static GstFlowReturn
gst_rtp_mpv_pay_flush (GstRTPMPVPay * rtpmpvpay)
{
  GstFlowReturn ret;
  guint avail;
  GstBufferList *list;
  GstBuffer *outbuf;

  guint8 *payload;

  avail = gst_adapter_available (rtpmpvpay->adapter);

  ret = GST_FLOW_OK;

  list =
      gst_buffer_list_new_sized (avail / (GST_RTP_BASE_PAYLOAD_MTU (rtpmpvpay) -
          RTP_HEADER_LEN) + 1);

  while (avail > 0) {
    guint towrite;
    guint packet_len;
    guint payload_len;
    GstRTPBuffer rtp = { NULL };
    GstBuffer *paybuf;

    packet_len = gst_rtp_buffer_calc_packet_len (avail + 4, 0, 0);

    towrite = MIN (packet_len, GST_RTP_BASE_PAYLOAD_MTU (rtpmpvpay));

    payload_len = gst_rtp_buffer_calc_payload_len (towrite, 0, 0);

    outbuf = gst_rtp_buffer_new_allocate (4, 0, 0);

    payload_len -= 4;

    gst_rtp_buffer_map (outbuf, GST_MAP_WRITE, &rtp);

    payload = gst_rtp_buffer_get_payload (&rtp);
    /* enable MPEG Video-specific header
     *
     *  0                   1                   2                   3
     *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     * |    MBZ  |T|         TR        | |N|S|B|E|  P  | | BFC | | FFC |
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *                                  AN              FBV     FFV
     */

    /* fill in the MPEG Video-specific header 
     * data is set to 0x0 here
     */
    memset (payload, 0x0, 4);

    avail -= payload_len;

    gst_rtp_buffer_set_marker (&rtp, avail == 0);
    gst_rtp_buffer_unmap (&rtp);

    paybuf = gst_adapter_take_buffer_fast (rtpmpvpay->adapter, payload_len);
    gst_rtp_copy_meta (GST_ELEMENT_CAST (rtpmpvpay), outbuf, paybuf,
        g_quark_from_static_string (GST_META_TAG_VIDEO_STR));
    outbuf = gst_buffer_append (outbuf, paybuf);

    GST_BUFFER_PTS (outbuf) = rtpmpvpay->first_ts;
    gst_buffer_list_add (list, outbuf);
  }

  ret = gst_rtp_base_payload_push_list (GST_RTP_BASE_PAYLOAD (rtpmpvpay), list);

  return ret;
}
Exemple #2
0
static GstFlowReturn
gst_rtp_mp4g_pay_flush (GstRtpMP4GPay * rtpmp4gpay)
{
  guint avail, total;
  GstBuffer *outbuf;
  GstFlowReturn ret;
  guint mtu;

  /* the data available in the adapter is either smaller
   * than the MTU or bigger. In the case it is smaller, the complete
   * adapter contents can be put in one packet. In the case the
   * adapter has more than one MTU, we need to fragment the MPEG data
   * over multiple packets. */
  total = avail = gst_adapter_available (rtpmp4gpay->adapter);

  ret = GST_FLOW_OK;
  mtu = GST_RTP_BASE_PAYLOAD_MTU (rtpmp4gpay);

  while (avail > 0) {
    guint towrite;
    guint8 *payload;
    guint payload_len;
    guint packet_len;
    GstRTPBuffer rtp = { NULL };

    /* this will be the total lenght of the packet */
    packet_len = gst_rtp_buffer_calc_packet_len (avail, 0, 0);

    /* fill one MTU or all available bytes, we need 4 spare bytes for
     * the AU header. */
    towrite = MIN (packet_len, mtu - 4);

    /* this is the payload length */
    payload_len = gst_rtp_buffer_calc_payload_len (towrite, 0, 0);

    GST_DEBUG_OBJECT (rtpmp4gpay,
        "avail %d, towrite %d, packet_len %d, payload_len %d", avail, towrite,
        packet_len, payload_len);

    /* create buffer to hold the payload, also make room for the 4 header bytes. */
    outbuf = gst_rtp_buffer_new_allocate (payload_len + 4, 0, 0);

    gst_rtp_buffer_map (outbuf, GST_MAP_WRITE, &rtp);

    /* copy payload */
    payload = gst_rtp_buffer_get_payload (&rtp);

    /* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- .. -+-+-+-+-+-+-+-+-+-+
     * |AU-headers-length|AU-header|AU-header|      |AU-header|padding|
     * |                 |   (1)   |   (2)   |      |   (n)   | bits  |
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- .. -+-+-+-+-+-+-+-+-+-+
     */
    /* AU-headers-length, we only have 1 AU-header */
    payload[0] = 0x00;
    payload[1] = 0x10;          /* we use 16 bits for the header */

