/* GStreamer * Copyright (C) 2003 Benjamin Otte * * gstaudioconvert.c: Convert audio to different audio formats automatically * * 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. */ /* Element-Checklist-Version: 5 */ /* * design decisions: * - audioconvert converts buffers in a set of supported caps. If it supports * a caps, it supports conversion from these caps to any other caps it * supports. (example: if it does A=>B and A=>C, it also does B=>C) * - audioconvert does not save state between buffers. Every incoming buffer is * converted and the converted buffer is pushed out. * conclusion: * audioconvert is not supposed to be a one-element-does-anything solution for * audio conversions. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include "plugin.h" GST_DEBUG_CATEGORY_STATIC (audio_convert_debug); #define GST_CAT_DEFAULT (audio_convert_debug) /*** DEFINITIONS **************************************************************/ #define GST_TYPE_AUDIO_CONVERT (gst_audio_convert_get_type()) #define GST_AUDIO_CONVERT(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_AUDIO_CONVERT,GstAudioConvert)) #define GST_AUDIO_CONVERT_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_AUDIO_CONVERT,GstAudioConvert)) #define GST_IS_AUDIO_CONVERT(obj) (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_AUDIO_CONVERT)) #define GST_IS_AUDIO_CONVERT_CLASS(obj) (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_AUDIO_CONVERT)) typedef struct _GstAudioConvert GstAudioConvert; typedef struct _GstAudioConvertCaps GstAudioConvertCaps; typedef struct _GstAudioConvertClass GstAudioConvertClass; /* this struct is a handy way of passing around all the caps info ... */ struct _GstAudioConvertCaps { /* general caps */ gboolean is_int; gint endianness; gint width; gint rate; gint channels; /* int audio caps */ gboolean sign; gint depth; /* float audio caps */ gint buffer_frames; }; struct _GstAudioConvert { GstElement element; /* pads */ GstPad *sink; GstPad *src; GstAudioConvertCaps srccaps; GstAudioConvertCaps sinkcaps; /* conversion functions */ GstBuffer *(*convert_internal) (GstAudioConvert * this, GstBuffer * buf); }; struct _GstAudioConvertClass { GstElementClass parent_class; }; static GstElementDetails audio_convert_details = { "Audio Conversion", "Filter/Converter/Audio", "Convert audio to different formats", "Benjamin Otte ", }; /* type functions */ static void gst_audio_convert_base_init (gpointer g_class); static void gst_audio_convert_class_init (GstAudioConvertClass * klass); static void gst_audio_convert_init (GstAudioConvert * audio_convert); /* gstreamer functions */ static void gst_audio_convert_chain (GstPad * pad, GstData * _data); static GstPadLinkReturn gst_audio_convert_link (GstPad * pad, const GstCaps * caps); static GstCaps *gst_audio_convert_fixate (GstPad * pad, const GstCaps * caps); static GstCaps *gst_audio_convert_getcaps (GstPad * pad); static GstElementStateReturn gst_audio_convert_change_state (GstElement * element); static GstBuffer *gst_audio_convert_buffer_to_default_format (GstAudioConvert * this, GstBuffer * buf); static GstBuffer *gst_audio_convert_buffer_from_default_format (GstAudioConvert * this, GstBuffer * buf); static GstBuffer *gst_audio_convert_channels (GstAudioConvert * this, GstBuffer * buf); /* AudioConvert signals and args */ enum { /* FILL ME */ LAST_SIGNAL }; enum { ARG_0, ARG_AGGRESSIVE, }; #define DEBUG_INIT(bla) \ GST_DEBUG_CATEGORY_INIT (audio_convert_debug, "audioconvert", 