ardour/ardour
ardour/ardour
13
1
Fork 0
Code Pull Requests Releases Activity

Fix latency compensation for audio data in portaudio backend

Browse Source 
For drivers that correctly report latency values(ASIO) this should result a
much closer alignment of audio in a loopback test. Measurement and
adjustment may still be needed, especially for non-ASIO drivers.

Testing with the RME HDSP Multiface and Yamaha AG06 using ASIO drivers results
in maximum offset of a couple of samples.
This commit is contained in:
Tim Mayberry 2015-11-30 19:21:58 +10:00
parent b4fb1d610b
commit e9be313c11
1 changed files with 12 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
libs/backends/portaudio/portaudio_backend.cc
View File

@ -1242,12 +1242,19 @@ PortAudioBackend::register_system_audio_ports()
const uint32_t a_ins = _n_inputs;
const uint32_t a_out = _n_outputs;
// XXX PA reported stream latencies don't match measurements
const uint32_t portaudio_reported_input_latency = _samples_per_period ; // _pcmio->capture_latency();
const uint32_t portaudio_reported_output_latency = /* _samples_per_period + */ _pcmio->playback_latency();
uint32_t capture_latency = 0;
uint32_t playback_latency = 0;
// guard against erroneous latency values
if (_pcmio->capture_latency() > _samples_per_period) {
capture_latency = _pcmio->capture_latency() - _samples_per_period;
}
if (_pcmio->playback_latency() > _samples_per_period) {
playback_latency = _pcmio->playback_latency() - _samples_per_period;
}
/* audio ports */
lr.min = lr.max = portaudio_reported_input_latency + (_measure_latency ? 0 : _systemic_audio_input_latency);
lr.min = lr.max = capture_latency + (_measure_latency ? 0 : _systemic_audio_input_latency);
for (uint32_t i = 0; i < a_ins; ++i) {
char tmp[64];
snprintf(tmp, sizeof(tmp), "system:capture_%d", i+1);
@ -1260,7 +1267,7 @@ PortAudioBackend::register_system_audio_ports()
_system_inputs.push_back (audio_port);
}
lr.min = lr.max = portaudio_reported_output_latency + (_measure_latency ? 0 : _systemic_audio_output_latency);
lr.min = lr.max = playback_latency + (_measure_latency ? 0 : _systemic_audio_output_latency);
for (uint32_t i = 0; i < a_out; ++i) {
char tmp[64];
snprintf(tmp, sizeof(tmp), "system:playback_%d", i+1);