--- /dev/null
+/* GStreamer AC3 parser
+ * Copyright (C) 2009 Tim-Philipp Müller <tim centricular net>
+ * Copyright (C) 2009 Mark Nauwelaerts <mnauw users sf net>
+ * Copyright (C) 2009 Nokia Corporation. All rights reserved.
+ * Contact: Stefan Kost <stefan.kost@nokia.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+/**
+ * SECTION:gstac3parse
+ * @short_description: AC3 parser
+ * @see_also: #GstAmrParse, #GstAACParse
+ *
+ * <refsect2>
+ * <para>
+ * This is an AC3 parser.
+ * </para>
+ * <title>Example launch line</title>
+ * <para>
+ * <programlisting>
+ * gst-launch filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink
+ * </programlisting>
+ * </para>
+ * </refsect2>
+ */
+
+/* TODO:
+ * - add support for audio/x-private1-ac3 as well
+ * - should accept framed and unframed input (needs decodebin fixes first)
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <string.h>
+
+#include "gstac3parse.h"
+#include <gst/base/gstbytereader.h>
+#include <gst/base/gstbitreader.h>
+
+GST_DEBUG_CATEGORY_STATIC (ac3_parse_debug);
+#define GST_CAT_DEFAULT ac3_parse_debug
+
+static const struct
+{
+ const guint bit_rate; /* nominal bit rate */
+ const guint frame_size[3]; /* frame size for 32kHz, 44kHz, and 48kHz */
+} frmsizcod_table[38] = {
+ {
+ 32, {
+ 64, 69, 96}}, {
+ 32, {
+ 64, 70, 96}}, {
+ 40, {
+ 80, 87, 120}}, {
+ 40, {
+ 80, 88, 120}}, {
+ 48, {
+ 96, 104, 144}}, {
+ 48, {
+ 96, 105, 144}}, {
+ 56, {
+ 112, 121, 168}}, {
+ 56, {
+ 112, 122, 168}}, {
+ 64, {
+ 128, 139, 192}}, {
+ 64, {
+ 128, 140, 192}}, {
+ 80, {
+ 160, 174, 240}}, {
+ 80, {
+ 160, 175, 240}}, {
+ 96, {
+ 192, 208, 288}}, {
+ 96, {
+ 192, 209, 288}}, {
+ 112, {
+ 224, 243, 336}}, {
+ 112, {
+ 224, 244, 336}}, {
+ 128, {
+ 256, 278, 384}}, {
+ 128, {
+ 256, 279, 384}}, {
+ 160, {
+ 320, 348, 480}}, {
+ 160, {
+ 320, 349, 480}}, {
+ 192, {
+ 384, 417, 576}}, {
+ 192, {
+ 384, 418, 576}}, {
+ 224, {
+ 448, 487, 672}}, {
+ 224, {
+ 448, 488, 672}}, {
+ 256, {
+ 512, 557, 768}}, {
+ 256, {
+ 512, 558, 768}}, {
+ 320, {
+ 640, 696, 960}}, {
+ 320, {
+ 640, 697, 960}}, {
+ 384, {
+ 768, 835, 1152}}, {
+ 384, {
+ 768, 836, 1152}}, {
+ 448, {
+ 896, 975, 1344}}, {
+ 448, {
+ 896, 976, 1344}}, {
+ 512, {
+ 1024, 1114, 1536}}, {
+ 512, {
+ 1024, 1115, 1536}}, {
+ 576, {
+ 1152, 1253, 1728}}, {
+ 576, {
+ 1152, 1254, 1728}}, {
+ 640, {
+ 1280, 1393, 1920}}, {
+ 640, {
+ 1280, 1394, 1920}}
+};
+
+static const guint fscod_rates[4] = { 48000, 44100, 32000, 0 };
+static const guint acmod_chans[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
+
+static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
+ GST_PAD_SRC,
+ GST_PAD_ALWAYS,
+ GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) true, "
+ " channels = (int) [ 1, 6 ], rate = (int) [ 32000, 48000 ]; "
+ "audio/ac3, framed = (boolean) true, "
+ " channels = (int) [ 1, 6 ], rate = (int) [ 32000, 48000 ] "));
+
+static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
+ GST_PAD_SINK,
+ GST_PAD_ALWAYS,
+ GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) false; "
+ "audio/ac3, framed = (boolean) false "));
+
+static void gst_ac3_parse_finalize (GObject * object);
+
+static gboolean gst_ac3_parse_start (GstBaseParse * parse);
+static gboolean gst_ac3_parse_stop (GstBaseParse * parse);
+static gboolean gst_ac3_parse_is_seekable (GstBaseParse * parse);
+static gboolean gst_ac3_parse_check_valid_frame (GstBaseParse * parse,
+ GstBuffer * buffer, guint * size, gint * skipsize);
+static GstFlowReturn gst_ac3_parse_parse_frame (GstBaseParse * parse,
+ GstBuffer * buf);
+
+GST_BOILERPLATE (GstAc3Parse, gst_ac3_parse, GstBaseParse, GST_TYPE_BASE_PARSE);
+
+static void
+gst_ac3_parse_base_init (gpointer klass)
