/* * GStreamer * Copyright (C) 2012-2013 Fluendo S.A. * Authors: Josep Torra Vallès * Andoni Morales Alastruey * * 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., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. * */ #include "gstosxcoreaudio.h" #include "gstosxcoreaudiocommon.h" GST_DEBUG_CATEGORY_STATIC (osx_audio_debug); #define GST_CAT_DEFAULT osx_audio_debug G_DEFINE_TYPE (GstCoreAudio, gst_core_audio, G_TYPE_OBJECT); #ifdef HAVE_IOS #include "gstosxcoreaudioremoteio.c" #else #include "gstosxcoreaudiohal.c" #endif static void gst_core_audio_class_init (GstCoreAudioClass * klass) { } static void gst_core_audio_init (GstCoreAudio * core_audio) { core_audio->is_passthrough = FALSE; core_audio->device_id = kAudioDeviceUnknown; core_audio->is_src = FALSE; core_audio->audiounit = NULL; core_audio->cached_caps = NULL; core_audio->cached_caps_valid = FALSE; #ifndef HAVE_IOS core_audio->hog_pid = -1; core_audio->disabled_mixing = FALSE; #endif } static gboolean _is_outer_scope (AudioUnitScope scope, AudioUnitElement element) { return (scope == kAudioUnitScope_Input && element == 1) || (scope == kAudioUnitScope_Output && element == 0); } static void _audio_unit_property_listener (void *inRefCon, AudioUnit inUnit, AudioUnitPropertyID inID, AudioUnitScope inScope, AudioUnitElement inElement) { GstCoreAudio *core_audio; core_audio = GST_CORE_AUDIO (inRefCon); g_assert (inUnit == core_audio->audiounit); switch (inID) { case kAudioUnitProperty_AudioChannelLayout: case kAudioUnitProperty_StreamFormat: if (_is_outer_scope (inScope, inElement)) { /* We don't push gst_event_new_caps here (for src), * nor gst_event_new_reconfigure (for sink), since Core Audio continues * to happily function with the old format, doing conversion/resampling * as needed. * This merely "refreshes" our PREFERRED caps. */ /* This function is called either from a Core Audio thread * or as a result of a Core Audio API (e.g. AudioUnitInitialize) * from our own thread. In the latter case, osxbuf can be * already locked (GStreamer's mutex is not recursive). * For this reason we use a boolean flag instead of nullifying * cached_caps. */ core_audio->cached_caps_valid = FALSE; } break; } } /************************** * Public API * *************************/ GstCoreAudio * gst_core_audio_new (GstObject * osxbuf) { GstCoreAudio *core_audio; core_audio = g_object_new (GST_TYPE_CORE_AUDIO, NULL); core_audio->osxbuf = osxbuf; core_audio->cached_caps = NULL; return core_audio; } gboolean gst_core_audio_close (GstCoreAudio * core_audio) { OSStatus status; /* Uninitialize the AudioUnit */ status = AudioUnitUninitialize (core_audio->audiounit); if (status) { GST_ERROR_OBJECT (core_audio, "Failed to uninitialize AudioUnit: %d", (int) status); return FALSE; } AudioUnitRemovePropertyListenerWithUserData (core_audio->audiounit, kAudioUnitProperty_AudioChannelLayout, _audio_unit_property_listener, core_audio); AudioUnitRemovePropertyListenerWithUserData (core_audio->audiounit, kAudioUnitProperty_StreamFormat, _audio_unit_property_listener, core_audio); /* core_audio->osxbuf is already locked at this point */ core_audio->cached_caps_valid = FALSE; gst_caps_replace (&core_audio->cached_caps, NULL); AudioComponentInstanceDispose (core_audio->audiounit); core_audio->audiounit = NULL; return TRUE; } gboolean gst_core_audio_open (GstCoreAudio * core_audio) { OSStatus status; /* core_audio->osxbuf is already locked at this point */ core_audio->cached_caps_valid = FALSE; gst_caps_replace (&core_audio->cached_caps, NULL); if (!gst_core_audio_open_impl (core_audio)) return FALSE; /* Add property listener */ status = AudioUnitAddPropertyListener (core_audio->audiounit, kAudioUnitProperty_AudioChannelLayout, _audio_unit_property_listener, core_audio); if (status != noErr) { GST_ERROR_OBJECT (core_audio, "Failed to add audio channel layout property " "listener for AudioUnit: %d", (int) status); } status = AudioUnitAddPropertyListener (core_audio->audiounit, kAudioUnitProperty_StreamFormat, _audio_unit_property_listener, core_audio); if (status != noErr) { GST_ERROR_OBJECT (core_audio, "Failed to add stream format property " "listener for AudioUnit: %d", (int) status); } /* Initialize the AudioUnit. We keep the audio unit initialized early so that * we can probe the underlying device. */ status = AudioUnitInitialize (core_audio->audiounit); if (status) { GST_ERROR_OBJECT (core_audio, "Failed to initialize AudioUnit: %d", (int) status); return FALSE; } return TRUE; } gboolean gst_core_audio_start_processing (GstCoreAudio * core_audio) { return gst_core_audio_start_processing_impl (core_audio); } gboolean gst_core_audio_pause_processing (GstCoreAudio * core_audio) { return gst_core_audio_pause_processing_impl (core_audio); } gboolean gst_core_audio_stop_processing (GstCoreAudio * core_audio) { return gst_core_audio_stop_processing_impl (core_audio); } gboolean gst_core_audio_get_samples_and_latency (GstCoreAudio * core_audio, gdouble rate, guint * samples, gdouble * latency) { return gst_core_audio_get_samples_and_latency_impl (core_audio, rate, samples, latency); } gboolean gst_core_audio_initialize (GstCoreAudio * core_audio, AudioStreamBasicDescription format, GstCaps * caps, gboolean is_passthrough) { guint32 frame_size; GST_DEBUG_OBJECT (core_audio, "Initializing: passthrough:%d caps:%" GST_PTR_FORMAT, is_passthrough, caps); if (!gst_core_audio_initialize_impl (core_audio, format, caps, is_passthrough, &frame_size)) { return FALSE; } if (core_audio->is_src) { /* create AudioBufferList needed for recording */ core_audio->recBufferSize = frame_size * format.mBytesPerFrame; core_audio->recBufferList = buffer_list_alloc (format.mChannelsPerFrame, core_audio->recBufferSize, /* Currently always TRUE (i.e. interleaved) */ !(format.mFormatFlags & kAudioFormatFlagIsNonInterleaved)); } return TRUE; } void gst_core_audio_uninitialize (GstCoreAudio * core_audio) { buffer_list_free (core_audio->recBufferList); core_audio->recBufferList = NULL; } void gst_core_audio_set_volume (GstCoreAudio * core_audio, gfloat volume) { AudioUnitSetParameter (core_audio->audiounit, kHALOutputParam_Volume, kAudioUnitScope_Global, 0, (float) volume, 0); } gboolean gst_core_audio_select_device (GstCoreAudio * core_audio) { return gst_core_audio_select_device_impl (core_audio); } void gst_core_audio_init_debug (void) { GST_DEBUG_CATEGORY_INIT (osx_audio_debug, "osxaudio", 0, "OSX Audio Elements"); } gboolean gst_core_audio_audio_device_is_spdif_avail (AudioDeviceID device_id) { return gst_core_audio_audio_device_is_spdif_avail_impl (device_id); } /* Does the channel have at least one positioned channel? * (GStreamer is more strict than Core Audio, in that it requires either * all channels to be positioned, or all unpositioned.) */ static gboolean _is_core_audio_layout_positioned (AudioChannelLayout * layout) { guint i; g_assert (layout->mChannelLayoutTag == kAudioChannelLayoutTag_UseChannelDescriptions); for (i = 0; i < layout->mNumberChannelDescriptions; ++i) { GstAudioChannelPosition p = gst_core_audio_channel_label_to_gst (layout->mChannelDescriptions[i].mChannelLabel, i, FALSE); if (p >= 0) /* not special positition */ return TRUE; } return FALSE; } static void _core_audio_parse_channel_descriptions (AudioChannelLayout * layout, guint * channels, guint64 * channel_mask, GstAudioChannelPosition * pos) { gboolean positioned; guint i; g_assert (layout->mChannelLayoutTag == kAudioChannelLayoutTag_UseChannelDescriptions); positioned = _is_core_audio_layout_positioned (layout); *channel_mask = 0; /* Go over all labels, either taking only positioned or only * unpositioned channels, up to GST_OSX_AUDIO_MAX_CHANNEL channels. * * The resulting 'pos' array will contain either: * - only regular (>= 0) positions * - only GST_AUDIO_CHANNEL_POSITION_NONE positions * in a compact form, skipping over all unsupported positions. */ *channels = 0; for (i = 0; i < layout->mNumberChannelDescriptions; ++i) { GstAudioChannelPosition p = gst_core_audio_channel_label_to_gst (layout->mChannelDescriptions[i].mChannelLabel, i, TRUE); /* In positioned layouts, skip all unpositioned channels. * In unpositioned layouts, skip all invalid channels. */ if ((positioned && p >= 0) || (!positioned && p == GST_AUDIO_CHANNEL_POSITION_NONE)) { if (pos) pos[*channels] = p; *channel_mask |= G_GUINT64_CONSTANT (1) << p; ++(*channels); if (*channels == GST_OSX_AUDIO_MAX_CHANNEL) break; /* not to overflow */ } } } gboolean gst_core_audio_parse_channel_layout (AudioChannelLayout * layout, guint * channels, guint64 * channel_mask, GstAudioChannelPosition * pos) { g_assert (channels != NULL); g_assert (channel_mask != NULL); g_assert (layout != NULL); if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_UseChannelDescriptions) { switch (layout->mNumberChannelDescriptions) { case 0: if (pos) pos[0] = GST_AUDIO_CHANNEL_POSITION_NONE; *channels = 0; *channel_mask = 0; return TRUE; case 1: if (pos) pos[0] = GST_AUDIO_CHANNEL_POSITION_MONO; *channels = 1; *channel_mask = 0; return TRUE; case 2: if (pos) { pos[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT; pos[1] = GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT; } *channels = 2; *channel_mask = GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT); return TRUE; default: _core_audio_parse_channel_descriptions (layout, channels, channel_mask, pos); return TRUE; } } else if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_Mono) { if (pos) pos[0] = GST_AUDIO_CHANNEL_POSITION_MONO; *channels = 1; *channel_mask = 0; return TRUE; } else if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_Stereo || layout->mChannelLayoutTag == kAudioChannelLayoutTag_StereoHeadphones || layout->mChannelLayoutTag == kAudioChannelLayoutTag_Binaural) { if (pos) { pos[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT; pos[1] = GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT; } *channels = 2; *channel_mask = GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT); return TRUE; } else if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_Quadraphonic) { if (pos) { pos[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT; pos[1] = GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT; pos[2] = GST_AUDIO_CHANNEL_POSITION_SURROUND_LEFT; pos[3] = GST_AUDIO_CHANNEL_POSITION_SURROUND_RIGHT; } *channels = 4; *channel_mask = GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (SURROUND_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (SURROUND_RIGHT); return TRUE; } else if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_Pentagonal) { if (pos) { pos[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT; pos[1] = GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT; pos[2] = GST_AUDIO_CHANNEL_POSITION_SURROUND_LEFT; pos[3] = GST_AUDIO_CHANNEL_POSITION_SURROUND_RIGHT; pos[4] = GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER; } *channels = 5; *channel_mask = GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (SURROUND_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (SURROUND_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_CENTER); return TRUE; } else if (layout->mChannelLayoutTag == kAudioChannelLayoutTag_Cube) { if (pos) { pos[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT; pos[1] = GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT; pos[2] = GST_AUDIO_CHANNEL_POSITION_REAR_LEFT; pos[3] = GST_AUDIO_CHANNEL_POSITION_REAR_RIGHT; pos[4] = GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_LEFT; pos[5] = GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_RIGHT; pos[6] = GST_AUDIO_CHANNEL_POSITION_TOP_REAR_LEFT; pos[7] = GST_AUDIO_CHANNEL_POSITION_TOP_REAR_RIGHT; } *channels = 8; *channel_mask = GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (REAR_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (REAR_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (TOP_FRONT_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (TOP_FRONT_RIGHT) | GST_AUDIO_CHANNEL_POSITION_MASK (TOP_REAR_LEFT) | GST_AUDIO_CHANNEL_POSITION_MASK (TOP_REAR_RIGHT); return TRUE; } else { GST_WARNING ("AudioChannelLayoutTag: %u not yet supported", layout->mChannelLayoutTag); *channels = 0; *channel_mask = 0; return FALSE; } } /* Converts an AudioStreamBasicDescription to preferred caps. * * These caps will indicate the AU element's canonical format, which won't * make Core Audio resample nor convert. * * NOTE ON MULTI-CHANNEL AUDIO: * * If layout is not NULL, resulting caps will only include the subset * of channels supported by GStreamer. If the Core Audio layout contained * ANY positioned channels, then ONLY positioned channels will be included * in the resulting caps. Otherwise, resulting caps will be unpositioned, * and include only unpositioned channels. * (Channels with unsupported AudioChannelLabel will be skipped either way.) * * Naturally, the number of channels indicated by 'channels' can be lower * than the AU element's total number of channels. */ GstCaps * gst_core_audio_asbd_to_caps (AudioStreamBasicDescription * asbd, AudioChannelLayout * layout) { GstAudioInfo info; GstAudioFormat format = GST_AUDIO_FORMAT_UNKNOWN; guint rate, channels, bps, endianness; guint64 channel_mask; gboolean sign, interleaved; GstAudioChannelPosition pos[GST_OSX_AUDIO_MAX_CHANNEL]; if (asbd->mFormatID != kAudioFormatLinearPCM) { GST_WARNING ("Only linear PCM is supported"); goto error; } if (!(asbd->mFormatFlags & kAudioFormatFlagIsPacked)) { GST_WARNING ("Only packed formats supported"); goto error; } if (asbd->mFormatFlags & kLinearPCMFormatFlagsSampleFractionMask) { GST_WARNING ("Fixed point audio is unsupported"); goto error; } rate = asbd->mSampleRate; if (rate == kAudioStreamAnyRate) { GST_WARNING ("No sample rate"); goto error; } bps = asbd->mBitsPerChannel; endianness = asbd->mFormatFlags & kAudioFormatFlagIsBigEndian ? G_BIG_ENDIAN : G_LITTLE_ENDIAN; sign = asbd->mFormatID & kAudioFormatFlagIsSignedInteger ? TRUE : FALSE; interleaved = asbd->mFormatFlags & kAudioFormatFlagIsNonInterleaved ? TRUE : FALSE; if (asbd->mFormatFlags & kAudioFormatFlagIsFloat) { if (bps == 32) { if (endianness == G_LITTLE_ENDIAN) format = GST_AUDIO_FORMAT_F32LE; else format = GST_AUDIO_FORMAT_F32BE; } else if (bps == 64) { if (endianness == G_LITTLE_ENDIAN) format = GST_AUDIO_FORMAT_F64LE; else format = GST_AUDIO_FORMAT_F64BE; } } else { format = gst_audio_format_build_integer (sign, endianness, bps, bps); } if (format == GST_AUDIO_FORMAT_UNKNOWN) { GST_WARNING ("Unsupported sample format"); goto error; } if (layout) { if (!gst_core_audio_parse_channel_layout (layout, &channels, &channel_mask, pos)) { GST_WARNING ("Failed to parse channel layout, best effort channels layout mapping will be used"); layout = NULL; } } if (layout) { /* The AU can have arbitrary channel order, but we're using GstAudioInfo * which supports only the GStreamer channel order. * Also, we're eventually producing caps, which only have channel-mask * (whose implied order is the GStreamer channel order). */ gst_audio_channel_positions_to_valid_order (pos, channels); gst_audio_info_set_format (&info, format, rate, channels, pos); } else { channels = MIN (asbd->mChannelsPerFrame, GST_OSX_AUDIO_MAX_CHANNEL); gst_audio_info_set_format (&info, format, rate, channels, NULL); } return gst_audio_info_to_caps (&info); error: return NULL; } static gboolean _core_audio_get_property (GstCoreAudio * core_audio, gboolean outer, AudioUnitPropertyID inID, void *inData, UInt32 * inDataSize) { OSStatus status; AudioUnitScope scope; AudioUnitElement element; scope = outer ? CORE_AUDIO_OUTER_SCOPE (core_audio) : CORE_AUDIO_INNER_SCOPE (core_audio); element = CORE_AUDIO_ELEMENT (core_audio); status = AudioUnitGetProperty (core_audio->audiounit, inID, scope, element, inData, inDataSize); return status == noErr; } static gboolean _core_audio_get_stream_format (GstCoreAudio * core_audio, AudioStreamBasicDescription * asbd, gboolean outer) { UInt32 size; size = sizeof (AudioStreamBasicDescription); return _core_audio_get_property (core_audio, outer, kAudioUnitProperty_StreamFormat, asbd, &size); } AudioChannelLayout * gst_core_audio_get_channel_layout (GstCoreAudio * core_audio, gboolean outer) { UInt32 size; AudioChannelLayout *layout; if (core_audio->is_src) { GST_WARNING_OBJECT (core_audio, "gst_core_audio_get_channel_layout not supported on source."); return NULL; } if (!_core_audio_get_property (core_audio, outer, kAudioUnitProperty_AudioChannelLayout, NULL, &size)) { GST_WARNING_OBJECT (core_audio, "unable to get channel layout"); return NULL; } layout = g_malloc (size); if (!_core_audio_get_property (core_audio, outer, kAudioUnitProperty_AudioChannelLayout, layout, &size)) { GST_WARNING_OBJECT (core_audio, "unable to get channel layout"); g_free (layout); return NULL; } return layout; } #define STEREO_CHANNEL_MASK \ (GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_LEFT) | \ GST_AUDIO_CHANNEL_POSITION_MASK (FRONT_RIGHT)) GstCaps * gst_core_audio_probe_caps (GstCoreAudio * core_audio, GstCaps * in_caps) { guint i, channels; gboolean spdif_allowed; AudioChannelLayout *layout; AudioStreamBasicDescription outer_asbd; gboolean got_outer_asbd; GstCaps *caps = NULL; guint64 channel_mask; /* Get the ASBD of the outer scope (i.e. input scope of Input, * output scope of Output). * This ASBD indicates the hardware format. */ got_outer_asbd = _core_audio_get_stream_format (core_audio, &outer_asbd, TRUE); /* Collect info about the HW capabilites and preferences */ spdif_allowed = gst_core_audio_audio_device_is_spdif_avail (core_audio->device_id); if (!core_audio->is_src) layout = gst_core_audio_get_channel_layout (core_audio, TRUE); else layout = NULL; /* no supported for sources */ GST_DEBUG_OBJECT (core_audio, "Selected device ID: %u SPDIF allowed: %d", (unsigned) core_audio->device_id, spdif_allowed); if (layout) { if (!gst_core_audio_parse_channel_layout (layout, &channels, &channel_mask, NULL)) { GST_WARNING_OBJECT (core_audio, "Failed to parse channel layout"); channel_mask = 0; } /* If available, start with the preferred caps. */ if (got_outer_asbd) caps = gst_core_audio_asbd_to_caps (&outer_asbd, layout); g_free (layout); } else if (got_outer_asbd) { channels = outer_asbd.mChannelsPerFrame; channel_mask = 0; /* If available, start with the preferred caps */ caps = gst_core_audio_asbd_to_caps (&outer_asbd, NULL); } else { GST_ERROR_OBJECT (core_audio, "Unable to get any information about hardware"); return NULL; } /* Append the allowed subset based on the template caps */ if (!caps) caps = gst_caps_new_empty (); for (i = 0; i < gst_caps_get_size (in_caps); i++) { GstStructure *in_s; in_s = gst_caps_get_structure (in_caps, i); if (gst_structure_has_name (in_s, "audio/x-ac3") || gst_structure_has_name (in_s, "audio/x-dts")) { if (spdif_allowed) { gst_caps_append_structure (caps, gst_structure_copy (in_s)); } } else { GstStructure *out_s; out_s = gst_structure_copy (in_s); gst_structure_set (out_s, "channels", G_TYPE_INT, channels, NULL); if (channel_mask != 0) { /* positioned layout */ gst_structure_set (out_s, "channel-mask", GST_TYPE_BITMASK, channel_mask, NULL); } else { /* unpositioned layout */ gst_structure_remove_field (out_s, "channel-mask"); } #ifndef HAVE_IOS if (core_audio->is_src && got_outer_asbd && outer_asbd.mSampleRate != kAudioStreamAnyRate) { /* According to Core Audio engineer, AUHAL does not support sample rate conversion. * on sources. Therefore, we fixate the sample rate. * * "You definitely cannot do rate conversion as part of getting input from AUHAL. * That's the most common cause of those "cannot do in current context" errors." * http://lists.apple.com/archives/coreaudio-api/2006/Sep/msg00088.html */ gst_structure_set (out_s, "rate", G_TYPE_INT, (gint) outer_asbd.mSampleRate, NULL); } #endif /* Special cases for upmixing and downmixing. * Other than that, the AUs don't upmix or downmix multi-channel audio, * e.g. if you push 5.1-surround audio to a stereo configuration, * the left and right channels will be played accordingly, * and the rest will be dropped. */ if (channels == 1) { /* If have mono, then also offer stereo since CoreAudio downmixes to it */ GstStructure *stereo = gst_structure_copy (out_s); gst_structure_remove_field (out_s, "channel-mask"); gst_structure_set (stereo, "channels", G_TYPE_INT, 2, "channel-mask", GST_TYPE_BITMASK, STEREO_CHANNEL_MASK, NULL); gst_caps_append_structure (caps, stereo); gst_caps_append_structure (caps, out_s); } else if (channels == 2 && (channel_mask == 0 || channel_mask == STEREO_CHANNEL_MASK)) { /* If have stereo channels, then also offer mono since CoreAudio * upmixes it. */ GstStructure *mono = gst_structure_copy (out_s); gst_structure_set (mono, "channels", G_TYPE_INT, 1, NULL); gst_structure_remove_field (mono, "channel-mask"); gst_structure_set (out_s, "channel-mask", GST_TYPE_BITMASK, STEREO_CHANNEL_MASK, NULL); gst_caps_append_structure (caps, out_s); gst_caps_append_structure (caps, mono); } else { /* Otherwhise just add the caps */ gst_caps_append_structure (caps, out_s); } } } GST_DEBUG_OBJECT (core_audio, "Probed caps:%" GST_PTR_FORMAT, caps); return caps; }