ref: 39b71fb516bf18304e0561d316ce2ce82814a4dd
dir: /src/mp3-duration.h/
/*
* Determine MP3 duration
* Copyright (c) 2007 robs@users.sourceforge.net
* Based on original ideas by Regis Boudin, Thibaut Varene & Pascal Giard
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This library 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 Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, write to the Free Software Foundation,
* Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301, USA.
*/
#include <sys/stat.h>
#if HAVE_ID3TAG && HAVE_UNISTD_H
static id3_utf8_t * utf8_id3tag_findframe(
struct id3_tag * tag, const char * const frameid, unsigned index)
{
struct id3_frame const * frame = id3_tag_findframe(tag, frameid, index);
if (frame) {
union id3_field const * field = id3_frame_field(frame, 1);
unsigned nstrings = id3_field_getnstrings(field);
while (nstrings--){
id3_ucs4_t const * ucs4 = id3_field_getstrings(field, nstrings);
if (ucs4)
return id3_ucs4_utf8duplicate(ucs4); /* Must call free() on this */
}
}
return NULL;
}
static sox_size_t id3tag_duration_ms(FILE * fp)
{
struct id3_file * id3struct;
struct id3_tag * tag;
id3_utf8_t * utf8;
sox_size_t duration_ms = 0;
int fd = dup(fileno(fp));
if ((id3struct = id3_file_fdopen(fd, ID3_FILE_MODE_READONLY))) {
if ((tag = id3_file_tag(id3struct)) && tag->frames)
if ((utf8 = utf8_id3tag_findframe(tag, "TLEN", 0))) {
if (atoi((char *)utf8) > 0)
duration_ms = atoi((char *)utf8);
free(utf8);
}
id3_file_close(id3struct);
}
else close(fd);
return duration_ms;
}
#endif
static unsigned long xing_frames(struct mad_bitptr ptr, unsigned bitlen)
{
#define XING_MAGIC ( ('X' << 24) | ('i' << 16) | ('n' << 8) | 'g' )
if (bitlen >= 96 && mad_bit_read(&ptr, 32) == XING_MAGIC &&
(mad_bit_read(&ptr, 32) & 1 )) /* XING_FRAMES */
return mad_bit_read(&ptr, 32);
return 0;
}
static void mad_timer_mult(mad_timer_t * t, double d)
{
t->seconds = d *= (t->seconds + t->fraction * (1. / MAD_TIMER_RESOLUTION));
t->fraction = (d - t->seconds) * MAD_TIMER_RESOLUTION + .5;
}
static sox_size_t mp3_duration_ms(FILE * fp, unsigned char *buffer)
{
struct mad_stream mad_stream;
struct mad_header mad_header;
struct mad_frame mad_frame;
mad_timer_t time = mad_timer_zero;
sox_size_t initial_bitrate = 0; /* Initialised to prevent warning */
sox_size_t tagsize = 0, consumed = 0, frames = 0;
sox_bool vbr = sox_false, depadded = sox_false;
#if HAVE_ID3TAG && HAVE_UNISTD_H
sox_size_t duration_ms = id3tag_duration_ms(fp);
if (duration_ms) {
sox_debug("got exact duration from ID3 TLEN");
return duration_ms;
}
#endif
mad_stream_init(&mad_stream);
mad_header_init(&mad_header);
mad_frame_init(&mad_frame);
do { /* Read data from the MP3 file */
int read, padding = 0;
size_t leftover = mad_stream.bufend - mad_stream.next_frame;
memcpy(buffer, mad_stream.this_frame, leftover);
read = fread(buffer + leftover, 1, INPUT_BUFFER_SIZE - leftover, fp);
if (read <= 0) {
sox_debug("got exact duration by scan to EOF (frames=%u leftover=%u)", frames, leftover);
break;
}
for (; !depadded && padding < read && !buffer[padding]; ++padding);
depadded = sox_true;
mad_stream_buffer(&mad_stream, buffer + padding, leftover + read - padding);
while (sox_true) { /* Decode frame headers */
mad_stream.error = MAD_ERROR_NONE;
if (mad_header_decode(&mad_header, &mad_stream) == -1) {
if (mad_stream.error == MAD_ERROR_BUFLEN)
break; /* Normal behaviour; get some more data from the file */
if (!MAD_RECOVERABLE(mad_stream.error)) {
sox_warn("unrecoverable MAD error");
break;
}
if (mad_stream.error == MAD_ERROR_LOSTSYNC) {
unsigned available = (mad_stream.bufend - mad_stream.this_frame);
tagsize = tagtype(mad_stream.this_frame, available);
if (tagsize) { /* It's some ID3 tags, so just skip */
if (tagsize >= available) {
fseeko(fp, (off_t)(tagsize - available), SEEK_CUR);
depadded = sox_false;
}
mad_stream_skip(&mad_stream, min(tagsize, available));
}
else sox_warn("MAD lost sync");
}
else sox_warn("recoverable MAD error");
continue; /* Not an audio frame */
}
mad_timer_add(&time, mad_header.duration);
consumed += mad_stream.next_frame - mad_stream.this_frame;
if (!frames) {
initial_bitrate = mad_header.bitrate;
/* Get the precise frame count from the XING header if present */
mad_frame.header = mad_header;
if (mad_frame_decode(&mad_frame, &mad_stream) == -1)
if (!MAD_RECOVERABLE(mad_stream.error)) {
sox_warn("unrecoverable MAD error");
break;
}
if ((frames = xing_frames(mad_stream.anc_ptr, mad_stream.anc_bitlen))) {
mad_timer_multiply(&time, (signed long)frames);
sox_debug("got exact duration from XING frame count (%u)", frames);
break;
}
}
else vbr |= mad_header.bitrate != initial_bitrate;
/* If not VBR, we can time just a few frames then extrapolate */
if (++frames == 10 && !vbr) {
struct stat filestat;
fstat(fileno(fp), &filestat);
mad_timer_mult(&time, (double)(filestat.st_size - tagsize) / consumed);
sox_debug("got approx. duration by CBR extrapolation");
break;
}
}
} while (mad_stream.error == MAD_ERROR_BUFLEN);
mad_frame_finish(&mad_frame);
mad_header_finish(&mad_header);
mad_stream_finish(&mad_stream);
rewind(fp);
return mad_timer_count(time, MAD_UNITS_MILLISECONDS);
}