gstreamer/gst/ac3parse/gstac3parse.c

/* GStreamer
 * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
 *
 * 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.
 */
/* Element-Checklist-Version: 5 */


#define PCM_BUFFER_SIZE		(1152*4)

/*#define DEBUG_ENABLED*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gstac3parse.h>

/* struct and table stolen from ac3dec by Aaron Holtzman */
struct frmsize_s {
  guint16 bit_rate;
  guint16 frm_size[3];
};

static struct frmsize_s frmsizecod_tbl[] = {
      { 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 } }};

/* elementfactory information */
static GstElementDetails ac3parse_details = GST_ELEMENT_DETAILS (
  "AC3 Parser",
  "Codec/Parser/Audio",
  "Parses and frames AC3 audio streams, provides seek",
  "Erik Walthinsen <omega@cse.ogi.edu>"
);

/* GstAc3Parse signals and args */
enum {
  /* FILL ME */
  LAST_SIGNAL
};

enum {
  ARG_0,
  ARG_SKIP,
  /* FILL ME */
};

static GstStaticPadTemplate gst_ac3parse_src_template =
GST_STATIC_PAD_TEMPLATE (
  "src",
  GST_PAD_SRC,
  GST_PAD_ALWAYS,
  GST_STATIC_CAPS (
    "audio/ac3, "
    "channels = (int) [ 1, 6 ], "
    "rate = (int) [ 32000, 48000 ]"
  )
);

static GstStaticPadTemplate gst_ac3parse_sink_template =
GST_STATIC_PAD_TEMPLATE (
  "sink",
  GST_PAD_SINK,
  GST_PAD_ALWAYS,
  GST_STATIC_CAPS ("audio/x-ac3")
);

static void	gst_ac3parse_class_init	  (gpointer g_class);
static void	gst_ac3parse_init	  (GstAc3Parse  *ac3parse);

static void	gst_ac3parse_chain	  (GstPad       *pad,
					   GstData	*data);

static void	gst_ac3parse_set_property (GObject      *object,
					   guint         prop_id,
					   const GValue *value,
					   GParamSpec   *pspec);
static void	gst_ac3parse_get_property (GObject      *object,
					   guint         prop_id,
					   GValue       *value,
					   GParamSpec   *pspec);

static GstElementStateReturn
		gst_ac3parse_change_state (GstElement   *element);

static GstElementClass *parent_class = NULL;
/*static guint gst_ac3parse_signals[LAST_SIGNAL] = { 0 };*/

GType
ac3parse_get_type (void)
{
  static GType ac3parse_type = 0;

  if (!ac3parse_type) {
    static const GTypeInfo ac3parse_info = {
      sizeof(GstAc3ParseClass),      NULL,
      NULL,
      (GClassInitFunc)gst_ac3parse_class_init,
      NULL,
      NULL,
      sizeof(GstAc3Parse),
      0,
      (GInstanceInitFunc)gst_ac3parse_init,
    };
    ac3parse_type = g_type_register_static(GST_TYPE_ELEMENT, "GstAc3Parse", &ac3parse_info, 0);
  }
  return ac3parse_type;
}

static void
gst_ac3parse_class_init (gpointer g_class)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;
  GstAc3ParseClass *klass;

  klass = (GstAc3ParseClass *)g_class;
  gobject_class = (GObjectClass*)klass;
  gstelement_class = (GstElementClass*)klass;

  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&gst_ac3parse_src_template));
  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&gst_ac3parse_sink_template));
  gst_element_class_set_details (gstelement_class,
      &ac3parse_details);

  g_object_class_install_property(G_OBJECT_CLASS(klass), ARG_SKIP,
    g_param_spec_int("skip","skip","skip",
                     G_MININT,G_MAXINT,0,G_PARAM_READWRITE)); /* CHECKME */

  parent_class = g_type_class_ref(GST_TYPE_ELEMENT);

  gobject_class->set_property = gst_ac3parse_set_property;
  gobject_class->get_property = gst_ac3parse_get_property;

  gstelement_class->change_state = gst_ac3parse_change_state;
}

static void
gst_ac3parse_init (GstAc3Parse *ac3parse)
{
  ac3parse->sinkpad = gst_pad_new_from_template (
      gst_static_pad_template_get (&gst_ac3parse_sink_template), "sink");
  gst_element_add_pad (GST_ELEMENT (ac3parse), ac3parse->sinkpad);
  gst_pad_set_chain_function (ac3parse->sinkpad, gst_ac3parse_chain);