0, "audio conversion element"); GST_BOILERPLATE_FULL (GstAudioConvert, gst_audio_convert, GstElement, GST_TYPE_ELEMENT, DEBUG_INIT); /*** GSTREAMER PROTOTYPES *****************************************************/ #define STATIC_CAPS \ GST_STATIC_CAPS ( \ "audio/x-raw-int, " \ "rate = (int) [ 1, MAX ], " \ "channels = (int) [ 1, 2 ], " \ "endianness = (int) { LITTLE_ENDIAN, BIG_ENDIAN }, " \ "width = (int) { 8, 16, 32 }, " \ "depth = (int) [ 1, 32 ], " \ "signed = (boolean) { true, false }; " \ "audio/x-raw-float, " \ "rate = (int) [ 1, MAX ], " \ "channels = (int) [ 1, 2 ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) 32, " \ "buffer-frames = (int) [ 0, MAX ]" \ ) static GstStaticPadTemplate gst_audio_convert_src_template = GST_STATIC_PAD_TEMPLATE ("src", GST_PAD_SRC, GST_PAD_ALWAYS, STATIC_CAPS); static GstStaticPadTemplate gst_audio_convert_sink_template = GST_STATIC_PAD_TEMPLATE ("sink", GST_PAD_SINK, GST_PAD_ALWAYS, STATIC_CAPS); /*** TYPE FUNCTIONS ***********************************************************/ static void gst_audio_convert_base_init (gpointer g_class) { GstElementClass *element_class = GST_ELEMENT_CLASS (g_class); gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&gst_audio_convert_src_template)); gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&gst_audio_convert_sink_template)); gst_element_class_set_details (element_class, &audio_convert_details); } static void gst_audio_convert_class_init (GstAudioConvertClass * klass) { GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass); gstelement_class->change_state = gst_audio_convert_change_state; } static void gst_audio_convert_init (GstAudioConvert * this) { /* sinkpad */ this->sink = gst_pad_new_from_template (gst_static_pad_template_get (&gst_audio_convert_sink_template), "sink"); gst_pad_set_getcaps_function (this->sink, gst_audio_convert_getcaps); gst_pad_set_link_function (this->sink, gst_audio_convert_link); gst_pad_set_fixate_function (this->sink, gst_audio_convert_fixate); gst_element_add_pad (GST_ELEMENT (this), this->sink); /* srcpad */ this->src = gst_pad_new_from_template (gst_static_pad_template_get (&gst_audio_convert_src_template), "src"); gst_pad_set_getcaps_function (this->src, gst_audio_convert_getcaps); gst_pad_set_link_function (this->src, gst_audio_convert_link); gst_pad_set_fixate_function (this->src, gst_audio_convert_fixate); gst_element_add_pad (GST_ELEMENT (this), this->src); gst_pad_set_chain_function (this->sink, gst_audio_convert_chain); /* clear important variables */ this->convert_internal = NULL; } /*** GSTREAMER FUNCTIONS ******************************************************/ static void gst_audio_convert_chain (GstPad * pad, GstData * data) { GstBuffer *buf = GST_BUFFER (data); GstAudioConvert *this; g_return_if_fail (GST_IS_PAD (pad)); g_return_if_fail (buf != NULL); g_return_if_fail (GST_IS_AUDIO_CONVERT (GST_OBJECT_PARENT (pad))); this = GST_AUDIO_CONVERT (GST_OBJECT_PARENT (pad)); /* FIXME */ if (GST_IS_EVENT (buf)) { gst_pad_event_default (pad, GST_EVENT (buf)); return; } if (!gst_pad_is_negotiated (this->sink)) { GST_ELEMENT_ERROR (this, CORE, NEGOTIATION, (NULL), ("Sink pad (connected to %s:%s) not negotiated before chain function", GST_DEBUG_PAD_NAME (gst_pad_get_peer (this->sink)))); return; } if (!gst_pad_is_negotiated (this->src)) { gst_data_unref (data); return; } /** * Theory of operation: * - convert the format (endianness, signedness, width, depth) to * (G_BYTE_ORDER, TRUE, 32, 32) * - convert