gstreamer/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2util.c
Seungha Yang cb7958e710 wasapi2: Add support for process loopback capture
Adding loopback capture mode for specified PID.

Note that this feature requires Windows 10 build 20348
(Windows 11/Windows Server 2022 or later),
and any process loopback related properties will not be exposed
if OS does not support it.

Example launch lines:
* wasapi2src loopback-mode=include-process-tree loopback-target-pid=<PID>
 Captures audio generated by an application (specified by PID)
 and its child process
* wasapi2src loopback-mode=exclude-process-tree loopback-target-pid=<PID>
 Captures desktop audio excluding PID and its child process

Fixes: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1278
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3195>
2022-10-17 23:28:48 +00:00

562 lines
18 KiB
C

/*
* Copyright (C) 2008 Ole André Vadla Ravnås <ole.andre.ravnas@tandberg.com>
* Copyright (C) 2018 Centricular Ltd.
* Author: Nirbheek Chauhan <nirbheek@centricular.com>
* Copyright (C) 2020 Seungha Yang <seungha@centricular.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.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "gstwasapi2util.h"
#include <audioclient.h>
#include <mmdeviceapi.h>
#include <winternl.h>
GST_DEBUG_CATEGORY_EXTERN (gst_wasapi2_debug);
#define GST_CAT_DEFAULT gst_wasapi2_debug
/* Desktop only defines */
#ifndef KSAUDIO_SPEAKER_MONO
#define KSAUDIO_SPEAKER_MONO (SPEAKER_FRONT_CENTER)
#endif
#ifndef KSAUDIO_SPEAKER_1POINT1
#define KSAUDIO_SPEAKER_1POINT1 (SPEAKER_FRONT_CENTER | SPEAKER_LOW_FREQUENCY)
#endif
#ifndef KSAUDIO_SPEAKER_STEREO
#define KSAUDIO_SPEAKER_STEREO (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT)
#endif
#ifndef KSAUDIO_SPEAKER_2POINT1
#define KSAUDIO_SPEAKER_2POINT1 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_LOW_FREQUENCY)
#endif
#ifndef KSAUDIO_SPEAKER_3POINT0
#define KSAUDIO_SPEAKER_3POINT0 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER)
#endif
#ifndef KSAUDIO_SPEAKER_3POINT1
#define KSAUDIO_SPEAKER_3POINT1 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | \
SPEAKER_FRONT_CENTER | SPEAKER_LOW_FREQUENCY)
#endif
#ifndef KSAUDIO_SPEAKER_QUAD
#define KSAUDIO_SPEAKER_QUAD (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | \
SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT)
#endif
#define KSAUDIO_SPEAKER_SURROUND (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | \
SPEAKER_FRONT_CENTER | SPEAKER_BACK_CENTER)
#ifndef KSAUDIO_SPEAKER_5POINT0
#define KSAUDIO_SPEAKER_5POINT0 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER | \
SPEAKER_SIDE_LEFT | SPEAKER_SIDE_RIGHT)
#endif
#define KSAUDIO_SPEAKER_5POINT1 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | \
SPEAKER_FRONT_CENTER | SPEAKER_LOW_FREQUENCY | \
SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT)
#ifndef KSAUDIO_SPEAKER_7POINT0
#define KSAUDIO_SPEAKER_7POINT0 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | SPEAKER_FRONT_CENTER | \
SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT | \
SPEAKER_SIDE_LEFT | SPEAKER_SIDE_RIGHT)
#endif
#ifndef KSAUDIO_SPEAKER_7POINT1
#define KSAUDIO_SPEAKER_7POINT1 (SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT | \
SPEAKER_FRONT_CENTER | SPEAKER_LOW_FREQUENCY | \
SPEAKER_BACK_LEFT | SPEAKER_BACK_RIGHT | \
SPEAKER_FRONT_LEFT_OF_CENTER | SPEAKER_FRONT_RIGHT_OF_CENTER)
#endif
/* *INDENT-OFF* */
static struct
