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  1. /*
  2. * Apple MJPEG-B decoder
  3. * Copyright (c) 2002 Alex Beregszaszi
  4. *
  5. * This file is part of FFmpeg.
  6. *
  7. * FFmpeg is free software; you can redistribute it and/or
  8. * modify it under the terms of the GNU Lesser General Public
  9. * License as published by the Free Software Foundation; either
  10. * version 2.1 of the License, or (at your option) any later version.
  11. *
  12. * FFmpeg is distributed in the hope that it will be useful,
  13. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15. * Lesser General Public License for more details.
  16. *
  17. * You should have received a copy of the GNU Lesser General Public
  18. * License along with FFmpeg; if not, write to the Free Software
  19. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20. */
  21. /**
  22. * @file
  23. * Apple MJPEG-B decoder.
  24. */
  25. #include "avcodec.h"
  26. #include "mjpeg.h"
  27. #include "mjpegdec.h"
  28. static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
  29. uint32_t offs= get_bits_long(gb, 32);
  30. if(offs >= size){
  31. av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
  32. return 0;
  33. }
  34. return offs;
  35. }
  36. static int mjpegb_decode_frame(AVCodecContext *avctx,
  37. void *data, int *data_size,
  38. AVPacket *avpkt)
  39. {
  40. const uint8_t *buf = avpkt->data;
  41. int buf_size = avpkt->size;
  42. MJpegDecodeContext *s = avctx->priv_data;
  43. const uint8_t *buf_end, *buf_ptr;
  44. AVFrame *picture = data;
  45. GetBitContext hgb; /* for the header */
  46. uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
  47. uint32_t field_size, sod_offs;
  48. buf_ptr = buf;
  49. buf_end = buf + buf_size;
  50. read_header:
  51. /* reset on every SOI */
  52. s->restart_interval = 0;
  53. s->restart_count = 0;
  54. s->mjpb_skiptosod = 0;
  55. init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
  56. skip_bits(&hgb, 32); /* reserved zeros */
  57. if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
  58. {
  59. av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
  60. return 0;
  61. }
  62. field_size = get_bits_long(&hgb, 32); /* field size */
  63. av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
  64. skip_bits(&hgb, 32); /* padded field size */
  65. second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
  66. av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
  67. dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
  68. av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
  69. if (dqt_offs)
  70. {
  71. init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
  72. s->start_code = DQT;
  73. if (ff_mjpeg_decode_dqt(s) < 0 &&
  74. avctx->error_recognition >= FF_ER_EXPLODE)
  75. return AVERROR_INVALIDDATA;
  76. }
  77. dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
  78. av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
  79. if (dht_offs)
  80. {
  81. init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
  82. s->start_code = DHT;
  83. ff_mjpeg_decode_dht(s);
  84. }
  85. sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
  86. av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
  87. if (sof_offs)
  88. {
  89. init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
  90. s->start_code = SOF0;
  91. if (ff_mjpeg_decode_sof(s) < 0)
  92. return -1;
  93. }
  94. sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
  95. av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
  96. sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
  97. av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
  98. if (sos_offs)
  99. {
  100. // init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
  101. init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
  102. s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
  103. s->start_code = SOS;
  104. if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
  105. avctx->error_recognition >= FF_ER_EXPLODE)
  106. return AVERROR_INVALIDDATA;
  107. }
  108. if (s->interlaced) {
  109. s->bottom_field ^= 1;
  110. /* if not bottom field, do not output image yet */
  111. if (s->bottom_field != s->interlace_polarity && second_field_offs)
  112. {
  113. buf_ptr = buf + second_field_offs;
  114. second_field_offs = 0;
  115. goto read_header;
  116. }
  117. }
  118. //XXX FIXME factorize, this looks very similar to the EOI code
  119. *picture= *s->picture_ptr;
  120. *data_size = sizeof(AVFrame);
  121. if(!s->lossless){
  122. picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
  123. picture->qstride= 0;
  124. picture->qscale_table= s->qscale_table;
  125. memset(picture->qscale_table, picture->quality, (s->width+15)/16);
  126. if(avctx->debug & FF_DEBUG_QP)
  127. av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
  128. picture->quality*= FF_QP2LAMBDA;
  129. }
  130. return buf_ptr - buf;
  131. }
  132. AVCodec ff_mjpegb_decoder = {
  133. .name = "mjpegb",
  134. .type = AVMEDIA_TYPE_VIDEO,
  135. .id = CODEC_ID_MJPEGB,
  136. .priv_data_size = sizeof(MJpegDecodeContext),
  137. .init = ff_mjpeg_decode_init,
  138. .close = ff_mjpeg_decode_end,
  139. .decode = mjpegb_decode_frame,
  140. .capabilities = CODEC_CAP_DR1,
  141. .max_lowres = 3,
  142. .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
  143. };