    /* +---------------------------------------+
     * |     AU-size                           |
     * +---------------------------------------+
     * |     AU-Index / AU-Index-delta         |
     * +---------------------------------------+
     * |     CTS-flag                          |
     * +---------------------------------------+
     * |     CTS-delta                         |
     * +---------------------------------------+
     * |     DTS-flag                          |
     * +---------------------------------------+
     * |     DTS-delta                         |
     * +---------------------------------------+
     * |     RAP-flag                          |
     * +---------------------------------------+
     * |     Stream-state                      |
     * +---------------------------------------+
     */
    /* The AU-header, no CTS, DTS, RAP, Stream-state 
     *
     * AU-size is always the total size of the AU, not the fragmented size 
     */
    payload[2] = (total & 0x1fe0) >> 5;
    payload[3] = (total & 0x1f) << 3;   /* we use 13 bits for the size, 3 bits index */

    /* copy stuff from adapter to payload */
    gst_adapter_copy (rtpmp4gpay->adapter, &payload[4], 0, payload_len);
    gst_adapter_flush (rtpmp4gpay->adapter, payload_len);

    /* marker only if the packet is complete */
    gst_rtp_buffer_set_marker (&rtp, avail <= payload_len);

    gst_rtp_buffer_unmap (&rtp);

    GST_BUFFER_TIMESTAMP (outbuf) = rtpmp4gpay->first_timestamp;
    GST_BUFFER_DURATION (outbuf) = rtpmp4gpay->first_duration;

    if (rtpmp4gpay->frame_len) {
      GST_BUFFER_OFFSET (outbuf) = rtpmp4gpay->offset;
      rtpmp4gpay->offset += rtpmp4gpay->frame_len;
    }

    ret = gst_rtp_base_payload_push (GST_RTP_BASE_PAYLOAD (rtpmp4gpay), outbuf);

    avail -= payload_len;
  }

  return ret;
}
static GstFlowReturn
gst_rtp_ac3_pay_flush (GstRtpAC3Pay * rtpac3pay)
{
  guint avail, FT, NF, mtu;
  GstBuffer *outbuf;
  GstFlowReturn ret;

  /* the data available in the adapter is either smaller
   * than the MTU or bigger. In the case it is smaller, the complete
   * adapter contents can be put in one packet. In the case the
   * adapter has more than one MTU, we need to split the AC3 data
   * over multiple packets. */
  avail = gst_adapter_available (rtpac3pay->adapter);

  ret = GST_FLOW_OK;

  FT = 0;
  /* number of frames */
  NF = rtpac3pay->NF;

  mtu = GST_RTP_BASE_PAYLOAD_MTU (rtpac3pay);

  GST_LOG_OBJECT (rtpac3pay, "flushing %u bytes", avail);

  while (avail > 0) {
    guint towrite;
    guint8 *payload;
    guint payload_len;
    guint packet_len;
    GstRTPBuffer rtp = { NULL, };
    GstBuffer *payload_buffer;

    /* this will be the total length of the packet */
    packet_len = gst_rtp_buffer_calc_packet_len (2 + avail, 0, 0);

    /* fill one MTU or all available bytes */
    towrite = MIN (packet_len, mtu);

    /* this is the payload length */
    payload_len = gst_rtp_buffer_calc_payload_len (towrite, 0, 0);

    /* create buffer to hold the payload */
    outbuf = gst_rtp_buffer_new_allocate (2, 0, 0);

    if (FT == 0) {
      /* check if it all fits */
      if (towrite < packet_len) {
        guint maxlen;

        GST_LOG_OBJECT (rtpac3pay, "we need to fragment");
        /* check if we will be able to put at least 5/8th of the total
         * frame in this first frame. */
        if ((avail * 5) / 8 >= (payload_len - 2))
          FT = 1;
        else
          FT = 2;
        /* check how many fragments we will need */
        maxlen = gst_rtp_buffer_calc_payload_len (mtu - 2, 0, 0);
        NF = (avail + maxlen - 1) / maxlen;
      }
    } else if (FT != 3) {
      /* remaining fragment */
      FT = 3;
    }

    /*
     *  0                   1
     *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     * |    MBZ    | FT|       NF      |
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     *
     * FT: 0: one or more complete frames
     *     1: initial 5/8 fragment
     *     2: initial fragment not 5/8
     *     3: other fragment
     * NF: amount of frames if FT = 0, else number of fragments.
     */
    gst_rtp_buffer_map (outbuf, GST_MAP_WRITE, &rtp);
    GST_LOG_OBJECT (rtpac3pay, "FT %u, NF %u", FT, NF);
    payload = gst_rtp_buffer_get_payload (&rtp);
    payload[0] = (FT & 3);
    payload[1] = NF;
    payload_len -= 2;

    if (avail == payload_len)
      gst_rtp_buffer_set_marker (&rtp, TRUE);
    gst_rtp_buffer_unmap (&rtp);

    payload_buffer =
        gst_adapter_take_buffer_fast (rtpac3pay->adapter, payload_len);
    gst_rtp_copy_meta (GST_ELEMENT_CAST (rtpac3pay), outbuf, payload_buffer,
        g_quark_from_static_string (GST_META_TAG_AUDIO_STR));

    outbuf = gst_buffer_append (outbuf, payload_buffer);

    avail -= payload_len;

