ec1e20ffe5
This is the same code that is in decklinkaudiosrc, audioringbuffer, audiomixer and various other places. Have it once instead of copying it everywhere. https://bugzilla.gnome.org/show_bug.cgi?id=787560
378 lines
10 KiB
C
378 lines
10 KiB
C
/* GStreamer
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* Copyright (C) 2017 Sebastian Dröge <sebastian@centricular.com>
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*
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* gstaudiostreamalign.h:
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "gstaudiostreamalign.h"
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/**
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* SECTION:gstaudiostreamalign
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* @title: GstAudioStreamAlign
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* @short_description: Helper object for tracking audio stream alignment and discontinuities
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*
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* #GstAudioStreamAlign provides a helper object that helps tracking audio
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* stream alignment and discontinuities, and detects discontinuities if
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* possible.
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*
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* See gst_audio_stream_align_new() for a description of its parameters and
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* gst_audio_stream_align_process() for the details of the processing.
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*/
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G_DEFINE_BOXED_TYPE (GstAudioStreamAlign, gst_audio_stream_align,
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(GBoxedCopyFunc) gst_audio_stream_align_copy,
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(GBoxedFreeFunc) gst_audio_stream_align_free);
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struct _GstAudioStreamAlign
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{
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gint rate;
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GstClockTime alignment_threshold;
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GstClockTime discont_wait;
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/* counter to keep track of timestamps */
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guint64 next_offset;
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/* Last time we noticed a discont */
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GstClockTime discont_time;
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};
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/**
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* gst_audio_stream_align_new:
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* @rate: a sample rate
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* @alignment_threshold: a alignment threshold in nanoseconds
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* @discont_wait: discont wait in nanoseconds
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*
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* Allocate a new #GstAudioStreamAlign with the given configuration. All
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* processing happens according to sample rate @rate, until
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* gst_audio_discont_wait_set_rate() is called with a new @rate.
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*
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* @alignment_threshold gives the tolerance in nanoseconds after which a
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* timestamp difference is considered a discontinuity. Once detected,
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* @discont_wait nanoseconds have to pass without going below the threshold
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* again until the output buffer is marked as a discontinuity. These can later
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* be re-configured with gst_audio_stream_align_set_alignment_threshold() and
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* gst_audio_stream_align_set_discont_wait().
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*
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* Returns: a new #GstAudioStreamAlign. free with gst_audio_stream_align_free().
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*
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* Since: 1.14
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*/
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GstAudioStreamAlign *
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gst_audio_stream_align_new (gint rate, GstClockTime alignment_threshold,
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GstClockTime discont_wait)
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{
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GstAudioStreamAlign *align;
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g_return_val_if_fail (rate > 0, NULL);
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align = g_new0 (GstAudioStreamAlign, 1);
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align->rate = rate;
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align->alignment_threshold = alignment_threshold;
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align->discont_wait = discont_wait;
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gst_audio_stream_align_mark_discont (align);
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return align;
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}
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/**
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* gst_audio_stream_align_copy:
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* @align: a #GstAudioStreamAlign
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*
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* Copy a GstAudioStreamAlign structure.
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*
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* Returns: a new #GstAudioStreamAlign. free with gst_audio_stream_align_free.
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*
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* Since: 1.14
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*/
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GstAudioStreamAlign *
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gst_audio_stream_align_copy (const GstAudioStreamAlign * align)
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{
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GstAudioStreamAlign *copy;
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g_return_val_if_fail (align != NULL, NULL);
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copy = g_new0 (GstAudioStreamAlign, 1);
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*copy = *align;
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return copy;
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}
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/**
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* gst_audio_stream_align_free:
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* @align: a #GstAudioStreamAlign
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*
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* Free a GstAudioStreamAlign structure previously allocated with gst_audio_stream_align_new()
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* or gst_audio_stream_align_copy().
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*
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* Since: 1.14
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*/
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void
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gst_audio_stream_align_free (GstAudioStreamAlign * align)
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{
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g_return_if_fail (align != NULL);
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g_free (align);
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}
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/**
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* gst_audio_discont_set_rate:
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* @align: a #GstAudioStreamAlign
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* @rate: a new sample rate
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*
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* Sets @rate as new sample rate for the following processing. If the sample
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* rate differs this implicitely marks the next data as discontinuous.
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*
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* Since: 1.14
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*/
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void
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gst_audio_stream_align_set_rate (GstAudioStreamAlign * align, gint rate)
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{
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g_return_if_fail (align != NULL);
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g_return_if_fail (rate > 0);
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if (align->rate == rate)
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return;
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align->rate = rate;
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gst_audio_stream_align_mark_discont (align);
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}
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/**
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* gst_audio_discont_get_rate:
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* @align: a #GstAudioStreamAlign
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*
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* Gets the currently configured sample rate.
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*
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* Returns: The currently configured sample rate
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*
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* Since: 1.14
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*/
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gint
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gst_audio_stream_align_get_rate (GstAudioStreamAlign * align)
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{
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g_return_val_if_fail (align != NULL, 0);
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return align->rate;
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}
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/**
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* gst_audio_discont_set_alignment_threshold:
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* @align: a #GstAudioStreamAlign
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* @alignment_treshold: a new alignment threshold
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*
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* Sets @alignment_treshold as new alignment threshold for the following processing.
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*
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* Since: 1.14
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*/
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void
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gst_audio_stream_align_set_alignment_threshold (GstAudioStreamAlign *
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align, GstClockTime alignment_threshold)
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{
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g_return_if_fail (align != NULL);
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align->alignment_threshold = alignment_threshold;
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}
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/**
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* gst_audio_discont_get_alignment_threshold:
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* @align: a #GstAudioStreamAlign
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*
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* Gets the currently configured alignment threshold.
