gstreamer/gst/audioparsers/gstac3parse.c

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/* 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.
*/
/**
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* SECTION:element-ac3parse
* @short_description: AC3 parser
* @see_also: #GstAmrParse, #GstAACParse
*
* This is an AC3 parser.
*
* <refsect2>
* <title>Example launch line</title>
* |[
* gst-launch filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink
* ]|
* </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 const guint numblks[4] = { 1, 2, 3, 6 };
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 ]; "
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"audio/x-eac3, 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; "
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"audio/x-eac3, 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_check_valid_frame (GstBaseParse * parse,
GstBaseParseFrame * frame, guint * size, gint * skipsize);
static GstFlowReturn gst_ac3_parse_parse_frame (GstBaseParse * parse,
GstBaseParseFrame * frame);
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);
}
static void
gst_ac3_parse_reset (GstAc3Parse * ac3parse)
{
ac3parse->channels = -1;
ac3parse->sample_rate = -1;
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ac3parse->eac = FALSE;
}
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_frame_header_ac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
guint * frame_size, guint * rate, guint * chans, guint * blks, guint * sid)
{
GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
guint8 fscod, frmsizcod, bsid, acmod, lfe_on;
GST_LOG_OBJECT (ac3parse, "parsing ac3");
gst_bit_reader_skip_unchecked (&bits, 16 + 16);
fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2);
frmsizcod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 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;
}
bsid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 5);
gst_bit_reader_skip_unchecked (&bits, 3); /* bsmod */
acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3);
/* spec not quite clear here: decoder should decode if less than 8,
* but seemingly only defines 6 and 8 cases */
if (bsid > 8) {
GST_DEBUG_OBJECT (ac3parse, "unexpected bsid=%d", bsid);
return FALSE;
} else if (bsid != 8 && bsid != 6) {
GST_DEBUG_OBJECT (ac3parse, "undefined bsid=%d", bsid);
}
if ((acmod & 0x1) && (acmod != 0x1)) /* 3 front channels */
gst_bit_reader_skip_unchecked (&bits, 2);
if ((acmod & 0x4)) /* if a surround channel exists */
gst_bit_reader_skip_unchecked (&bits, 2);
if (acmod == 0x2) /* if in 2/0 mode */
gst_bit_reader_skip_unchecked (&bits, 2);
lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 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;
if (blks)
*blks = 6;
if (sid)
*sid = 0;
return TRUE;
}
static gboolean
gst_ac3_parse_frame_header_eac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
guint * frame_size, guint * rate, guint * chans, guint * blks, guint * sid)
{
GstBitReader bits = GST_BIT_READER_INIT_FROM_BUFFER (buf);
guint16 frmsiz, sample_rate, blocks;
guint8 strmtyp, fscod, fscod2, acmod, lfe_on, strmid, numblkscod;
GST_LOG_OBJECT (ac3parse, "parsing e-ac3");
gst_bit_reader_skip_unchecked (&bits, 16);
strmtyp = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* strmtyp */
if (G_UNLIKELY (strmtyp == 3)) {
GST_DEBUG_OBJECT (ac3parse, "bad strmtyp %d", strmtyp);
return FALSE;
}
strmid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* substreamid */
frmsiz = gst_bit_reader_get_bits_uint16_unchecked (&bits, 11); /* frmsiz */
fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod */
if (fscod == 3) {
fscod2 = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod2 */
if (G_UNLIKELY (fscod2 == 3)) {
GST_DEBUG_OBJECT (ac3parse, "invalid fscod2");
return FALSE;
}
sample_rate = fscod_rates[fscod2] / 2;
blocks = 6;
} else {
numblkscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* numblkscod */
sample_rate = fscod_rates[fscod];
blocks = numblks[numblkscod];
}
acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* acmod */
lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 1); /* lfeon */
gst_bit_reader_skip_unchecked (&bits, 5); /* bsid */
if (frame_size)
*frame_size = (frmsiz + 1) * 2;
if (rate)
*rate = sample_rate;
if (chans)
*chans = acmod_chans[acmod] + lfe_on;
if (blks)
