gstreamer/gst-libs/gst/pbutils/codec-utils.c

/* GStreamer base utils library codec-specific utility functions
 * Copyright (C) 2010 Arun Raghavan <arun.raghavan@collabora.co.uk>
 *               2010 Collabora Multimedia
 *               2010 Nokia Corporation
 *
 * 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:gstpbutilscodecutils
 * @short_description: Miscellaneous codec-specific utility functions
 *
 * <refsect2>
 * <para>
 * Provides numerous codec-specific ulility functions such as functions to
 * provide the codec profile and level in human-readable string form from
 * header data.
 * </para>
 * </refsect2>
 */

#include "pbutils.h"

#define GST_SIMPLE_CAPS_HAS_NAME(caps,name) \
    gst_structure_has_name(gst_caps_get_structure((caps),0),(name))

#define GST_SIMPLE_CAPS_HAS_FIELD(caps,field) \
    gst_structure_has_field(gst_caps_get_structure((caps),0),(field))

/**
 * gst_codec_utils_aac_get_sample_rate_from_index:
 * @sr_idx: Sample rate index as from the AudioSpecificConfig (MPEG-4
 *          container) or ADTS frame header
 *
 * Translates the sample rate index found in AAC headers to the actual sample
 * rate.
 *
 * Returns: The sample rate if @sr_idx is valid, 0 otherwise.
 */
guint
gst_codec_utils_aac_get_sample_rate_from_index (guint sr_idx)
{
  static const guint aac_sample_rates[] = { 96000, 88200, 64000, 48000, 44100,
    32000, 24000, 22050, 16000, 12000, 11025, 8000
  };

  if (G_LIKELY (sr_idx < G_N_ELEMENTS (aac_sample_rates)))
    return aac_sample_rates[sr_idx];

  GST_WARNING ("Invalid sample rate index %u", sr_idx);
  return 0;
}

/**
 * gst_codec_utils_aac_get_profile:
 * @audio_config: a pointer to the AudioSpecificConfig as specified in the
 *                Elementary Stream Descriptor (esds) in ISO/IEC 14496-1 (see
 *                below for a more details).
 * @len: Length of @audio_config in bytes
 *
 * Returns the profile of the given AAC stream as a string. The profile is
 * determined using the AudioObjectType field which is in the first 5 bits of
 * @audio_config.
 *
 * <note>
 * HE-AAC support has not yet been implemented.
 * </note>
 *
 * Returns: The profile as a const string and NULL if the profile could not be
 * determined.
 */
const gchar *
gst_codec_utils_aac_get_profile (const guint8 * audio_config, guint len)
{
  guint profile;

  if (len < 1)
    return NULL;

  profile = audio_config[0] >> 3;
  switch (profile) {
    case 1:
      return "main";
    case 2:
      return "lc";
    case 3:
      return "ssr";
    case 4:
      return "ltp";
    default:
      break;
  }

  GST_DEBUG ("Invalid profile idx: %u", profile);
  return NULL;
}

/**
 * gst_codec_utils_aac_get_level:
 * @audio_config: a pointer to the AudioSpecificConfig as specified in the
 *                Elementary Stream Descriptor (esds) in ISO/IEC 14496-1 (see
 *                below for a more detailed description).
 * @len: Length of @audio_config in bytes
 *
 * Determines the level of a stream as defined in ISO/IEC 14496-3. For AAC LC
 * streams, the constraints from the AAC audio profile are applied. For AAC
 * Main, LTP, SSR and others, the Main profile is used.
 *
 * The @audio_config parameter follows the following format, starting from the
 * most significant bit of the first byte:
 *
 * Bit 0:4 contains the AudioObjectType
 * Bit 5:8 contains the sample frequency index (if this is 0xf, then the next
 *         24 bits define the actual sample frequency, and subsequent fields
 *         are appropriately shifted).
 * Bit 9:12 contains the channel configuration
 *
 * <note>
 * HE-AAC support has not yet been implemented.
 * </note>
 *
 * Returns: The level as a const string and NULL if the level could not be
 * determined.
 */
const gchar *
gst_codec_utils_aac_get_level (const guint8 * audio_config, guint len)
{
  int profile, sr_idx, channel_config, rate;
  /* Number of single channel elements, channel pair elements, low frequency
   * elements, independently switched coupling channel elements, and
   * dependently switched coupling channel elements.
   *
   * Note: The 2 CCE types are ignored for now as they require us to actually
   * parse the first frame, and they are rarely found in actual streams.
   */
  int num_sce = 0, num_cpe = 0, num_lfe = 0, num_cce_indep = 0, num_cce_dep = 0;
  int num_channels;
  /* Processor and RAM Complexity Units (calculated and "reference" for single
   * channel) */
  int pcu, rcu, pcu_ref, rcu_ref;
  int ret = -1;

