mirror of https://git.ffmpeg.org/ffmpeg.git
685 lines
20 KiB
C
685 lines
20 KiB
C
/*
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* H.261 decoder
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* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2004 Maarten Daniels
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* H.261 decoder.
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*/
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#include "libavutil/avassert.h"
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#include "libavutil/thread.h"
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#include "avcodec.h"
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#include "codec_internal.h"
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#include "decode.h"
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#include "mpeg_er.h"
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#include "mpegutils.h"
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#include "mpegvideo.h"
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#include "mpegvideodec.h"
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#include "h261.h"
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#define H261_MBA_VLC_BITS 8
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#define H261_MTYPE_VLC_BITS 6
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#define H261_MV_VLC_BITS 7
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#define H261_CBP_VLC_BITS 9
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#define TCOEFF_VLC_BITS 9
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#define MBA_STUFFING 33
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#define MBA_STARTCODE 34
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static VLC h261_mba_vlc;
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static VLC h261_mtype_vlc;
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static VLC h261_mv_vlc;
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static VLC h261_cbp_vlc;
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typedef struct H261DecContext {
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MpegEncContext s;
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H261Context common;
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int current_mba;
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int mba_diff;
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int current_mv_x;
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int current_mv_y;
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int gob_number;
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int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
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} H261DecContext;
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static av_cold void h261_decode_init_static(void)
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{
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VLC_INIT_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
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ff_h261_mba_bits, 1, 1,
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ff_h261_mba_code, 1, 1, 540);
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VLC_INIT_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
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ff_h261_mtype_bits, 1, 1,
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ff_h261_mtype_code, 1, 1, 80);
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VLC_INIT_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
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&ff_h261_mv_tab[0][1], 2, 1,
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&ff_h261_mv_tab[0][0], 2, 1, 144);
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VLC_INIT_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
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&ff_h261_cbp_tab[0][1], 2, 1,
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&ff_h261_cbp_tab[0][0], 2, 1, 512);
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INIT_FIRST_VLC_RL(ff_h261_rl_tcoeff, 552);
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}
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static av_cold int h261_decode_init(AVCodecContext *avctx)
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{
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static AVOnce init_static_once = AV_ONCE_INIT;
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H261DecContext *const h = avctx->priv_data;
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MpegEncContext *const s = &h->s;
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s->private_ctx = &h->common;
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// set defaults
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ff_mpv_decode_init(s, avctx);
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s->out_format = FMT_H261;
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s->low_delay = 1;
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avctx->pix_fmt = AV_PIX_FMT_YUV420P;
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h->gob_start_code_skipped = 0;
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ff_thread_once(&init_static_once, h261_decode_init_static);
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return 0;
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}
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static inline void h261_init_dest(MpegEncContext *s)
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{
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const unsigned block_size = 8 >> s->avctx->lowres;
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ff_init_block_index(s);
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s->dest[0] += 2 * block_size;
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s->dest[1] += block_size;
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s->dest[2] += block_size;
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}
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/**
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* Decode the group of blocks header or slice header.
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* @return <0 if an error occurred
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*/
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static int h261_decode_gob_header(H261DecContext *h)
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{
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unsigned int val;
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MpegEncContext *const s = &h->s;
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if (!h->gob_start_code_skipped) {
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/* Check for GOB Start Code */
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val = show_bits(&s->gb, 15);
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if (val)
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return -1;
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/* We have a GBSC */
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skip_bits(&s->gb, 16);
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}
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h->gob_start_code_skipped = 0;
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h->gob_number = get_bits(&s->gb, 4); /* GN */
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s->qscale = get_bits(&s->gb, 5); /* GQUANT */
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/* Check if gob_number is valid */
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if (s->mb_height == 18) { // CIF
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if ((h->gob_number <= 0) || (h->gob_number > 12))
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return -1;
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} else { // QCIF
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if ((h->gob_number != 1) && (h->gob_number != 3) &&
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(h->gob_number != 5))
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return -1;
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}
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/* GEI */
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if (skip_1stop_8data_bits(&s->gb) < 0)
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return AVERROR_INVALIDDATA;
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if (s->qscale == 0) {
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av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n");
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if (s->avctx->err_recognition & (AV_EF_BITSTREAM | AV_EF_COMPLIANT))
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return -1;
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}
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/* For the first transmitted macroblock in a GOB, MBA is the absolute
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* address. For subsequent macroblocks, MBA is the difference between
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* the absolute addresses of the macroblock and the last transmitted
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* macroblock. */
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h->current_mba = 0;
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h->mba_diff = 0;
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return 0;
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}
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/**
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* Decode the group of blocks / video packet header.