{
guint64 wasapi_pos;
GstAudioChannelPosition gst_pos;
} wasapi_to_gst_pos[] = {
{SPEAKER_FRONT_LEFT, GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT},
{SPEAKER_FRONT_RIGHT, GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT},
{SPEAKER_FRONT_CENTER, GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER},
{SPEAKER_LOW_FREQUENCY, GST_AUDIO_CHANNEL_POSITION_LFE1},
{SPEAKER_BACK_LEFT, GST_AUDIO_CHANNEL_POSITION_REAR_LEFT},
{SPEAKER_BACK_RIGHT, GST_AUDIO_CHANNEL_POSITION_REAR_RIGHT},
{SPEAKER_FRONT_LEFT_OF_CENTER,
GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER},
{SPEAKER_FRONT_RIGHT_OF_CENTER,
GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER},
{SPEAKER_BACK_CENTER, GST_AUDIO_CHANNEL_POSITION_REAR_CENTER},
/* Enum values diverge from this point onwards */
{SPEAKER_SIDE_LEFT, GST_AUDIO_CHANNEL_POSITION_SIDE_LEFT},
{SPEAKER_SIDE_RIGHT, GST_AUDIO_CHANNEL_POSITION_SIDE_RIGHT},
{SPEAKER_TOP_CENTER, GST_AUDIO_CHANNEL_POSITION_TOP_CENTER},
{SPEAKER_TOP_FRONT_LEFT, GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_LEFT},
{SPEAKER_TOP_FRONT_CENTER, GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_CENTER},
{SPEAKER_TOP_FRONT_RIGHT, GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_RIGHT},
{SPEAKER_TOP_BACK_LEFT, GST_AUDIO_CHANNEL_POSITION_TOP_REAR_LEFT},
{SPEAKER_TOP_BACK_CENTER, GST_AUDIO_CHANNEL_POSITION_TOP_REAR_CENTER},
{SPEAKER_TOP_BACK_RIGHT, GST_AUDIO_CHANNEL_POSITION_TOP_REAR_RIGHT}
};
static DWORD default_ch_masks[] = {
0,
KSAUDIO_SPEAKER_MONO,
/* 2ch */
KSAUDIO_SPEAKER_STEREO,
/* 2.1ch */
/* KSAUDIO_SPEAKER_3POINT0 ? */
KSAUDIO_SPEAKER_2POINT1,
/* 4ch */
/* KSAUDIO_SPEAKER_3POINT1 or KSAUDIO_SPEAKER_SURROUND ? */
KSAUDIO_SPEAKER_QUAD,
/* 5ch */
KSAUDIO_SPEAKER_5POINT0,
/* 5.1ch */
KSAUDIO_SPEAKER_5POINT1,
/* 7ch */
KSAUDIO_SPEAKER_7POINT0,
/* 7.1ch */
KSAUDIO_SPEAKER_7POINT1,
};
/* *INDENT-ON* */
static const gchar *
hresult_to_string_fallback (HRESULT hr)
{
const gchar *s = "unknown error";
switch (hr) {
case AUDCLNT_E_NOT_INITIALIZED:
s = "AUDCLNT_E_NOT_INITIALIZED";
break;
case AUDCLNT_E_ALREADY_INITIALIZED:
s = "AUDCLNT_E_ALREADY_INITIALIZED";
break;
case AUDCLNT_E_WRONG_ENDPOINT_TYPE:
s = "AUDCLNT_E_WRONG_ENDPOINT_TYPE";
break;
case AUDCLNT_E_DEVICE_INVALIDATED:
s = "AUDCLNT_E_DEVICE_INVALIDATED";
break;
case AUDCLNT_E_NOT_STOPPED:
s = "AUDCLNT_E_NOT_STOPPED";
break;
case AUDCLNT_E_BUFFER_TOO_LARGE:
s = "AUDCLNT_E_BUFFER_TOO_LARGE";
break;
case AUDCLNT_E_OUT_OF_ORDER:
s = "AUDCLNT_E_OUT_OF_ORDER";
break;
case AUDCLNT_E_UNSUPPORTED_FORMAT:
s = "AUDCLNT_E_UNSUPPORTED_FORMAT";
break;
case AUDCLNT_E_INVALID_DEVICE_PERIOD:
s = "AUDCLNT_E_INVALID_DEVICE_PERIOD";
break;
case AUDCLNT_E_INVALID_SIZE:
s = "AUDCLNT_E_INVALID_SIZE";
break;
case AUDCLNT_E_DEVICE_IN_USE:
s = "AUDCLNT_E_DEVICE_IN_USE";
break;
case AUDCLNT_E_BUFFER_OPERATION_PENDING:
s = "AUDCLNT_E_BUFFER_OPERATION_PENDING";
break;
case AUDCLNT_E_BUFFER_SIZE_ERROR:
s = "AUDCLNT_E_BUFFER_SIZE_ERROR";
break;
case AUDCLNT_E_BUFFER_SIZE_NOT_ALIGNED:
s = "AUDCLNT_E_BUFFER_SIZE_NOT_ALIGNED";
break;
case AUDCLNT_E_THREAD_NOT_REGISTERED:
s = "AUDCLNT_E_THREAD_NOT_REGISTERED";
break;
case AUDCLNT_E_EXCLUSIVE_MODE_NOT_ALLOWED:
s = "AUDCLNT_E_EXCLUSIVE_MODE_NOT_ALLOWED";
break;
case AUDCLNT_E_ENDPOINT_CREATE_FAILED:
s = "AUDCLNT_E_ENDPOINT_CREATE_FAILED";
break;
case AUDCLNT_E_SERVICE_NOT_RUNNING:
s = "AUDCLNT_E_SERVICE_NOT_RUNNING";
break;
case AUDCLNT_E_EVENTHANDLE_NOT_EXPECTED:
