yading@10: /*
yading@10:  * Apple MJPEG-B decoder
yading@10:  * Copyright (c) 2002 Alex Beregszaszi
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * Apple MJPEG-B decoder.
yading@10:  */
yading@10: 
yading@10: #include "avcodec.h"
yading@10: #include "mjpeg.h"
yading@10: #include "mjpegdec.h"
yading@10: 
yading@10: static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
yading@10:     uint32_t offs= get_bits_long(gb, 32);
yading@10:     if(offs >= size){
yading@10:         av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
yading@10:         return 0;
yading@10:     }
yading@10:     return offs;
yading@10: }
yading@10: 
yading@10: static int mjpegb_decode_frame(AVCodecContext *avctx,
yading@10:                               void *data, int *got_frame,
yading@10:                               AVPacket *avpkt)
yading@10: {
yading@10:     const uint8_t *buf = avpkt->data;
yading@10:     int buf_size = avpkt->size;
yading@10:     MJpegDecodeContext *s = avctx->priv_data;
yading@10:     const uint8_t *buf_end, *buf_ptr;
yading@10:     GetBitContext hgb; /* for the header */
yading@10:     uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
yading@10:     uint32_t field_size, sod_offs;
yading@10:     int ret;
yading@10: 
yading@10:     buf_ptr = buf;
yading@10:     buf_end = buf + buf_size;
yading@10:     s->got_picture = 0;
yading@10: 
yading@10: read_header:
yading@10:     /* reset on every SOI */
yading@10:     s->restart_interval = 0;
yading@10:     s->restart_count = 0;
yading@10:     s->mjpb_skiptosod = 0;
yading@10: 
yading@10:     if (buf_end - buf_ptr >= 1 << 28)
yading@10:         return AVERROR_INVALIDDATA;
yading@10: 
yading@10:     init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
yading@10: 
yading@10:     skip_bits(&hgb, 32); /* reserved zeros */
yading@10: 
yading@10:     if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
yading@10:     {
yading@10:         av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
yading@10:         return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     field_size = get_bits_long(&hgb, 32); /* field size */
yading@10:     av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
yading@10:     skip_bits(&hgb, 32); /* padded field size */
yading@10:     second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
yading@10: 
yading@10:     dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
yading@10:     if (dqt_offs)
yading@10:     {
yading@10:         init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
yading@10:         s->start_code = DQT;
yading@10:         if (ff_mjpeg_decode_dqt(s) < 0 &&
yading@10:             (avctx->err_recognition & AV_EF_EXPLODE))
yading@10:           return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
yading@10:     if (dht_offs)
yading@10:     {
yading@10:         init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
yading@10:         s->start_code = DHT;
yading@10:         ff_mjpeg_decode_dht(s);
yading@10:     }
yading@10: 
yading@10:     sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
yading@10:     if (sof_offs)
yading@10:     {
yading@10:         init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
yading@10:         s->start_code = SOF0;
yading@10:         if (ff_mjpeg_decode_sof(s) < 0)
yading@10:             return -1;
yading@10:     }
yading@10: 
yading@10:     sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
yading@10:     sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
yading@10:     av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
yading@10:     if (sos_offs)
yading@10:     {
yading@10:         init_get_bits(&s->gb, buf_ptr + sos_offs,
yading@10:                       8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
yading@10:         s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
yading@10:         s->start_code = SOS;
yading@10:         if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
yading@10:             (avctx->err_recognition & AV_EF_EXPLODE))
yading@10:           return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     if (s->interlaced) {
yading@10:         s->bottom_field ^= 1;
yading@10:         /* if not bottom field, do not output image yet */
yading@10:         if (s->bottom_field != s->interlace_polarity && second_field_offs)
yading@10:         {
yading@10:             buf_ptr = buf + second_field_offs;
yading@10:             goto read_header;
yading@10:             }
yading@10:     }
yading@10: 
yading@10:     //XXX FIXME factorize, this looks very similar to the EOI code
yading@10: 
yading@10:     if(!s->got_picture) {
yading@10:         av_log(avctx, AV_LOG_WARNING, "no picture\n");
yading@10:         return buf_size;
yading@10:     }
yading@10: 
yading@10:     if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)
yading@10:         return ret;
yading@10:     *got_frame = 1;
yading@10: 
yading@10:     if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
yading@10:         av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
yading@10:                FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));
yading@10:     }
yading@10: 
yading@10:     return buf_size;
yading@10: }
yading@10: 
yading@10: AVCodec ff_mjpegb_decoder = {
yading@10:     .name           = "mjpegb",
yading@10:     .type           = AVMEDIA_TYPE_VIDEO,
yading@10:     .id             = AV_CODEC_ID_MJPEGB,
yading@10:     .priv_data_size = sizeof(MJpegDecodeContext),
yading@10:     .init           = ff_mjpeg_decode_init,
yading@10:     .close          = ff_mjpeg_decode_end,
yading@10:     .decode         = mjpegb_decode_frame,
yading@10:     .capabilities   = CODEC_CAP_DR1,
yading@10:     .max_lowres     = 3,
yading@10:     .long_name      = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
yading@10: };