Rockbox open source high quality audio player as a Music Player Daemon
mpris
rockbox
mpd
libadwaita
audio
rust
zig
deno
Codecs: mp4: Fix sbr detections for some files
Use logic from libfaad/mp4.c AudioSpecificConfig2 for sbr detection
Fixes FS#12856
Change-Id: I235aa27830aa99f1307b303347f7affe7deafbe3
authored by
roman.artiukhin
and committed by
Solomon Peachy
35150b83
951e2395
+7
-6
+7
-6
lib/rbcodec/metadata/mp4.c
+7
-6
lib/rbcodec/metadata/mp4.c
···
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{
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unsigned char buf[8] = {0};
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bool sbr = false;
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bool sbr_signaled = false;
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lseek(fd, 4, SEEK_CUR); /* Version and flags. */
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read(fd, buf, 1); /* Verify ES_DescrTag. */
···
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* Object type - 5 bits
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* Frequency index - 4 bits
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* Channel configuration - 4 bits
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* Also see libfaad/mp4.c AudioSpecificConfig2 (consider using it instead of manual parsing)
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*/
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bits = get_long_be(buf);
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type = bits >> 27; /* Object type - 5 bits */
···
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if (type == 5)
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{
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sbr = bits >> 31;
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sbr_signaled = true;
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if (sbr)
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{
···
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}
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}
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-
if (!sbr && (id3->frequency <= 24000) && (length <= 2))
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if (!sbr && !sbr_signaled && id3->frequency <= 24000)
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{
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/* Double the frequency for low-frequency files without a "long"
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* DecSpecificConfig header. The file may or may not contain SBR,
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* but here we guess it does if the header is short. This can
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* fail on some files, but it's the best we can do, short of
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* decoding (parts of) the file.
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/* As stated in libfaad/mp4.c AudioSpecificConfig2:
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* no SBR signalled, this could mean either implicit signalling or no SBR in this file
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* MPEG specification states: assume SBR on files with samplerate <= 24000 Hz
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*/
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id3->frequency *= 2;
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sbr = true;