  g_return_val_if_fail (audio_config != NULL, NULL);

  if (len < 2)
    return NULL;

  profile = audio_config[0] >> 3;
  /* FIXME: add support for sr_idx = 0xf */
  sr_idx = ((audio_config[0] & 0x7) << 1) | ((audio_config[1] & 0x80) >> 7);
  rate = gst_codec_utils_aac_get_sample_rate_from_index (sr_idx);
  channel_config = (audio_config[1] & 0x7f) >> 3;

  if (rate == 0)
    return NULL;

  switch (channel_config) {
    case 0:
      /* Channel config is defined in the AudioObjectType's SpecificConfig,
       * which requires some amount of digging through the headers. I only see
       * this done in the MPEG conformance streams - FIXME */
      GST_WARNING ("Found a stream with channel configuration in the "
          "AudioSpecificConfig. Please file a bug with a link to the media if "
          "possible.");
      return NULL;
    case 1:
      /* front center */
      num_sce = 1;
      break;
    case 2:
      /* front left and right */
      num_cpe = 1;
      break;
    case 3:
      /* front left, right, and center */
      num_sce = 1;
      num_cpe = 1;
      break;
    case 4:
      /* front left, right, and center; rear surround */
      num_sce = 2;
      num_cpe = 1;
      break;
    case 5:
      /* front left, right, and center; rear left and right surround */
      num_sce = 1;
      num_cpe = 2;
      break;
    case 6:
      /* front left, right, center and LFE; rear left and right surround */
      num_sce = 1;
      num_cpe = 2;
      break;
    case 7:
      /* front left, right, center and LFE; outside front left and right;
       * rear left and right surround */
      num_sce = 1;
      num_cpe = 3;
      num_lfe = 1;
      break;
    default:
      GST_WARNING ("Unknown channel config in header: %d", channel_config);
      return NULL;
  }

  switch (profile) {
    case 0:                    /* NULL */
      GST_WARNING ("profile 0 is not a valid profile");
      return NULL;
    case 2:                    /* LC */
      pcu_ref = 3;
      rcu_ref = 3;
      break;
    case 3:                    /* SSR */
      pcu_ref = 4;
      rcu_ref = 3;
      break;
    case 4:                    /* LTP */
      pcu_ref = 4;
      rcu_ref = 4;
      break;
    case 1:                    /* Main */
    default:
      /* Other than a couple of ER profiles, Main is the worst-case */
      pcu_ref = 5;
      rcu_ref = 5;
      break;
  }

  /* "fs_ref" is 48000 Hz for AAC Main/LC/SSR/LTP. SBR's fs_ref is defined as
   * 24000/48000 (in/out), for SBR streams. Actual support is a FIXME */

  pcu = ((float) rate / 48000) * pcu_ref *
      ((2 * num_cpe) + num_sce + num_lfe + num_cce_indep + (0.3 * num_cce_dep));

  rcu = ((float) rcu_ref) * (num_sce + (0.5 * num_lfe) + (0.5 * num_cce_indep) +
      (0.4 * num_cce_dep));

  if (num_cpe < 2)
    rcu += (rcu_ref + (rcu_ref - 1)) * num_cpe;
  else
    rcu += (rcu_ref + (rcu_ref - 1) * ((2 * num_cpe) - 1));