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*
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* Returns: The currently configured alignment threshold
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*
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* Since: 1.14
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*/
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GstClockTime
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gst_audio_stream_align_get_alignment_threshold (GstAudioStreamAlign * align)
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{
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g_return_val_if_fail (align != NULL, 0);
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return align->alignment_threshold;
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}
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/**
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* gst_audio_discont_set_discont_wait:
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* @align: a #GstAudioStreamAlign
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* @alignment_treshold: a new discont wait
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*
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* Sets @alignment_treshold as new discont wait for the following processing.
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*
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* Since: 1.14
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*/
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void
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gst_audio_stream_align_set_discont_wait (GstAudioStreamAlign * align,
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GstClockTime discont_wait)
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{
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g_return_if_fail (align != NULL);
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align->discont_wait = discont_wait;
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}
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/**
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* gst_audio_discont_get_discont_wait:
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* @align: a #GstAudioStreamAlign
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*
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* Gets the currently configured discont wait.
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*
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* Returns: The currently configured discont wait
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*
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* Since: 1.14
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*/
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GstClockTime
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gst_audio_stream_align_get_discont_wait (GstAudioStreamAlign * align)
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{
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g_return_val_if_fail (align != NULL, 0);
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return align->discont_wait;
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}
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/**
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* gst_audio_stream_align_mark_discont:
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* @align: a #GstAudioStreamAlign
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*
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* Marks the next buffer as discontinuous and resets timestamp tracking.
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*
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* Since: 1.14
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*/
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void
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gst_audio_stream_align_mark_discont (GstAudioStreamAlign * align)
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{
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g_return_if_fail (align != NULL);
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align->next_offset = -1;
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align->discont_time = GST_CLOCK_TIME_NONE;
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}
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/**
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* gst_audio_stream_align_process:
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* @align: a #GstAudioStreamAlign
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* @discont: if this data is considered to be discontinuous
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* @timestamp: a #GstClockTime of the start of the data
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* @n_samples: number of samples to process
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* @out_timestamp: (out): output timestamp of the data
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* @out_duration: (out): output duration of the data
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* @out_sample_position: (out): output sample position of the start of the data
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*
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* Processes data with @timestamp and @n_samples, and returns the output
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* timestamp, duration and sample position together with a boolean to signal
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* whether a discontinuity was detected or not. All non-discontinuous data
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* will have perfect timestamps and durations.
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*
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* A discontinuity is detected once the difference between the actual
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* timestamp and the timestamp calculated from the sample count since the last
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* discontinuity differs by more than the alignment threshold for a duration
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* longer than discont wait.
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*
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* Returns: %TRUE if a discontinuity was detected, %FALSE otherwise.
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*
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* Since: 1.14
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*/
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gboolean
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gst_audio_stream_align_process (GstAudioStreamAlign * align,
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gboolean discont, GstClockTime timestamp, guint n_samples,
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GstClockTime * out_timestamp, GstClockTime * out_duration,
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guint64 * out_sample_position)
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{
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GstClockTime start_time, end_time, duration;
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guint64 start_offset, end_offset;
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g_return_val_if_fail (align != NULL, FALSE);
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start_time = timestamp;
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start_offset = gst_util_uint64_scale (start_time, align->rate, GST_SECOND);
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end_offset = start_offset + n_samples;
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end_time = gst_util_uint64_scale_int (end_offset, GST_SECOND, align->rate);
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duration = end_time - start_time;
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if (align->next_offset == (guint64) - 1 || discont) {
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discont = TRUE;
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} else {
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guint64 diff, max_sample_diff;
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/* Check discont */
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if (start_offset <= align->next_offset)
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diff = align->next_offset - start_offset;
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else
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diff = start_offset - align->next_offset;
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max_sample_diff =
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gst_util_uint64_scale_int (align->alignment_threshold,
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align->rate, GST_SECOND);
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/* Discont! */
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if (G_UNLIKELY (diff >= max_sample_diff)) {
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if (align->discont_wait > 0) {
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if (align->discont_time == GST_CLOCK_TIME_NONE) {
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align->discont_time = start_time;
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} else if ((start_time >= align->discont_time
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&& start_time - align->discont_time >= align->discont_wait)
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|| (start_time < align->discont_time
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&& align->discont_time - start_time >= align->discont_wait)) {
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discont = TRUE;
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align->discont_time = GST_CLOCK_TIME_NONE;
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}
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} else {
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discont = TRUE;
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}
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} else if (G_UNLIKELY (align->discont_time != GST_CLOCK_TIME_NONE)) {
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/* we have had a discont, but are now back on track! */
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align->discont_time = GST_CLOCK_TIME_NONE;
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}
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}
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if (discont) {
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/* Have discont, need resync and use the capture timestamps */
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if (align->next_offset != (guint64) - 1)
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GST_INFO ("Have discont. Expected %"
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G_GUINT64_FORMAT ", got %" G_GUINT64_FORMAT,
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align->next_offset, start_offset);
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align->next_offset = end_offset;
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/* Got a discont and adjusted, reset the discont_time marker */
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align->discont_time = GST_CLOCK_TIME_NONE;
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} else {
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/* No discont, just keep counting */
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timestamp =
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gst_util_uint64_scale (align->next_offset, GST_SECOND, align->rate);
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start_offset = align->next_offset;
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align->next_offset += n_samples;
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duration =
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gst_util_uint64_scale (align->next_offset, GST_SECOND,
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align->rate) - timestamp;
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}
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if (out_timestamp)
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*out_timestamp = timestamp;
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if (out_duration)
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*out_duration = duration;
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if (out_sample_position)
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*out_sample_position = start_offset;
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return discont;
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}
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