|
|
|
|
|
|
|
|
|
/* max compressed frame size */
|
|
|
|
|
#define MPA_MAX_CODED_FRAME_SIZE 1200
|
|
|
|
|
|
|
|
|
|
#define MPA_FRAME_SIZE 1152
|
|
|
|
|
#define MPA_MAX_CHANNELS 2
|
|
|
|
|
|
|
|
|
|
#define SAMPLES_BUF_SIZE 4096
|
|
|
|
|
#define SBLIMIT 32 /* number of subbands */
|
|
|
|
|
#define DCT_BITS 14 /* number of bits for the DCT */
|
|
|
|
|
#define MUL(a,b) (((a) * (b)) >> DCT_BITS)
|
|
|
|
|
#define FIX(a) ((int)((a) * (1 << DCT_BITS)))
|
|
|
|
|
|
|
|
|
|
typedef struct MpegAudioContext {
|
|
|
|
|
PutBitContext pb;
|
|
|
|
|
int nb_channels;
|
|
|
|
|
int freq, bit_rate;
|
|
|
|
|
int lsf; /* 1 if mpeg2 low bitrate selected */
|
|
|
|
|
int bitrate_index; /* bit rate */
|
|
|
|
|
int freq_index;
|
|
|
|
|
int frame_size; /* frame size, in bits, without padding */
|
|
|
|
|
INT64 nb_samples; /* total number of samples encoded */
|
|
|
|
|
/* padding computation */
|
|
|
|
|
int frame_frac, frame_frac_incr, do_padding;
|
|
|
|
|
short samples_buf[MPA_MAX_CHANNELS][SAMPLES_BUF_SIZE]; /* buffer for filter */
|
|
|
|
|
int samples_offset[MPA_MAX_CHANNELS]; /* offset in samples_buf */
|
|
|
|
|
int sb_samples[MPA_MAX_CHANNELS][3][12][SBLIMIT];
|
|
|
|
|
unsigned char scale_factors[MPA_MAX_CHANNELS][SBLIMIT][3]; /* scale factors */
|
|
|
|
|
/* code to group 3 scale factors */
|
|
|
|
|
unsigned char scale_code[MPA_MAX_CHANNELS][SBLIMIT];
|
|
|
|
|
int sblimit; /* number of used subbands */
|
|
|
|
|
const unsigned char *alloc_table;
|
|
|
|
|
} MpegAudioContext;
|
|
|
|
|
|
