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488 lines
14 KiB
C
488 lines
14 KiB
C
/* GStreamer AC3 parser
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* Copyright (C) 2009 Tim-Philipp Müller <tim centricular net>
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* Copyright (C) 2009 Mark Nauwelaerts <mnauw users sf net>
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* Copyright (C) 2009 Nokia Corporation. All rights reserved.
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* Contact: Stefan Kost <stefan.kost@nokia.com>
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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., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gstac3parse
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* @short_description: AC3 parser
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* @see_also: #GstAmrParse, #GstAACParse
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*
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* <refsect2>
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* <para>
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* This is an AC3 parser.
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* </para>
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* <title>Example launch line</title>
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* <para>
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* <programlisting>
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* gst-launch filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink
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* </programlisting>
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* </para>
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* </refsect2>
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*/
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/* TODO:
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* - add support for audio/x-private1-ac3 as well
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* - should accept framed and unframed input (needs decodebin fixes first)
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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 <string.h>
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#include "gstac3parse.h"
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#include <gst/base/gstbytereader.h>
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#include <gst/base/gstbitreader.h>
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GST_DEBUG_CATEGORY_STATIC (ac3_parse_debug);
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#define GST_CAT_DEFAULT ac3_parse_debug
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static const struct
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{
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const guint bit_rate; /* nominal bit rate */
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const guint frame_size[3]; /* frame size for 32kHz, 44kHz, and 48kHz */
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} frmsizcod_table[38] = {
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{
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32, {
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64, 69, 96}}, {
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32, {
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64, 70, 96}}, {
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40, {
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80, 87, 120}}, {
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40, {
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80, 88, 120}}, {
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48, {
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96, 104, 144}}, {
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48, {
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96, 105, 144}}, {
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56, {
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112, 121, 168}}, {
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56, {
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112, 122, 168}}, {
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64, {
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128, 139, 192}}, {
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64, {
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128, 140, 192}}, {
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80, {
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160, 174, 240}}, {
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80, {
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160, 175, 240}}, {
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96, {
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192, 208, 288}}, {
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96, {
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192, 209, 288}}, {
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112, {
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224, 243, 336}}, {
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112, {
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224, 244, 336}}, {
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128, {
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256, 278, 384}}, {
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128, {
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256, 279, 384}}, {
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160, {
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320, 348, 480}}, {
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160, {
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320, 349, 480}}, {
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192, {
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384, 417, 576}}, {
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192, {
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384, 418, 576}}, {
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224, {
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448, 487, 672}}, {
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224, {
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448, 488, 672}}, {
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256, {
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512, 557, 768}}, {
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256, {
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512, 558, 768}}, {
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320, {
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640, 696, 960}}, {
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320, {
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640, 697, 960}}, {
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384, {
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768, 835, 1152}}, {
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384, {
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768, 836, 1152}}, {
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448, {
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896, 975, 1344}}, {
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448, {
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896, 976, 1344}}, {
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512, {
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1024, 1114, 1536}}, {
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512, {
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1024, 1115, 1536}}, {
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576, {
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1152, 1253, 1728}}, {
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576, {
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1152, 1254, 1728}}, {
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640, {