    GST_BUFFER_PTS (outbuf) = rtpac3pay->first_ts;
    GST_BUFFER_DURATION (outbuf) = rtpac3pay->duration;

    ret = gst_rtp_base_payload_push (GST_RTP_BASE_PAYLOAD (rtpac3pay), outbuf);
  }

  return ret;
}
Exemple #4
0
static GstFlowReturn
gst_rtp_asf_pay_handle_packet (GstRtpAsfPay * rtpasfpay, GstBuffer * buffer)
{
    GstRTPBasePayload *rtppay;
    GstAsfPacketInfo *packetinfo;
    guint8 flags;
    guint8 *data;
    guint32 packet_util_size;
    guint32 packet_offset;
    guint32 size_left;
    GstFlowReturn ret = GST_FLOW_OK;

    rtppay = GST_RTP_BASE_PAYLOAD (rtpasfpay);
    packetinfo = &rtpasfpay->packetinfo;

    if (!gst_asf_parse_packet (buffer, packetinfo, TRUE,
                               rtpasfpay->asfinfo.packet_size)) {
        GST_ERROR_OBJECT (rtpasfpay, "Error while parsing asf packet");
        gst_buffer_unref (buffer);
        return GST_FLOW_ERROR;
    }

    if (packetinfo->packet_size == 0)
        packetinfo->packet_size = rtpasfpay->asfinfo.packet_size;

    GST_LOG_OBJECT (rtpasfpay, "Packet size: %" G_GUINT32_FORMAT
                    ", padding: %" G_GUINT32_FORMAT, packetinfo->packet_size,
                    packetinfo->padding);

    /* update padding field to 0 */
    if (packetinfo->padding > 0) {
        GstAsfPacketInfo info;
        /* find padding field offset */
        guint offset = packetinfo->err_cor_len + 2 +
                       gst_asf_get_var_size_field_len (packetinfo->packet_field_type) +
                       gst_asf_get_var_size_field_len (packetinfo->seq_field_type);
        buffer = gst_buffer_make_writable (buffer);
        switch (packetinfo->padd_field_type) {
        case ASF_FIELD_TYPE_DWORD:
            gst_buffer_memset (buffer, offset, 0, 4);
            break;
        case ASF_FIELD_TYPE_WORD:
            gst_buffer_memset (buffer, offset, 0, 2);
            break;
        case ASF_FIELD_TYPE_BYTE:
            gst_buffer_memset (buffer, offset, 0, 1);
            break;
        case ASF_FIELD_TYPE_NONE:
        default:
            break;
        }
        gst_asf_parse_packet (buffer, &info, FALSE, 0);
    }

    if (packetinfo->padding != 0)
        packet_util_size = rtpasfpay->asfinfo.packet_size - packetinfo->padding;
    else
        packet_util_size = packetinfo->packet_size;
    packet_offset = 0;
    while (packet_util_size > 0) {
        /* Even if we don't fill completely an output buffer we
         * push it when we add an fragment. Because it seems that
         * it is not possible to determine where a asf packet
         * fragment ends inside a rtp packet payload.
         * This flag tells us to push the packet.
         */
        gboolean force_push = FALSE;
        GstRTPBuffer rtp;

        /* we have no output buffer pending, create one */
        if (rtpasfpay->current == NULL) {
            GST_LOG_OBJECT (rtpasfpay, "Creating new output buffer");
            rtpasfpay->current =
                gst_rtp_buffer_new_allocate_len (GST_RTP_BASE_PAYLOAD_MTU (rtpasfpay),
                                                 0, 0);
            rtpasfpay->cur_off = 0;
            rtpasfpay->has_ts = FALSE;
            rtpasfpay->marker = FALSE;
        }
        gst_rtp_buffer_map (rtpasfpay->current, GST_MAP_READWRITE, &rtp);
        data = gst_rtp_buffer_get_payload (&rtp);
        data += rtpasfpay->cur_off;
        size_left = gst_rtp_buffer_get_payload_len (&rtp) - rtpasfpay->cur_off;

        GST_DEBUG_OBJECT (rtpasfpay, "Input buffer bytes consumed: %"
                          G_GUINT32_FORMAT "/%" G_GSIZE_FORMAT, packet_offset,
                          gst_buffer_get_size (buffer));

