Changes: - Mention that source outputs have volume too. - Don't claim that most distributions have flat volumes enabled. - Volumes use a cubic scale, not logarithmic. - Reword the warning about using the conversion functions on hardware volumes. The old wording gave the incorrect impression that hardware volumes could never be converted to dB or linear scale. --- src/pulse/volume.h | 39 ++++++++++++++++++--------------------- 1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/src/pulse/volume.h b/src/pulse/volume.h index 8cf4fa45b..03497f747 100644 --- a/src/pulse/volume.h +++ b/src/pulse/volume.h @@ -34,9 +34,9 @@ * * \section overv_sec Overview * - * Sinks, sources, sink inputs and samples can all have their own volumes. - * To deal with these, The PulseAudio library contains a number of functions - * that ease handling. + * Sinks, sources, sink inputs, source outputs and samples can all have their + * own volumes. To deal with these, The PulseAudio library contains a number of + * functions that ease handling. * * The basic volume type in PulseAudio is the \ref pa_volume_t type. Most of * the time, applications will use the aggregated pa_cvolume structure that @@ -47,13 +47,12 @@ * * There is no single well-defined meaning attached to the 100% volume for a * sink input. In fact, it depends on the server configuration. With flat - * volumes enabled (the default in most Linux distributions), it means the - * maximum volume that the sound hardware is capable of, which is usually so - * high that you absolutely must not set sink input volume to 100% unless the - * the user explicitly requests that (note that usually you shouldn't set the - * volume anyway if the user doesn't explicitly request it, instead, let - * PulseAudio decide the volume for the sink input). With flat volumes disabled - * (the default in Ubuntu), the sink input volume is relative to the sink + * volumes enabled, it means the maximum volume that the sound hardware is + * capable of, which is usually so high that you absolutely must not set sink + * input volume to 100% unless the the user explicitly requests that (note that + * usually you shouldn't set the volume anyway if the user doesn't explicitly + * request it, instead, let PulseAudio decide the volume for the sink input). + * With flat volumes disabled the sink input volume is relative to the sink * volume, so 100% sink input volume means that the sink input is played at the * current sink volume level. In this case 100% is often a good default volume * for a sink input, although you still should let PulseAudio decide the @@ -62,9 +61,9 @@ * * \section calc_sec Calculations * - * The volumes in PulseAudio are logarithmic in nature and applications - * shouldn't perform calculations with them directly. Instead, they should - * be converted to and from either dB or a linear scale: + * The volumes in PulseAudio are cubic in nature and applications shouldn't + * perform calculations with them directly. Instead, they should be converted + * to and from either dB or a linear scale: * * \li dB - pa_sw_volume_from_dB() / pa_sw_volume_to_dB() * \li Linear - pa_sw_volume_from_linear() / pa_sw_volume_to_linear() @@ -72,14 +71,12 @@ * For simple multiplication, pa_sw_volume_multiply() and * pa_sw_cvolume_multiply() can be used. * - * Calculations can only be reliably performed on software volumes - * as it is commonly unknown what scale hardware volumes relate to. - * - * The functions described above are only valid when used with - * software volumes. Hence it is usually a better idea to treat all - * volume values as opaque with a range from PA_VOLUME_MUTED (0%) to - * PA_VOLUME_NORM (100%) and to refrain from any calculations with - * them. + * It's often unknown what scale hardware volumes relate to. Don't use the + * above functions on sink and source volumes, unless the sink or source in + * question has the PA_SINK_DECIBEL_VOLUME or PA_SOURCE_DECIBEL_VOLUME flag + * set. The conversion functions are rarely needed anyway, most of the time + * it's sufficient to treat all volumes as opaque with a range from + * PA_VOLUME_MUTED (0%) to PA_VOLUME_NORM (100%). * * \section conv_sec Convenience Functions * -- 2.14.2 _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