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* @return <0 if no resync found
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*/
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static int h261_resync(H261DecContext *h)
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{
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MpegEncContext *const s = &h->s;
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int left, ret;
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if (h->gob_start_code_skipped) {
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ret = h261_decode_gob_header(h);
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if (ret >= 0)
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return 0;
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} else {
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if (show_bits(&s->gb, 15) == 0) {
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ret = h261_decode_gob_header(h);
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if (ret >= 0)
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return 0;
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}
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// OK, it is not where it is supposed to be ...
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s->gb = s->last_resync_gb;
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align_get_bits(&s->gb);
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left = get_bits_left(&s->gb);
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for (; left > 15 + 1 + 4 + 5; left -= 8) {
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if (show_bits(&s->gb, 15) == 0) {
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GetBitContext bak = s->gb;
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ret = h261_decode_gob_header(h);
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if (ret >= 0)
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return 0;
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s->gb = bak;
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}
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skip_bits(&s->gb, 8);
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}
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}
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return -1;
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}
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/**
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* Decode skipped macroblocks.
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* @return 0
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*/
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static int h261_decode_mb_skipped(H261DecContext *h, int mba1, int mba2)
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{
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MpegEncContext *const s = &h->s;
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int i;
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s->mb_intra = 0;
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for (i = mba1; i < mba2; i++) {
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int j, xy;
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s->mb_x = ((h->gob_number - 1) % 2) * 11 + i % 11;
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s->mb_y = ((h->gob_number - 1) / 2) * 3 + i / 11;
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xy = s->mb_x + s->mb_y * s->mb_stride;
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h261_init_dest(s);
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for (j = 0; j < 6; j++)
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s->block_last_index[j] = -1;
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s->mv_dir = MV_DIR_FORWARD;
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s->mv_type = MV_TYPE_16X16;
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s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
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s->mv[0][0][0] = 0;
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s->mv[0][0][1] = 0;
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s->mb_skipped = 1;
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h->common.mtype &= ~MB_TYPE_H261_FIL;
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if (s->current_picture.motion_val[0]) {
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int b_stride = 2*s->mb_width + 1;
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int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
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s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
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s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
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}
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ff_mpv_reconstruct_mb(s, s->block);
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}
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return 0;
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}
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static const int mvmap[17] = {
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0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16
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};
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static int decode_mv_component(GetBitContext *gb, int v)
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{
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int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
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/* check if mv_diff is valid */
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if (mv_diff < 0)
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return v;
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mv_diff = mvmap[mv_diff];
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if (mv_diff && !get_bits1(gb))
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mv_diff = -mv_diff;
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v += mv_diff;
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if (v <= -16)
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v += 32;
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else if (v >= 16)
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v -= 32;
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return v;
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}
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/**
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* Decode a macroblock.
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* @return <0 if an error occurred
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*/
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static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded)
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{
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MpegEncContext *const s = &h->s;
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int level, i, j, run;
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RLTable *rl = &ff_h261_rl_tcoeff;
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const uint8_t *scan_table;
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/* For the variable length encoding there are two code tables, one being
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* used for the first transmitted LEVEL in INTER, INTER + MC and
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* INTER + MC + FIL blocks, the second for all other LEVELs except the
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* first one in INTRA blocks which is fixed length coded with 8 bits.