*blks = blocks;
if (sid)
*sid = (strmtyp & 0x1) << 3 | strmid;
return TRUE;
}
static gboolean
gst_ac3_parse_frame_header (GstAc3Parse * parse, GstBuffer * buf,
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guint * framesize, guint * rate, guint * chans, guint * blocks,
guint * sid, gboolean * eac)
{
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);
sync = gst_bit_reader_get_bits_uint16_unchecked (&bits, 16);
gst_bit_reader_skip_unchecked (&bits, 16 + 8);
bsid = gst_bit_reader_peek_bits_uint8_unchecked (&bits, 5);
if (G_UNLIKELY (sync != 0x0b77))
return FALSE;
GST_LOG_OBJECT (parse, "bsid = %d", bsid);
if (bsid <= 10) {
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if (eac)
*eac = FALSE;
return gst_ac3_parse_frame_header_ac3 (parse, buf, framesize, rate, chans,
blocks, sid);
} else if (bsid <= 16) {
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if (eac)
*eac = TRUE;
return gst_ac3_parse_frame_header_eac3 (parse, buf, framesize, rate, chans,
blocks, sid);
} else {
GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
return FALSE;
}
}
static gboolean
gst_ac3_parse_check_valid_frame (GstBaseParse * parse,
GstBaseParseFrame * frame, guint * framesize, gint * skipsize)
{
GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
GstBuffer *buf = frame->buffer;
GstByteReader reader = GST_BYTE_READER_INIT_FROM_BUFFER (buf);
gint off;
gboolean lost_sync, draining;
if (G_UNLIKELY (GST_BUFFER_SIZE (buf) < 6))
return FALSE;
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) - 3;
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,
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NULL, NULL, NULL)) {
*skipsize = off + 2;
return FALSE;
}
GST_LOG_OBJECT (parse, "got frame");
lost_sync = GST_BASE_PARSE_LOST_SYNC (parse);
draining = GST_BASE_PARSE_DRAINING (parse);
if (lost_sync && !draining) {
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guint16 word = 0;
GST_DEBUG_OBJECT (ac3parse, "resyncing; checking next frame syncword");
if (!gst_byte_reader_skip (&reader, *framesize) ||
!gst_byte_reader_get_uint16_be (&reader, &word)) {
GST_DEBUG_OBJECT (ac3parse, "... but not sufficient data");
gst_base_parse_set_min_frame_size (parse, *framesize + 6);
*skipsize = 0;
return FALSE;
} else {
if (word != 0x0b77) {
GST_DEBUG_OBJECT (ac3parse, "0x%x not OK", word);
*skipsize = off + 2;
return FALSE;
} else {
/* ok, got sync now, let's assume constant frame size */
gst_base_parse_set_min_frame_size (parse, *framesize);
}
}
}
return TRUE;
}
static GstFlowReturn
gst_ac3_parse_parse_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
{
GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
GstBuffer *buf = frame->buffer;
guint fsize, rate, chans, blocks, sid;
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gboolean eac;
if (!gst_ac3_parse_frame_header (ac3parse, buf, &fsize, &rate, &chans,
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&blocks, &sid, &eac))
goto broken_header;
GST_LOG_OBJECT (parse, "size: %u, rate: %u, chans: %u", fsize, rate, chans);
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if (G_UNLIKELY (sid)) {
/* dependent frame, no need to (ac)count for or consider further */
GST_LOG_OBJECT (parse, "sid: %d", sid);
frame->flags |= GST_BASE_PARSE_FRAME_FLAG_NO_FRAME;
/* TODO maybe also mark as DELTA_UNIT,
* if that does not surprise baseparse elsewhere */
/* occupies same time space as previous base frame */
if (G_LIKELY (GST_BUFFER_TIMESTAMP (buf) >= GST_BUFFER_DURATION (buf)))
GST_BUFFER_TIMESTAMP (buf) -= GST_BUFFER_DURATION (buf);
/* only return if we already arranged for caps */
if (G_LIKELY (ac3parse->sample_rate > 0))
return GST_FLOW_OK;
}
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if (G_UNLIKELY (ac3parse->sample_rate != rate || ac3parse->channels != chans
|| ac3parse->eac != ac3parse->eac)) {
GstCaps *caps = gst_caps_new_simple (eac ? "audio/x-eac3" : "audio/x-ac3",
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"framed", G_TYPE_BOOLEAN, TRUE, "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);
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ac3parse->sample_rate = rate;
ac3parse->channels = chans;
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ac3parse->eac = eac;
gst_base_parse_set_frame_rate (parse, rate, 256 * blocks, 2, 2);
}
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;
}
}