        GST_DEBUG_OBJECT (rtpasfpay, "Output rtpbuffer status");
        GST_DEBUG_OBJECT (rtpasfpay, "Current offset: %" G_GUINT32_FORMAT,
                          rtpasfpay->cur_off);
        GST_DEBUG_OBJECT (rtpasfpay, "Size left: %" G_GUINT32_FORMAT, size_left);
        GST_DEBUG_OBJECT (rtpasfpay, "Has ts: %s",
                          rtpasfpay->has_ts ? "yes" : "no");
        if (rtpasfpay->has_ts) {
            GST_DEBUG_OBJECT (rtpasfpay, "Ts: %" G_GUINT32_FORMAT, rtpasfpay->ts);
        }

        flags = 0;
        if (packetinfo->has_keyframe) {
            flags = flags | 0x80;
        }
        flags = flags | 0x20;       /* Relative timestamp is present */

        if (!rtpasfpay->has_ts) {
            /* this is the first asf packet, its send time is the
             * rtp packet timestamp */
            rtpasfpay->has_ts = TRUE;
            rtpasfpay->ts = packetinfo->send_time;
        }

        if (size_left >= packet_util_size + 8) {
            /* enough space for the rest of the packet */
            if (packet_offset == 0) {
                flags = flags | 0x40;
                GST_WRITE_UINT24_BE (data + 1, packet_util_size);
            } else {
                GST_WRITE_UINT24_BE (data + 1, packet_offset);
                force_push = TRUE;
            }
            data[0] = flags;
            GST_WRITE_UINT32_BE (data + 4,
                                 (gint32) (packetinfo->send_time) - (gint32) rtpasfpay->ts);
            gst_buffer_extract (buffer, packet_offset, data + 8, packet_util_size);

            /* updating status variables */
            rtpasfpay->cur_off += 8 + packet_util_size;
            size_left -= packet_util_size + 8;
            packet_offset += packet_util_size;
            packet_util_size = 0;
            rtpasfpay->marker = TRUE;
        } else {
            /* fragment packet */
            data[0] = flags;
            GST_WRITE_UINT24_BE (data + 1, packet_offset);
            GST_WRITE_UINT32_BE (data + 4,
                                 (gint32) (packetinfo->send_time) - (gint32) rtpasfpay->ts);
            gst_buffer_extract (buffer, packet_offset, data + 8, size_left - 8);

            /* updating status variables */
            rtpasfpay->cur_off += size_left;
            packet_offset += size_left - 8;
            packet_util_size -= size_left - 8;
            size_left = 0;
            force_push = TRUE;
        }

        /* there is not enough room for any more buffers */
        if (force_push || size_left <= 8) {

            gst_rtp_buffer_set_ssrc (&rtp, rtppay->current_ssrc);
            gst_rtp_buffer_set_marker (&rtp, rtpasfpay->marker);
            gst_rtp_buffer_set_payload_type (&rtp, GST_RTP_BASE_PAYLOAD_PT (rtppay));
            gst_rtp_buffer_set_seq (&rtp, rtppay->seqnum + 1);
            gst_rtp_buffer_set_timestamp (&rtp, packetinfo->send_time);
            gst_rtp_buffer_unmap (&rtp);

            /* trim remaining bytes not used */
            if (size_left != 0) {
                gst_buffer_set_size (rtpasfpay->current,
                                     gst_buffer_get_size (rtpasfpay->current) - size_left);
            }

            GST_BUFFER_TIMESTAMP (rtpasfpay->current) = GST_BUFFER_TIMESTAMP (buffer);

            rtppay->seqnum++;
            rtppay->timestamp = packetinfo->send_time;

            GST_DEBUG_OBJECT (rtpasfpay, "Pushing rtp buffer");
            ret =
                gst_pad_push (GST_RTP_BASE_PAYLOAD_SRCPAD (rtppay),
                              rtpasfpay->current);
            rtpasfpay->current = NULL;
            if (ret != GST_FLOW_OK) {
                gst_buffer_unref (buffer);
                return ret;
            }
        }
    }
    gst_buffer_unref (buffer);
    return ret;
}
Exemple #5
0
static GstFlowReturn
gst_rtp_h263p_pay_flush (GstRtpH263PPay * rtph263ppay)
{
  guint avail;
  GstBuffer *outbuf;
  GstFlowReturn ret;
  gboolean fragmented;

  avail = gst_adapter_available (rtph263ppay->adapter);
  if (avail == 0)
    return GST_FLOW_OK;

  fragmented = FALSE;
  /* This algorithm assumes the H263/+/++ encoder sends complete frames in each
   * buffer */
  /* With Fragmentation Mode at GST_FRAGMENTATION_MODE_NORMAL:
   *  This algorithm implements the Follow-on packets method for packetization.
   *  This assumes low packet loss network. 
   * With Fragmentation Mode at GST_FRAGMENTATION_MODE_SYNC:
   *  This algorithm separates large frames at synchronisation points (Segments)
   *  (See RFC 4629 section 6). It would be interesting to have a property such as network
   *  quality to select between both packetization methods */
  /* TODO Add VRC supprt (See RFC 4629 section 5.2) */

  while (avail > 0) {
    guint towrite;
    guint8 *payload;
    guint payload_len;
    gint header_len;
    guint next_gop = 0;
    gboolean found_gob = FALSE;
    GstRTPBuffer rtp = { NULL };

    if (rtph263ppay->fragmentation_mode == GST_FRAGMENTATION_MODE_SYNC) {
      /* start after 1st gop possible */
      guint parsed_len = 3;
      const guint8 *parse_data = NULL;

      parse_data = gst_adapter_map (rtph263ppay->adapter, avail);

