/* GStreamer AC3 parser * Copyright (C) 2009 Tim-Philipp Müller * Copyright (C) 2009 Mark Nauwelaerts * Copyright (C) 2009 Nokia Corporation. All rights reserved. * Contact: Stefan Kost * * 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:element-ac3parse * @short_description: AC3 parser * @see_also: #GstAmrParse, #GstAACParse * * This is an AC3 parser. * * * Example launch line * |[ * gst-launch filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink * ]| * */ /* 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 #include "gstac3parse.h" #include #include 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 ]; " "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; " "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 "); } 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; ac3parse->blocks = -1; ac3parse->eac = FALSE; } static void gst_ac3_parse_init (GstAc3Parse * ac3parse, GstAc3ParseClass * klass) { gst_base_parse_set_min_frame_size (GST_BASE_PARSE (ac3parse), 6); 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, 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) { if (eac) *eac = FALSE; return gst_ac3_parse_frame_header_ac3 (parse, buf, framesize, rate, chans, blocks, sid); } else if (bsid <= 16) { 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, 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) { 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; gboolean eac, update_rate = FALSE; if (!gst_ac3_parse_frame_header (ac3parse, buf, &fsize, &rate, &chans, &blocks, &sid, &eac)) goto broken_header; GST_LOG_OBJECT (parse, "size: %u, blocks: %u, rate: %u, chans: %u", fsize, blocks, rate, chans); 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; } 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", "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); ac3parse->sample_rate = rate; ac3parse->channels = chans; ac3parse->eac = eac; update_rate = TRUE; } if (G_UNLIKELY (ac3parse->blocks != blocks)) { ac3parse->blocks = blocks; update_rate = TRUE; } if (G_UNLIKELY (update_rate)) 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; } }