diff options
Diffstat (limited to 'pica-client/capturegain.cpp')
| -rw-r--r-- | pica-client/capturegain.cpp | 150 |
1 files changed, 113 insertions, 37 deletions
diff --git a/pica-client/capturegain.cpp b/pica-client/capturegain.cpp index 2f2ea2d..8f89718 100644 --- a/pica-client/capturegain.cpp +++ b/pica-client/capturegain.cpp @@ -18,6 +18,7 @@ #include <QDebug> #include <QtGlobal> +#include <QStringList> #include <cmath> #ifdef Q_OS_LINUX @@ -114,48 +115,31 @@ public: bool open(const QString &pcmName) { - const QString card = alsaCardFromPcm(pcmName); - const QByteArray cardUtf8 = card.toUtf8(); - - if (snd_mixer_open(&m_mixer, 0) < 0) + // The card the PCM name points at, and then the real cards as + // fallbacks. "default" is not a card at all on a machine running a + // sound server: attaching to it lands on the server's own software + // volume, which is applied to samples the converter has already + // digitised. That control cannot undo clipping - scaling a clipped + // buffer down just gives a quieter clipped buffer - so calibrating + // against it would turn the microphone down forever without the + // clipping ever going away. Only a gain ahead of the ADC is any use + // here, and tryCard() insists on one. + QStringList candidates; + candidates << alsaCardFromPcm(pcmName); + + if (candidates.first() == QLatin1String("default")) { - m_mixer = nullptr; - return false; + for (int card = 0; card < 8; card++) + candidates << (QStringLiteral("hw:") + QString::number(card)); } - if (snd_mixer_attach(m_mixer, cardUtf8.constData()) < 0 || - snd_mixer_selem_register(m_mixer, nullptr, nullptr) < 0 || - snd_mixer_load(m_mixer) < 0) - return false; - - // "Capture" is what the recording gain is called on essentially every - // card that has one; "Mic" turns up on the ones that do not separate - // the input selector from the gain. Failing both, take the first - // element that has a capture volume at all. - m_elem = findNamed("Capture"); - if (!m_elem) - m_elem = findNamed("Mic"); - if (!m_elem) + for (int i = 0; i < candidates.size(); i++) { - for (snd_mixer_elem_t *e = snd_mixer_first_elem(m_mixer); e; e = snd_mixer_elem_next(e)) - { - if (snd_mixer_selem_is_active(e) && snd_mixer_selem_has_capture_volume(e)) - { - m_elem = e; - break; - } - } + if (tryCard(candidates[i])) + return true; } - if (!m_elem) - return false; - - if (snd_mixer_selem_get_capture_volume_range(m_elem, &m_min, &m_max) < 0 || m_max <= m_min) - return false; - - m_name = QString::fromUtf8(snd_mixer_selem_get_name(m_elem)) + - QStringLiteral(" on ") + card; - return true; + return false; } bool gain(double *out) override @@ -176,6 +160,24 @@ public: return true; } + bool gainDb(double *out) override + { + if (!m_elem || !out) + return false; + + snd_mixer_handle_events(m_mixer); + + // ALSA reports hundredths of a decibel. Not every element has a dB + // mapping - the software controls a sound server exposes often do not. + long v = 0; + if (snd_mixer_selem_get_capture_dB(m_elem, SND_MIXER_SCHN_FRONT_LEFT, &v) < 0 && + snd_mixer_selem_get_capture_dB(m_elem, SND_MIXER_SCHN_MONO, &v) < 0) + return false; + + *out = double(v) / 100.0; + return true; + } + bool setGain(double value) override { if (!m_elem) @@ -188,6 +190,60 @@ public: QString description() const override { return m_name; } private: + // A candidate has to have a decibel range as well as a volume range. That + // is what separates a converter gain from a sound server's software fader: + // the hardware control knows what its steps are worth in dB, the software + // one only has a slider position. It is also what lets the caller bound + // the total cut in dB, which is the only unit that means the same thing on + // every backend. + bool tryCard(const QString &card) + { + if (m_mixer) + { + snd_mixer_close(m_mixer); + m_mixer = nullptr; + m_elem = nullptr; + } + + if (snd_mixer_open(&m_mixer, 0) < 0) + { + m_mixer = nullptr; + return false; + } + + const QByteArray cardUtf8 = card.toUtf8(); + if (snd_mixer_attach(m_mixer, cardUtf8.constData()) < 0 || + snd_mixer_selem_register(m_mixer, nullptr, nullptr) < 0 || + snd_mixer_load(m_mixer) < 0) + return false; + + // "Capture" is what the recording gain is called on essentially every + // card that has one; "Mic" turns up on the ones that do not separate + // the input selector from the gain. + m_elem = findNamed("Capture"); + if (!m_elem) + m_elem = findNamed("Mic"); + if (!m_elem) + m_elem = findNamed("Digital"); + + if (!m_elem) + return false; + + if (snd_mixer_selem_get_capture_volume_range(m_elem, &m_min, &m_max) < 0 || m_max <= m_min) + return false; + + long dbMin = 0, dbMax = 0; + if (snd_mixer_selem_get_capture_dB_range(m_elem, &dbMin, &dbMax) < 0 || dbMax <= dbMin) + { + m_elem = nullptr; + return false; + } + + m_name = QString::fromUtf8(snd_mixer_selem_get_name(m_elem)) + + QStringLiteral(" on ") + card; + return true; + } + snd_mixer_elem_t *findNamed(const char *want) { for (snd_mixer_elem_t *e = snd_mixer_first_elem(m_mixer); e; e = snd_mixer_elem_next(e)) @@ -220,7 +276,7 @@ class PulseCaptureGain : public CaptureGainControl public: PulseCaptureGain() : m_mainloop(nullptr), m_ctx(nullptr), m_channels(1), - m_pending(false), m_ok(false), m_value(0.0) {} + m_pending(false), m_ok(false), m_value(0.0), m_valueDb(0.0) {} ~PulseCaptureGain() override { @@ -293,6 +349,24 @@ public: return m_ok; } + // pa_sw_volume_to_dB() returns -inf for a muted control, which is true but + // useless as a number to do arithmetic on. + bool gainDb(double *out) override + { + if (!out) + return false; + + double ignored; + if (!gain(&ignored)) + return false; + + if (m_valueDb < -200.0 || m_valueDb > 200.0) + return false; + + *out = m_valueDb; + return true; + } + bool setGain(double value) override { if (!m_ctx || m_source.isEmpty()) @@ -393,6 +467,7 @@ private: // The loudest channel, so a step down is a step down for all of them // rather than only for whichever happens to be quietest. self->m_value = clampGainAmplified(double(pa_cvolume_max(&info->volume)) / double(PA_VOLUME_NORM)); + self->m_valueDb = pa_sw_volume_to_dB(pa_cvolume_max(&info->volume)); self->m_ok = true; } @@ -411,6 +486,7 @@ private: bool m_pending; bool m_ok; double m_value; + double m_valueDb; }; #endif // HAVE_LIBPULSE |