s = "AUDCLNT_E_EVENTHANDLE_NOT_EXPECTED";
break;
case AUDCLNT_E_EXCLUSIVE_MODE_ONLY:
s = "AUDCLNT_E_EXCLUSIVE_MODE_ONLY";
break;
case AUDCLNT_E_BUFDURATION_PERIOD_NOT_EQUAL:
s = "AUDCLNT_E_BUFDURATION_PERIOD_NOT_EQUAL";
break;
case AUDCLNT_E_EVENTHANDLE_NOT_SET:
s = "AUDCLNT_E_EVENTHANDLE_NOT_SET";
break;
case AUDCLNT_E_INCORRECT_BUFFER_SIZE:
s = "AUDCLNT_E_INCORRECT_BUFFER_SIZE";
break;
case AUDCLNT_E_CPUUSAGE_EXCEEDED:
s = "AUDCLNT_E_CPUUSAGE_EXCEEDED";
break;
case AUDCLNT_S_BUFFER_EMPTY:
s = "AUDCLNT_S_BUFFER_EMPTY";
break;
case AUDCLNT_S_THREAD_ALREADY_REGISTERED:
s = "AUDCLNT_S_THREAD_ALREADY_REGISTERED";
break;
case AUDCLNT_S_POSITION_STALLED:
s = "AUDCLNT_S_POSITION_STALLED";
break;
case E_POINTER:
s = "E_POINTER";
break;
case E_INVALIDARG:
s = "E_INVALIDARG";
break;
}
return s;
}
gchar *
gst_wasapi2_util_get_error_message (HRESULT hr)
{
gchar *error_text = NULL;
error_text = g_win32_error_message ((gint) hr);
if (!error_text || strlen (error_text) == 0) {
g_free (error_text);
error_text = g_strdup (hresult_to_string_fallback (hr));
}
return error_text;
}
gboolean
_gst_wasapi2_result (HRESULT hr, GstDebugCategory * cat, const gchar * file,
const gchar * function, gint line)
{
#ifndef GST_DISABLE_GST_DEBUG
gboolean ret = TRUE;
if (FAILED (hr)) {
gchar *error_text = NULL;
gboolean free_string = TRUE;
error_text = g_win32_error_message ((gint) hr);
/* g_win32_error_message() seems to be returning empty string for
* AUDCLNT_* cases */
if (!error_text || strlen (error_text) == 0) {
g_free (error_text);
error_text = (gchar *) hresult_to_string_fallback (hr);
free_string = FALSE;
}
gst_debug_log (cat, GST_LEVEL_WARNING, file, function, line,
NULL, "WASAPI call failed: 0x%x, %s", (guint) hr, error_text);
if (free_string)
g_free (error_text);
ret = FALSE;
}
return ret;
#else
return SUCCEEDED (hr);
#endif
}
static void
gst_wasapi_util_channel_position_all_none (guint channels,
GstAudioChannelPosition * position)
{
guint i;
for (i = 0; i < channels; i++)
position[i] = GST_AUDIO_CHANNEL_POSITION_NONE;
}
guint64
gst_wasapi2_util_waveformatex_to_channel_mask (WAVEFORMATEX * format,
GstAudioChannelPosition ** out_position)
{
guint i, ch;
guint64 mask = 0;
GstAudioChannelPosition *pos = NULL;
WORD nChannels = 0;
DWORD dwChannelMask = 0;
nChannels = format->nChannels;
if (format->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
WAVEFORMATEXTENSIBLE *extensible = (WAVEFORMATEXTENSIBLE *) format;
dwChannelMask = extensible->dwChannelMask;
}
if (out_position)
*out_position = NULL;
if (nChannels > 2 && !dwChannelMask) {
GST_WARNING ("Unknown channel mask value for %d channel stream", nChannels);
if (nChannels >= G_N_ELEMENTS (default_ch_masks)) {
GST_ERROR ("To may channels %d", nChannels);
return 0;
}
dwChannelMask = default_ch_masks[nChannels];
}
pos = g_new (GstAudioChannelPosition, nChannels);
gst_wasapi_util_channel_position_all_none (nChannels, pos);
/* Too many channels, have to assume that they are all non-positional */
if (nChannels > G_N_ELEMENTS (wasapi_to_gst_pos)) {
GST_INFO ("Got too many (%i) channels, assuming non-positional", nChannels);
goto out;
}
/* Too many bits in the channel mask, and the bits don't match nChannels */
if (dwChannelMask >> (G_N_ELEMENTS (wasapi_to_gst_pos) + 1) != 0) {
GST_WARNING ("Too many bits in channel mask (%lu), assuming "
"non-positional", dwChannelMask);
goto out;
}
/* Map WASAPI's channel mask to Gstreamer's channel mask and positions.
