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Improve accuracy a little when seeking and resuming MP3 files. Mainly noticable for low-bitrate files with large ID3V2 tags, and no effect if no ID3V2 tag. Should be ported to hwcodec targets. :)

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11402 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Magnus Holmgren 2006-10-30 20:19:21 +00:00
parent 02da4e6130
commit 39fe51e88d
1 changed files with 12 additions and 8 deletions
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20
apps/playback.c
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@ -1452,13 +1452,12 @@ static int codec_get_file_pos(void)
else
return -1;
pos += id3->first_frame_offset;
/* Don't seek right to the end of the file so that we can
transition properly to the next song */
if (pos >= (int)(id3->filesize - id3->id3v1len))
pos = id3->filesize - id3->id3v1len - 1;
/* skip past id3v2 tag and other leading garbage */
else if (pos < (int)id3->first_frame_offset)
pos = id3->first_frame_offset;
return pos;
}
@ -2316,6 +2315,9 @@ static bool audio_loadcodec(bool start_play)
/* TODO: Copied from mpeg.c. Should be moved somewhere else. */
static void audio_set_elapsed(struct mp3entry* id3)
{
unsigned long offset = id3->offset > id3->first_frame_offset ?
id3->offset - id3->first_frame_offset : 0;
if ( id3->vbr ) {
if ( id3->has_toc ) {
/* calculate elapsed time using TOC */
@ -2324,7 +2326,7 @@ static void audio_set_elapsed(struct mp3entry* id3)
/* find wich percent we're at */
for (i=0; i<100; i++ )
if ( id3->offset < id3->toc[i] * (id3->filesize / 256) )
if ( offset < id3->toc[i] * (id3->filesize / 256) )
break;
i--;
@ -2338,7 +2340,7 @@ static void audio_set_elapsed(struct mp3entry* id3)
else
nextpos = 256;
remainder = id3->offset - (relpos * (id3->filesize / 256));
remainder = offset - (relpos * (id3->filesize / 256));
/* set time for this percent (divide before multiply to prevent
overflow on long files. loss of precision is negligible on
@ -2352,15 +2354,17 @@ static void audio_set_elapsed(struct mp3entry* id3)
}
else {
/* no TOC exists. set a rough estimate using average bitrate */
int tpk = id3->length / (id3->filesize / 1024);
id3->elapsed = id3->offset / 1024 * tpk;
int tpk = id3->length /
((id3->filesize - id3->first_frame_offset - id3->id3v1len) /
1024);
id3->elapsed = offset / 1024 * tpk;
}
}
else
{
/* constant bitrate, use exact calculation */
if (id3->bitrate != 0)
id3->elapsed = id3->offset / (id3->bitrate / 8);
id3->elapsed = offset / (id3->bitrate / 8);
}
}