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1280, 1393, 1920}}, {
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640, {
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1280, 1394, 1920}}
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};
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static const guint fscod_rates[4] = { 48000, 44100, 32000, 0 };
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static const guint acmod_chans[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
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static const guint numblks[4] = { 1, 2, 3, 6 };
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static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
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GST_PAD_SRC,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) true, "
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" channels = (int) [ 1, 6 ], rate = (int) [ 32000, 48000 ]; "
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"audio/ac3, framed = (boolean) true, "
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" channels = (int) [ 1, 6 ], rate = (int) [ 32000, 48000 ] "));
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static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
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GST_PAD_SINK,
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GST_PAD_ALWAYS,
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GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) false; "
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"audio/ac3, framed = (boolean) false "));
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static void gst_ac3_parse_finalize (GObject * object);
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static gboolean gst_ac3_parse_start (GstBaseParse * parse);
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static gboolean gst_ac3_parse_stop (GstBaseParse * parse);
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static gboolean gst_ac3_parse_is_seekable (GstBaseParse * parse);
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static gboolean gst_ac3_parse_check_valid_frame (GstBaseParse * parse,
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GstBuffer * buffer, guint * size, gint * skipsize);
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static GstFlowReturn gst_ac3_parse_parse_frame (GstBaseParse * parse,
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GstBuffer * buf);
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GST_BOILERPLATE (GstAc3Parse, gst_ac3_parse, GstBaseParse, GST_TYPE_BASE_PARSE);
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static void
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gst_ac3_parse_base_init (gpointer klass)
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{
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GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
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gst_element_class_add_pad_template (element_class,
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gst_static_pad_template_get (&sink_template));
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gst_element_class_add_pad_template (element_class,
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gst_static_pad_template_get (&src_template));
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gst_element_class_set_details_simple (element_class,
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"AC3 audio stream parser", "Codec/Parser/Audio",
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"AC3 parser", "Tim-Philipp Müller <tim centricular net>");
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}
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static void
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gst_ac3_parse_class_init (GstAc3ParseClass * klass)
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{
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GstBaseParseClass *parse_class = GST_BASE_PARSE_CLASS (klass);
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GObjectClass *object_class = G_OBJECT_CLASS (klass);
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GST_DEBUG_CATEGORY_INIT (ac3_parse_debug, "ac3parse", 0,
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"AC3 audio stream parser");
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object_class->finalize = gst_ac3_parse_finalize;
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parse_class->start = GST_DEBUG_FUNCPTR (gst_ac3_parse_start);
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parse_class->stop = GST_DEBUG_FUNCPTR (gst_ac3_parse_stop);
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parse_class->check_valid_frame =
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GST_DEBUG_FUNCPTR (gst_ac3_parse_check_valid_frame);
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parse_class->parse_frame = GST_DEBUG_FUNCPTR (gst_ac3_parse_parse_frame);
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parse_class->is_seekable = GST_DEBUG_FUNCPTR (gst_ac3_parse_is_seekable);
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}
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static void
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gst_ac3_parse_reset (GstAc3Parse * ac3parse)
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{
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ac3parse->channels = -1;
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ac3parse->sample_rate = -1;
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}
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static void
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gst_ac3_parse_init (GstAc3Parse * ac3parse, GstAc3ParseClass * klass)
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{
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gst_base_parse_set_min_frame_size (GST_BASE_PARSE (ac3parse), 64 * 2);
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gst_ac3_parse_reset (ac3parse);
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}
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static void
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gst_ac3_parse_finalize (GObject * object)
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{
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G_OBJECT_CLASS (parent_class)->finalize (object);
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}
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static gboolean
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gst_ac3_parse_start (GstBaseParse * parse)
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{
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GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
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GST_DEBUG_OBJECT (parse, "starting");
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gst_ac3_parse_reset (ac3parse);
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return TRUE;
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}
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static gboolean
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gst_ac3_parse_stop (GstBaseParse * parse)
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{
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GST_DEBUG_OBJECT (parse, "stopping");
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return TRUE;
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}
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static gboolean
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gst_ac3_parse_is_seekable (GstBaseParse * parse)
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{
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return TRUE;
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}
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static gboolean