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* NOTE: The two code tables only differ in one VLC so we handle that
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* manually. */
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scan_table = s->intra_scantable.permutated;
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if (s->mb_intra) {
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/* DC coef */
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level = get_bits(&s->gb, 8);
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// 0 (00000000b) and -128 (10000000b) are FORBIDDEN
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if ((level & 0x7F) == 0) {
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av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n",
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level, s->mb_x, s->mb_y);
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return -1;
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}
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/* The code 1000 0000 is not used, the reconstruction level of 1024
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* being coded as 1111 1111. */
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if (level == 255)
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level = 128;
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block[0] = level;
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i = 1;
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} else if (coded) {
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// Run Level Code
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// EOB Not possible for first level when cbp is available (that's why the table is different)
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// 0 1 1s
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// * * 0*
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int check = show_bits(&s->gb, 2);
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i = 0;
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if (check & 0x2) {
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skip_bits(&s->gb, 2);
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block[0] = (check & 0x1) ? -1 : 1;
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i = 1;
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}
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} else {
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i = 0;
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}
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if (!coded) {
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s->block_last_index[n] = i - 1;
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return 0;
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}
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{
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OPEN_READER(re, &s->gb);
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i--; // offset by -1 to allow direct indexing of scan_table
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for (;;) {
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UPDATE_CACHE(re, &s->gb);
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GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
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if (run == 66) {
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if (level) {
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CLOSE_READER(re, &s->gb);
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av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n",
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s->mb_x, s->mb_y);
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return -1;
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}
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/* escape */
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/* The remaining combinations of (run, level) are encoded with a
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* 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits
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* level. */
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run = SHOW_UBITS(re, &s->gb, 6) + 1;
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SKIP_CACHE(re, &s->gb, 6);
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level = SHOW_SBITS(re, &s->gb, 8);
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SKIP_COUNTER(re, &s->gb, 6 + 8);
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} else if (level == 0) {
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break;
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} else {
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if (SHOW_UBITS(re, &s->gb, 1))
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level = -level;
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SKIP_COUNTER(re, &s->gb, 1);
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}
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i += run;
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if (i >= 64) {
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CLOSE_READER(re, &s->gb);
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av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n",
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s->mb_x, s->mb_y);
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return -1;
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}
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j = scan_table[i];
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block[j] = level;
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}
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CLOSE_READER(re, &s->gb);
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}
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s->block_last_index[n] = i;
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return 0;
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}
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static int h261_decode_mb(H261DecContext *h)
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{
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MpegEncContext *const s = &h->s;
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H261Context *const com = &h->common;
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int i, cbp, xy;
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cbp = 63;
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// Read mba
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do {
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h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table,
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H261_MBA_VLC_BITS, 2);
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/* Check for slice end */
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/* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
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if (h->mba_diff == MBA_STARTCODE) { // start code
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h->gob_start_code_skipped = 1;
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return SLICE_END;
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}
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} while (h->mba_diff == MBA_STUFFING); // stuffing
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if (h->mba_diff < 0) {
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if (get_bits_left(&s->gb) <= 7)
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return SLICE_END;
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av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
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return SLICE_ERROR;
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}
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h->mba_diff += 1;
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h->current_mba += h->mba_diff;
