| 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 | /** |
| 23 | * @file |
| 24 | * Apple MJPEG-B decoder. |
| 25 | */ |
| 26 | |
| 27 | #include <inttypes.h> |
| 28 | |
| 29 | #include "avcodec.h" |
| 30 | #include "mjpeg.h" |
| 31 | #include "mjpegdec.h" |
| 32 | |
| 33 | static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){ |
| 34 | uint32_t offs= get_bits_long(gb, 32); |
| 35 | if(offs >= size){ |
| 36 | av_log(avctx, AV_LOG_WARNING, err_msg, offs, size); |
| 37 | return 0; |
| 38 | } |
| 39 | return offs; |
| 40 | } |
| 41 | |
| 42 | static int mjpegb_decode_frame(AVCodecContext *avctx, |
| 43 | void *data, int *got_frame, |
| 44 | AVPacket *avpkt) |
| 45 | { |
| 46 | const uint8_t *buf = avpkt->data; |
| 47 | int buf_size = avpkt->size; |
| 48 | MJpegDecodeContext *s = avctx->priv_data; |
| 49 | const uint8_t *buf_end, *buf_ptr; |
| 50 | GetBitContext hgb; /* for the header */ |
| 51 | uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs; |
| 52 | uint32_t field_size, sod_offs; |
| 53 | int ret; |
| 54 | |
| 55 | buf_ptr = buf; |
| 56 | buf_end = buf + buf_size; |
| 57 | s->got_picture = 0; |
| 58 | |
| 59 | read_header: |
| 60 | /* reset on every SOI */ |
| 61 | s->restart_interval = 0; |
| 62 | s->restart_count = 0; |
| 63 | s->mjpb_skiptosod = 0; |
| 64 | |
| 65 | if (buf_end - buf_ptr >= 1 << 28) |
| 66 | return AVERROR_INVALIDDATA; |
| 67 | |
| 68 | init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8); |
| 69 | |
| 70 | skip_bits(&hgb, 32); /* reserved zeros */ |
| 71 | |
| 72 | if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) |
| 73 | { |
| 74 | av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n"); |
| 75 | return AVERROR_INVALIDDATA; |
| 76 | } |
| 77 | |
| 78 | field_size = get_bits_long(&hgb, 32); /* field size */ |
| 79 | av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size); |
| 80 | skip_bits(&hgb, 32); /* padded field size */ |
| 81 | second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); |
| 82 | av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n", |
| 83 | second_field_offs); |
| 84 | |
| 85 | dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); |
| 86 | av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs); |
| 87 | if (dqt_offs) |
| 88 | { |
| 89 | init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); |
| 90 | s->start_code = DQT; |
| 91 | if (ff_mjpeg_decode_dqt(s) < 0 && |
| 92 | (avctx->err_recognition & AV_EF_EXPLODE)) |
| 93 | return AVERROR_INVALIDDATA; |
| 94 | } |
| 95 | |
| 96 | dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); |
| 97 | av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs); |
| 98 | if (dht_offs) |
| 99 | { |
| 100 | init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); |
| 101 | s->start_code = DHT; |
| 102 | ff_mjpeg_decode_dht(s); |
| 103 | } |
| 104 | |
| 105 | sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); |
| 106 | av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs); |
| 107 | if (sof_offs) |
| 108 | { |
| 109 | init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); |
| 110 | s->start_code = SOF0; |
| 111 | if (ff_mjpeg_decode_sof(s) < 0) |
| 112 | return -1; |
| 113 | } |
| 114 | |
| 115 | sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); |
| 116 | av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs); |
| 117 | sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); |
| 118 | av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs); |
| 119 | if (sos_offs) |
| 120 | { |
| 121 | init_get_bits(&s->gb, buf_ptr + sos_offs, |
| 122 | 8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs)); |
| 123 | s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16)); |
| 124 | s->start_code = SOS; |
| 125 | if (ff_mjpeg_decode_sos(s, NULL, 0, NULL) < 0 && |
| 126 | (avctx->err_recognition & AV_EF_EXPLODE)) |
| 127 | return AVERROR_INVALIDDATA; |
| 128 | } |
| 129 | |
| 130 | if (s->interlaced) { |
| 131 | s->bottom_field ^= 1; |
| 132 | /* if not bottom field, do not output image yet */ |
| 133 | if (s->bottom_field != s->interlace_polarity && second_field_offs) |
| 134 | { |
| 135 | buf_ptr = buf + second_field_offs; |
| 136 | goto read_header; |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | //XXX FIXME factorize, this looks very similar to the EOI code |
| 141 | |
| 142 | if(!s->got_picture) { |
| 143 | av_log(avctx, AV_LOG_WARNING, "no picture\n"); |
| 144 | return buf_size; |
| 145 | } |
| 146 | |
| 147 | if ((ret = av_frame_ref(data, s->picture_ptr)) < 0) |
| 148 | return ret; |
| 149 | *got_frame = 1; |
| 150 | |
| 151 | if (!s->lossless && avctx->debug & FF_DEBUG_QP) { |
| 152 | av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", |
| 153 | FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2])); |
| 154 | } |
| 155 | |
| 156 | return buf_size; |
| 157 | } |
| 158 | |
| 159 | AVCodec ff_mjpegb_decoder = { |
| 160 | .name = "mjpegb", |
| 161 | .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), |
| 162 | .type = AVMEDIA_TYPE_VIDEO, |
| 163 | .id = AV_CODEC_ID_MJPEGB, |
| 164 | .priv_data_size = sizeof(MJpegDecodeContext), |
| 165 | .init = ff_mjpeg_decode_init, |
| 166 | .close = ff_mjpeg_decode_end, |
| 167 | .decode = mjpegb_decode_frame, |
| 168 | .capabilities = CODEC_CAP_DR1, |
| 169 | .max_lowres = 3, |
| 170 | }; |