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gst_ac3_parse_frame_header_ac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
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guint * frame_size, guint * rate, guint * chans, guint * blks, guint * sid)
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{
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GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
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guint8 fscod, frmsizcod, bsid, bsmod, acmod, lfe_on;
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gst_bit_reader_skip (&bits, 16 + 16);
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gst_bit_reader_get_bits_uint8 (&bits, &fscod, 2);
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gst_bit_reader_get_bits_uint8 (&bits, &frmsizcod, 6);
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if (G_UNLIKELY (fscod == 3 || frmsizcod >= G_N_ELEMENTS (frmsizcod_table))) {
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GST_DEBUG_OBJECT (ac3parse, "bad fscod=%d frmsizcod=%d", fscod, frmsizcod);
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return FALSE;
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}
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gst_bit_reader_get_bits_uint8 (&bits, &bsid, 5);
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gst_bit_reader_get_bits_uint8 (&bits, &bsmod, 3);
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gst_bit_reader_get_bits_uint8 (&bits, &acmod, 3);
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/* FIXME: are other bsids ok as well? check spec */
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if (bsid != 8 && bsid != 6) {
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GST_DEBUG_OBJECT (ac3parse, "unexpected bsid=%d", bsid);
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return FALSE;
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}
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if ((acmod & 0x1) && (acmod != 0x1)) /* 3 front channels */
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gst_bit_reader_skip (&bits, 2);
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if ((acmod & 0x4)) /* if a surround channel exists */
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gst_bit_reader_skip (&bits, 2);
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if (acmod == 0x2) /* if in 2/0 mode */
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gst_bit_reader_skip (&bits, 2);
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gst_bit_reader_get_bits_uint8 (&bits, &lfe_on, 1);
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if (frame_size)
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*frame_size = frmsizcod_table[frmsizcod].frame_size[fscod] * 2;
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if (rate)
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*rate = fscod_rates[fscod];
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if (chans)
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*chans = acmod_chans[acmod] + lfe_on;
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if (blks)
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*blks = 6;
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if (sid)
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*sid = 0;
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return TRUE;
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}
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static gboolean
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gst_ac3_parse_frame_header_eac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
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guint * frame_size, guint * rate, guint * chans, guint * blks, guint * sid)
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{
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GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
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guint16 frmsiz, sample_rate, blocks;
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guint8 strmtyp, fscod, fscod2, acmod, lfe_on, strmid, numblkscod;
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gst_bit_reader_skip (&bits, 16 + 16);
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gst_bit_reader_get_bits_uint8 (&bits, &strmtyp, 2); /* strmtyp */
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if (G_UNLIKELY (strmtyp == 3)) {
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GST_DEBUG_OBJECT (ac3parse, "bad strmtyp %d", strmtyp);
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return FALSE;
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}
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gst_bit_reader_get_bits_uint8 (&bits, &strmid, 3); /* substreamid */
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gst_bit_reader_get_bits_uint16 (&bits, &frmsiz, 11); /* frmsiz */
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gst_bit_reader_get_bits_uint8 (&bits, &fscod, 2); /* fscod */
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if (fscod == 3) {
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gst_bit_reader_get_bits_uint8 (&bits, &fscod2, 2); /* fscod2 */
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if (G_UNLIKELY (fscod2 == 3)) {
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GST_DEBUG_OBJECT (ac3parse, "invalid fscod2");
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return FALSE;
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}
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sample_rate = fscod_rates[fscod2] / 2;
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blocks = 6;
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} else {
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gst_bit_reader_get_bits_uint8 (&bits, &numblkscod, 2); /* numblkscod */
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sample_rate = fscod_rates[fscod];
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blocks = numblks[numblkscod];
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}
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gst_bit_reader_get_bits_uint8 (&bits, &acmod, 3); /* acmod */
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gst_bit_reader_get_bits_uint8 (&bits, &lfe_on, 1); /* lfeon */
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gst_bit_reader_skip (&bits, 5); /* bsid */
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if (frame_size)
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*frame_size = (frmsiz + 1) * 2;
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if (rate)
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*rate = sample_rate;
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if (chans)
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*chans = acmod_chans[acmod] + lfe_on;
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if (blks)
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*blks = blocks;
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if (sid)
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*sid = (strmtyp & 0x1) << 3 | strmid;
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return TRUE;
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}
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static gboolean
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gst_ac3_parse_frame_header (GstAc3Parse * parse, GstBuffer * buf,
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guint * framesize, guint * rate, guint * chans, guint * blocks, guint * sid)
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{
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GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
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guint16 sync;
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guint8 bsid;
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GST_MEMDUMP_OBJECT (parse, "AC3 frame sync", GST_BUFFER_DATA (buf), 16);