+{
+ GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+
+ gst_element_class_add_pad_template (element_class,
+ gst_static_pad_template_get (&sink_template));
+ gst_element_class_add_pad_template (element_class,
+ gst_static_pad_template_get (&src_template));
+
+ gst_element_class_set_details_simple (element_class,
+ "AC3 audio stream parser", "Codec/Parser/Audio",
+ "AC3 parser", "Tim-Philipp Müller <tim centricular net>");
+}
+
+static void
+gst_ac3_parse_class_init (GstAc3ParseClass * klass)
+{
+ GstBaseParseClass *parse_class = GST_BASE_PARSE_CLASS (klass);
+ GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+ GST_DEBUG_CATEGORY_INIT (ac3_parse_debug, "ac3parse", 0,
+ "AC3 audio stream parser");
+
+ object_class->finalize = gst_ac3_parse_finalize;
+
+ parse_class->start = GST_DEBUG_FUNCPTR (gst_ac3_parse_start);
+ parse_class->stop = GST_DEBUG_FUNCPTR (gst_ac3_parse_stop);
+ parse_class->check_valid_frame =
+ GST_DEBUG_FUNCPTR (gst_ac3_parse_check_valid_frame);
+ parse_class->parse_frame = GST_DEBUG_FUNCPTR (gst_ac3_parse_parse_frame);
+ parse_class->is_seekable = GST_DEBUG_FUNCPTR (gst_ac3_parse_is_seekable);
+}
+
+static void
+gst_ac3_parse_reset (GstAc3Parse * ac3parse)
+{
+ ac3parse->channels = -1;
+ ac3parse->sample_rate = -1;
+}
+
+static void
+gst_ac3_parse_init (GstAc3Parse * ac3parse, GstAc3ParseClass * klass)
+{
+ gst_base_parse_set_min_frame_size (GST_BASE_PARSE (ac3parse), 64 * 2);
+ gst_ac3_parse_reset (ac3parse);
+}
+
+static void
+gst_ac3_parse_finalize (GObject * object)
+{
+ G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gboolean
+gst_ac3_parse_start (GstBaseParse * parse)
+{
+ GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
+
+ GST_DEBUG_OBJECT (parse, "starting");
+
+ gst_ac3_parse_reset (ac3parse);
+
+ return TRUE;
+}
+
+static gboolean
+gst_ac3_parse_stop (GstBaseParse * parse)
+{
+ GST_DEBUG_OBJECT (parse, "stopping");
+
+ return TRUE;
+}
+
+static gboolean
+gst_ac3_parse_is_seekable (GstBaseParse * parse)
+{
+ return TRUE;
+}
+
+static gboolean
+gst_ac3_parse_frame_header_ac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
+ guint * frame_size, guint * rate, guint * chans)
+{
+ GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
+ guint8 fscod, frmsizcod, bsid, bsmod, acmod, lfe_on;
+
+ gst_bit_reader_skip (&bits, 16 + 16);
+ gst_bit_reader_get_bits_uint8 (&bits, &fscod, 2);
+ gst_bit_reader_get_bits_uint8 (&bits, &frmsizcod, 6);
+
+ if (G_UNLIKELY (fscod == 3 || frmsizcod >= G_N_ELEMENTS (frmsizcod_table))) {
+ GST_DEBUG_OBJECT (ac3parse, "bad fscod=%d frmsizcod=%d", fscod, frmsizcod);
+ return FALSE;
+ }
+
+ gst_bit_reader_get_bits_uint8 (&bits, &bsid, 5);
+ gst_bit_reader_get_bits_uint8 (&bits, &bsmod, 3);
+ gst_bit_reader_get_bits_uint8 (&bits, &acmod, 3);
+
+ /* FIXME: are other bsids ok as well? check spec */
+ if (bsid != 8 && bsid != 6) {
+ GST_DEBUG_OBJECT (ac3parse, "unexpected bsid=%d", bsid);
+ return FALSE;
+ }
+
+ if ((acmod & 0x1) && (acmod != 0x1)) /* 3 front channels */
+ gst_bit_reader_skip (&bits, 2);
+ if ((acmod & 0x4)) /* if a surround channel exists */
+ gst_bit_reader_skip (&bits, 2);
+ if (acmod == 0x2) /* if in 2/0 mode */
+ gst_bit_reader_skip (&bits, 2);
+
+ gst_bit_reader_get_bits_uint8 (&bits, &lfe_on, 1);
+
+ if (frame_size)
+ *frame_size = frmsizcod_table[frmsizcod].frame_size[fscod] * 2;
+ if (rate)
+ *rate = fscod_rates[fscod];
+ if (chans)
+ *chans = acmod_chans[acmod] + lfe_on;
+
+ return TRUE;
+}
+
+static gboolean
+gst_ac3_parse_frame_header_eac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
+ guint * frame_size, guint * rate, guint * chans)
+{
+ GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
