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