rate and channels * - convert back to output format */ buf = gst_audio_convert_buffer_to_default_format (this, buf); buf = gst_audio_convert_channels (this, buf); buf = gst_audio_convert_buffer_from_default_format (this, buf); gst_pad_push (this->src, GST_DATA (buf)); } /* this function is complicated now, but it will be unnecessary when we convert * rate. */ static GstCaps * gst_audio_convert_getcaps (GstPad * pad) { GstAudioConvert *this; GstPad *otherpad; GstStructure *structure; GstCaps *othercaps, *caps; const GstCaps *templcaps; int i, size; g_return_val_if_fail (GST_IS_PAD (pad), NULL); g_return_val_if_fail (GST_IS_AUDIO_CONVERT (GST_OBJECT_PARENT (pad)), NULL); this = GST_AUDIO_CONVERT (GST_OBJECT_PARENT (pad)); otherpad = (pad == this->src) ? this->sink : this->src; /* all we want to find out is the rate */ templcaps = gst_pad_get_pad_template_caps (pad); othercaps = gst_pad_get_allowed_caps (otherpad); size = gst_caps_get_size (othercaps); for (i = size - 1; i >= 0; i--) { structure = gst_caps_get_structure (othercaps, i); gst_structure_remove_field (structure, "channels"); gst_structure_remove_field (structure, "endianness"); gst_structure_remove_field (structure, "width"); gst_structure_remove_field (structure, "depth"); gst_structure_remove_field (structure, "signed"); structure = gst_structure_copy (structure); if (strcmp (gst_structure_get_name (structure), "audio/x-raw-int") == 0) { gst_structure_set_name (structure, "audio/x-raw-float"); if (pad == this->sink) { gst_structure_set (structure, "buffer-frames", GST_TYPE_INT_RANGE, 0, G_MAXINT, NULL); } else { gst_structure_set (structure, "buffer-frames", G_TYPE_INT, 0, NULL); } } else { gst_structure_set_name (structure, "audio/x-raw-int"); gst_structure_remove_field (structure, "buffer-frames"); } gst_caps_append_structure (othercaps, structure); } caps = gst_caps_intersect (othercaps, templcaps); gst_caps_free (othercaps); return caps; } static gboolean gst_audio_convert_parse_caps (const GstCaps * gst_caps, GstAudioConvertCaps * caps) { GstStructure *structure = gst_caps_get_structure (gst_caps, 0); g_return_val_if_fail (gst_caps_is_fixed (gst_caps), FALSE); g_return_val_if_fail (caps != NULL, FALSE); caps->endianness = G_BYTE_ORDER; caps->is_int = (strcmp (gst_structure_get_name (structure), "audio/x-raw-int") == 0); if (!gst_structure_get_int (structure, "channels", &caps->channels) || !gst_structure_get_int (structure, "width", &caps->width) || !gst_structure_get_int (structure, "rate", &caps->rate) || (caps->is_int && (!gst_structure_get_boolean (structure, "signed", &caps->sign) || !gst_structure_get_int (structure, "depth", &caps->depth) || (caps->width != 8 && !gst_structure_get_int (structure, "endianness", &caps->endianness)))) || (!caps->is_int && !gst_structure_get_int (structure, "buffer-frames", &caps->buffer_frames))) { GST_DEBUG ("could not get some values from structure"); return FALSE; } return TRUE; } static GstPadLinkReturn gst_audio_convert_link (GstPad * pad, const GstCaps * caps) { GstAudioConvert *this; GstPad *otherpad; GstAudioConvertCaps ac_caps, other_ac_caps; GstCaps *othercaps; guint i; GstPadLinkReturn ret; g_return_val_if_fail (GST_IS_PAD (pad), GST_PAD_LINK_REFUSED); g_return_val_if_fail (GST_IS_AUDIO_CONVERT (GST_OBJECT_PARENT (pad)), GST_PAD_LINK_REFUSED); this = GST_AUDIO_CONVERT (GST_OBJECT_PARENT (pad)); otherpad = (pad == this->src ? this->sink : this->src); /* negotiate sinkpad first */ if (pad == this->src && !gst_pad_is_negotiated (this->sink)) return GST_PAD_LINK_DELAYED; if (!gst_audio_convert_parse_caps (caps, &ac_caps)) return GST_PAD_LINK_REFUSED; /* ok, not those - try setting "any" caps */ othercaps = gst_pad_get_allowed_caps (otherpad); for (i = 0; i < gst_caps_get_size (othercaps); i++) { GstStructure *structure = gst_caps_get_structure (othercaps, i); gst_structure_set (structure, "rate", G_TYPE_INT, ac_caps.rate, NULL); if (strcmp (gst_structure_get_name (structure), "audio/x-raw-float") == 0) { if (!ac_caps.is_int) { gst_structure_set (structure, "buffer-frames", G_TYPE_INT, ac_caps.buffer_frames, NULL); } else { gst_structure_set (structure, "buffer-frames", G_TYPE_INT, 0, NULL); } } } if (this->sink == pad) { this->sinkcaps = ac_caps; } else { this->srccaps = ac_caps; } GST_LOG_OBJECT (this, "trying to set caps to %" GST_PTR_FORMAT, othercaps); ret = gst_pad_try_set_caps_nonfixed (otherpad, othercaps); gst_caps_free (othercaps); if (ret < GST_PAD_LINK_OK) return ret; /* woohoo, got it */ if (!gst_audio_convert_parse_caps (gst_pad_get_negotiated_caps (otherpad), &other_ac_caps)) { g_critical ("internal negotiation error"); return GST_PAD_LINK_REFUSED; } if (this->sink == pad) { this->srccaps = other_ac_caps; this->sinkcaps = ac_caps; } else { this->srccaps = ac_caps; this->sinkcaps = other_ac_caps; } GST_DEBUG_OBJECT (this, "negotiated pad to %" GST_PTR_FORMAT, caps); return GST_PAD_LINK_OK; } /* tries to fixate the given field of the given caps to the given int value */ gboolean _fixate_caps_to_int (GstCaps ** caps, const gchar * field, gint value) { GstCaps *try, *isect_lower, *isect_higher; gboolean ret = FALSE; guint i; /* First try to see if we can fixate by intersecting given caps with * simple audio caps with ranges starting/ending with value */ try = gst_caps_new_simple ("audio/x-raw-int", field, GST_TYPE_INT_RANGE, G_MININT, value - 1, NULL); gst_caps_append (try, gst_caps_new_simple ("audio/x-raw-float", field, GST_TYPE_INT_RANGE, G_MININT, value - 1, NULL)); isect_lower = gst_caps_intersect (*caps, try); gst_caps_free (try); if (!gst_caps_is_empty (isect_lower)) { try = gst_caps_new_simple ("audio/x-raw-int", field, GST_TYPE_INT_RANGE, value, G_MAXINT, NULL); gst_caps_append (try, gst_caps_new_simple ("audio/x-raw-float", field, GST_TYPE_INT_RANGE, value, G_MAXINT, NULL)); isect_higher = gst_caps_intersect (*caps, try); /* FIXME: why choose to end up with the higher range, and not the fixed * value ? */ if (!gst_caps_is_empty (isect_higher)) { gst_caps_free (*caps); *caps = isect_higher; ret = TRUE; } else { gst_caps_free (isect_higher); } } gst_caps_free (isect_lower); /* FIXME: why don't we already return here when ret == TRUE ? */ for (i = 0; i < gst_caps_get_size (*caps); i++) { GstStructure *structure = gst_caps_get_structure (*caps, i); if (gst_structure_has_field (structure, field)) ret |= gst_caps_structure_fixate_field_nearest_int (structure, field, value); } return ret; } static GstCaps * gst_audio_convert_fixate (GstPad * pad, const GstCaps * caps) { GstAudioConvert *this = GST_AUDIO_CONVERT (gst_object_get_parent (GST_OBJECT (pad))); GstPad *otherpad = (pad == this->sink ? this->src : this->sink); GstAudioConvertCaps ac_caps = (pad == this->sink ? this->srccaps : this->sinkcaps); GstCaps *copy; /* only fixate when we're proxying, so we don't fixate to some crap the other side doesn't want */ if (!GST_PAD_IS_NEGOTIATING (otherpad)) return NULL; copy = gst_caps_copy (caps); if (_fixate_caps_to_int (©, "channels", ac_caps.channels)) return copy; if (_fixate_caps_to_int (©, "width", ac_caps.is_int ? ac_caps.width : 16)) return copy; if (_fixate_caps_to_int (©, "depth", ac_caps.is_int ? ac_caps.depth : 16)) return copy; gst_caps_free (copy); return NULL; } static GstElementStateReturn gst_audio_convert_change_state (GstElement * element) { GstAudioConvert *this = GST_AUDIO_CONVERT (element); switch (GST_STATE_TRANSITION (element)) { case GST_STATE_PAUSED_TO_READY: this->convert_internal = NULL; break; default: break; } if (parent_class->change_state) { return parent_class->change_state (element); } else { return GST_STATE_SUCCESS; } } /* return a writable buffer of size which ideally is the same as before - You must unref the new buffer - The size of the old buffer is undefined after this operation */ static GstBuffer * gst_audio_convert_get_buffer (GstBuffer * buf, guint size) { GstBuffer *ret; GST_LOG ("new buffer of size %u requested. Current is: data: %p - size: %u - maxsize: %u", size, buf->data, buf->size, buf->maxsize); if (buf->maxsize >= size && gst_buffer_is_writable (buf)) { gst_buffer_ref (buf); buf->size = size; GST_LOG ("returning same buffer with adjusted values. data: %p - size: %u - maxsize: %u", buf->data, buf->size, buf->maxsize); return buf; } else { ret = gst_buffer_new_and_alloc (size); g_assert (ret); gst_buffer_stamp (ret, buf); GST_LOG ("returning new buffer. data: %p - size: %u - maxsize: %u", ret->data, ret->size, ret->maxsize); return ret; } } static inline guint8 GUINT8_IDENTITY (guint8 x) { return x; } static inline guint8 GINT8_IDENTITY (gint8 x) { return x; } #define CONVERT_TO(to, from, type, sign, endianness, LE_FUNC, BE_FUNC) \ G_STMT_START{ \ type value; \ memcpy (&value, from, sizeof (type)); \ from -= sizeof (type); \ value = (endianness == G_LITTLE_ENDIAN) ? LE_FUNC (value) : BE_FUNC (value); \ if (sign) { \ to = value; \ } else { \ to = (gint64) value - (1 << (sizeof (type) * 8 - 1)); \ } \ }G_STMT_END; static GstBuffer * gst_audio_convert_buffer_to_default_format (GstAudioConvert * this, GstBuffer * buf) { GstBuffer *ret; gint i, count; gint64 cur = 0; gint32 write; gint32 *dest; guint8 *src; if (this->sinkcaps.is_int) { if (this->sinkcaps.width == 32 && this->sinkcaps.depth == 32 && this->sinkcaps.endianness == G_BYTE_ORDER && this->sinkcaps.sign == TRUE) return buf; ret = gst_audio_convert_get_buffer (buf, buf->size * 32 / this->sinkcaps.width); count = ret->size / 4; src = buf->data + (count - 1) * (this->sinkcaps.width / 8); dest = (gint32 *) ret->data; for (i = count - 1; i >= 0; i--) { switch (this->sinkcaps.width) { case 8: if (this->sinkcaps.sign) { CONVERT_TO (cur, src, gint8, this->sinkcaps.sign, this->sinkcaps.endianness, GINT8_IDENTITY, GINT8_IDENTITY); } else { CONVERT_TO (cur, src, guint8, this->sinkcaps.sign, this->sinkcaps.endianness, GUINT8_IDENTITY, GUINT8_IDENTITY); } break; case 16: if (this->sinkcaps.sign) { CONVERT_TO (cur, src, gint16, this->sinkcaps.sign, this->sinkcaps.endianness, GINT16_FROM_LE, GINT16_FROM_BE); } else { CONVERT_TO (cur, src, guint16, this->sinkcaps.sign, this->sinkcaps.endianness, GUINT16_FROM_LE, GUINT16_FROM_BE); } break; case 32: if (this->sinkcaps.sign) { CONVERT_TO (cur, src, gint32, this->sinkcaps.sign, this->sinkcaps.endianness, GINT32_FROM_LE, GINT32_FROM_BE); } else { CONVERT_TO (cur, src, guint32, this->sinkcaps.sign, this->sinkcaps.endianness, GUINT32_FROM_LE, GUINT32_FROM_BE); } break; default: g_assert_not_reached (); } cur = cur * ((gint64) 