diff options
| -rw-r--r-- | lib/rbcodec/metadata/mp3data.c | 55 |
1 files changed, 37 insertions, 18 deletions
diff --git a/lib/rbcodec/metadata/mp3data.c b/lib/rbcodec/metadata/mp3data.c index 8c800c798a..83605126d6 100644 --- a/lib/rbcodec/metadata/mp3data.c +++ b/lib/rbcodec/metadata/mp3data.c @@ -212,18 +212,27 @@ static bool headers_have_same_type(unsigned long header1, 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, unsigned long reference_header, int(*getfunc)(int fd, unsigned char *c), bool single_header) { - uint32_t header=0; - uint32_t ref_header=0; - long ref_header_pos=0; + unsigned long header=0; unsigned char tmp; 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 * of this pair is assumed to be the first valid MPEG frame header of the * whole stream. */ @@ -234,33 +243,43 @@ static unsigned long __find_next_frame(int fd, long *offset, long max_offset, return 0; header |= tmp; pos++; - + /* Abort if max_offset is reached. Stop parsing. */ if (max_offset > 0 && pos > max_offset) return 0; - + if (is_mp3frameheader(header)) { if (single_header) { /* 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. */ if (headers_have_same_type(reference_header, header)) break; } else { - /* The current header is valid. Compare it against the last - one we found. NOTE: ref_header MUST come second! */ - if (headers_have_same_type(header, ref_header)) { - /* Found a match, return the header and offset of the FIRST */ - header = ref_header; - lseek(fd, ref_header_pos, SEEK_SET); + /* The current header is valid. Now gather the frame size, + * seek to this byte position and check if there is another + * valid MPEG frame header of the same type. */ + struct mp3info info; + + /* 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; - } - /* Otherwise look for another.. */ - ref_header = header; - ref_header_pos = lseek(fd, 0, SEEK_CUR); } } - + } while (true); *offset = pos - 4; |