FFmpeg/libavcodec/hevc_sei.c

/*
 * HEVC Supplementary Enhancement Information messages
 *
 * Copyright (C) 2012 - 2013 Guillaume Martres
 * Copyright (C) 2012 - 2013 Gildas Cocherel
 * Copyright (C) 2013 Vittorio Giovara
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "hevc.h"
#include "golomb.h"

static void decode_nal_sei_decoded_picture_hash(HEVCContext *s,
                                                int payload_size)
{
    int cIdx, i;
    uint8_t hash_type;
    //uint16_t picture_crc;
    //uint32_t picture_checksum;
    GetBitContext *gb = &s->HEVClc->gb;
    hash_type = get_bits(gb, 8);

    for (cIdx = 0; cIdx < 3/*((s->sps->chroma_format_idc == 0) ? 1 : 3)*/; cIdx++) {
        if (hash_type == 0) {
            s->is_md5 = 1;
            for (i = 0; i < 16; i++)
                s->md5[cIdx][i] = get_bits(gb, 8);
        } else if (hash_type == 1) {
            // picture_crc = get_bits(gb, 16);
            skip_bits(gb, 16);
        } else if (hash_type == 2) {
            // picture_checksum = get_bits(gb, 32);
            skip_bits(gb, 32);
        }
    }
}

static void decode_nal_sei_frame_packing_arrangement(HEVCContext *s)
{
    GetBitContext *gb = &s->HEVClc->gb;
    int cancel, type, quincunx;

    get_ue_golomb(gb);                  // frame_packing_arrangement_id
    cancel = get_bits1(gb);             // frame_packing_cancel_flag
    if (cancel == 0 ){
        type     = get_bits(gb, 7);     // frame_packing_arrangement_type
        quincunx = get_bits1(gb);       // quincunx_sampling_flag
        skip_bits(gb, 6);               // content_interpretation_type

        // the following skips spatial_flipping_flag frame0_flipped_flag
        // field_views_flag current_frame_is_frame0_flag
        // frame0_self_contained_flag frame1_self_contained_flag
        skip_bits(gb, 6);

        if (quincunx == 0 && type != 5)
            skip_bits(gb, 16);  // frame[01]_grid_position_[xy]
        skip_bits(gb, 8);       // frame_packing_arrangement_reserved_byte
        skip_bits1(gb);         // frame_packing_arrangement_persistance_flag
    }
    skip_bits1(gb);             // upsampled_aspect_ratio_flag
}

static int decode_pic_timing(HEVCContext *s)
{
    GetBitContext *gb = &s->HEVClc->gb;
    HEVCSPS *sps = (HEVCSPS*)s->sps_list[s->active_seq_parameter_set_id]->data;

    if (!sps)
        return(AVERROR(ENOMEM));

    if (sps->vui.frame_field_info_present_flag) {
        int pic_struct = get_bits(gb, 4);
        s->picture_struct = AV_PICTURE_STRUCTURE_UNKNOWN;
        if (pic_struct == 2) {
            av_log(s->avctx, AV_LOG_DEBUG, "BOTTOM Field\n");
            s->picture_struct = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
        } else if (pic_struct == 1) {
            av_log(s->avctx, AV_LOG_DEBUG, "TOP Field\n");
            s->picture_struct = AV_PICTURE_STRUCTURE_TOP_FIELD;
        }
        get_bits(gb, 2);                   // source_scan_type
        get_bits(gb, 1);                   // duplicate_flag
    }
    return 1;
}

static void active_parameter_sets(HEVCContext *s)
{
    GetBitContext *gb = &s->HEVClc->gb;
    int num_sps_ids_minus1;
    int i;

    get_bits(gb, 4); // active_video_parameter_set_id
    get_bits(gb, 1); // self_contained_cvs_flag
    get_bits(gb, 1); // num_sps_ids_minus1
    num_sps_ids_minus1 = get_ue_golomb_long(gb); // num_sps_ids_minus1

    s->active_seq_parameter_set_id = get_ue_golomb_long(gb);

    for (i = 1; i <= num_sps_ids_minus1; i++)
        get_ue_golomb_long(gb); // active_seq_parameter_set_id[i]
}

static int decode_nal_sei_message(HEVCContext *s)
{
    GetBitContext *gb = &s->HEVClc->gb;

    int payload_type = 0;
    int payload_size = 0;
    int byte = 0xFF;
    av_log(s->avctx, AV_LOG_DEBUG, "Decoding SEI\n");

    while (byte == 0xFF) {
        byte          = get_bits(gb, 8);
        payload_type += byte;
    }
    byte = 0xFF;
    while (byte == 0xFF) {
        byte          = get_bits(gb, 8);
        payload_size += byte;
    }
    if (s->nal_unit_type == NAL_SEI_PREFIX) {
        if (payload_type == 256 /*&& s->decode_checksum_sei*/) {
            decode_nal_sei_decoded_picture_hash(s, payload_size);
            return 1;
        } else if (payload_type == 45) {
            decode_nal_sei_frame_packing_arrangement(s);
            return 1;
        } else if (payload_type == 1){
            int ret = decode_pic_timing(s);
            av_log(s->avctx, AV_LOG_DEBUG, "Skipped PREFIX SEI %d\n", payload_type);
            skip_bits(gb, 8 * payload_size);
            return ret;
        } else if (payload_type == 129){
            active_parameter_sets(s);
            av_log(s->avctx, AV_LOG_DEBUG, "Skipped PREFIX SEI %d\n", payload_type);
            return 1;
        } else {
            av_log(s->avctx, AV_LOG_DEBUG, "Skipped PREFIX SEI %d\n", payload_type);
            skip_bits(gb, 8*payload_size);
            return 1;
        }
    } else { /* nal_unit_type == NAL_SEI_SUFFIX */
        if (payload_type == 132 /* && s->decode_checksum_sei */)
            decode_nal_sei_decoded_picture_hash(s, payload_size);
        else {
            av_log(s->avctx, AV_LOG_DEBUG, "Skipped SUFFIX SEI %d\n", payload_type);
            skip_bits(gb, 8 * payload_size);
        }
        return 1;
    }
}

static int more_rbsp_data(GetBitContext *gb)
{
    return get_bits_left(gb) > 0 && show_bits(gb, 8) != 0x80;
}

int ff_hevc_decode_nal_sei(HEVCContext *s)
{
    int ret;

    do {
        ret = decode_nal_sei_message(s);
        if (ret < 0)
            return(AVERROR(ENOMEM));
    } while (more_rbsp_data(&s->HEVClc->gb));
    return 1;
}