* If the no. of bits in the mask > nChannels, we will ignore the extra. */
for (i = 0, ch = 0; i < G_N_ELEMENTS (wasapi_to_gst_pos) && ch < nChannels;
i++) {
if (!(dwChannelMask & wasapi_to_gst_pos[i].wasapi_pos))
/* no match, try next */
continue;
mask |= G_GUINT64_CONSTANT (1) << wasapi_to_gst_pos[i].gst_pos;
pos[ch++] = wasapi_to_gst_pos[i].gst_pos;
}
/* XXX: Warn if some channel masks couldn't be mapped? */
GST_DEBUG ("Converted WASAPI mask 0x%" G_GINT64_MODIFIER "x -> 0x%"
G_GINT64_MODIFIER "x", (guint64) dwChannelMask, (guint64) mask);
out:
if (out_position) {
*out_position = pos;
} else {
g_free (pos);
}
return mask;
}
const gchar *
gst_wasapi2_util_waveformatex_to_audio_format (WAVEFORMATEX * format)
{
const gchar *fmt_str = NULL;
GstAudioFormat fmt = GST_AUDIO_FORMAT_UNKNOWN;
switch (format->wFormatTag) {
case WAVE_FORMAT_PCM:
fmt = gst_audio_format_build_integer (TRUE, G_LITTLE_ENDIAN,
format->wBitsPerSample, format->wBitsPerSample);
break;
case WAVE_FORMAT_IEEE_FLOAT:
if (format->wBitsPerSample == 32)
fmt = GST_AUDIO_FORMAT_F32LE;
else if (format->wBitsPerSample == 64)
fmt = GST_AUDIO_FORMAT_F64LE;
break;
case WAVE_FORMAT_EXTENSIBLE:
{
WAVEFORMATEXTENSIBLE *ex = (WAVEFORMATEXTENSIBLE *) format;
if (IsEqualGUID (&ex->SubFormat, &KSDATAFORMAT_SUBTYPE_PCM)) {
fmt = gst_audio_format_build_integer (TRUE, G_LITTLE_ENDIAN,
format->wBitsPerSample, ex->Samples.wValidBitsPerSample);
} else if (IsEqualGUID (&ex->SubFormat, &KSDATAFORMAT_SUBTYPE_IEEE_FLOAT)) {
if (format->wBitsPerSample == 32
&& ex->Samples.wValidBitsPerSample == 32)
fmt = GST_AUDIO_FORMAT_F32LE;
else if (format->wBitsPerSample == 64 &&
ex->Samples.wValidBitsPerSample == 64)
fmt = GST_AUDIO_FORMAT_F64LE;
}
break;
}
default:
break;
}
if (fmt != GST_AUDIO_FORMAT_UNKNOWN)
fmt_str = gst_audio_format_to_string (fmt);
return fmt_str;
}
gboolean
gst_wasapi2_util_parse_waveformatex (WAVEFORMATEX * format,
GstCaps * template_caps, GstCaps ** out_caps,
GstAudioChannelPosition ** out_positions)
{
const gchar *afmt;
guint64 channel_mask;
*out_caps = NULL;
/* TODO: handle SPDIF and other encoded formats */
/* 1 or 2 channels <= 16 bits sample size OR
* 1 or 2 channels > 16 bits sample size or >2 channels */
if (format->wFormatTag != WAVE_FORMAT_PCM &&
format->wFormatTag != WAVE_FORMAT_IEEE_FLOAT &&
format->wFormatTag != WAVE_FORMAT_EXTENSIBLE)
/* Unhandled format tag */
return FALSE;
/* WASAPI can only tell us one canonical mix format that it will accept. The
* alternative is calling IsFormatSupported on all combinations of formats.