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gst_bit_reader_get_bits_uint16 (&bits, &sync, 16);
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gst_bit_reader_skip (&bits, 16 + 8);
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gst_bit_reader_peek_bits_uint8 (&bits, &bsid, 5);
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if (G_UNLIKELY (sync != 0x0b77))
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return FALSE;
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if (bsid <= 10) {
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return gst_ac3_parse_frame_header_ac3 (parse, buf, framesize, rate, chans,
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blocks, sid);
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} else if (bsid <= 16) {
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return gst_ac3_parse_frame_header_eac3 (parse, buf, framesize, rate, chans,
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blocks, sid);
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} else {
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GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
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return FALSE;
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}
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}
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static gboolean
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gst_ac3_parse_check_valid_frame (GstBaseParse * parse, GstBuffer * buf,
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guint * framesize, gint * skipsize)
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{
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GstByteReader reader = GST_BYTE_READER_INIT_FROM_BUFFER (buf);
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GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
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gint off;
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gboolean sync, drain;
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if (G_UNLIKELY (GST_BUFFER_SIZE (buf) < 6))
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return FALSE;
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off = gst_byte_reader_masked_scan_uint32 (&reader, 0xffff0000, 0x0b770000,
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0, GST_BUFFER_SIZE (buf));
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GST_LOG_OBJECT (parse, "possible sync at buffer offset %d", off);
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/* didn't find anything that looks like a sync word, skip */
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if (off < 0) {
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*skipsize = GST_BUFFER_SIZE (buf) - 2;
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return FALSE;
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}
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/* possible frame header, but not at offset 0? skip bytes before sync */
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if (off > 0) {
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*skipsize = off;
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return FALSE;
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}
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/* make sure the values in the frame header look sane */
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if (!gst_ac3_parse_frame_header (ac3parse, buf, framesize, NULL, NULL,
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NULL, NULL)) {
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*skipsize = off + 2;
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return FALSE;
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}
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GST_LOG_OBJECT (parse, "got frame");
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sync = gst_base_parse_get_sync (parse);
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drain = gst_base_parse_get_drain (parse);
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if (!sync && !drain) {
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guint16 word;
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GST_DEBUG_OBJECT (ac3parse, "resyncing; checking next frame syncword");
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if (!gst_byte_reader_skip (&reader, *framesize) ||
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!gst_byte_reader_get_uint16_be (&reader, &word)) {
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GST_DEBUG_OBJECT (ac3parse, "... but not sufficient data");
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gst_base_parse_set_min_frame_size (parse, *framesize + 6);
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*skipsize = 0;
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return FALSE;
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} else {
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if (word != 0x0b77) {
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GST_DEBUG_OBJECT (ac3parse, "0x%x not OK", word);
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*skipsize = off + 2;
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return FALSE;
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} else {
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/* ok, got sync now, let's assume constant frame size */
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gst_base_parse_set_min_frame_size (parse, *framesize);
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}
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}
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}
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return TRUE;
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}
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static GstFlowReturn
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gst_ac3_parse_parse_frame (GstBaseParse * parse, GstBuffer * buf)
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{
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GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
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guint fsize, rate, chans, blocks, sid;
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if (!gst_ac3_parse_frame_header (ac3parse, buf, &fsize, &rate, &chans,
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&blocks, &sid))
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goto broken_header;
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GST_LOG_OBJECT (parse, "size: %u, rate: %u, chans: %u", fsize, rate, chans);
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if (G_UNLIKELY (sid)) {
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GST_LOG_OBJECT (parse, "sid: %d", sid);
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GST_BUFFER_FLAG_SET (buf, GST_BASE_PARSE_BUFFER_FLAG_NO_FRAME);
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}
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if (G_UNLIKELY (ac3parse->sample_rate != rate || ac3parse->channels != chans)) {
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GstCaps *caps = gst_caps_new_simple ("audio/x-ac3",
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"framed", G_TYPE_BOOLEAN, TRUE, "rate", G_TYPE_INT, rate,
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"channels", G_TYPE_INT, chans, NULL);
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gst_buffer_set_caps (buf, caps);
|
|
gst_pad_set_caps (GST_BASE_PARSE_SRC_PAD (parse), caps);
|
|
gst_caps_unref (caps);
|
|
|
|
ac3parse->sample_rate = rate;
|
|
ac3parse->channels = chans;
|
|
|
|
gst_base_parse_set_frame_props (parse, rate, 256 * blocks, 50);
|
|
}
|
|
|
|
return GST_FLOW_OK;
|
|
|
|
/* ERRORS */
|
|
broken_header:
|
|
{
|
|
/* this really shouldn't ever happen */
|
|
GST_ELEMENT_ERROR (parse, STREAM, DECODE, (NULL), (NULL));
|
|
return GST_FLOW_ERROR;
|
|
}
|
|
}
|