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| author | Justin Ruggles <justin.ruggles@gmail.com> | 2011-10-25 15:13:19 -0400 |
|---|---|---|
| committer | Justin Ruggles <justin.ruggles@gmail.com> | 2011-10-29 15:16:53 -0400 |
| commit | 9f48039a37b5e0064fe66c74bc3533043b3c0815 (patch) | |
| tree | db2f6c6039558692ada0d6bfdd40548136d2e4b8 /libavcodec/binkaudio.c | |
| parent | 101ef19ef4dc9f5c3d536aee8fcc10fff2af4d9e (diff) | |
| download | ffmpeg-9f48039a37b5e0064fe66c74bc3533043b3c0815.tar.gz | |
binkaudio: pre-calculate quantization factors
Diffstat (limited to 'libavcodec/binkaudio.c')
| -rw-r--r-- | libavcodec/binkaudio.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/libavcodec/binkaudio.c b/libavcodec/binkaudio.c index 27e8ff5a84..ae1997d961 100644 --- a/libavcodec/binkaudio.c +++ b/libavcodec/binkaudio.c @@ -39,6 +39,8 @@ extern const uint16_t ff_wma_critical_freqs[25]; +static float quant_table[95]; + #define MAX_CHANNELS 2 #define BINK_BLOCK_MAX_SIZE (MAX_CHANNELS << 11) @@ -107,6 +109,10 @@ static av_cold int decode_init(AVCodecContext *avctx) s->block_size = (s->frame_len - s->overlap_len) * s->channels; sample_rate_half = (sample_rate + 1) / 2; s->root = 2.0 / sqrt(s->frame_len); + for (i = 0; i < 95; i++) { + /* constant is result of 0.066399999/log10(M_E) */ + quant_table[i] = expf(i * 0.15289164787221953823f) * s->root; + } /* calculate number of bands */ for (s->num_bands = 1; s->num_bands < 25; s->num_bands++) @@ -190,9 +196,8 @@ static int decode_block(BinkAudioContext *s, short *out, int use_dct) if (get_bits_left(gb) < s->num_bands * 8) return AVERROR_INVALIDDATA; for (i = 0; i < s->num_bands; i++) { - /* constant is result of 0.066399999/log10(M_E) */ int value = get_bits(gb, 8); - quant[i] = expf(FFMIN(value, 95) * 0.15289164787221953823f) * s->root; + quant[i] = quant_table[FFMIN(value, 95)]; } k = 0; |