      /* Check if we have a gob or eos , eossbs */
      /* FIXME EOS and EOSSBS packets should never contain any gobs and vice-versa */
      if (avail >= 3 && *parse_data == 0 && *(parse_data + 1) == 0
          && *(parse_data + 2) >= 0x80) {
        GST_DEBUG_OBJECT (rtph263ppay, " Found GOB header");
        found_gob = TRUE;
      }
      /* Find next and cut the packet accordingly */
      /* TODO we should get as many gobs as possible until MTU is reached, this
       * code seems to just get one GOB per packet */
      while (parsed_len + 2 < avail) {
        if (parse_data[parsed_len] == 0 && parse_data[parsed_len + 1] == 0
            && parse_data[parsed_len + 2] >= 0x80) {
          next_gop = parsed_len;
          GST_DEBUG_OBJECT (rtph263ppay, " Next GOB Detected at :  %d",
              next_gop);
          break;
        }
        parsed_len++;
      }
      gst_adapter_unmap (rtph263ppay->adapter);
    }

    /* for picture start frames (non-fragmented), we need to remove the first
     * two 0x00 bytes and set P=1 */
    header_len = (fragmented && !found_gob) ? 2 : 0;

    towrite = MIN (avail, gst_rtp_buffer_calc_payload_len
        (GST_RTP_BASE_PAYLOAD_MTU (rtph263ppay) - header_len, 0, 0));

    if (next_gop > 0)
      towrite = MIN (next_gop, towrite);

    payload_len = header_len + towrite;

    outbuf = gst_rtp_buffer_new_allocate (payload_len, 0, 0);

    gst_rtp_buffer_map (outbuf, GST_MAP_WRITE, &rtp);
    /* last fragment gets the marker bit set */
    gst_rtp_buffer_set_marker (&rtp, avail > towrite ? 0 : 1);

    payload = gst_rtp_buffer_get_payload (&rtp);

    gst_adapter_copy (rtph263ppay->adapter, &payload[header_len], 0, towrite);

    /*  0                   1
     *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     * |   RR    |P|V|   PLEN    |PEBIT|
     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     */
    /* if fragmented or gop header , write p bit =1 */
    payload[0] = (fragmented && !found_gob) ? 0x00 : 0x04;
    payload[1] = 0;

    GST_BUFFER_TIMESTAMP (outbuf) = rtph263ppay->first_timestamp;
    GST_BUFFER_DURATION (outbuf) = rtph263ppay->first_duration;
    gst_rtp_buffer_unmap (&rtp);

    gst_adapter_flush (rtph263ppay->adapter, towrite);

    ret =
        gst_rtp_base_payload_push (GST_RTP_BASE_PAYLOAD (rtph263ppay), outbuf);

    avail -= towrite;
    fragmented = TRUE;
  }

  return ret;
}
static GstFlowReturn
gst_rtp_vraw_pay_handle_buffer (GstRTPBasePayload * payload, GstBuffer * buffer)
{
  GstRtpVRawPay *rtpvrawpay;
  GstFlowReturn ret = GST_FLOW_OK;
  gfloat packets_per_packline;
  guint pgroups_per_packet;
  guint packlines_per_list, buffers_per_list;
  guint lines_delay;            /* after how many packed lines we push out a buffer list */
  guint last_line;              /* last pack line number we pushed out a buffer list     */
  guint line, offset;
  guint8 *p0, *yp, *up, *vp;
  guint ystride, uvstride;
  guint xinc, yinc;
  guint pgroup;
  guint mtu;
  guint width, height;
  gint field, fields;
  GstVideoFormat format;
  GstVideoFrame frame;
  gint interlaced;
  gboolean use_buffer_lists;
  GstBufferList *list = NULL;
  GstRTPBuffer rtp = { NULL, };

  rtpvrawpay = GST_RTP_VRAW_PAY (payload);

  if (!gst_video_frame_map (&frame, &rtpvrawpay->vinfo, buffer, GST_MAP_READ)) {
    gst_buffer_unref (buffer);
    return GST_FLOW_ERROR;
  }

