gstreamer/sys/wasapi/gstwasapiutil.h
Nirbheek Chauhan 1450851095 wasapi: Rewrite most of the code to make it work
Both the source and the sink elements were broken in a number of ways:

* prepare() was assuming that the format was always S16LE 2ch 44.1KHz.
  We now probe the preferred format with GetMixFormat().
* Device initialization was done with the wrong buffer size
  (buffer_time is in microseconds, not nanoseconds).
* sink_write() and src_read() were just plain wrong and would never
  write or read anything useful.
* Some functions in prepare() were always returning FALSE which meant
  trying to use the elements would *always* fail.
* get_caps() and delay() were not implemented at all.

TODO: support for >2 channels
TODO: pro-audio low-latency
TODO: SPDIF and other encoded passthroughs

Three new properties are now implemented: role, mute, and device.

* 'role' designates the stream role of the initialized device, see:
   https://msdn.microsoft.com/en-us/library/windows/desktop/dd370842(v=vs.85).aspx
* 'device' is a system-wide GUIDesque string for a specific device.
* 'mute' is a sink property and simply mutes it.

On my Windows 8.1 system, the lowest latency that works is:

  wasapisrc buffer-time=20000
  wasapisink buffer-time=10000

aka, 20ms and 10ms respectively. These values are close to the lowest
possible with the IAudioClient interface. Further improvements require
porting to IAudioClient2 or IAudioClient3.

https://docs.microsoft.com/en-us/windows-hardware/drivers/audio/low-latency-audio
2018-01-22 14:18:53 +05:30

65 lines
2.2 KiB
C

/*
* Copyright (C) 2008 Ole André Vadla Ravnås <ole.andre.ravnas@tandberg.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifndef __GST_WASAPI_UTIL_H__
#define __GST_WASAPI_UTIL_H__
#include <gst/gst.h>
#include <gst/audio/audio.h>
#include <gst/audio/gstaudiosrc.h>
#include <gst/audio/gstaudiosink.h>
#include <audioclient.h>
/* Device role enum property */
typedef enum
{
GST_WASAPI_DEVICE_ROLE_CONSOLE,
GST_WASAPI_DEVICE_ROLE_MULTIMEDIA,
GST_WASAPI_DEVICE_ROLE_COMMS
} GstWasapiDeviceRole;
#define GST_WASAPI_DEVICE_TYPE_ROLE (gst_wasapi_device_role_get_type())
GType gst_wasapi_device_role_get_type (void);
/* Utilities */
gint gst_wasapi_device_role_to_erole (gint role);
gint gst_wasapi_erole_to_device_role (gint erole);
const gchar *gst_wasapi_util_hresult_to_string (HRESULT hr);
gboolean
gst_wasapi_util_get_device_client (GstElement * element,
gboolean capture,
gint role, const wchar_t * device_name, IAudioClient ** ret_client);
gboolean gst_wasapi_util_get_render_client (GstElement * element,
IAudioClient * client, IAudioRenderClient ** ret_render_client);
gboolean gst_wasapi_util_get_capture_client (GstElement * element,
IAudioClient * client, IAudioCaptureClient ** ret_capture_client);
gboolean gst_wasapi_util_get_clock (GstElement * element,
IAudioClient * client, IAudioClock ** ret_clock);
GstCaps *gst_wasapi_util_waveformatex_to_caps (WAVEFORMATEXTENSIBLE * format,
GstCaps * template_caps);
#endif /* __GST_WASAPI_UTIL_H__ */