  num_channels = num_sce + (2 * num_cpe) + num_lfe;

  if (profile == 2) {
    /* AAC LC => return the level as per the 'AAC Profile' */
    if (num_channels <= 2 && rate <= 24000 && pcu <= 3 && rcu <= 5)
      ret = 1;
    else if (num_channels <= 2 && rate <= 48000 && pcu <= 6 && rcu <= 5)
      ret = 2;
    /* There is no level 3 for the AAC Profile */
    else if (num_channels <= 5 && rate <= 48000 && pcu <= 19 && rcu <= 15)
      ret = 4;
    else if (num_channels <= 5 && rate <= 96000 && pcu <= 38 && rcu <= 15)
      ret = 5;
  } else {
    /* Return the level as per the 'Main Profile' */
    if (pcu < 40 && rcu < 20)
      ret = 1;
    else if (pcu < 80 && rcu < 64)
      ret = 2;
    else if (pcu < 160 && rcu < 128)
      ret = 3;
    else if (pcu < 320 && rcu < 256)
      ret = 4;
  }

  if (ret == -1) {
    GST_WARNING ("couldn't determine level: profile=%u, rate=%u, "
        "channel_config=%u, pcu=%d,rcu=%d", profile, rate, channel_config, pcu,
        rcu);
    return NULL;
  } else {
    /* For fast and convenient int -> string conversion */
    static const char itoa[][2] = {
      "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"
    };

    g_assert (ret < G_N_ELEMENTS (itoa));
    return itoa[ret];
  }
}

/**
 * gst_codec_utils_aac_caps_set_level_and_profile:
 * @caps: the #GstCaps to which level and profile fields are to be added
 * @audio_config: a pointer to the AudioSpecificConfig as specified in the
 *                Elementary Stream Descriptor (esds) in ISO/IEC 14496-1 (see
 *                below for a more details).
 * @len: Length of @audio_config in bytes
 *
 * Sets the level and profile on @caps if it can be determined from
 * @audio_config. See #gst_codec_utils_aac_get_level() and
 * gst_codec_utils_aac_get_profile() for more details on the parameters.
 * @caps must be audio/mpeg caps with an "mpegversion" field of either 2 or 4.
 * If mpegversion is 4, the <tt>base-profile</tt> field is also set in @caps.
 *
 * Returns: TRUE if the level and profile could be set, FALSE otherwise.
 */
gboolean
gst_codec_utils_aac_caps_set_level_and_profile (GstCaps * caps,
    const guint8 * audio_config, guint len)
{
  GstStructure *s;
  const gchar *level, *profile;
  int mpegversion = 0;

  g_return_val_if_fail (GST_IS_CAPS (caps), FALSE);
  g_return_val_if_fail (GST_CAPS_IS_SIMPLE (caps), FALSE);
  g_return_val_if_fail (GST_SIMPLE_CAPS_HAS_NAME (caps, "audio/mpeg"), FALSE);
  g_return_val_if_fail (GST_SIMPLE_CAPS_HAS_FIELD (caps, "mpegversion"), FALSE);
  g_return_val_if_fail (audio_config != NULL, FALSE);

  s = gst_caps_get_structure (caps, 0);

  gst_structure_get_int (s, "mpegversion", &mpegversion);
  g_return_val_if_fail (mpegversion == 2 || mpegversion == 4, FALSE);

  level = gst_codec_utils_aac_get_level (audio_config, len);

  if (level != NULL)
    gst_structure_set (s, "level", G_TYPE_STRING, level, NULL);

  profile = gst_codec_utils_aac_get_profile (audio_config, len);

  if (profile != NULL) {
    if (mpegversion == 4) {
      gst_structure_set (s, "base-profile", G_TYPE_STRING, profile,
          "profile", G_TYPE_STRING, profile, NULL);
    } else {
      gst_structure_set (s, "profile", G_TYPE_STRING, profile, NULL);
    }
  }

  return (level != NULL && profile != NULL);
}