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Revert "FS#13299: Simplify VBR frame parsing in the metadata decoder."

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This reverts commit 756c0d2ac8.

Change-Id: I5f98972f69e7645239fd9218c9d4eeb9bd2ec7a5
This commit is contained in:
Solomon Peachy 2021-06-16 16:46:14 -04:00
parent 7aade87863
commit fa9ddd5af9
1 changed files with 37 additions and 18 deletions
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55
lib/rbcodec/metadata/mp3data.c
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@ -212,18 +212,27 @@ static bool headers_have_same_type(unsigned long header1,
return header1 ? (header1 == header2) : true; return header1 ? (header1 == header2) : true;
} }
/* Helper function to read 4-byte in big endian format. */
static void read_uint32be_mp3data(int fd, unsigned long *data)
{
#ifdef ROCKBOX_BIG_ENDIAN
(void)read(fd, (char*)data, 4);
#else
(void)read(fd, (char*)data, 4);
*data = betoh32(*data);
#endif
}
static unsigned long __find_next_frame(int fd, long *offset, long max_offset, static unsigned long __find_next_frame(int fd, long *offset, long max_offset,
unsigned long reference_header, unsigned long reference_header,
int(*getfunc)(int fd, unsigned char *c), int(*getfunc)(int fd, unsigned char *c),
bool single_header) bool single_header)
{ {
uint32_t header=0; unsigned long header=0;
uint32_t ref_header=0;
long ref_header_pos=0;
unsigned char tmp; unsigned char tmp;
long pos = 0; long pos = 0;
/* We will search until we find two consecutive MPEG frame headers with /* We will search until we find two consecutive MPEG frame headers with
* the same MPEG version, layer and sampling frequency. The first header * the same MPEG version, layer and sampling frequency. The first header
* of this pair is assumed to be the first valid MPEG frame header of the * of this pair is assumed to be the first valid MPEG frame header of the
* whole stream. */ * whole stream. */
@ -234,33 +243,43 @@ static unsigned long __find_next_frame(int fd, long *offset, long max_offset,
return 0; return 0;
header |= tmp; header |= tmp;
pos++; pos++;
/* Abort if max_offset is reached. Stop parsing. */ /* Abort if max_offset is reached. Stop parsing. */
if (max_offset > 0 && pos > max_offset) if (max_offset > 0 && pos > max_offset)
return 0; return 0;
if (is_mp3frameheader(header)) { if (is_mp3frameheader(header)) {
if (single_header) { if (single_header) {
/* We search for one _single_ valid header that has the same /* We search for one _single_ valid header that has the same
* type as the reference_header (if reference_header != 0). * type as the reference_header (if reference_header != 0).
* In this case we are finished. */ * In this case we are finished. */
if (headers_have_same_type(reference_header, header)) if (headers_have_same_type(reference_header, header))
break; break;
} else { } else {
/* The current header is valid. Compare it against the last /* The current header is valid. Now gather the frame size,
one we found. NOTE: ref_header MUST come second! */ * seek to this byte position and check if there is another
if (headers_have_same_type(header, ref_header)) { * valid MPEG frame header of the same type. */
/* Found a match, return the header and offset of the FIRST */ struct mp3info info;
header = ref_header;
lseek(fd, ref_header_pos, SEEK_SET); /* Gather frame size from given header and seek to next
* frame header. */
mp3headerinfo(&info, header);
lseek(fd, info.frame_size-4, SEEK_CUR);
/* Read possible next frame header and seek back to last frame
* headers byte position. */
reference_header = 0;
read_uint32be_mp3data(fd, &reference_header);
//
lseek(fd, -info.frame_size, SEEK_CUR);
/* If the current header is of the same type as the previous
* header we are finished. */
if (headers_have_same_type(header, reference_header))
break; break;
}
/* Otherwise look for another.. */
ref_header = header;
ref_header_pos = lseek(fd, 0, SEEK_CUR);
} }
} }
} while (true); } while (true);
*offset = pos - 4; *offset = pos - 4;