From b2bf3cfe322549cdc7bbc1603642ff4137a5e2bb Mon Sep 17 00:00:00 2001 From: Vitor Sessak Date: Sun, 15 Nov 2009 10:41:46 +0000 Subject: Implement ff_decode_pitch_lag() that is used by both AMR and SIPR. Based on code written by Colin McQuillan during his SoC project. Originally committed as revision 20540 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/acelp_pitch_delay.c | 44 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'libavcodec/acelp_pitch_delay.c') diff --git a/libavcodec/acelp_pitch_delay.c b/libavcodec/acelp_pitch_delay.c index 4c809d7eeb..c3e2409c1e 100644 --- a/libavcodec/acelp_pitch_delay.c +++ b/libavcodec/acelp_pitch_delay.c @@ -140,3 +140,47 @@ float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, return val; } + +void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, + const int prev_lag_int, const int subframe, + int third_as_first, int resolution) +{ + /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */ + if (subframe == 0 || (subframe == 2 && third_as_first)) { + + if (pitch_index < 197) + pitch_index += 59; + else + pitch_index = 3 * pitch_index - 335; + + } else { + if (resolution == 4) { + int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, + PITCH_DELAY_MAX - 9); + + // decoding with 4-bit resolution + if (pitch_index < 4) { + // integer only precision for [search_range_min, search_range_min+3] + pitch_index = 3 * (pitch_index + search_range_min) + 1; + } else if (pitch_index < 12) { + // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3] + pitch_index += 3 * search_range_min + 7; + } else { + // integer only precision for [search_range_min+6, search_range_min+9] + pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; + } + } else { + // decoding with 5 or 6 bit resolution, 1/3 fractional precision + pitch_index--; + + if (resolution == 5) { + pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, + PITCH_DELAY_MAX - 19); + } else + pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, + PITCH_DELAY_MAX - 9); + } + } + *lag_int = pitch_index * 10923 >> 15; + *lag_frac = pitch_index - 3 * *lag_int - 1; +} -- cgit v1.2.3