smf.c

VLC Player Source Code

/*****************************************************************************
 * smf.c : Standard MIDI File (.mid) demux module for vlc
 *****************************************************************************
 * Copyright © 2007 Rémi Denis-Courmont
 * $Id$
 *
 * 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.
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_plugin.h>
#include <vlc_demux.h>
#include <vlc_aout.h>
#include <vlc_codecs.h>
#include <vlc_charset.h>
#include <limits.h>

#include <assert.h>

#define TEMPO_MIN  20
#define TEMPO_MAX 250 /* Beats per minute */

static int  Open  (vlc_object_t *);
static void Close (vlc_object_t *);

vlc_module_begin ();
    set_description (N_("SMF demuxer"));
    set_category (CAT_INPUT);
    set_subcategory (SUBCAT_INPUT_DEMUX);
    set_capability ("demux", 20);
    set_callbacks (Open, Close);
vlc_module_end ();

static int Demux   (demux_t *);
static int Control (demux_t *, int i_query, va_list args);

typedef struct smf_track_t
{
    int64_t  offset; /* Read offset in the file (stream_Tell) */
    int64_t  end;    /* End offset in the file */
    uint64_t next;   /* Time of next message (in term of pulses) */
    uint8_t  running_event; /* Running (previous) event */
} mtrk_t;

static int ReadDeltaTime (stream_t *s, mtrk_t *track);

struct demux_sys_t
{
    es_out_id_t *es;
    date_t       pts;
    uint64_t     pulse; /* Pulses counter */

    unsigned     ppqn;   /* Pulses Per Quarter Note */
    /* by the way, "quarter note" is "noire" in French */

    unsigned     trackc; /* Number of tracks */
    mtrk_t       trackv[0]; /* Track states */
};

/*****************************************************************************
 * Open: check file and initializes structures
 *****************************************************************************/
static int Open (vlc_object_t * p_this)
{
    demux_t       *p_demux = (demux_t *)p_this;
    stream_t      *stream = p_demux->s;
    demux_sys_t   *p_sys;
    const uint8_t *peek;
    unsigned       tracks, ppqn;
    bool     multitrack;

    /* (Try to) parse the SMF header */
    /* Header chunk always has 6 bytes payload */
    if (stream_Peek (stream, &peek, 14) < 14)
        return VLC_EGENERIC;

    /* Skip RIFF MIDI header if present */
    if (!memcmp (peek, "RIFF", 4) && !memcmp (peek + 8, "RMID", 4))
    {
        uint32_t riff_len = GetDWLE (peek + 4);

        msg_Dbg (p_this, "detected RIFF MIDI file (%u bytes)",
                 (unsigned)riff_len);
        if ((stream_Read (stream, NULL, 12) < 12))
            return VLC_EGENERIC;

        /* Look for the RIFF data chunk */
        for (;;)
        {
            char chnk_hdr[8];
            uint32_t chnk_len;

            if ((riff_len < 8)
             || (stream_Read (stream, chnk_hdr, 8) < 8))
                return VLC_EGENERIC;

            riff_len -= 8;
            chnk_len = GetDWLE (chnk_hdr + 4);
            if (riff_len < chnk_len)
                return VLC_EGENERIC;
            riff_len -= chnk_len;

            if (!memcmp (chnk_hdr, "data", 4))
                break; /* found! */

            if (stream_Read (stream, NULL, chnk_len) < (ssize_t)chnk_len)
                return VLC_EGENERIC;
        }

        /* Read real SMF header. Assume RIFF data chunk length is proper. */
        if (stream_Peek (stream, &peek, 14) < 14)
            return VLC_EGENERIC;
    }

    if (memcmp (peek, "MThd\x00\x00\x00\x06", 8))
        return VLC_EGENERIC;
    peek += 8;

    /* First word: SMF type */
    switch (GetWBE (peek))
    {
        case 0:
            multitrack = false;
            break;
        case 1:
            multitrack = true;
            break;
        default:
            /* We don't implement SMF2 (as do many) */
            msg_Err (p_this, "unsupported SMF file type %u", GetWBE (peek));
            return VLC_EGENERIC;
    }
    peek += 2;

    /* Second word: number of tracks */
    tracks = GetWBE (peek);
    peek += 2;
    if (!multitrack && (tracks != 1))
    {
        msg_Err (p_this, "invalid SMF type 0 file");
        return VLC_EGENERIC;
    }

    msg_Dbg (p_this, "detected Standard MIDI File (type %u) with %u track(s)",
             multitrack, tracks);