1 << (32 - this->sinkcaps.depth)); cur = CLAMP (cur, -((gint64) 1 << 32), (gint64) 0x7FFFFFFF); write = cur; memcpy (&dest[i], &write, 4); } } else { /* float2int */ gfloat *in; gint32 *out; /* should just give the same buffer, unless it's not writable -- float is * already 32 bits */ ret = gst_audio_convert_get_buffer (buf, buf->size); in = (gfloat *) GST_BUFFER_DATA (buf); out = (gint32 *) GST_BUFFER_DATA (ret); for (i = buf->size / sizeof (float); i > 0; i--) { *in *= 2147483647.0f + .5; *out = (gint32) CLAMP ((gint64) * in, -2147483648ll, 2147483647ll); out++; in++; } } gst_buffer_unref (buf); return ret; } #define POPULATE(format, be_func, le_func) G_STMT_START{ \ format val; \ format* p = (format *) dest; \ int_value >>= (32 - this->srccaps.depth); \ if (this->srccaps.sign) { \ val = (format) int_value; \ } else { \ val = (format) int_value + (1 << (this->srccaps.depth - 1)); \ } \ switch (this->srccaps.endianness) { \ case G_LITTLE_ENDIAN: \ val = le_func (val); \ break; \ case G_BIG_ENDIAN: \ val = be_func (val); \ break; \ default: \ g_assert_not_reached (); \ }; \ *p = val; \ p ++; \ dest = (guint8 *) p; \ }G_STMT_END static GstBuffer * gst_audio_convert_buffer_from_default_format (GstAudioConvert * this, GstBuffer * buf) { GstBuffer *ret; guint count, i; gint32 *src; if (this->srccaps.is_int && this->srccaps.width == 32 && this->srccaps.depth == 32 && this->srccaps.endianness == G_BYTE_ORDER && this->srccaps.sign == TRUE) return buf; if (this->srccaps.is_int) { guint8 *dest; count = buf->size / 4; /* size is undefined after gst_audio_convert_get_buffer! */ ret = gst_audio_convert_get_buffer (buf, buf->size * this->srccaps.width / 32); dest = ret->data; src = (gint32 *) buf->data; for (i = 0; i < count; i++) { gint32 int_value = *src; src++; switch (this->srccaps.width) { case 8: if (this->srccaps.sign) { POPULATE (gint8, GINT8_IDENTITY, GINT8_IDENTITY); } else { POPULATE (guint8, GUINT8_IDENTITY, GUINT8_IDENTITY); } break; case 16: if (this->srccaps.sign) { POPULATE (gint16, GINT16_TO_BE, GINT16_TO_LE); } else { POPULATE (guint16, GUINT16_TO_BE, GUINT16_TO_LE); } break; case 32: if (this->srccaps.sign) { POPULATE (gint32, GINT32_TO_BE, GINT32_TO_LE); } else { POPULATE (guint32, GUINT32_TO_BE, GUINT32_TO_LE); } break; default: g_assert_not_reached (); } } } else { gfloat *dest; /* 1 / (2^31-1) * i */ #define INT2FLOAT(i) (4.6566128752457969e-10 * ((gfloat)i)) count = buf->size / 4; /* size is undefined after gst_audio_convert_get_buffer! */ ret = gst_audio_convert_get_buffer (buf, buf->size * this->srccaps.width / 32); dest = (gfloat *) ret->data; src = (gint32 *) buf->data; for (i = 0; i < count; i++) { *dest = (4.6566128752457969e-10 * ((gfloat) * src)); dest++; src++; } } gst_buffer_unref (buf); return ret; } static GstBuffer * gst_audio_convert_channels (GstAudioConvert * this, GstBuffer * buf) { GstBuffer *ret; gint i, count; gint32 *src, *dest; if (this->sinkcaps.channels == this->srccaps.channels) return buf; count = GST_BUFFER_SIZE (buf) / 4 / this->sinkcaps.channels; ret = gst_audio_convert_get_buffer (buf, count * 4 * this->srccaps.channels); src = (gint32 *) GST_BUFFER_DATA (buf); dest = (gint32 *) GST_BUFFER_DATA (ret); if (this->sinkcaps.channels > this->srccaps.channels) { for (i = 0; i < count; i++) { *dest = *src >> 1; src++; *dest += (*src >> 1) + (*src & 1); src++; dest++; } } else { for (i = count - 1; i >= 0; i--) { dest[2 * i] = dest[2 * i + 1] = src[i]; } } gst_buffer_unref (buf); return ret; }