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AAC: optimise bitstream reading in decode_spectrum_and_dequant()
Using the low-level macros directly avoids redundant open/update/close cycles. 2-3% faster on ARM, PPC, and Core i7. Originally committed as revision 21224 to svn://svn.ffmpeg.org/ffmpeg/trunktags/v0.6
Måns Rullgård
16 years ago
1 changed files with 65 additions and 28 deletions
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+65 -28libavcodec/aac.c
+ 65
- 28
libavcodec/aac.c
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| @@ -993,6 +993,7 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| const uint16_t *cb_vector_idx = ff_aac_codebook_vector_idx[cbt_m1]; | |||
| VLC_TYPE (*vlc_tab)[2] = vlc_spectral[cbt_m1].table; | |||
| const int cb_size = ff_aac_spectral_sizes[cbt_m1]; | |||
| OPEN_READER(re, gb); | |||
| switch (cbt_m1 >> 1) { | |||
| case 0: | |||
| @@ -1001,15 +1002,18 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| int len = off_len; | |||
| do { | |||
| const int index = get_vlc2(gb, vlc_tab, 8, 2); | |||
| int code; | |||
| unsigned cb_idx; | |||
| if (index >= cb_size) { | |||
| err_idx = index; | |||
| UPDATE_CACHE(re, gb); | |||
| GET_VLC(code, re, gb, vlc_tab, 8, 2); | |||
| if (code >= cb_size) { | |||
| err_idx = code; | |||
| goto err_cb_overflow; | |||
| } | |||
| cb_idx = cb_vector_idx[index]; | |||
| cb_idx = cb_vector_idx[code]; | |||
| cf = VMUL4(cf, vq, cb_idx, sf + idx); | |||
| } while (len -= 4); | |||
| } | |||
| @@ -1021,19 +1025,26 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| int len = off_len; | |||
| do { | |||
| const int index = get_vlc2(gb, vlc_tab, 8, 2); | |||
| int code; | |||
| unsigned nnz; | |||
| unsigned cb_idx; | |||
| uint32_t bits; | |||
| if (index >= cb_size) { | |||
| err_idx = index; | |||
| UPDATE_CACHE(re, gb); | |||
| GET_VLC(code, re, gb, vlc_tab, 8, 2); | |||
| if (code >= cb_size) { | |||
| err_idx = code; | |||
| goto err_cb_overflow; | |||
| } | |||
| cb_idx = cb_vector_idx[index]; | |||
| #if MIN_CACHE_BITS < 20 | |||
| UPDATE_CACHE(re, gb); | |||
| #endif | |||
| cb_idx = cb_vector_idx[code]; | |||
| nnz = cb_idx >> 8 & 15; | |||
| bits = get_bits(gb, nnz) << (32-nnz); | |||
| bits = SHOW_UBITS(re, gb, nnz) << (32-nnz); | |||
| LAST_SKIP_BITS(re, gb, nnz); | |||
| cf = VMUL4S(cf, vq, cb_idx, bits, sf + idx); | |||
| } while (len -= 4); | |||
| } | |||
| @@ -1045,15 +1056,18 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| int len = off_len; | |||
| do { | |||
| const int index = get_vlc2(gb, vlc_tab, 8, 2); | |||
| int code; | |||
| unsigned cb_idx; | |||
| if (index >= cb_size) { | |||
| err_idx = index; | |||
| UPDATE_CACHE(re, gb); | |||
| GET_VLC(code, re, gb, vlc_tab, 8, 2); | |||
| if (code >= cb_size) { | |||
| err_idx = code; | |||
| goto err_cb_overflow; | |||
| } | |||
| cb_idx = cb_vector_idx[index]; | |||
| cb_idx = cb_vector_idx[code]; | |||
| cf = VMUL2(cf, vq, cb_idx, sf + idx); | |||
