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128 lines
3.6 KiB
C
128 lines
3.6 KiB
C
/*
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* payload_parsers.c
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* Copyright (C) 2011 Janne Grunau
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*
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* Authors:
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* Janne Grunau <janne.grunau@collabora.co.uk>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "payload_parsers.h"
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#include <gst/base/gstbitreader.h>
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#define PICTURE_START_CODE 0x00000100
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#define GROUP_START_CODE 0x000001B8
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typedef struct Mpeg2PictureHeader
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{
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guint16 temporal_reference;
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guint8 picture_coding_type;
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guint16 vbv_delay;
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/* picture_coding_type == 2 || picture_coding_type */
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guint8 full_pel_forward_vector;
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guint8 forward_f_code;
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/* picture_coding_type == 3 */
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guint8 full_pel_backward_vector;
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guint8 backward_f_code;
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} Mpeg2PictureHeader;
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static guint8 *
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find_start_code (guint32 * start_code, guint8 * buffer, guint8 * buffer_end)
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{
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if (G_UNLIKELY (buffer == NULL) || G_UNLIKELY (buffer_end == NULL)
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|| G_UNLIKELY (start_code == NULL))
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return NULL;
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while (buffer <= buffer_end) {
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*start_code <<= 8;
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*start_code |= *buffer++;
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if ((*start_code & 0xffffff00) == 0x00000100)
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return buffer;
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}
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return NULL;
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}
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static gboolean
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parse_mpeg2_picture_header (Mpeg2PictureHeader * hdr, guint8 * buffer,
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guint8 * buffer_end)
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{
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GstBitReader br = GST_BIT_READER_INIT (buffer, buffer_end - buffer);
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if (gst_bit_reader_get_remaining (&br) < 40)
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return FALSE;
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hdr->temporal_reference = gst_bit_reader_get_bits_uint16_unchecked (&br, 10);
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hdr->picture_coding_type = gst_bit_reader_get_bits_uint8_unchecked (&br, 3);
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hdr->vbv_delay = gst_bit_reader_get_bits_uint16_unchecked (&br, 16);
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if (hdr->picture_coding_type == 2 || hdr->picture_coding_type == 3) {
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hdr->full_pel_forward_vector =
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gst_bit_reader_get_bits_uint8_unchecked (&br, 1);
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hdr->forward_f_code = gst_bit_reader_get_bits_uint8_unchecked (&br, 3);
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}
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if (hdr->picture_coding_type == 3) {
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hdr->full_pel_backward_vector =
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gst_bit_reader_get_bits_uint8_unchecked (&br, 1);
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hdr->backward_f_code = gst_bit_reader_get_bits_uint8_unchecked (&br, 3);
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}
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return TRUE;
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}
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gboolean
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gst_tsdemux_has_mpeg2_keyframe (guint32 * state,
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MpegTSPacketizerPacket * packet)
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{
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//guint32 i = 0;
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guint8 *data = packet->payload;
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guint8 *data_end = packet->data_end;
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GST_LOG ("state: 0x%08x", *state);
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while (data <= data_end) {
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data = find_start_code (state, data, data_end);
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if (!data)
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return FALSE;
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GST_LOG ("found start code: 0x%08x", *state);
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if (*state == GROUP_START_CODE) {
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GST_DEBUG ("found group start code");
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*state = 0xffffffff;
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return TRUE;
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} else if (*state == PICTURE_START_CODE) {
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Mpeg2PictureHeader hdr = { 0 };
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gboolean success;
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*state = 0xffffffff;
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success = parse_mpeg2_picture_header (&hdr, data, data_end);
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GST_DEBUG ("found picture start code, %sparsed, picture coding type: %d",
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success ? "" : "not ", hdr.picture_coding_type);
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return success && hdr.picture_coding_type == 1;
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}
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}
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return FALSE;
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}
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