* Instead, it's simpler and faster to require conversion inside gstreamer */
afmt = gst_wasapi2_util_waveformatex_to_audio_format (format);
if (afmt == NULL)
return FALSE;
*out_caps = gst_caps_copy (template_caps);
channel_mask = gst_wasapi2_util_waveformatex_to_channel_mask (format,
out_positions);
gst_caps_set_simple (*out_caps,
"format", G_TYPE_STRING, afmt,
"channels", G_TYPE_INT, format->nChannels,
"rate", G_TYPE_INT, format->nSamplesPerSec, NULL);
if (channel_mask) {
gst_caps_set_simple (*out_caps,
"channel-mask", GST_TYPE_BITMASK, channel_mask, NULL);
}
return TRUE;
}
gboolean
gst_wasapi2_can_automatic_stream_routing (void)
{
#ifdef GST_WASAPI2_WINAPI_ONLY_APP
/* Assume we are on very recent OS */
return TRUE;
#else
static gboolean ret = FALSE;
static gsize version_once = 0;
if (g_once_init_enter (&version_once)) {
OSVERSIONINFOEXW osverinfo;
typedef NTSTATUS (WINAPI fRtlGetVersion) (PRTL_OSVERSIONINFOEXW);
fRtlGetVersion *RtlGetVersion = NULL;
HMODULE hmodule = NULL;
memset (&osverinfo, 0, sizeof (OSVERSIONINFOEXW));
osverinfo.dwOSVersionInfoSize = sizeof (OSVERSIONINFOEXW);
hmodule = LoadLibraryW (L"ntdll.dll");
if (hmodule)
RtlGetVersion =
(fRtlGetVersion *) GetProcAddress (hmodule, "RtlGetVersion");
if (RtlGetVersion) {
RtlGetVersion (&osverinfo);
/* automatic stream routing requires Windows 10
* Anniversary Update (version 1607, build number 14393.0) */
if (osverinfo.dwMajorVersion > 10 ||
(osverinfo.dwMajorVersion == 10 && osverinfo.dwBuildNumber >= 14393))
ret = TRUE;
}
if (hmodule)
FreeLibrary (hmodule);
g_once_init_leave (&version_once, 1);
}
GST_INFO ("Automatic stream routing support: %d", ret);
return ret;
#endif
}
gboolean
gst_wasapi2_can_process_loopback (void)
{
#ifdef GST_WASAPI2_WINAPI_ONLY_APP
/* FIXME: Needs WinRT (Windows.System.Profile) API call
* for OS version check */
return FALSE;
#else
static gboolean ret = FALSE;
static gsize version_once = 0;
if (g_once_init_enter (&version_once)) {
OSVERSIONINFOEXW osverinfo;
typedef NTSTATUS (WINAPI fRtlGetVersion) (PRTL_OSVERSIONINFOEXW);
fRtlGetVersion *RtlGetVersion = NULL;
HMODULE hmodule = NULL;
memset (&osverinfo, 0, sizeof (OSVERSIONINFOEXW));
osverinfo.dwOSVersionInfoSize = sizeof (OSVERSIONINFOEXW);
hmodule = LoadLibraryW (L"ntdll.dll");
if (hmodule)
RtlGetVersion =
(fRtlGetVersion *) GetProcAddress (hmodule, "RtlGetVersion");
if (RtlGetVersion) {
RtlGetVersion (&osverinfo);
/* Process loopback requires Windows 10 build 20348
* https://learn.microsoft.com/en-us/windows/win32/api/audioclientactivationparams/ns-audioclientactivationparams-audioclient_process_loopback_params
*
* Note: "Windows 10 build 20348" would mean "Windows server 2022" or
* "Windows 11", since build number of "Windows 10 version 21H2" is
* still 19044.XXX
*/
if (osverinfo.dwMajorVersion > 10 ||
(osverinfo.dwMajorVersion == 10 && osverinfo.dwBuildNumber >= 20348))
ret = TRUE;
}
if (hmodule)
FreeLibrary (hmodule);
g_once_init_leave (&version_once, 1);
}
GST_INFO ("Process loopback support: %d", ret);
return ret;
#endif
}
WAVEFORMATEX *
gst_wasapi2_get_default_mix_format (void)
{
WAVEFORMATEX *format;
/* virtual loopback device might not provide mix format. Create our default
* mix format */
format = CoTaskMemAlloc (sizeof (WAVEFORMATEX));
format->wFormatTag = WAVE_FORMAT_PCM;
format->nChannels = 2;
format->nSamplesPerSec = 44100;
format->wBitsPerSample = 16;
format->nBlockAlign = format->nChannels * format->wBitsPerSample / 8;
format->nAvgBytesPerSec = format->nSamplesPerSec * format->nBlockAlign;
return format;
}