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Diffstat (limited to 'libs/ardour/smf_reader.cc')
-rw-r--r-- | libs/ardour/smf_reader.cc | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/libs/ardour/smf_reader.cc b/libs/ardour/smf_reader.cc new file mode 100644 index 0000000000..48ec3dc386 --- /dev/null +++ b/libs/ardour/smf_reader.cc @@ -0,0 +1,285 @@ +/* + Copyright (C) 2008 Paul Davis + Written by Dave Robillard + + 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., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +#include <cstring> +#include <cstdio> +#include <cassert> +#include <iostream> +#include <glibmm/miscutils.h> +#include <midi++/events.h> + +#include <ardour/smf_reader.h> +#include <ardour/midi_util.h> + +using namespace std; + +namespace ARDOUR { + + +SMFReader::SMFReader(const string filename) + : _fd(NULL) + , _ppqn(0) + , _track(0) + , _track_size(0) +{ + if (filename.length() > 0) { + open(filename); + } +} + + +SMFReader::~SMFReader() +{ + if (_fd) + close(); +} + + +bool +SMFReader::open(const string& filename) throw (logic_error, UnsupportedTime) +{ + if (_fd) + throw logic_error("Attempt to start new read while write in progress."); + + cout << "Opening SMF file " << filename << " for reading." << endl; + + _fd = fopen(filename.c_str(), "r+"); + + if (_fd) { + // Read type (bytes 8..9) + fseek(_fd, 0, SEEK_SET); + char mthd[5]; + mthd[4] = '\0'; + fread(mthd, 1, 4, _fd); + if (strcmp(mthd, "MThd")) { + cerr << filename << " is not an SMF file, aborting." << endl; + fclose(_fd); + _fd = NULL; + return false; + } + + // Read type (bytes 8..9) + fseek(_fd, 8, SEEK_SET); + uint16_t type_be = 0; + fread(&type_be, 2, 1, _fd); + _type = GUINT16_FROM_BE(type_be); + + // Read number of tracks (bytes 10..11) + uint16_t num_tracks_be = 0; + fread(&num_tracks_be, 2, 1, _fd); + _num_tracks = GUINT16_FROM_BE(num_tracks_be); + + // Read PPQN (bytes 12..13) + uint16_t ppqn_be = 0; + fread(&ppqn_be, 2, 1, _fd); + _ppqn = GUINT16_FROM_BE(ppqn_be); + + // TODO: Absolute (SMPTE seconds) time support + if ((_ppqn & 0x8000) != 0) + throw UnsupportedTime(); + + seek_to_track(1); + + return true; + } else { + return false; + } +} + + +/** Seek to the start of a given track, starting from 1. + * Returns true if specified track was found. + */ +bool +SMFReader::seek_to_track(unsigned track) throw (std::logic_error) +{ + if (track == 0) + throw logic_error("Seek to track 0 out of range (must be >= 1)"); + + if (!_fd) + throw logic_error("Attempt to seek to track on unopened SMF file."); + + unsigned track_pos = 0; + + fseek(_fd, 14, SEEK_SET); + char id[5]; + id[4] = '\0'; + uint32_t chunk_size = 0; + + while (!feof(_fd)) { + fread(id, 1, 4, _fd); + + if (!strcmp(id, "MTrk")) { + ++track_pos; + } else { + std::cerr << "Unknown chunk ID " << id << endl; + } + + uint32_t chunk_size_be; + fread(&chunk_size_be, 4, 1, _fd); + chunk_size = GUINT32_FROM_BE(chunk_size_be); + + if (track_pos == track) + break; + + fseek(_fd, chunk_size, SEEK_CUR); + } + + if (!feof(_fd) && track_pos == track) { + _track = track; + _track_size = chunk_size; + return true; + } else { + return false; + } +} + + +/** Read an event from the current position in file. + * + * File position MUST be at the beginning of a delta time, or this will die very messily. + * ev.buffer must be of size ev.size, and large enough for the event. The returned event + * will have it's time field set to it's delta time (so it's the caller's responsibility + * to keep track of delta time, even for ignored events). + * + * Returns event length (including status byte) on success, 0 if event was + * skipped (eg a meta event), or -1 on EOF (or end of track). + * + * If @a buf is not large enough to hold the event, 0 will be returned, but ev_size + * set to the actual size of the event. + */ +int +SMFReader::read_event(size_t buf_len, + uint8_t* buf, + uint32_t* ev_size, + uint32_t* delta_time) + throw (std::logic_error, PrematureEOF, CorruptFile) +{ + if (_track == 0) + throw logic_error("Attempt to read from unopened SMF file"); + + if (!_fd || feof(_fd)) { + return -1; + } + + assert(buf_len > 0); + assert(buf); + assert(ev_size); + assert(delta_time); + + // Running status state + static uint8_t last_status = 0; + static uint32_t last_size = 0; + + *delta_time = read_var_len(_fd); + int status = fgetc(_fd); + if (status == EOF) + throw PrematureEOF(); + else if (status > 0xFF) + throw CorruptFile(); + + if (status < 0x80) { + if (last_status == 0) + throw CorruptFile(); + status = last_status; + *ev_size = last_size; + fseek(_fd, -1, SEEK_CUR); + } else { + last_status = status; + *ev_size = midi_event_size(status) + 1; + last_size = *ev_size; + } + + buf[0] = (uint8_t)status; + + if (status == 0xFF) { + *ev_size = 0; + if (feof(_fd)) + throw PrematureEOF(); + uint8_t type = fgetc(_fd); + const uint32_t size = read_var_len(_fd); + /*cerr.flags(ios::hex); + cerr << "SMF - meta 0x" << (int)type << ", size = "; + cerr.flags(ios::dec); + cerr << size << endl;*/ + + if ((uint8_t)type == 0x2F) { + return -1; // we hit the logical EOF anyway... + } else { + fseek(_fd, size, SEEK_CUR); + return 0; + } + } + + if (*ev_size > buf_len || *ev_size == 0 || feof(_fd)) { + //cerr << "SMF - Skipping event" << endl; + // Skip event, return 0 + fseek(_fd, *ev_size - 1, SEEK_CUR); + return 0; + } else { + // Read event, return size + if (ferror(_fd)) + throw CorruptFile(); + + fread(buf+1, 1, *ev_size - 1, _fd); + + if ((buf[0] & 0xF0) == 0x90 && buf[2] == 0) { + buf[0] = (0x80 | (buf[0] & 0x0F)); + buf[2] = 0x40; + } + + return *ev_size; + } +} + + +void +SMFReader::close() +{ + if (_fd) + fclose(_fd); + + _fd = NULL; +} + + +uint32_t +SMFReader::read_var_len(FILE* fd) throw (PrematureEOF) +{ + if (feof(fd)) + throw PrematureEOF(); + + uint32_t value; + uint8_t c; + + if ( (value = getc(fd)) & 0x80 ) { + value &= 0x7F; + do { + if (feof(fd)) + throw PrematureEOF(); + value = (value << 7) + ((c = getc(fd)) & 0x7F); + } while (c & 0x80); + } + + return value; +} + + +} // namespace ARDOUR + |