1 | //
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2 | // mpeg4-part2 in mipsel receivers
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3 | // http://forums.openpli.org/topic/39326-gstreamer10-and-mpeg4-part2/?hl=%2Bmpeg4+%2Bpart2
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4 | //
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5 |
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6 | #define MPEG4P2_MAX_B_FRAMES_COUNT 5
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7 |
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8 | typedef struct
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9 | {
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10 | int b_frames_count;
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11 | int first_ip_frame_written;
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12 | int64_t packet_duration;
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13 | AVPacket *b_frames[MPEG4P2_MAX_B_FRAMES_COUNT];
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14 | AVPacket *second_ip_frame;
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15 | } Mpeg4P2Context;
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16 |
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17 |
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18 | static void set_packet(AVPacket **pkt_dest, AVPacket *pkt_src)
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19 | {
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20 | if (pkt_dest == NULL)
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21 | return;
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22 | if (*pkt_dest != NULL)
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23 | {
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24 | wrapped_packet_unref(*pkt_dest);
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25 | av_free(*pkt_dest);
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26 | }
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27 | *pkt_dest = av_malloc(sizeof(AVPacket));
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28 | av_copy_packet(*pkt_dest, pkt_src);
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29 | }
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30 |
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31 | static int filter_packet(AVBitStreamFilterContext *bsf_ctx, AVCodecContext *enc_ctx, AVPacket *pkt)
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32 | {
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33 | int ret;
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34 | AVPacket new_pkt = *pkt;
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35 | ret = av_bitstream_filter_filter(bsf_ctx, enc_ctx, NULL,
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36 | &new_pkt.data, &new_pkt.size,
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37 | pkt->data, pkt->size,
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38 | pkt->flags & AV_PKT_FLAG_KEY);
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39 | if (ret == 0 && new_pkt.data != pkt->data)
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40 | {
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41 | if ((ret = av_copy_packet(&new_pkt, pkt)) < 0)
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42 | return -1;
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43 | ret = 1;
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44 | }
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45 | if (ret > 0)
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46 | {
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47 | pkt->side_data = NULL;
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48 | pkt->side_data_elems = 0;
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49 | wrapped_packet_unref(pkt);
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50 | new_pkt.buf = av_buffer_create(new_pkt.data, new_pkt.size,
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51 | av_buffer_default_free, NULL, 0);
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52 | if (!new_pkt.buf)
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53 | return -1;
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54 | }
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55 | if (ret < 0)
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56 | {
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57 | ffmpeg_err("Failed to filter bitstream with filter %s for stream %d with codec %s\n",
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58 | bsf_ctx->filter->name, pkt->stream_index,
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59 | avcodec_get_name(enc_ctx->codec_id));
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60 | return -1;
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61 | }
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62 | *pkt = new_pkt;
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63 | return 0;
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64 | }
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65 |
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66 | static void mpeg4p2_context_reset(Mpeg4P2Context *context)
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67 | {
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68 | if (context == NULL)
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69 | return;
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70 | int i;
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71 | for (i=0; i < MPEG4P2_MAX_B_FRAMES_COUNT; i++)
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72 | {
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73 | if (context->b_frames[i] != NULL)
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74 | {
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75 | wrapped_packet_unref(context->b_frames[i]);
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76 | av_free(context->b_frames[i]);
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77 | }
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78 | context->b_frames[i] = NULL;
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79 | }
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80 | if (context->second_ip_frame != NULL)
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81 | {
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82 | wrapped_packet_unref(context->second_ip_frame);
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83 | av_free(context->second_ip_frame);
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84 | }
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85 | context->second_ip_frame = NULL;
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86 |
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87 | context->b_frames_count = 0;
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88 | context->first_ip_frame_written = 0;
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89 | context->packet_duration = 0;
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90 | }
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91 |
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92 | static void mpeg4p2_write(Context_t *ctx, Track_t *track, int avContextIdx, int64_t *currentVideoPts, int64_t *latestPts, AVPacket *pkt)
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93 | {
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94 | *currentVideoPts = track->pts = calcPts(avContextIdx, track->stream, pkt->pts);
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95 | if ((*currentVideoPts > *latestPts) && (*currentVideoPts != INVALID_PTS_VALUE))
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96 | {
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97 | *latestPts = *currentVideoPts;
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98 | }
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99 | track->dts = calcPts(avContextIdx, track->stream, pkt->dts);
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100 |
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101 | AudioVideoOut_t avOut;
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102 | avOut.data = pkt->data;
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103 | avOut.len = pkt->size;
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104 | avOut.pts = track->pts;
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105 | avOut.dts = track->dts;
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106 | avOut.extradata = track->extraData;
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107 | avOut.extralen = track->extraSize;
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108 | avOut.frameRate = track->frame_rate;
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109 | avOut.timeScale = track->TimeScale;
