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AAC: More adjustments to how the frequency is read. Still not perfect, but this is probably as good as it can get.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13274 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Magnus Holmgren 2007-04-26 17:59:24 +00:00
parent 386d838b87
commit 832bbf72a8
1 changed files with 13 additions and 2 deletions
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15
apps/metadata.c
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@ -1306,10 +1306,10 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3,
id3->frequency *= 2; id3->frequency *= 2;
} }
} }
/* TODO: Should check that there is at least 16 bits left */
/* Skip 13 bits from above, plus 3 bits, then read 11 bits */ /* Skip 13 bits from above, plus 3 bits, then read 11 bits */
else if (((bits >> 5) & 0x7ff) == 0x2b7) /* extensionAudioObjectType */ else if ((length >= 4) && (((bits >> 5) & 0x7ff) == 0x2b7))
{ {
/* extensionAudioObjectType */
DEBUGF("MP4: extensionAudioType\n"); DEBUGF("MP4: extensionAudioType\n");
type = bits & 0x1f; /* Object type - 5 bits*/ type = bits & 0x1f; /* Object type - 5 bits*/
bits = get_long_be(&buf[4]); bits = get_long_be(&buf[4]);
@ -1343,6 +1343,17 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3,
} }
} }
} }
if (!sbr && (id3->frequency <= 24000) && (length <= 2))
{
/* Double the frequency for low-frequency files without a "long"
* DecSpecificConfig header. The file may or may not contain SBR,
* but here we guess it does if the header is short. This can
* fail on some files, but it's the best we can do, short of
* decoding (parts of) the file.
*/
id3->frequency *= 2;
}
} }
return sbr; return sbr;