Implement mp3 import, using minimp3

1 files changed, 223 insertions, 0 deletions

diff --git a/libs/ardour/mp3fileimportable.cc b/libs/ardour/mp3fileimportable.cc
new file mode 100644
index 0000000000..5ccb1d0355
--- /dev/null
+++ b/libs/ardour/mp3fileimportable.cc
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2008-2017 Paul Davis <paul@linuxaudiosystems.com>
+ * Copyright (C) 2019 Robin Gareus <robin@gareus.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.
+ */
+
+#define MINIMP3_IMPLEMENTATION
+
+#include <fcntl.h>
+
+#ifdef PLATFORM_WINDOWS
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#endif
+
+#include <glib.h>
+#include "pbd/gstdio_compat.h"
+
+#include "pbd/error.h"
+#include "ardour/mp3fileimportable.h"
+
+using namespace ARDOUR;
+using namespace std;
+
+Mp3FileImportableSource::Mp3FileImportableSource (const string& path)
+	: _fd (-1)
+	, _map_addr (0)
+	, _map_length (0)
+	, _buffer (0)
+	, _remain (0)
+	, _read_position (0)
+	, _pcm_off (0)
+	, _n_frames (0)
+{
+	mp3dec_init (&_mp3d);
+	memset (&_info, 0, sizeof (_info));
+
+	GStatBuf statbuf;
+	if (g_stat (path.c_str(), &statbuf) != 0) {
+		throw failed_constructor ();
+	}
+
+	_fd = g_open (path.c_str (), O_RDONLY, 0444);
+	if (_fd == -1) {
+		throw failed_constructor ();
+	}
+	_map_length = statbuf.st_size;
+
+#ifdef PLATFORM_WINDOWS
+	HANDLE file_handle = (HANDLE) _get_osfhandle (int(_fd));
+
+	HANDLE map_handle = CreateFileMapping (file_handle, NULL, PAGE_READONLY, 0, 0, NULL);
+	if (map_handle == NULL) {
+		close (_fd);
+		throw failed_constructor ();
+	}
+
+	LPVOID view_handle = MapViewOfFile (map_handle, FILE_MAP_READ, 0, 0, _map_length);
+	if (view_handle == NULL) {
+		CloseHandle (map_handle);
+		close (_fd);
+		throw failed_constructor ();
+		return -1;
+	}
+	_map_addr = (const uint8_t*)view_handle;
+	CloseHandle (map_handle);
+#else
+	_map_addr = (const uint8_t *)mmap (NULL, _map_length, PROT_READ, MAP_PRIVATE, _fd, 0);
+	if (_map_addr == MAP_FAILED) {
+		close (_fd);
+		throw failed_constructor ();
+	}
+#endif
+
+	_buffer = _map_addr;
+	_remain = _map_length;
+
+	if (!decode_mp3 ()) {
+		unmap_mem ();
+		throw failed_constructor ();
+	}
+
+	_length = _n_frames * _map_length / _info.frame_bytes;
+}
+
+Mp3FileImportableSource::~Mp3FileImportableSource ()
+{
+	unmap_mem ();
+}
+
+void
+Mp3FileImportableSource::unmap_mem ()
+{
+#ifdef PLATFORM_WINDOWS
+	if (_map_addr) {
+		UnmapViewOfFile (_map_addr);
+	}
+#else
+	munmap ((void*) _map_addr, _map_length);
+#endif
+	close (_fd);
+	_map_addr = 0;
+}
+
+int
+Mp3FileImportableSource::decode_mp3 ()
+{
+	_pcm_off = 0;
+	do {
+		_n_frames = mp3dec_decode_frame (&_mp3d, _buffer, _remain, _pcm, &_info);
+		_buffer += _info.frame_bytes;
+		_remain -= _info.frame_bytes;
+		if (_n_frames) {
+			break;
+		}
+	} while (_info.frame_bytes);
+	return _n_frames;
+}
+
+void
+Mp3FileImportableSource::seek (samplepos_t pos)
+{
+	if (_read_position == pos) {
+		return;
+	}
+
+	/* rewind, then decode to pos */
+	if (pos < _read_position) {
+		_buffer = _map_addr;
+		_remain = _map_length;
+		_read_position = 0;
+		_pcm_off = 0;
+		mp3dec_init (&_mp3d);
+		decode_mp3 ();
+	}
+
+	while (_read_position + _n_frames <= pos) {
+		if (!decode_mp3 ()) {
+			break;
+		}
+		_read_position += _n_frames;
+	}
+
+	if (_n_frames >= 0) {
+		_pcm_off = _info.channels * (pos - _read_position);
+		_n_frames -= pos - _read_position;
+		_read_position = pos;
+	}
+	assert (_pcm_off >= 0 && _pcm_off < MINIMP3_MAX_SAMPLES_PER_FRAME);
+}
+
+samplecnt_t
+Mp3FileImportableSource::read (Sample* dst, samplecnt_t nframes)
+{
+	size_t dst_off = 0;
+	int remain = nframes; // == samples * channels
+	while (remain > 0) {
+		samplecnt_t samples_to_copy = std::min (remain, _n_frames * _info.channels);
+		if (samples_to_copy > 0) {
+			memcpy (&dst[dst_off], &_pcm[_pcm_off], samples_to_copy * sizeof (Sample));
+			remain         -= samples_to_copy;
+			dst_off        += samples_to_copy;
+			_n_frames      -= samples_to_copy / _info.channels;
+			_pcm_off       += samples_to_copy;
+			_read_position += samples_to_copy / _info.channels;
+		}
+		assert (_n_frames >= 0);
+		if (_n_frames <= 0 && !decode_mp3 ()) {
+			/* EOF, or decode error */
+			break;
+		}
+	}
+	return dst_off;
+}
+
+samplecnt_t
+Mp3FileImportableSource::read_unlocked (Sample* dst, samplepos_t start, samplecnt_t cnt, uint32_t chn)
+{
+	const uint32_t n_chn = channels ();
+	if (chn > n_chn || cnt == 0) {
+		return 0;
+	}
+	if (start != _read_position) {
+		seek (start);
+	}
+
+	size_t dst_off = 0;
+	samplecnt_t remain = cnt;
+
+	while (remain > 0) {
+		samplecnt_t samples_to_copy = std::min (remain, (samplecnt_t)_n_frames);
+
+		for (samplecnt_t n = 0; n < samples_to_copy; ++n) {
+			dst[dst_off] = _pcm[_pcm_off + chn];
+			dst_off        += 1;
+			remain         -= 1;
+			_n_frames      -= 1;
+			_pcm_off       += n_chn;
+			_read_position += 1;
+		}
+
+		assert (_n_frames >= 0);
+		if (_n_frames <= 0 && !decode_mp3 ()) {
+			/* EOF, or decode error */
+			break;
+		}
+	}
+	return dst_off;
+}