| } while (len -= 2); | |||
| } | |||
| @@ -1066,19 +1080,23 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| int len = off_len; | |||
| do { | |||
| const int index = get_vlc2(gb, vlc_tab, 8, 2); | |||
| int code; | |||
| unsigned nnz; | |||
| unsigned cb_idx; | |||
| unsigned sign; | |||
| if (index >= cb_size) { | |||
| err_idx = index; | |||
| UPDATE_CACHE(re, gb); | |||
| GET_VLC(code, re, gb, vlc_tab, 8, 2); | |||
| if (code >= cb_size) { | |||
| err_idx = code; | |||
| goto err_cb_overflow; | |||
| } | |||
| cb_idx = cb_vector_idx[index]; | |||
| cb_idx = cb_vector_idx[code]; | |||
| nnz = cb_idx >> 8 & 15; | |||
| sign = get_bits(gb, nnz) << (cb_idx >> 12); | |||
| sign = SHOW_UBITS(re, gb, nnz) << (cb_idx >> 12); | |||
| LAST_SKIP_BITS(re, gb, nnz); | |||
| cf = VMUL2S(cf, vq, cb_idx, sign, sf + idx); | |||
| } while (len -= 2); | |||
| } | |||
| @@ -1091,39 +1109,56 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| int len = off_len; | |||
| do { | |||
| const int index = get_vlc2(gb, vlc_tab, 8, 2); | |||
| int code; | |||
| unsigned nzt, nnz; | |||
| unsigned cb_idx; | |||
| uint32_t bits; | |||
| int j; | |||
| if (!index) { | |||
| UPDATE_CACHE(re, gb); | |||
| GET_VLC(code, re, gb, vlc_tab, 8, 2); | |||
| if (!code) { | |||
| *icf++ = 0; | |||
| *icf++ = 0; | |||
| continue; | |||
| } | |||
| if (index >= cb_size) { | |||
| err_idx = index; | |||
| if (code >= cb_size) { | |||
| err_idx = code; | |||
| goto err_cb_overflow; | |||
| } | |||
| cb_idx = cb_vector_idx[index]; | |||
| cb_idx = cb_vector_idx[code]; | |||
| nnz = cb_idx >> 12; | |||
| nzt = cb_idx >> 8; | |||
| bits = get_bits(gb, nnz) << (32-nnz); | |||
| bits = SHOW_UBITS(re, gb, nnz) << (32-nnz); | |||
| LAST_SKIP_BITS(re, gb, nnz); | |||
| for (j = 0; j < 2; j++) { | |||
| if (nzt & 1<<j) { | |||
| int n = 4; | |||
| uint32_t b; | |||
| int n; | |||
| /* The total length of escape_sequence must be < 22 bits according | |||
| to the specification (i.e. max is 111111110xxxxxxxxxxxx). */ | |||
| while (get_bits1(gb) && n < 13) n++; | |||
| if (n == 13) { | |||
| UPDATE_CACHE(re, gb); | |||
| b = GET_CACHE(re, gb); | |||
| b = 31 - av_log2(~b); | |||
| if (b > 8) { | |||
| av_log(ac->avccontext, AV_LOG_ERROR, "error in spectral data, ESC overflow\n"); | |||
| return -1; | |||
| } | |||
| n = (1 << n) + get_bits(gb, n); | |||
| #if MIN_CACHE_BITS < 21 | |||
| LAST_SKIP_BITS(re, gb, b + 1); | |||
| UPDATE_CACHE(re, gb); | |||
| #else | |||
| SKIP_BITS(re, gb, b + 1); | |||
| #endif | |||
| b += 4; | |||
| n = (1 << b) + SHOW_UBITS(re, gb, b); | |||
| LAST_SKIP_BITS(re, gb, b); | |||
| *icf++ = cbrt_tab[n] | (bits & 1<<31); | |||
| bits <<= 1; | |||
| } else { | |||
| @@ -1138,6 +1173,8 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024], | |||
| ac->dsp.vector_fmul_scalar(cfo, cfo, sf[idx], off_len); | |||
| } | |||
| } | |||
| CLOSE_READER(re, gb); | |||
| } | |||
| } | |||
| coef += g_len << 7; | |||