vgmstream/src/meta/ffmpeg.c

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#include "meta.h"
#include "../coding/coding.h"
#ifdef VGM_USE_FFMPEG
static int read_pos_file(uint8_t* buf, size_t bufsize, STREAMFILE* sf);
static int find_ogg_loops(ffmpeg_codec_data* data, int32_t* p_loop_start, int32_t* p_loop_end);
/* parses any file supported by FFmpeg and not handled elsewhere (mainly: MP4/AAC, MP3, MPC, FLAC) */
VGMSTREAM* init_vgmstream_ffmpeg(STREAMFILE* sf) {
VGMSTREAM* vgmstream = NULL;
ffmpeg_codec_data* data = NULL;
int loop_flag = 0;
int32_t loop_start = 0, loop_end = 0, num_samples = 0;
int total_subsongs, target_subsong = sf->stream_index;
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/* no checks */
//if (!check_extensions(sf, "..."))
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// goto fail;
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/* don't try to open headers and other mini files */
if (get_streamfile_size(sf) <= 0x1000)
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goto fail;
if (target_subsong == 0) target_subsong = 1;
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/* init ffmpeg */
data = init_ffmpeg_header_offset_subsong(sf, NULL, 0, 0, get_streamfile_size(sf), target_subsong);
if (!data) return NULL;
total_subsongs = data->streamCount; /* uncommon, ex. wmv [Lost Odyssey (X360)] */
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if (target_subsong < 0 || target_subsong > total_subsongs || total_subsongs < 1) goto fail;
/* try to get .pos data */
{
uint8_t posbuf[4+4+4];
if (read_pos_file(posbuf, 4+4+4, sf)) {
loop_start = get_s32le(posbuf+0);
loop_end = get_s32le(posbuf+4);
loop_flag = 1; /* incorrect looping will be validated outside */
/* FFmpeg can't always determine totalSamples correctly so optionally load it (can be 0/NULL)
* won't crash and will output silence if no loop points and bigger than actual stream's samples */
num_samples = get_s32le(posbuf+8);
}
}
/* try to read Ogg loop tags (abridged) */
if (loop_flag == 0 && read_u32be(0x00, sf) == 0x4F676753) { /* "OggS" */
loop_flag = find_ogg_loops(data, &loop_start, &loop_end);
}
/* hack for AAC files (will return 0 samples if not an actual file) */
if (!num_samples && check_extensions(sf, "aac,laac")) {
num_samples = aac_get_samples(sf, 0x00, get_streamfile_size(sf));
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}
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#ifdef VGM_USE_MPEG
/* hack for MP3 files (will return 0 samples if not an actual file)
* .mus: Marc Ecko's Getting Up (PC) */
if (!num_samples && check_extensions(sf, "mp3,lmp3,mus")) {
num_samples = mpeg_get_samples(sf, 0x00, get_streamfile_size(sf));
}
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#endif
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/* hack for MPC, that seeks/resets incorrectly due to seek table shenanigans */
if (read_u32be(0x00, sf) == 0x4D502B07 || /* "MP+\7" (Musepack V7) */
read_u32be(0x00, sf) == 0x4D50434B) { /* "MPCK" (Musepack V8) */
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ffmpeg_set_force_seek(data);
}
/* default but often inaccurate when calculated using bitrate (wrong for VBR) */
if (!num_samples) {
num_samples = data->totalSamples; /* may be 0 if FFmpeg can't precalculate it */
}
/* build VGMSTREAM */
vgmstream = allocate_vgmstream(data->channels, loop_flag);
if (!vgmstream) goto fail;
vgmstream->sample_rate = data->sampleRate;
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vgmstream->meta_type = meta_FFMPEG;
vgmstream->coding_type = coding_FFmpeg;
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vgmstream->codec_data = data;
vgmstream->layout_type = layout_none;
vgmstream->num_samples = num_samples;
vgmstream->loop_start_sample = loop_start;
vgmstream->loop_end_sample = loop_end;
vgmstream->channel_layout = ffmpeg_get_channel_layout(vgmstream->codec_data);
return vgmstream;
fail:
free_ffmpeg(data);
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if (vgmstream) {
vgmstream->codec_data = NULL;
close_vgmstream(vgmstream);
}
return NULL;
}
/* open file containing looping data and copy to buffer, returns true if found and copied */
int read_pos_file(uint8_t* buf, size_t bufsize, STREAMFILE* sf) {
char posname[PATH_LIMIT];
char filename[PATH_LIMIT];
/*size_t bytes_read;*/
STREAMFILE* sf_pos = NULL;
get_streamfile_name(sf,filename,sizeof(filename));
if (strlen(filename)+4 > sizeof(posname))
goto fail;
/* try to open a posfile using variations: "(name.ext).pos" */
{
strcpy(posname, filename);
strcat(posname, ".pos");
sf_pos = open_streamfile(sf, posname);;
if (sf_pos) goto found;
goto fail;
}
found:
//if (get_streamfile_size(sf_pos) != bufsize) goto fail;
/* allow pos files to be of different sizes in case of new features, just fill all we can */
memset(buf, 0, bufsize);
read_streamfile(buf, 0, bufsize, sf_pos);
close_streamfile(sf_pos);
return 1;
fail:
close_streamfile(sf_pos);
return 0;
}
/* loop tag handling could be unified with ogg_vorbis.c, but that one has a extra features too */
static int find_ogg_loops(ffmpeg_codec_data* data, int32_t* p_loop_start, int32_t* p_loop_end) {
char* endptr;
const char* value;
int loop_flag = 0;
int32_t loop_start = -1, loop_end = -1;
// Try to detect the loop flags based on current file metadata
value = ffmpeg_get_metadata_value(data, "LoopStart");
if (value != NULL) {
loop_start = strtol(value, &endptr, 10);
loop_flag = 1;
}
value = ffmpeg_get_metadata_value(data, "LoopEnd");
if (value != NULL) {
loop_end = strtol(value, &endptr, 10);
loop_flag = 1;
}
if (loop_flag) {
if (loop_end <= 0) {
// Detected a loop, but loop_end is still undefined or wrong. Try to calculate it.
value = ffmpeg_get_metadata_value(data, "LoopLength");
if (value != NULL) {
int loop_length = strtol(value, &endptr, 10);
if (loop_start != -1) loop_end = loop_start + loop_length;
}
}
if (loop_end <= 0) {
// Looks a calculation was not possible, or tag value is wrongly set. Use the end of track as end value
loop_end = data->totalSamples;
}
if (loop_start <= 0) {
// Weird edge case: loopend is defined and there's a loop, but loopstart was never defined. Reset to sane value
loop_start = 0;
}
} else {
// Every other attempt to detect loop information failed, reset start/end flags to sane values
loop_start = 0;
loop_end = 0;
}
*p_loop_start = loop_start;
*p_loop_end = loop_end;
return loop_flag;
}
#endif