From d1a5c4216c5774b1513f15542c4b2a1a8a9f39a2 Mon Sep 17 00:00:00 2001 From: Loren Merritt Date: Sun, 30 Sep 2007 03:01:56 +0000 Subject: 20% faster lpc, 6% overall flac decoding Originally committed as revision 10627 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/flac.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) (limited to 'libavcodec/flac.c') diff --git a/libavcodec/flac.c b/libavcodec/flac.c index 5c0a2f76b1..480ede2a20 100644 --- a/libavcodec/flac.c +++ b/libavcodec/flac.c @@ -315,6 +315,7 @@ static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order) int i, j; int coeff_prec, qlevel; int coeffs[pred_order]; + int32_t *decoded = s->decoded[channel]; // av_log(s->avctx, AV_LOG_DEBUG, " SUBFRAME LPC\n"); @@ -323,8 +324,8 @@ static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order) for (i = 0; i < pred_order; i++) { - s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps); -// av_log(s->avctx, AV_LOG_DEBUG, " %d: %d\n", i, s->decoded[channel][i]); + decoded[i] = get_sbits(&s->gb, s->curr_bps); +// av_log(s->avctx, AV_LOG_DEBUG, " %d: %d\n", i, decoded[i]); } coeff_prec = get_bits(&s->gb, 4) + 1; @@ -356,32 +357,34 @@ static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order) { sum = 0; for (j = 0; j < pred_order; j++) - sum += (int64_t)coeffs[j] * s->decoded[channel][i-j-1]; - s->decoded[channel][i] += sum >> qlevel; + sum += (int64_t)coeffs[j] * decoded[i-j-1]; + decoded[i] += sum >> qlevel; } } else { for (i = pred_order; i < s->blocksize-1; i += 2) { - int c = coeffs[pred_order-1]; - int s0 = c * s->decoded[channel][i-pred_order]; - int s1 = 0; + int c; + int d = decoded[i-pred_order]; + int s0 = 0, s1 = 0; for (j = pred_order-1; j > 0; j--) { - int d = s->decoded[channel][i-j]; - s1 += c*d; - c = coeffs[j-1]; + c = coeffs[j]; s0 += c*d; + d = decoded[i-j]; + s1 += c*d; } - s0 = s->decoded[channel][i] += s0 >> qlevel; - s1 += c * s0; - s->decoded[channel][i+1] += s1 >> qlevel; + c = coeffs[0]; + s0 += c*d; + d = decoded[i] += s0 >> qlevel; + s1 += c*d; + decoded[i+1] += s1 >> qlevel; } if (i < s->blocksize) { int sum = 0; for (j = 0; j < pred_order; j++) - sum += coeffs[j] * s->decoded[channel][i-j-1]; - s->decoded[channel][i] += sum >> qlevel; + sum += coeffs[j] * decoded[i-j-1]; + decoded[i] += sum >> qlevel; } } -- cgit v1.2.3