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-rw-r--r--src/output/plugins/AlsaOutputPlugin.cxx41
1 files changed, 21 insertions, 20 deletions
diff --git a/src/output/plugins/AlsaOutputPlugin.cxx b/src/output/plugins/AlsaOutputPlugin.cxx
index 0ebf3ddbe..33a090274 100644
--- a/src/output/plugins/AlsaOutputPlugin.cxx
+++ b/src/output/plugins/AlsaOutputPlugin.cxx
@@ -62,12 +62,11 @@ struct AlsaOutput {
bool use_mmap;
/**
- * Enable DSD over USB according to the dCS suggested
- * standard?
+ * Enable DSD over PCM according to the DoP standard standard?
*
- * @see http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf
+ * @see http://dsd-guide.com/dop-open-standard
*/
- bool dsd_usb;
+ bool dop;
/** libasound's buffer_time setting (in microseconds) */
unsigned int buffer_time;
@@ -153,7 +152,9 @@ AlsaOutput::Configure(const config_param &param, Error &error)
use_mmap = param.GetBlockValue("use_mmap", false);
- dsd_usb = param.GetBlockValue("dsd_usb", false);
+ dop = param.GetBlockValue("dop", false) ||
+ /* legacy name from MPD 0.18 and older: */
+ param.GetBlockValue("dsd_usb", false);
buffer_time = param.GetBlockValue("buffer_time",
MPD_ALSA_BUFFER_TIME_US);
@@ -639,34 +640,34 @@ alsa_setup_dsd(AlsaOutput *ad, const AudioFormat audio_format,
bool *shift8_r, bool *packed_r, bool *reverse_endian_r,
Error &error)
{
- assert(ad->dsd_usb);
+ assert(ad->dop);
assert(audio_format.format == SampleFormat::DSD);
/* pass 24 bit to alsa_setup() */
- AudioFormat usb_format = audio_format;
- usb_format.format = SampleFormat::S24_P32;
- usb_format.sample_rate /= 2;
+ AudioFormat dop_format = audio_format;
+ dop_format.format = SampleFormat::S24_P32;
+ dop_format.sample_rate /= 2;
- const AudioFormat check = usb_format;
+ const AudioFormat check = dop_format;
- if (!alsa_setup(ad, usb_format, packed_r, reverse_endian_r, error))
+ if (!alsa_setup(ad, dop_format, packed_r, reverse_endian_r, error))
return false;
- /* if the device allows only 32 bit, shift all DSD-over-USB
+ /* if the device allows only 32 bit, shift all DoP
samples left by 8 bit and leave the lower 8 bit cleared;
the DSD-over-USB documentation does not specify whether
this is legal, but there is anecdotical evidence that this
is possible (and the only option for some devices) */
- *shift8_r = usb_format.format == SampleFormat::S32;
- if (usb_format.format == SampleFormat::S32)
- usb_format.format = SampleFormat::S24_P32;
+ *shift8_r = dop_format.format == SampleFormat::S32;
+ if (dop_format.format == SampleFormat::S32)
+ dop_format.format = SampleFormat::S24_P32;
- if (usb_format != check) {
+ if (dop_format != check) {
/* no bit-perfect playback, which is required
for DSD over USB */
error.Format(alsa_output_domain,
- "Failed to configure DSD-over-USB on ALSA device \"%s\"",
+ "Failed to configure DSD-over-PCM on ALSA device \"%s\"",
alsa_device(ad));
delete[] ad->silence;
return false;
@@ -681,9 +682,9 @@ alsa_setup_or_dsd(AlsaOutput *ad, AudioFormat &audio_format,
{
bool shift8 = false, packed, reverse_endian;
- const bool dsd_usb = ad->dsd_usb &&
+ const bool dop = ad->dop &&
audio_format.format == SampleFormat::DSD;
- const bool success = dsd_usb
+ const bool success = dop
? alsa_setup_dsd(ad, audio_format,
&shift8, &packed, &reverse_endian,
error)
@@ -694,7 +695,7 @@ alsa_setup_or_dsd(AlsaOutput *ad, AudioFormat &audio_format,
ad->pcm_export->Open(audio_format.format,
audio_format.channels,
- dsd_usb, shift8, packed, reverse_endian);
+ dop, shift8, packed, reverse_endian);
return true;
}