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livetrax/libs/ardour/mp3fileimportable.cc

241 lines
5.6 KiB
C++

/*
* 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 std;
namespace ARDOUR {
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 ();
}
_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 ();
}
/* estimate length, fixed bitrate */
_length = _n_frames * _map_length / _info.frame_bytes;
#if 1 /* detect accurate length by parsing frame headers */
_length = _n_frames;
while (decode_mp3 (true)) {
_length += _n_frames;
}
_read_position = _length;
seek (0);
#endif
}
Mp3FileImportableSource::~Mp3FileImportableSource ()
{
unmap_mem ();
}
void
Mp3FileImportableSource::unmap_mem ()
{
#ifdef PLATFORM_WINDOWS
if (_map_addr) {
UnmapViewOfFile (_map_addr);
}
#else
munmap (const_cast<unsigned char*>(_map_addr), _map_length);
#endif
close (_fd);
_map_addr = 0;
}
int
Mp3FileImportableSource::decode_mp3 (bool parse_only)
{
_pcm_off = 0;
do {
_n_frames = mp3dec_decode_frame (&_mp3d, _buffer, _remain, parse_only ? NULL : _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) {
/* skip ahead, until the frame before the target,
* then start decoding. This provides sufficient
* context to prevent audible hiccups, while still
* providing fast and accurate seeking.
*/
if (!decode_mp3 (_read_position + 3 * _n_frames <= pos)) {
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 < 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;
}
}