I try rewind mpeg2 video(set playback rate to -1), however, segment fault caused at gstvaapidecoder_mpeg2.c:1461, traced by gdb, I found that packet.data value is 0x0. So, I think it is necessary to judge the value of packet.data before 1461, how do you think?
  Else, It was strange to me why packet.data was 0x0 when rewind, and it was a valid value when playback normally, Dose mpeg2 video not support rewinding?

souce code:
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1454  if (!gst_buffer_map (buffer, &map_info, GST_MAP_READ)) {
1455    GST_ERROR ("failed to map buffer");
1456    return GST_VAAPI_DECODER_STATUS_ERROR_UNKNOWN;
1457  }
1458
1459  packet.data = map_info.data + unit->offset;
1460  packet.size = unit->size;
1461  packet.type = packet.data[3];
1462  packet.offset = 4;
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