gstreamer/sys/wasapi/gstwasapisrc.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

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2.1 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_SRC_H__
#define __GST_WASAPI_SRC_H__
#include "gstwasapiutil.h"
G_BEGIN_DECLS
#define GST_TYPE_WASAPI_SRC \
(gst_wasapi_src_get_type ())
#define GST_WASAPI_SRC(obj) \
(G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_WASAPI_SRC, GstWasapiSrc))
#define GST_WASAPI_SRC_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_WASAPI_SRC, GstWasapiSrcClass))
#define GST_IS_WASAPI_SRC(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_WASAPI_SRC))
#define GST_IS_WASAPI_SRC_CLASS(klass) \
(G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_WASAPI_SRC))
typedef struct _GstWasapiSrc GstWasapiSrc;
typedef struct _GstWasapiSrcClass GstWasapiSrcClass;
struct _GstWasapiSrc
{
GstAudioSrc parent;
IAudioClient *client;
IAudioClock *client_clock;
guint64 client_clock_freq;
IAudioCaptureClient *capture_client;
HANDLE event_handle;
/* Actual size of the allocated buffer */
guint buffer_frame_count;
/* The mix format that wasapi prefers in shared mode */
WAVEFORMATEX *mix_format;
/* The probed caps that we can accept */
GstCaps *cached_caps;
/* properties */
gint role;
wchar_t *device;
};
struct _GstWasapiSrcClass
{
GstAudioSrcClass parent_class;
};
GType gst_wasapi_src_get_type (void);
G_END_DECLS
#endif /* __GST_WASAPI_SRC_H__ */