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if (h->current_mba > MBA_STUFFING)
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return SLICE_ERROR;
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s->mb_x = ((h->gob_number - 1) % 2) * 11 + ((h->current_mba - 1) % 11);
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s->mb_y = ((h->gob_number - 1) / 2) * 3 + ((h->current_mba - 1) / 11);
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xy = s->mb_x + s->mb_y * s->mb_stride;
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h261_init_dest(s);
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// Read mtype
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com->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
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if (com->mtype < 0) {
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av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index %d\n",
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com->mtype);
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return SLICE_ERROR;
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}
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av_assert0(com->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map));
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com->mtype = ff_h261_mtype_map[com->mtype];
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// Read mquant
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if (IS_QUANT(com->mtype))
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ff_set_qscale(s, get_bits(&s->gb, 5));
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s->mb_intra = IS_INTRA4x4(com->mtype);
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// Read mv
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if (IS_16X16(com->mtype)) {
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/* Motion vector data is included for all MC macroblocks. MVD is
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* obtained from the macroblock vector by subtracting the vector
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* of the preceding macroblock. For this calculation the vector
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* of the preceding macroblock is regarded as zero in the
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* following three situations:
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* 1) evaluating MVD for macroblocks 1, 12 and 23;
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* 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
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* 3) MTYPE of the previous macroblock was not MC. */
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if ((h->current_mba == 1) || (h->current_mba == 12) ||
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(h->current_mba == 23) || (h->mba_diff != 1)) {
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h->current_mv_x = 0;
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h->current_mv_y = 0;
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}
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h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x);
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h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y);
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} else {
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h->current_mv_x = 0;
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h->current_mv_y = 0;
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}
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// Read cbp
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if (HAS_CBP(com->mtype))
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cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 1) + 1;
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if (s->mb_intra) {
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s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
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goto intra;
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}
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//set motion vectors
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s->mv_dir = MV_DIR_FORWARD;
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s->mv_type = MV_TYPE_16X16;
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s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
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s->mv[0][0][0] = h->current_mv_x * 2; // gets divided by 2 in motion compensation
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s->mv[0][0][1] = h->current_mv_y * 2;
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if (s->current_picture.motion_val[0]) {
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int b_stride = 2*s->mb_width + 1;
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int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
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s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
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s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
|
|
}
|
|
|
|
intra:
|
|
/* decode each block */
|
|
if (s->mb_intra || HAS_CBP(com->mtype)) {
|
|
s->bdsp.clear_blocks(s->block[0]);
|
|
for (i = 0; i < 6; i++) {
|
|
if (h261_decode_block(h, s->block[i], i, cbp & 32) < 0)
|
|
return SLICE_ERROR;
|
|
cbp += cbp;
|
|
}
|
|
} else {
|
|
for (i = 0; i < 6; i++)
|
|
s->block_last_index[i] = -1;
|
|
}
|
|
|
|
ff_mpv_reconstruct_mb(s, s->block);
|
|
|
|
return SLICE_OK;
|
|
}
|
|
|
|
/**
|
|
* Decode the H.261 picture header.
|
|
* @return <0 if no startcode found
|
|
*/
|
|
static int h261_decode_picture_header(H261DecContext *h)
|
|
{
|
|
MpegEncContext *const s = &h->s;
|
|
int format, i;
|
|
uint32_t startcode = 0;
|
|
|
|
for (i = get_bits_left(&s->gb); i > 24; i -= 1) {
|
|
startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
|
|
|
|
if (startcode == 0x10)
|
|
break;
|
|
}
|
|
|
|
if (startcode != 0x10) {
|
|
av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
|
|
return -1;
|
|
}
|
|
|
|
/* temporal reference */
|
|
skip_bits(&s->gb, 5); /* picture timestamp */
|
|
|
|
s->avctx->framerate = (AVRational) { 30000, 1001 };
|
|
|
|
/* PTYPE starts here */
|
|
skip_bits1(&s->gb); /* split screen off */
|
|
skip_bits1(&s->gb); /* camera off */
|
|
skip_bits1(&s->gb); /* freeze picture release off */
|
|
|
|
format = get_bits1(&s->gb);
|
|
|
|
// only 2 formats possible
|
|
if (format == 0) { // QCIF
|
|
s->width = 176;
|
|
s->height = 144;
|
|
} else { // CIF
|
|
s->width = 352;
|
|
s->height = 288;
|
|
}
|
|
|
|
skip_bits1(&s->gb); /* still image mode off */
|
|
skip_bits1(&s->gb); /* Reserved */
|
|
|
|
/* PEI */
|
|
if (skip_1stop_8data_bits(&s->gb) < 0)
|
|
return AVERROR_INVALIDDATA;
|
|
|
|
/* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first
|
|
* frame, the codec crashes if it does not contain all I-blocks
|
|
* (e.g. when a packet is lost). */
|
|
s->pict_type = AV_PICTURE_TYPE_P;
|
|
|
|
h->gob_number = 0;
|
|
return 0;
|
|
}
|
|
|
|
static int h261_decode_gob(H261DecContext *h)
|
|
{
|
|
MpegEncContext *const s = &h->s;
|
|
|
|
ff_set_qscale(s, s->qscale);
|
|
|
|
/* decode mb's */
|
|
while (h->current_mba <= MBA_STUFFING) {
|
|
int ret;
|
|
/* DCT & quantize */
|
|
ret = h261_decode_mb(h);
|
|
if (ret < 0) {
|
|
if (ret == SLICE_END) {
|
|
h261_decode_mb_skipped(h, h->current_mba, 33);
|
|
return 0;
|
|
}
|
|
av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n",
|
|
s->mb_x + s->mb_y * s->mb_stride);
|
|
return -1;
|
|
}
|
|
|
|
h261_decode_mb_skipped(h,
|
|
h->current_mba - h->mba_diff,
|
|
h->current_mba - 1);
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
/**
|
|
* returns the number of bytes consumed for building the current frame
|
|
*/
|
|
static int get_consumed_bytes(MpegEncContext *s, int buf_size)
|
|
{
|
|
int pos = get_bits_count(&s->gb) >> 3;
|
|
if (pos == 0)
|
|
pos = 1; // avoid infinite loops (i doubt that is needed but ...)