+ guint16 frmsiz, sample_rate;
+ guint8 strmtyp, fscod, fscod2, acmod, lfe_on;
+
+ gst_bit_reader_skip (&bits, 16 + 16);
+ gst_bit_reader_get_bits_uint8 (&bits, &strmtyp, 2); /* strmtyp */
+ if (G_UNLIKELY (strmtyp == 3)) {
+ GST_DEBUG_OBJECT (ac3parse, "bad strmtyp %d", strmtyp);
+ return FALSE;
+ }
+
+ gst_bit_reader_skip (&bits, 3); /* substreamid */
+ gst_bit_reader_get_bits_uint16 (&bits, &frmsiz, 11); /* frmsiz */
+ gst_bit_reader_get_bits_uint8 (&bits, &fscod, 2); /* fscod */
+ if (fscod == 3) {
+ gst_bit_reader_get_bits_uint8 (&bits, &fscod2, 2); /* fscod2 */
+ if (G_UNLIKELY (fscod2 == 3)) {
+ GST_DEBUG_OBJECT (ac3parse, "invalid fscod2");
+ return FALSE;
+ }
+ sample_rate = fscod_rates[fscod2] / 2;
+ } else {
+ gst_bit_reader_skip (&bits, 2); /* numblkscod */
+ sample_rate = fscod_rates[fscod];
+ }
+
+ gst_bit_reader_get_bits_uint8 (&bits, &acmod, 3); /* acmod */
+ gst_bit_reader_get_bits_uint8 (&bits, &lfe_on, 1); /* lfeon */
+
+ gst_bit_reader_skip (&bits, 5); /* bsid */
+
+ if (frame_size)
+ *frame_size = (frmsiz + 1) * 2;
+ if (rate)
+ *rate = sample_rate;
+ if (chans)
+ *chans = acmod_chans[acmod] + lfe_on;
+
+ return TRUE;
+}
+
+static gboolean
+gst_ac3_parse_frame_header (GstAc3Parse * parse, GstBuffer * buf,
+ guint * framesize, guint * rate, guint * chans)
+{
+ GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
+ guint16 sync;
+ guint8 bsid;
+
+ GST_MEMDUMP_OBJECT (parse, "AC3 frame sync", GST_BUFFER_DATA (buf), 16);
+
+ gst_bit_reader_get_bits_uint16 (&bits, &sync, 16);
+ gst_bit_reader_skip (&bits, 16 + 8);
+ gst_bit_reader_peek_bits_uint8 (&bits, &bsid, 5);
+
+ if (G_UNLIKELY (sync != 0x0b77))
+ return FALSE;
+
+ if (bsid <= 10) {
+ return gst_ac3_parse_frame_header_ac3 (parse, buf, framesize, rate, chans);
+ } else if (bsid <= 16) {
+ return gst_ac3_parse_frame_header_eac3 (parse, buf, framesize, rate, chans);
+ } else {
+ GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
+ return FALSE;
+ }
+}
+
+static gboolean
+gst_ac3_parse_check_valid_frame (GstBaseParse * parse, GstBuffer * buf,
+ guint * framesize, gint * skipsize)
+{
+ GstByteReader reader = GST_BYTE_READER_INIT_FROM_BUFFER (buf);
+ GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
+ gint off;
+
+ off = gst_byte_reader_masked_scan_uint32 (&reader, 0xffff0000, 0x0b770000,
+ 0, GST_BUFFER_SIZE (buf));
+
+ GST_LOG_OBJECT (parse, "possible sync at buffer offset %d", off);
+
+ /* didn't find anything that looks like a sync word, skip */
+ if (off < 0) {
+ *skipsize = GST_BUFFER_SIZE (buf) - 2;
+ return FALSE;
+ }
+
+ /* possible frame header, but not at offset 0? skip bytes before sync */
+ if (off > 0) {
+ *skipsize = off;
+ return FALSE;
+ }
+
+ /* make sure the values in the frame header look sane */
+ if (!gst_ac3_parse_frame_header (ac3parse, buf, framesize, NULL, NULL)) {
+ *skipsize = off + 2;
+ return FALSE;
+ }
+
+ GST_LOG_OBJECT (parse, "got frame");
+ /* FIXME: do further/better checks here? */
+ return TRUE;
+}
+
+static GstFlowReturn
+gst_ac3_parse_parse_frame (GstBaseParse * parse, GstBuffer * buf)
+{
+ GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
+ guint fsize, rate, chans;
+
+ if (!gst_ac3_parse_frame_header (ac3parse, buf, &fsize, &rate, &chans))
+ goto broken_header;
+
+ GST_LOG_OBJECT (parse, "size: %u, rate: %u, chans: %u", fsize, rate, chans);
+ {
+ GstCaps *caps = gst_caps_new_simple ("audio/x-ac3", "rate", G_TYPE_INT,
+ rate, "channels", G_TYPE_INT, chans, NULL);
+ gst_buffer_set_caps (buf, caps);
+ gst_pad_set_caps (GST_BASE_PARSE_SRC_PAD (parse), caps);
+ gst_caps_unref (caps);
+ }
+
+ 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;
+ }
+}
projects / platform / upstream / gst-plugins-good.git / commitdiff