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Codecs: mp4: Fix sbr detections for some files

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Use logic from libfaad/mp4.c AudioSpecificConfig2 for sbr detection

Fixes FS#12856

Change-Id: I235aa27830aa99f1307b303347f7affe7deafbe3
This commit is contained in:
roman.artiukhin 2023-09-20 16:08:45 +03:00 • committed by Solomon Peachy
parent 951e239517
commit 35150b83d4
1 changed files with 7 additions and 6 deletions
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13
lib/rbcodec/metadata/mp4.c
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@ -213,6 +213,7 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
{
unsigned char buf[8] = {0};
bool sbr = false;
bool sbr_signaled = false;
lseek(fd, 4, SEEK_CUR); /* Version and flags. */
read(fd, buf, 1); /* Verify ES_DescrTag. */
@ -282,6 +283,7 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
* Object type - 5 bits
* Frequency index - 4 bits
* Channel configuration - 4 bits
* Also see libfaad/mp4.c AudioSpecificConfig2 (consider using it instead of manual parsing)
*/
bits = get_long_be(buf);
type = bits >> 27; /* Object type - 5 bits */
@ -326,6 +328,7 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
if (type == 5)
{
sbr = bits >> 31;
sbr_signaled = true;
if (sbr)
{
@ -353,13 +356,11 @@ static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
}
}
if (!sbr && (id3->frequency <= 24000) && (length <= 2))
if (!sbr && !sbr_signaled && id3->frequency <= 24000)
{
/* 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.
/* As stated in libfaad/mp4.c AudioSpecificConfig2:
* no SBR signalled, this could mean either implicit signalling or no SBR in this file
* MPEG specification states: assume SBR on files with samplerate <= 24000 Hz
*/
id3->frequency *= 2;
sbr = true;