  ac3parse->srcpad = gst_pad_new_from_template (
      gst_static_pad_template_get (&gst_ac3parse_src_template), "src");
  gst_pad_use_explicit_caps (ac3parse->srcpad);
  gst_element_add_pad (GST_ELEMENT (ac3parse), ac3parse->srcpad);

  ac3parse->partialbuf = NULL;
  ac3parse->skip = 0;

  ac3parse->sample_rate = ac3parse->channels = -1;
}

static void
gst_ac3parse_chain (GstPad *pad, GstData *_data)
{
  GstBuffer *buf = GST_BUFFER (_data);
  GstAc3Parse *ac3parse;
  guchar *data;
  glong size,offset = 0;
  guint16 header;
  guint8 channeldata, acmod, mask;
  GstBuffer *outbuf = NULL;
  gint bpf;
  guint sample_rate = -1, channels = -1;

  g_return_if_fail(pad != NULL);
  g_return_if_fail(GST_IS_PAD(pad));
  g_return_if_fail(buf != NULL);
/*  g_return_if_fail(GST_IS_BUFFER(buf)); */

  ac3parse = GST_AC3PARSE(GST_OBJECT_PARENT (pad));
  GST_DEBUG ("ac3parse: received buffer of %d bytes", GST_BUFFER_SIZE (buf));

  /* deal with partial frame from previous buffer */
  if (ac3parse->partialbuf) {

    ac3parse->partialbuf = gst_buffer_merge(ac3parse->partialbuf, buf);
    /* and the one we received.. */
    gst_buffer_unref(buf);
  }
  else {
    ac3parse->partialbuf = buf;
  }

  data = GST_BUFFER_DATA(ac3parse->partialbuf);
  size = GST_BUFFER_SIZE(ac3parse->partialbuf);

  /* we're searching for at least 7 bytes. first the
   * syncinfo, where 2 bytes are for the syncword
   * (header ID, 0x0b77), 2 bytes crc1 (checksum) and 1 byte
   * fscod+fmrsizecod (framerate/bitrate) and then the
   * bitstreaminfo bsid (version), bsmod (data type) and
   * acmod (channel info, 3 bits). Then some "maybe"
   * bits, and then the LFE indicator (subwoofer bit) */
  while (offset < size-6) {
    int skipped = 0;

    GST_DEBUG ("ac3parse: offset %ld, size %ld ",offset, size);

    /* search for a possible start byte */
    for (;((data[offset] != 0x0b) && (offset < size-6));offset++) skipped++ ;
    if (skipped) {
      fprintf(stderr, "ac3parse: **** now at %ld skipped %d bytes (FIXME?)\n",offset,skipped);
    }
    /* construct the header word */
    header = GUINT16_TO_BE(*((guint16 *)(data+offset)));
/*    g_print("AC3PARSE: sync word is 0x%02X\n",header); */
    /* if it's a valid header, go ahead and send off the frame */
    if (header == 0x0b77) {
      gint rate, fsize;
/*      g_print("AC3PARSE: found sync at %d\n",offset); */
      /* get the bits we're interested in */
      rate = (data[offset+4] >> 6) & 0x3;
      switch (rate) {
        case 0x0: /* 00b */
          sample_rate = 48000;
          break;
        case 0x1: /* 01b */
          sample_rate = 44100;
          break;
        case 0x2: /* 10b */
          sample_rate = 32000;
          break;
        case 0x3: /* 11b */
        default:
          /* reserved. if this happens, we're screwed */
          g_assert (0);
          break;
      }
      fsize = data[offset+4] & 0x3f;
      /* calculate the bpf of the frame */
      bpf = frmsizecod_tbl[fsize].frm_size[rate] * 2;
      /* calculate number of channels */
      channeldata = data[offset+6]; /* skip bsid/bsmod */
      acmod = (channeldata >> 5) & 0x7;
      switch (acmod) {
        case 0x1: /* 001b = 1 channel */
          channels = 1;
          break;
        case 0x0: /* 000b = 2 independent channels*/
        case 0x2: /* 010b = 2x front (stereo) */
          channels = 2;
          break;
        case 0x3: /* 011b = 3 front */
        case 0x4: /* 100b = 2 front, 1 rear */
          channels = 3;
          break;
        case 0x5: /* 101b = 3 front, 1 rear */
        case 0x6: /* 110b = 2 front, 2 rear */
          channels = 4;
          break;
        case 0x7: /* 111b = 3 front, 2 rear */
          channels = 5;
          break;
        default:
          /* whaaaaaaaaaaaaaa!!!!!!!!!!! */
          g_assert (0);
      }
      /* fetch LFE bit (subwoofer) */
      mask = 0x10;
      if (acmod & 0x1 && acmod != 0x1) /* 3 front speakers? */
        mask >>= 2;
      if (acmod & 0x4) /* surround channel? */
        mask >>= 2;
      if (acmod == 0x2) /* 2/0 mode? */
        mask >>= 2;
      if (channeldata & mask) /* LFE: do we have a subwoofer channel? */
        channels++;
      /* if we don't have the whole frame... */
      if ((size - offset) < bpf) {
	GST_DEBUG ("ac3parse: partial buffer needed %ld < %d ",size-offset, bpf);
	break;
      } else {
        gboolean need_capsnego = FALSE;