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110 | avOut.width = track->width;
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111 | avOut.height = track->height;
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112 | avOut.type = "video";
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113 |
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114 | if (ctx->output->video->Write(ctx, &avOut) < 0)
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115 | {
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116 | ffmpeg_err("writing data to video device failed\n");
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117 | }
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118 | }
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119 |
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120 | static int mpeg4p2_write_packet(Context_t *ctx, Mpeg4P2Context *mpeg4p2_ctx, Track_t *track, int cAVIdx, int64_t *pts_current, int64_t *pts_latest, AVPacket *pkt)
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121 | {
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122 | uint8_t *data = pkt->data;
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123 | int data_len = pkt->size;
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124 | int pos = 0;
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125 | if (mpeg4p2_ctx->packet_duration == 0)
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126 | {
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127 | mpeg4p2_ctx->packet_duration = pkt->duration;
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128 | }
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129 | while (pos < data_len)
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130 | {
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131 | if (memcmp(&data[pos], "\x00\x00\x01\xb6", 4))
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132 | {
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133 | pos++;
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134 | continue;
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135 | }
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136 | pos += 4;
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137 | switch ((data[pos] & 0xC0) >> 6)
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138 | {
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139 | case 0: // I-Frame
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140 | case 1: // P-Frame
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141 | if (!mpeg4p2_ctx->first_ip_frame_written)
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142 | {
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143 | mpeg4p2_ctx->first_ip_frame_written = 1;
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144 | pkt->pts = pkt->dts + mpeg4p2_ctx->packet_duration;
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145 | ffmpeg_printf(100, "Writing first I/P packet\n");
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146 | mpeg4p2_write(ctx, track, cAVIdx, pts_current, pts_latest, pkt);
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147 | return 0;
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148 | }
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149 | else if (!mpeg4p2_ctx->second_ip_frame)
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150 | {
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151 | set_packet(&mpeg4p2_ctx->second_ip_frame, pkt);
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152 | return 0;
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153 | }
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154 | else
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155 | {
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156 | if (!mpeg4p2_ctx->b_frames_count)
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157 | {
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158 | mpeg4p2_ctx->second_ip_frame->pts = mpeg4p2_ctx->second_ip_frame->dts + mpeg4p2_ctx->packet_duration;
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159 | ffmpeg_printf(100,"Writing second I/P packet(1)\n");
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160 | mpeg4p2_write(ctx, track, cAVIdx, pts_current, pts_latest, mpeg4p2_ctx->second_ip_frame);
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161 | set_packet(&mpeg4p2_ctx->second_ip_frame, pkt);
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162 | return 0;
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163 | }
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164 | else
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165 | {
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166 | mpeg4p2_ctx->second_ip_frame->pts = mpeg4p2_ctx->b_frames[mpeg4p2_ctx->b_frames_count -1]->dts + mpeg4p2_ctx->packet_duration;
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167 | mpeg4p2_ctx->b_frames[0]->pts = mpeg4p2_ctx->second_ip_frame->dts + mpeg4p2_ctx->packet_duration;
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168 | int i;
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169 | for (i =1; i < mpeg4p2_ctx->b_frames_count; i++)
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170 | {
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171 | mpeg4p2_ctx->b_frames[i]->pts = mpeg4p2_ctx->b_frames[i-1]->dts + mpeg4p2_ctx->packet_duration;
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172 | }
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173 | ffmpeg_printf(100, "Writing second I/P packet(2)\n");
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174 | mpeg4p2_write(ctx, track, cAVIdx, pts_current, pts_latest, mpeg4p2_ctx->second_ip_frame);
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175 | set_packet(&mpeg4p2_ctx->second_ip_frame, pkt);
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176 | for (i =0; i< mpeg4p2_ctx->b_frames_count; i++)
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177 | {
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178 | ffmpeg_printf(100, "Writing B-frame[%d]\n", i);
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179 | mpeg4p2_write(ctx, track, cAVIdx, pts_current, pts_latest, mpeg4p2_ctx->b_frames[i]);
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180 | }
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181 | mpeg4p2_ctx->b_frames_count = 0;
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182 | return 0;
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183 | }
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184 | }
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185 | break;
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186 | case 3: // S-Frame
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187 | break;
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188 | case 2: // B-Frame
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189 | if (!mpeg4p2_ctx->second_ip_frame)
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190 | {
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191 | ffmpeg_err("Cannot predict B-Frame without surrounding I/P-Frames, dropping...");
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192 | return 0;
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193 | }
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194 | if (mpeg4p2_ctx->b_frames_count == MPEG4P2_MAX_B_FRAMES_COUNT)
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195 | {
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196 | ffmpeg_err("Oops max B-Frames count = %d, reached", MPEG4P2_MAX_B_FRAMES_COUNT);
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197 | // not recoverable, to fix just increase MPEG4P2_MAX_B_FRAMES_COUNT
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198 | return -1;
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199 | }
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200 | else
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201 | {
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202 | ffmpeg_printf(100, "Storing B-Frame\n");
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203 | set_packet(&mpeg4p2_ctx->b_frames[mpeg4p2_ctx->b_frames_count++], pkt);
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204 | return 0;
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205 | }
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206 | case 4:
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207 | default:
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208 | break;
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209 | }
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210 | }
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211 | return 0;
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212 | }
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213 |
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