  GST_LOG_OBJECT (rtpvrawpay, "new frame of %" G_GSIZE_FORMAT " bytes",
      gst_buffer_get_size (buffer));

  /* get pointer and strides of the planes */
  p0 = GST_VIDEO_FRAME_PLANE_DATA (&frame, 0);
  yp = GST_VIDEO_FRAME_COMP_DATA (&frame, 0);
  up = GST_VIDEO_FRAME_COMP_DATA (&frame, 1);
  vp = GST_VIDEO_FRAME_COMP_DATA (&frame, 2);

  ystride = GST_VIDEO_FRAME_COMP_STRIDE (&frame, 0);
  uvstride = GST_VIDEO_FRAME_COMP_STRIDE (&frame, 1);

  mtu = GST_RTP_BASE_PAYLOAD_MTU (payload);

  /* amount of bytes for one pixel */
  pgroup = rtpvrawpay->pgroup;
  width = GST_VIDEO_INFO_WIDTH (&rtpvrawpay->vinfo);
  height = GST_VIDEO_INFO_HEIGHT (&rtpvrawpay->vinfo);

  interlaced = GST_VIDEO_INFO_IS_INTERLACED (&rtpvrawpay->vinfo);

  format = GST_VIDEO_INFO_FORMAT (&rtpvrawpay->vinfo);

  yinc = rtpvrawpay->yinc;
  xinc = rtpvrawpay->xinc;

  /* after how many packed lines we push out a buffer list */
  lines_delay = GST_ROUND_UP_4 (height / rtpvrawpay->chunks_per_frame);

  /* calculate how many buffers we expect to store in a single buffer list */
  pgroups_per_packet = (mtu - (12 + 14)) / pgroup;
  packets_per_packline = width / (xinc * pgroups_per_packet * 1.0);
  packlines_per_list = height / (yinc * rtpvrawpay->chunks_per_frame);
  buffers_per_list = packlines_per_list * packets_per_packline;
  buffers_per_list = GST_ROUND_UP_8 (buffers_per_list);

  use_buffer_lists = buffers_per_list > 1 &&
      (rtpvrawpay->chunks_per_frame < (height / yinc));

  fields = 1 + interlaced;

  /* start with line 0, offset 0 */
  for (field = 0; field < fields; field++) {
    line = field;
    offset = 0;
    last_line = 0;

    if (use_buffer_lists)
      list = gst_buffer_list_new_sized (buffers_per_list);

    /* write all lines */
    while (line < height) {
      guint left, pack_line;
      GstBuffer *out;
      guint8 *outdata, *headers;
      gboolean next_line, complete = FALSE;
      guint length, cont, pixels;

      /* get the max allowed payload length size, we try to fill the complete MTU */
      left = gst_rtp_buffer_calc_payload_len (mtu, 0, 0);
      out = gst_rtp_buffer_new_allocate (left, 0, 0);

      if (field == 0) {
        GST_BUFFER_PTS (out) = GST_BUFFER_PTS (buffer);
      } else {
        GST_BUFFER_PTS (out) = GST_BUFFER_PTS (buffer) +
            GST_BUFFER_DURATION (buffer) / 2;
      }

      gst_rtp_buffer_map (out, GST_MAP_WRITE, &rtp);
      outdata = gst_rtp_buffer_get_payload (&rtp);

      GST_LOG_OBJECT (rtpvrawpay, "created buffer of size %u for MTU %u", left,
          mtu);

      /*
       *   0                   1                   2                   3
       *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       *  |   Extended Sequence Number    |            Length             |
       *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       *  |F|          Line No            |C|           Offset            |
       *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       *  |            Length             |F|          Line No            |
       *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       *  |C|           Offset            |                               .
       *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               .
       *  .                                                               .
       *  .                 Two (partial) lines of video data             .
       *  .                                                               .
       *  +---------------------------------------------------------------+
       */

      /* need 2 bytes for the extended sequence number */
      *outdata++ = 0;
      *outdata++ = 0;
      left -= 2;

      /* the headers start here */
      headers = outdata;

      /* make sure we can fit at least *one* header and pixel */
      if (!(left > (6 + pgroup))) {
        gst_rtp_buffer_unmap (&rtp);
        gst_buffer_unref (out);
        goto too_small;
      }

      /* while we can fit at least one header and one pixel */
      while (left > (6 + pgroup)) {
        /* we need a 6 bytes header */
        left -= 6;

        /* get how may bytes we need for the remaining pixels */
        pixels = width - offset;
        length = (pixels * pgroup) / xinc;

        if (left >= length) {
          /* pixels and header fit completely, we will write them and skip to the
           * next line. */
          next_line = TRUE;
        } else {
          /* line does not fit completely, see how many pixels fit */
          pixels = (left / pgroup) * xinc;
          length = (pixels * pgroup) / xinc;
          next_line = FALSE;
        }
        GST_LOG_OBJECT (rtpvrawpay, "filling %u bytes in %u pixels", length,
            pixels);
        left -= length;

