diff options
author | Maarten Bosmans <mkbosmans@gmail.com> | 2011-01-07 01:25:55 +0100 |
---|---|---|
committer | Colin Guthrie <cguthrie@mandriva.org> | 2011-02-25 10:34:37 +0000 |
commit | 90c5520e03bbccf6c1d9f87221d3742cc70b53ed (patch) | |
tree | 46aed8205bdf1f1266739dd6ca885e36f6983a9d /src/modules/module-loopback.c | |
parent | 09770e577991d49cf826bdf80b0f9559f1e67820 (diff) |
Limit rate adjustments to small, inaudible jumps
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.
Diffstat (limited to 'src/modules/module-loopback.c')
-rw-r--r-- | src/modules/module-loopback.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/src/modules/module-loopback.c b/src/modules/module-loopback.c index ca06314d..e0277c17 100644 --- a/src/modules/module-loopback.c +++ b/src/modules/module-loopback.c @@ -167,13 +167,13 @@ 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); @@ -186,9 +186,21 @@ 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); } |