    /* Third/last word: timing */
    ppqn = GetWBE (peek);
    if (ppqn & 0x8000)
    {
        /* FIXME */
        msg_Err (p_this, "SMPTE timestamps not implemented");
        return VLC_EGENERIC;
    }
    else
    {
        msg_Dbg (p_this, " %u pulses per quarter note", ppqn);
    }

    p_sys = malloc (sizeof (*p_sys) + (sizeof (mtrk_t) * tracks));
    if (p_sys == NULL)
        return VLC_ENOMEM;

    /* We've had a valid SMF header - now skip it*/
    if (stream_Read (stream, NULL, 14) < 14)
        goto error;

    p_demux->pf_demux   = Demux;
    p_demux->pf_control = Control;
    p_demux->p_sys      = p_sys;

    /* Default SMF tempo is 120BPM, i.e. half a second per quarter note */
    date_Init (&p_sys->pts, ppqn * 2, 1);
    date_Set (&p_sys->pts, 1);
    p_sys->pulse        = 0;
    p_sys->ppqn         = ppqn;

    p_sys->trackc       = tracks;
    /* Prefetch track offsets */
    for (unsigned i = 0; i < tracks; i++)
    {
        uint8_t head[8];

        if (i > 0)
        {
            /* Seeking screws streaming up, but there is no way around this,
             * as SMF1 tracks are performed simultaneously.
             * Not a big deal as SMF1 are usually only a few kbytes anyway. */
            if (stream_Seek (stream,  p_sys->trackv[i-1].end))
            {
                msg_Err (p_this, "cannot build SMF index (corrupted file?)");
                goto error;
            }
        }

        for (;;)
        {
            stream_Read (stream, head, 8);
            if (memcmp (head, "MTrk", 4) == 0)
                break;

            msg_Dbg (p_this, "skipping unknown SMF chunk");
            stream_Read (stream, NULL, GetDWBE (head + 4));
        }

        p_sys->trackv[i].offset = stream_Tell (stream);
        p_sys->trackv[i].end = p_sys->trackv[i].offset + GetDWBE (head + 4);
        p_sys->trackv[i].next = 0;
        ReadDeltaTime (stream, p_sys->trackv + i);
        p_sys->trackv[i].running_event = 0xF6;
        /* Why 0xF6 (Tuning Calibration)?
         * Because it has zero bytes of data, so the parser will detect the
         * error if the first event uses running status. */
    }

    es_format_t  fmt;
    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC('M', 'I', 'D', 'I'));
    fmt.audio.i_channels = 2;
    fmt.audio.i_original_channels = fmt.audio.i_physical_channels =
        AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
    fmt.audio.i_rate = 44100; /* dummy value */
    p_sys->es = es_out_Add (p_demux->out, &fmt);

    return VLC_SUCCESS;

error:
    free (p_sys);
    return VLC_EGENERIC;
}

/**
 * Releases allocate resources.
 */
static void Close (vlc_object_t * p_this)
{
    demux_t *p_demux = (demux_t *)p_this;
    demux_sys_t *p_sys = p_demux->p_sys;

    free (p_sys);
}

/**
 * Reads MIDI variable length (7, 14, 21 or 28 bits) integer.
 * @return read value, or -1 on EOF/error.
 */
static int32_t ReadVarInt (stream_t *s)
{
    uint32_t val = 0;
    uint8_t byte;

    for (unsigned i = 0; i < 4; i++)
    {
        if (stream_Read (s, &byte, 1) < 1)
            return -1;

        val = (val << 7) | (byte & 0x7f);
        if ((byte & 0x80) == 0)
            return val;
    }

    return -1;
}


/**
 * Reads (delta) time from the next event of a given track.
 * @param s stream to read data from (must be positioned at the right offset)
 */
static int ReadDeltaTime (stream_t *s, mtrk_t *track)
{
    int32_t delta_time;

    assert (stream_Tell (s) == track->offset);

    if (track->offset >= track->end)
    {
        /* This track is done */
        track->next = UINT64_MAX;
        return 0;
    }

    delta_time = ReadVarInt (s);
    if (delta_time < 0)
        return -1;

    track->next += delta_time;
    track->offset = stream_Tell (s);
    return 0;
}


/**
 * Non-MIDI Meta events handler
 */
static
int HandleMeta (demux_t *p_demux, mtrk_t *tr)
{
    stream_t *s = p_demux->s;
    demux_sys_t *p_sys = p_demux->p_sys;
    uint8_t *payload;
    uint8_t type;
    int32_t length;
    int ret = 0;

    if (stream_Read (s, &type, 1) != 1)