From d7391a9593e7f0b6623a51a6135a3798914773b5 Mon Sep 17 00:00:00 2001 From: Ari Koivula Date: Tue, 27 Sep 2016 23:14:57 +0300 Subject: [PATCH] Improve default for number of parallel frames --- src/encoder.c | 84 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 54 insertions(+), 30 deletions(-) diff --git a/src/encoder.c b/src/encoder.c index 45e2a2cc..b686e158 100644 --- a/src/encoder.c +++ b/src/encoder.c @@ -36,41 +36,65 @@ static int size_of_wpp_ends(int threads) static int select_owf_auto(const kvz_config *const cfg) { - if (cfg->wpp) { - // If wpp is on, select owf such that less than 15% of the - // frame is covered by the are threads can not work at the same time. + if (cfg->intra_period == 1) { + if (cfg->wpp) { + // If wpp is on, select owf such that less than 15% of the + // frame is covered by the are threads can not work at the same time. + const int lcu_width = CEILDIV(cfg->width, LCU_WIDTH); + const int lcu_height = CEILDIV(cfg->height, LCU_WIDTH); + + // Find the largest number of threads per frame that satifies the + // the condition: wpp start/stop inefficiency takes up less than 15% + // of frame area. + int threads_per_frame = 1; + const int wpp_treshold = lcu_width * lcu_height * 15 / 100; + while ((threads_per_frame + 1) * 2 < lcu_width && + threads_per_frame + 1 < lcu_height && + size_of_wpp_ends(threads_per_frame + 1) < wpp_treshold) { + ++threads_per_frame; + } + + const int threads = MAX(cfg->threads, 1); + const int frames = CEILDIV(threads, threads_per_frame); + + // Convert from number of parallel frames to number of additional frames. + return CLIP(0, threads - 1, frames - 1); + } else { + // If wpp is not on, select owf such that there is enough + // tiles for twice the number of threads. + + int tiles_per_frame = cfg->tiles_width_count * cfg->tiles_height_count; + int threads = (cfg->threads > 1 ? cfg->threads : 1); + int frames = CEILDIV(threads * 4, tiles_per_frame); + + // Limit number of frames to 1.25x the number of threads for the case + // where there is only 1 tile per frame. + frames = CLIP(1, threads * 4 / 3, frames); + return frames - 1; + } + } else { + // Try and estimate a good number of parallel frames for inter. const int lcu_width = CEILDIV(cfg->width, LCU_WIDTH); const int lcu_height = CEILDIV(cfg->height, LCU_WIDTH); + int threads_per_frame = MIN(lcu_width / 2, lcu_height); + int threads = cfg->threads; - // Find the largest number of threads per frame that satifies the - // the condition: wpp start/stop inefficiency takes up less than 15% - // of frame area. - int threads_per_frame = 1; - const int wpp_treshold = lcu_width * lcu_height * 15 / 100; - while ((threads_per_frame + 1) * 2 < lcu_width && - threads_per_frame + 1 < lcu_height && - size_of_wpp_ends(threads_per_frame + 1) < wpp_treshold) - { - ++threads_per_frame; + // If all threads fit into one frame, at least two parallel frames should + // be used to reduce the effect of WPP spin-up and wind-down. + int frames = 1; + + while (threads > 0 && threads_per_frame > 0) { + frames += 1; + threads -= threads_per_frame; + threads_per_frame -= 2; } - const int threads = MAX(cfg->threads, 1); - const int frames = CEILDIV(threads, threads_per_frame); - - // Convert from number of parallel frames to number of additional frames. - return CLIP(0, threads - 1, frames - 1); - } else { - // If wpp is not on, select owf such that there is enough - // tiles for twice the number of threads. - - int tiles_per_frame= cfg->tiles_width_count * cfg->tiles_height_count; - int threads = (cfg->threads > 1 ? cfg->threads : 1); - int frames = CEILDIV(threads * 4, tiles_per_frame); - - // Limit number of frames to 1.25x the number of threads for the case - // where there is only 1 tile per frame. - frames = CLIP(1, threads * 4 / 3, frames); - return frames - 1; + if (cfg->gop_lowdelay && cfg->gop_lp_definition.t > 1) { + // Temporal skipping makes every other frame very fast to encode so + // more parallel frames should be used. + frames *= 2; + } + return CLIP(0, cfg->threads * 2 - 1, frames - 1); } }