	outbuf = gst_buffer_create_sub (ac3parse->partialbuf,offset,bpf);

        /* make sure our properties still match */
        if (channels > 0 && ac3parse->channels != channels) {
          ac3parse->channels = channels;
          need_capsnego = TRUE;
        }
        if (sample_rate > 0 && ac3parse->sample_rate != sample_rate) {
          ac3parse->sample_rate = sample_rate;
          need_capsnego = TRUE;
        }
        if (need_capsnego) {
          GstCaps *newcaps;
          newcaps = gst_caps_new_simple ("audio/x-ac3",
	      "channels", G_TYPE_INT, channels,
	      "rate",     G_TYPE_INT, sample_rate, NULL);
          gst_pad_set_explicit_caps (ac3parse->srcpad, newcaps);
        }

	offset += bpf;
	if (ac3parse->skip == 0 && GST_PAD_IS_LINKED(ac3parse->srcpad)) {
	  GST_DEBUG ("ac3parse: pushing buffer of %d bytes",GST_BUFFER_SIZE(outbuf));
          gst_pad_push(ac3parse->srcpad,GST_DATA (outbuf));
	}
	else {
	  GST_DEBUG ("ac3parse: skipping buffer of %d bytes",GST_BUFFER_SIZE(outbuf));
          gst_buffer_unref(outbuf);
	  ac3parse->skip--;
	}
      }
    } else {
      offset++;
      fprintf(stderr, "ac3parse: *** wrong header, skipping byte (FIXME?)\n");
    }
  }
  /* if we have processed this block and there are still */
  /* bytes left not in a partial block, copy them over. */
  if (size-offset > 0) {
    gint remainder = (size - offset);
    GST_DEBUG ("ac3parse: partial buffer needed %d for trailing bytes",remainder);

    outbuf = gst_buffer_create_sub(ac3parse->partialbuf,offset,remainder);
    gst_buffer_unref(ac3parse->partialbuf);
    ac3parse->partialbuf = outbuf;
  }
}

static void
gst_ac3parse_set_property (GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec)
{
  GstAc3Parse *src;

  /* it's not null if we got it, but it might not be ours */
  g_return_if_fail(GST_IS_AC3PARSE(object));
  src = GST_AC3PARSE(object);

  switch (prop_id) {
    case ARG_SKIP:
      src->skip = g_value_get_int (value);
      break;
    default:
      break;
  }
}

static void
gst_ac3parse_get_property (GObject *object, guint prop_id, GValue *value, GParamSpec *pspec)
{
  GstAc3Parse *src;

  /* it's not null if we got it, but it might not be ours */
  g_return_if_fail(GST_IS_AC3PARSE(object));
  src = GST_AC3PARSE(object);

  switch (prop_id) {
    case ARG_SKIP:
      g_value_set_int (value, src->skip);
      break;
    default:
      break;
  }
}

static GstElementStateReturn
gst_ac3parse_change_state (GstElement *element)
{
  GstAc3Parse *ac3parse = GST_AC3PARSE(element);

  switch (GST_STATE_TRANSITION (element)) {
    case GST_STATE_PAUSED_TO_READY:
      /* reset stream info */
      ac3parse->channels = ac3parse->sample_rate = -1;
      break;
  }

  if (GST_ELEMENT_CLASS (parent_class)->change_state)
    return GST_ELEMENT_CLASS (parent_class)->change_state (element);

  return GST_STATE_SUCCESS;
}

static gboolean
plugin_init (GstPlugin *plugin)
{
  if(!gst_element_register(plugin, "ac3parse", GST_RANK_SECONDARY,
      GST_TYPE_AC3PARSE)){
    return FALSE;
  }

  return TRUE;
}

GST_PLUGIN_DEFINE(
  GST_VERSION_MAJOR,
  GST_VERSION_MINOR,
  "ac3parse",
  "ac3 parsing",
  plugin_init,
  VERSION,
  "LGPL",
  GST_PACKAGE,
  GST_ORIGIN
)