header),
                v && *mp3.id3.title? mp3.id3.title : "(title tag not set)",
                v && *mp3.id3.artist? mp3.id3.artist : "(artist tag not set)",
                v && *mp3.id3.album? mp3.id3.album : "(album tag not set)",
                v && *mp3.id3.year? mp3.id3.year : "????",
                v && *mp3.id3.comment? mp3.id3.comment : "(comment tag not set)"
        );
}

/*
 * Remove trailing whitespace from the end of a string
 */
static char *unpad(char *string)
{
        char *pos = string + strlen(string) - 1;
        while (isspace(pos[0]))
                (pos--)[0] = 0;
        return string;
}

static int compare_headers(struct mp3header *h1,struct mp3header *h2)
{
        if ((*(uint*)h1) == (*(uint*)h2))
                return 1;
        if ((h1->version == h2->version) &&
                        (h1->layer == h2->layer) &&
                        (h1->crc == h2->crc) &&
                        (h1->freq == h2->freq) &&
                        (h1->mode == h2->mode) &&
                        (h1->copyright == h2->copyright) &&
                        (h1->original == h2->original) &&
                        (h1->emphasis == h2->emphasis))
                return 1;
        return 0;
}

/*
 * get next MP3 frame header.
 *
 * On success, the header frame length is returned and the given header
 * structure that is filled in.  A return value of zero means that we did not
 * retrieve a valid frame header, and a negative return value indicates an
 * error.
 */
static int get_header(unsigned char *map, off_t numbytes, off_t *fpos,
        struct mp3header *header)
{
        int fl, ret;

        if (*fpos + FRAME_HEADER_SIZE > numbytes) {
                *fpos = numbytes - 1;
                header->sync = 0;
                return 0;
        }
        header->layer = (map[*fpos + 1] >> 1) & 3;
        header->sync = (((int)map[*fpos]<<4) | ((int)(map[*fpos + 1]&0xE0)>>4));
        if (map[*fpos + 1] & 0x10)
                header->version = (map[*fpos + 1] >> 3) & 1;
        else
                header->version = 2;
        if ((header->sync != 0xFFE) || (header->layer != 1)) {
                ret = 0;
                header->sync = 0;
                goto out;
        }
        header->crc = map[*fpos + 1] & 1;
        header->bitrate = (map[*fpos + 2] >> 4) & 0x0F;
        header->freq = (map[*fpos + 2] >> 2) & 0x3;
        header->padding = (map[*fpos + 2] >>1) & 0x1;
        header->mode = (map[*fpos + 3] >> 6) & 0x3;
        fl = frame_length(header);
        ret = (fl >= MIN_FRAME_SIZE)? fl : -E_FRAME_LENGTH;
out:
        *fpos += FRAME_HEADER_SIZE;
        return ret;
}

/*
 * find the next mp3 header
 *
 * Return the length of the next frame header or zero if the end of the file is
 * reached.
 */
static int mp3_seek_next_header(unsigned char *map, off_t numbytes, off_t *fpos)
{
        int k, l = 0, first_len;
        struct mp3header h, h2;
        long valid_start = 0;

        for (; *fpos < numbytes; (*fpos)++) {
                if (map[*fpos] != 0xff)
                        continue;
                valid_start = *fpos;
                first_len = get_header(map, numbytes, fpos, &h);
                if (first_len <= 0)
                        continue;
                *fpos += first_len - FRAME_HEADER_SIZE;
                for (k = 1; k < MIN_CONSEC_GOOD_FRAMES; k++) {
                        if ((l = get_header(map, numbytes, fpos, &h2)) <= 0)
                                break;
                        if (!compare_headers(&h, &h2))
                                break;
                        *fpos += l - FRAME_HEADER_SIZE;
                }
                if (k == MIN_CONSEC_GOOD_FRAMES) {
                        *fpos = valid_start;
                        memcpy(&(mp3.header), &h2, sizeof(struct mp3header));
                        return first_len;
                }
        }
        return 0;
}

static void mp3_get_id3(unsigned char *map, off_t numbytes, off_t *fpos)
{
        mp3.id3_isvalid = 0;
        mp3.id3.title[0] = '\0';
        mp3.id3.artist[0] = '\0';
        mp3.id3.album[0] = '\0';
        mp3.id3.comment[0] = '\0';
        mp3.id3.year[0] = '\0';
        if (numbytes < 128)
                return;
        *fpos = numbytes - 128;
        if (strncmp("TAG", map + *fpos, 3)) {
                PARA_INFO_LOG("%s", "no id3 tag\n");
                return;
        }
        *fpos = numbytes - 125;
        memcpy(mp3.id3.title, map + *fpos, 30);
        *fpos += 30;
        mp3.id3.title[30] = '\0';
        memcpy(mp3.id3.artist, map + *fpos, 30);
        *fpos += 30;
        mp3.id3.artist[30] = '\0';
        memcpy(mp3.id3.album, map + *fpos, 30);
        *fpos += 30;
        mp3.id3.album[30] = '\0';
        memcpy(mp3.id3.year, map + *fpos, 4);
        *fpos += 4;
        mp3.id3.year[4] = '\0';
        memcpy(mp3.id3.comment, map + *fpos, 30);
        mp3.id3.comment[30] = '\0';
        mp3.id3_isvalid = 1;
        unpad(mp3.id3.title);
        unpad(mp3.id3.artist);
        unpad(mp3.id3.album);
        unpad(mp3.id3.year);
        unpad(mp3.id3.comment);
}

