From 8b4cb54595baeeb1d9b7d11a842ef7946e43a55a Mon Sep 17 00:00:00 2001 From: Maarten Bosmans Date: Fri, 7 Jan 2011 01:25:55 +0100 Subject: Limit rate adjustments to small, inaudible jumps MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The same logic is applied to the sample rate adjustments in module-rtp-recv, module-loopback and module-combine: - Each time an adjustment is made, the new rate can differ at most 2‰ from the old rate. Such a step is equal to 3.5 cents (a cent is 1/100th of a semitone) and as 5 cents is generally considered the smallest observable difference in pitch, this results in inaudible adjustments. - The sample rate of the stream can only differ from the rate of the corresponding sink by 25%. As these adjustments are meant to account for very small clock drifts, any large deviation from the base rate suggests something is seriously wrong. - If the calculated rate is within 20Hz of the base rate, set it to the base rate. This saves CPU because no resampling is necessary. --- src/modules/module-combine.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'src/modules/module-combine.c') diff --git a/src/modules/module-combine.c b/src/modules/module-combine.c index bcea229f..3104ed68 100644 --- a/src/modules/module-combine.c +++ b/src/modules/module-combine.c @@ -217,23 +217,29 @@ static void adjust_rates(struct userdata *u) { base_rate = u->sink->sample_spec.rate; PA_IDXSET_FOREACH(o, u->outputs, idx) { - uint32_t r = base_rate; + uint32_t new_rate = base_rate; + uint32_t current_rate = o->sink_input->sample_spec.rate; if (!o->sink_input || !PA_SINK_IS_OPENED(pa_sink_get_state(o->sink))) continue; - if (o->total_latency < target_latency) - r -= (uint32_t) ((((double) (target_latency - o->total_latency))/(double)u->adjust_time)*(double)r); - else if (o->total_latency > target_latency) - r += (uint32_t) ((((double) (o->total_latency - target_latency))/(double)u->adjust_time)*(double)r); + if (o->total_latency != target_latency) + new_rate += (uint32_t) (((double) o->total_latency - (double) target_latency) / (double) u->adjust_time * (double) new_rate); - if (r < (uint32_t) (base_rate*0.9) || r > (uint32_t) (base_rate*1.1)) { - pa_log_warn("[%s] sample rates too different, not adjusting (%u vs. %u).", o->sink_input->sink->name, base_rate, r); - pa_sink_input_set_rate(o->sink_input, base_rate); + if (new_rate < (uint32_t) (base_rate*0.8) || new_rate > (uint32_t) (base_rate*1.25)) { + pa_log_warn("[%s] sample rates too different, not adjusting (%u vs. %u).", o->sink_input->sink->name, base_rate, new_rate); + new_rate = base_rate; } else { - pa_log_info("[%s] new rate is %u Hz; ratio is %0.3f; latency is %0.0f usec.", o->sink_input->sink->name, r, (double) r / base_rate, (float) o->total_latency); - pa_sink_input_set_rate(o->sink_input, r); + if (base_rate < new_rate + 20 && new_rate < base_rate + 20) + new_rate = base_rate; + /* Do the adjustment in small steps; 2‰ can be considered inaudible */ + if (new_rate < (uint32_t) (current_rate*0.998) || new_rate > (uint32_t) (current_rate*1.002)) { + pa_log_info("[%s] new rate of %u Hz not within 2‰ of %u Hz, forcing smaller adjustment", o->sink_input->sink->name, new_rate, current_rate); + new_rate = PA_CLAMP(new_rate, (uint32_t) (current_rate*0.998), (uint32_t) (current_rate*1.002)); + } + pa_log_info("[%s] new rate is %u Hz; ratio is %0.3f; latency is %0.2f msec.", o->sink_input->sink->name, new_rate, (double) new_rate / base_rate, (double) o->total_latency / PA_USEC_PER_MSEC); } + pa_sink_input_set_rate(o->sink_input, new_rate); } pa_asyncmsgq_send(u->sink->asyncmsgq, PA_MSGOBJECT(u->sink), SINK_MESSAGE_UPDATE_LATENCY, NULL, (int64_t) avg_total_latency, NULL); -- cgit