        /* write length */
        *outdata++ = (length >> 8) & 0xff;
        *outdata++ = length & 0xff;

        /* write line no */
        *outdata++ = ((line >> 8) & 0x7f) | ((field << 7) & 0x80);
        *outdata++ = line & 0xff;

        if (next_line) {
          /* go to next line we do this here to make the check below easier */
          line += yinc;
        }

        /* calculate continuation marker */
        cont = (left > (6 + pgroup) && line < height) ? 0x80 : 0x00;

        /* write offset and continuation marker */
        *outdata++ = ((offset >> 8) & 0x7f) | cont;
        *outdata++ = offset & 0xff;

        if (next_line) {
          /* reset offset */
          offset = 0;
          GST_LOG_OBJECT (rtpvrawpay, "go to next line %u", line);
        } else {
          offset += pixels;
          GST_LOG_OBJECT (rtpvrawpay, "next offset %u", offset);
        }

        if (!cont)
          break;
      }
      GST_LOG_OBJECT (rtpvrawpay, "consumed %u bytes",
          (guint) (outdata - headers));

      /* second pass, read headers and write the data */
      while (TRUE) {
        guint offs, lin;

        /* read length and cont */
        length = (headers[0] << 8) | headers[1];
        lin = ((headers[2] & 0x7f) << 8) | headers[3];
        offs = ((headers[4] & 0x7f) << 8) | headers[5];
        cont = headers[4] & 0x80;
        pixels = length / pgroup;
        headers += 6;

        GST_LOG_OBJECT (payload,
            "writing length %u, line %u, offset %u, cont %d", length, lin, offs,
            cont);

        switch (format) {
          case GST_VIDEO_FORMAT_RGB:
          case GST_VIDEO_FORMAT_RGBA:
          case GST_VIDEO_FORMAT_BGR:
          case GST_VIDEO_FORMAT_BGRA:
          case GST_VIDEO_FORMAT_UYVY:
          case GST_VIDEO_FORMAT_UYVP:
            offs /= xinc;
            memcpy (outdata, p0 + (lin * ystride) + (offs * pgroup), length);
            outdata += length;
            break;
          case GST_VIDEO_FORMAT_AYUV:
          {
            gint i;
            guint8 *datap;

            datap = p0 + (lin * ystride) + (offs * 4);

            for (i = 0; i < pixels; i++) {
              *outdata++ = datap[2];
              *outdata++ = datap[1];
              *outdata++ = datap[3];
              datap += 4;
            }
            break;
          }
          case GST_VIDEO_FORMAT_I420:
          {
            gint i;
            guint uvoff;
            guint8 *yd1p, *yd2p, *udp, *vdp;

            yd1p = yp + (lin * ystride) + (offs);
            yd2p = yd1p + ystride;
            uvoff = (lin / yinc * uvstride) + (offs / xinc);
            udp = up + uvoff;
            vdp = vp + uvoff;

            for (i = 0; i < pixels; i++) {
              *outdata++ = *yd1p++;
              *outdata++ = *yd1p++;
              *outdata++ = *yd2p++;
              *outdata++ = *yd2p++;
              *outdata++ = *udp++;
              *outdata++ = *vdp++;
            }
            break;
          }
          case GST_VIDEO_FORMAT_Y41B:
          {
            gint i;
            guint uvoff;
            guint8 *ydp, *udp, *vdp;

            ydp = yp + (lin * ystride) + offs;
            uvoff = (lin / yinc * uvstride) + (offs / xinc);
            udp = up + uvoff;
            vdp = vp + uvoff;

            for (i = 0; i < pixels; i++) {
              *outdata++ = *udp++;
              *outdata++ = *ydp++;
              *outdata++ = *ydp++;
              *outdata++ = *vdp++;
              *outdata++ = *ydp++;
              *outdata++ = *ydp++;
            }
            break;
          }
          default:
            gst_rtp_buffer_unmap (&rtp);
            gst_buffer_unref (out);
            goto unknown_sampling;
        }

        if (!cont)
          break;
      }

      if (line >= height) {
        GST_LOG_OBJECT (rtpvrawpay, "field/frame complete, set marker");
        gst_rtp_buffer_set_marker (&rtp, TRUE);
        complete = TRUE;
      }
      gst_rtp_buffer_unmap (&rtp);
      if (left > 0) {
        GST_LOG_OBJECT (rtpvrawpay, "we have %u bytes left", left);
        gst_buffer_resize (out, 0, gst_buffer_get_size (out) - left);
      }

      gst_rtp_copy_video_meta (rtpvrawpay, out, buffer);

      /* Now either push out the buffer directly */
      if (!use_buffer_lists) {
        ret = gst_rtp_base_payload_push (payload, out);
        continue;
      }