static int find_valid_start(unsigned char *map, off_t numbytes, off_t *fpos)
{
        int frame_len;

        frame_len = get_header(map, numbytes, fpos, &mp3.header);
        if (frame_len < 0)
                return frame_len;
        if (!frame_len) {
                frame_len = mp3_seek_next_header(map, numbytes, fpos);
                if (frame_len <= 0)
                        return frame_len;
        } else
                *fpos -= FRAME_HEADER_SIZE;
        if (frame_len <= 1)
                return -E_FRAME_LENGTH;
        return frame_len;
}

static int mp3_read_info(unsigned char *map, off_t numbytes,
                struct audio_format_info *afi)
{
        long fl_avg = 0, freq_avg = 0, br_avg = 0;
        int ret, len = 0, old_br = -1;
        struct timeval total_time = {0, 0};
        unsigned chunk_table_size = 1000; /* gets increased on demand */
        off_t fpos = 0;

        afi->chunks_total = 0;
        afi->chunk_table = para_malloc(chunk_table_size * sizeof(size_t));
        mp3_get_id3(map, numbytes, &fpos);
        fpos = 0;
        mp3.vbr = 0;
        while (1) {
                int freq, br, fl;
                struct timeval tmp, cct; /* current chunk time */
                fpos += len;
                len = find_valid_start(map, numbytes, &fpos);
                if (len <= 0)
                        break;
                freq = header_frequency(&mp3.header);
                br = header_bitrate(&mp3.header);
                fl = frame_length(&mp3.header);
                if (freq < 0 || br < 0 || fl < 0)
                        continue;
                tmp.tv_sec = fl;
                tmp.tv_usec = 0;
                tv_divide(br * 125, &tmp, &cct);
                tv_add(&cct, &total_time, &tmp);
                total_time = tmp;
                //PARA_DEBUG_LOG("%s: br: %d, freq: %d, fl: %d, cct: %lu\n", __func__, br, freq, fl, cct.tv_usec);
                if (afi->chunks_total >= chunk_table_size) {
                        chunk_table_size *= 2;
                        afi->chunk_table = para_realloc(afi->chunk_table,
                                chunk_table_size * sizeof(size_t));
                }
                afi->chunk_table[afi->chunks_total] = fpos;
//              if (afi->chunks_total < 10 || !(afi->chunks_total % 1000))
//                      PARA_INFO_LOG("chunk #%lu: %zd\n", afi->chunks_total,
//                              afi->chunk_table[afi->chunks_total]);
                afi->chunks_total++;
                if (afi->chunks_total == 1) {
                        freq_avg = freq;
                        br_avg = br;
                        old_br = br;
                        fl_avg = fl;
                        continue;
                }
                freq_avg += (freq - freq_avg) / (afi->chunks_total + 1);
                fl_avg += (fl - fl_avg) / (afi->chunks_total + 1);
                br_avg += (br - br_avg) / ((long)afi->chunks_total + 1);
                if (old_br != br)
                        mp3.vbr = 1;
                old_br = br;
        }
        ret = -E_MP3_INFO;
        if (!afi->chunks_total || !freq_avg || !br_avg)
                goto err_out;
        afi->chunk_table[afi->chunks_total] = numbytes - 1;
        afi->bitrate = br_avg;
        afi->frequency = freq_avg;
        afi->channels = header_channels(&mp3.header);
        afi->seconds_total = (tv2ms(&total_time) + 500) / 1000;
        tv_divide(afi->chunks_total, &total_time, &afi->chunk_tv);
        PARA_DEBUG_LOG("%lu chunks, each %lums\n", afi->chunks_total,
                tv2ms(&afi->chunk_tv));
        tv_scale(3, &afi->chunk_tv, &afi->eof_tv);
        PARA_DEBUG_LOG("eof timeout: %lu\n", tv2ms(&afi->eof_tv));
        return 1;
err_out:
        PARA_ERROR_LOG("%s\n", PARA_STRERROR(-ret));
        free(afi->chunk_table);
        return ret;
}

/*
 * Read mp3 information from audio file
 */
static int mp3_get_file_info(char *map, off_t numbytes,
                struct audio_format_info *afi)
{
        int ret;

        ret = mp3_read_info((unsigned char *)map, numbytes, afi);
        if (ret < 0)
                return ret;
        write_info_str(afi);
        if (afi->seconds_total < 2 || !afi->chunks_total)
                return -E_MP3_INFO;
        return 1;
}

static const char* mp3_suffixes[] = {"mp3", NULL};

/**
 * the init function of the mp3 audio format handler
 *
 * \param afh pointer to the struct to initialize
 */
void mp3_init(struct audio_format_handler *afh)
{
        afh->get_file_info = mp3_get_file_info;
        afh->suffixes = mp3_suffixes;
}