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-loopback.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'src/modules/module-loopback.c') diff --git a/src/modules/module-loopback.c b/src/modules/module-loopback.c index dfd5e766..2b1f5055 100644 --- a/src/modules/module-loopback.c +++ b/src/modules/module-loopback.c @@ -175,13 +175,13 @@ static void adjust_rates(struct userdata *u) { buffer_latency = pa_bytes_to_usec(buffer, &u->sink_input->sample_spec); - pa_log_info("Loopback overall latency is %0.2f ms + %0.2f ms + %0.2f ms = %0.2f ms", + pa_log_debug("Loopback overall latency is %0.2f ms + %0.2f ms + %0.2f ms = %0.2f ms", (double) u->latency_snapshot.sink_latency / PA_USEC_PER_MSEC, (double) buffer_latency / PA_USEC_PER_MSEC, (double) u->latency_snapshot.source_latency / PA_USEC_PER_MSEC, ((double) u->latency_snapshot.sink_latency + buffer_latency + u->latency_snapshot.source_latency) / PA_USEC_PER_MSEC); - pa_log_info("Should buffer %zu bytes, buffered at minimum %zu bytes", + pa_log_debug("Should buffer %zu bytes, buffered at minimum %zu bytes", u->latency_snapshot.max_request*2, u->latency_snapshot.min_memblockq_length); @@ -194,9 +194,21 @@ static void adjust_rates(struct userdata *u) { else new_rate = base_rate + (((u->latency_snapshot.min_memblockq_length - u->latency_snapshot.max_request*2) / fs) *PA_USEC_PER_SEC)/u->adjust_time; - pa_log_info("Old rate %lu Hz, new rate %lu Hz", (unsigned long) old_rate, (unsigned long) new_rate); + if (new_rate < (uint32_t) (base_rate*0.8) || new_rate > (uint32_t) (base_rate*1.25)) { + pa_log_warn("Sample rates too different, not adjusting (%u vs. %u).", base_rate, new_rate); + new_rate = base_rate; + } else { + 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) (old_rate*0.998) || new_rate > (uint32_t) (old_rate*1.002)) { + pa_log_info("New rate of %u Hz not within 2‰ of %u Hz, forcing smaller adjustment", new_rate, old_rate); + new_rate = PA_CLAMP(new_rate, (uint32_t) (old_rate*0.998), (uint32_t) (old_rate*1.002)); + } + } pa_sink_input_set_rate(u->sink_input, new_rate); + pa_log_debug("[%s] Updated sampling rate to %lu Hz.", u->sink_input->sink->name, (unsigned long) new_rate); pa_core_rttime_restart(u->core, u->time_event, pa_rtclock_now() + u->adjust_time); } -- cgit