      /* or add the buffer to buffer list ... */
      gst_buffer_list_add (list, out);

      /* .. and check if we need to push out the list */
      pack_line = (line - field) / fields;
      if (complete || (pack_line > last_line && pack_line % lines_delay == 0)) {
        GST_LOG_OBJECT (rtpvrawpay, "pushing list of %u buffers up to pack "
            "line %u", gst_buffer_list_length (list), pack_line);
        ret = gst_rtp_base_payload_push_list (payload, list);
        list = NULL;
        if (!complete)
          list = gst_buffer_list_new_sized (buffers_per_list);
        last_line = pack_line;
      }
    }

  }

  gst_video_frame_unmap (&frame);
  gst_buffer_unref (buffer);

  return ret;

  /* ERRORS */
unknown_sampling:
  {
    GST_ELEMENT_ERROR (payload, STREAM, FORMAT,
        (NULL), ("unimplemented sampling"));
    gst_video_frame_unmap (&frame);
    gst_buffer_unref (buffer);
    return GST_FLOW_NOT_SUPPORTED;
  }
too_small:
  {
    GST_ELEMENT_ERROR (payload, RESOURCE, NO_SPACE_LEFT,
        (NULL), ("not enough space to send at least one pixel"));
    gst_video_frame_unmap (&frame);
    gst_buffer_unref (buffer);
    return GST_FLOW_NOT_SUPPORTED;
  }
}
/* calculate the min and max length of a packet. This depends on the configured
 * mtu and min/max_ptime values. We cache those so that we don't have to redo
 * all the calculations */
static gboolean
gst_rtp_base_audio_payload_get_lengths (GstRTPBasePayload *
    basepayload, guint * min_payload_len, guint * max_payload_len,
    guint * align)
{
  GstRTPBaseAudioPayload *payload;
  GstRTPBaseAudioPayloadPrivate *priv;
  guint max_mtu, mtu;
  guint maxptime_octets;
  guint minptime_octets;
  guint ptime_mult_octets;

  payload = GST_RTP_BASE_AUDIO_PAYLOAD_CAST (basepayload);
  priv = payload->priv;

  if (priv->align == 0)
    return FALSE;

  mtu = GST_RTP_BASE_PAYLOAD_MTU (payload);

  /* check cached values */
  if (G_LIKELY (priv->cached_mtu == mtu
          && priv->cached_ptime_multiple ==
          basepayload->ptime_multiple
          && priv->cached_ptime == basepayload->ptime
          && priv->cached_max_ptime == basepayload->max_ptime
          && priv->cached_min_ptime == basepayload->min_ptime)) {
    /* if nothing changed, return cached values */
    *min_payload_len = priv->cached_min_length;
    *max_payload_len = priv->cached_max_length;
    *align = priv->cached_align;
    return TRUE;
  }

  ptime_mult_octets = priv->time_to_bytes (payload,
      basepayload->ptime_multiple);
  *align = ALIGN_DOWN (MAX (priv->align, ptime_mult_octets), priv->align);

  /* ptime max */
  if (basepayload->max_ptime != -1) {
    maxptime_octets = priv->time_to_bytes (payload, basepayload->max_ptime);
  } else {
    maxptime_octets = G_MAXUINT;
  }
  /* MTU max */
  max_mtu = gst_rtp_buffer_calc_payload_len (mtu, 0, 0);
  /* round down to alignment */
  max_mtu = ALIGN_DOWN (max_mtu, *align);

  /* combine max ptime and max payload length */
  *max_payload_len = MIN (max_mtu, maxptime_octets);

  /* min number of bytes based on a given ptime */
  minptime_octets = priv->time_to_bytes (payload, basepayload->min_ptime);
  /* must be at least one frame size */
  *min_payload_len = MAX (minptime_octets, *align);

  if (*min_payload_len > *max_payload_len)
    *min_payload_len = *max_payload_len;

  /* If the ptime is specified in the caps, tried to adhere to it exactly */
  if (basepayload->ptime) {
    guint ptime_in_bytes = priv->time_to_bytes (payload,
        basepayload->ptime);

    /* clip to computed min and max lengths */
    ptime_in_bytes = MAX (*min_payload_len, ptime_in_bytes);
    ptime_in_bytes = MIN (*max_payload_len, ptime_in_bytes);

    *min_payload_len = *max_payload_len = ptime_in_bytes;
  }

  /* cache values */
  priv->cached_mtu = mtu;
  priv->cached_ptime = basepayload->ptime;
  priv->cached_min_ptime = basepayload->min_ptime;
  priv->cached_max_ptime = basepayload->max_ptime;
  priv->cached_ptime_multiple = basepayload->ptime_multiple;
  priv->cached_min_length = *min_payload_len;
  priv->cached_max_length = *max_payload_len;
  priv->cached_align = *align;

  return TRUE;
}