|
|
if (pos + 10 > buf_size)
|
|
pos = buf_size; // oops ;)
|
|
|
|
return pos;
|
|
}
|
|
|
|
static int h261_decode_frame(AVCodecContext *avctx, AVFrame *pict,
|
|
int *got_frame, AVPacket *avpkt)
|
|
{
|
|
H261DecContext *const h = avctx->priv_data;
|
|
const uint8_t *buf = avpkt->data;
|
|
int buf_size = avpkt->size;
|
|
MpegEncContext *s = &h->s;
|
|
int ret;
|
|
|
|
ff_dlog(avctx, "*****frame %"PRId64" size=%d\n", avctx->frame_num, buf_size);
|
|
ff_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
|
|
|
|
h->gob_start_code_skipped = 0;
|
|
|
|
init_get_bits(&s->gb, buf, buf_size * 8);
|
|
|
|
ret = h261_decode_picture_header(h);
|
|
|
|
/* skip if the header was thrashed */
|
|
if (ret < 0) {
|
|
av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
|
|
return -1;
|
|
}
|
|
|
|
if (s->width != avctx->coded_width || s->height != avctx->coded_height) {
|
|
ff_mpv_common_end(s);
|
|
}
|
|
|
|
if (!s->context_initialized) {
|
|
if ((ret = ff_mpv_common_init(s)) < 0)
|
|
return ret;
|
|
|
|
ret = ff_set_dimensions(avctx, s->width, s->height);
|
|
if (ret < 0)
|
|
return ret;
|
|
}
|
|
|
|
if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) ||
|
|
(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) ||
|
|
avctx->skip_frame >= AVDISCARD_ALL)
|
|
return buf_size;
|
|
|
|
if (ff_mpv_frame_start(s, avctx) < 0)
|
|
return -1;
|
|
|
|
ff_mpeg_er_frame_start(s);
|
|
|
|
/* decode each macroblock */
|
|
s->mb_x = 0;
|
|
s->mb_y = 0;
|
|
|
|
while (h->gob_number < (s->mb_height == 18 ? 12 : 5)) {
|
|
if (h261_resync(h) < 0)
|
|
break;
|
|
h261_decode_gob(h);
|
|
}
|
|
ff_mpv_frame_end(s);
|
|
|
|
av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type);
|
|
av_assert0(s->current_picture.f->pict_type == s->pict_type);
|
|
|
|
if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0)
|
|
return ret;
|
|
ff_print_debug_info(s, s->current_picture_ptr, pict);
|
|
|
|
*got_frame = 1;
|
|
|
|
return get_consumed_bytes(s, buf_size);
|
|
}
|
|
|
|
static av_cold int h261_decode_end(AVCodecContext *avctx)
|
|
{
|
|
H261DecContext *const h = avctx->priv_data;
|
|
MpegEncContext *s = &h->s;
|
|
|
|
ff_mpv_common_end(s);
|
|
return 0;
|
|
}
|
|
|
|
const FFCodec ff_h261_decoder = {
|
|
.p.name = "h261",
|
|
CODEC_LONG_NAME("H.261"),
|
|
.p.type = AVMEDIA_TYPE_VIDEO,
|
|
.p.id = AV_CODEC_ID_H261,
|
|
.priv_data_size = sizeof(H261DecContext),
|
|
.init = h261_decode_init,
|
|
.close = h261_decode_end,
|
|
FF_CODEC_DECODE_CB(h261_decode_frame),
|
|
.p.capabilities = AV_CODEC_CAP_DR1,
|
|
.p.max_lowres = 3,
|
|
};
|