nut.c

FFmpeg is an audio/video conversion tool. It includes libavcodec, the leading open source codec libr

            st->codec.codec_type = CODEC_TYPE_AUDIO;
            st->codec.codec_id = codec_get_wav_id(tmp);
            if (st->codec.codec_id == CODEC_ID_NONE)
                av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
            break;
        default:
            av_log(s, AV_LOG_ERROR, "Unknown stream class (%d)\n", class);
            return -1;
    }
    s->bit_rate += get_v(bc);
    get_vb(bc); /* language code */
    nom = get_v(bc);
    denom = get_v(bc);
    nut->stream[stream_id].msb_timestamp_shift = get_v(bc);
    nut->stream[stream_id].decode_delay= get_v(bc);
    get_byte(bc); /* flags */

    /* codec specific data headers */
    while(get_v(bc) != 0){
        st->codec.extradata_size= get_v(bc);
        st->codec.extradata= av_mallocz(st->codec.extradata_size);
        get_buffer(bc, st->codec.extradata, st->codec.extradata_size);            
//	    url_fskip(bc, get_v(bc));
    }
    
    if (class == 0) /* VIDEO */
    {
        st->codec.width = get_v(bc);
        st->codec.height = get_v(bc);
        st->codec.sample_aspect_ratio.num= get_v(bc);
        st->codec.sample_aspect_ratio.den= get_v(bc);
        get_v(bc); /* csp type */

        st->codec.frame_rate = nom;
        st->codec.frame_rate_base = denom;
    }
    if (class == 32) /* AUDIO */
    {
        st->codec.sample_rate = get_v(bc);
        get_v(bc); // samplerate_den
        st->codec.channels = get_v(bc);
    }
    if(check_checksum(bc)){
        av_log(s, AV_LOG_ERROR, "Stream header %d checksum missmatch\n", stream_id);
        return -1;
    }
    av_set_pts_info(s->streams[stream_id], 60, denom, nom);
    nut->stream[stream_id].rate_num= nom;
    nut->stream[stream_id].rate_den= denom;
    return 0;
}

static int decode_info_header(NUTContext *nut){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;
    
    get_packetheader(nut, bc, 1);

    for(;;){
        int id= get_v(bc);
        char *name, *type, custom_name[256], custom_type[256];

        if(!id)
            break;
        else if(id >= sizeof(info_table)/sizeof(info_table[0])){
            av_log(s, AV_LOG_ERROR, "info id is too large %d %d\n", id, sizeof(info_table)/sizeof(info_table[0]));
            return -1;
        }

        type= info_table[id][1];
        name= info_table[id][0];
//av_log(s, AV_LOG_DEBUG, "%d %s %s\n", id, type, name);

        if(!type){
            get_str(bc, custom_type, sizeof(custom_type));
            type= custom_type;
        }
        if(!name){
            get_str(bc, custom_name, sizeof(custom_name));
            name= custom_name;
        }
        
        if(!strcmp(type, "v")){
            int value= get_v(bc);
        }else{
            if(!strcmp(name, "Author"))
                get_str(bc, s->author, sizeof(s->author));
            else if(!strcmp(name, "Title"))
                get_str(bc, s->title, sizeof(s->title));
            else if(!strcmp(name, "Copyright"))
                get_str(bc, s->copyright, sizeof(s->copyright));
            else if(!strcmp(name, "Description"))
                get_str(bc, s->comment, sizeof(s->comment));
            else
                get_str(bc, NULL, 0);
        }
    }
    if(check_checksum(bc)){
        av_log(s, AV_LOG_ERROR, "Info header checksum missmatch\n");
        return -1;
    }
    return 0;
}

static int nut_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
    NUTContext *nut = s->priv_data;
    ByteIOContext *bc = &s->pb;
    int64_t pos;
    int inited_stream_count;

    nut->avf= s;
    
    /* main header */
    pos=0;
    for(;;){
        pos= find_startcode(bc, MAIN_STARTCODE, pos)+1;
        if (pos<0){
            av_log(s, AV_LOG_ERROR, "no main startcode found\n");
            return -1;
        }
        if(decode_main_header(nut) >= 0)
            break;
    }
    
    
    s->bit_rate = 0;

    nut->stream = av_malloc(sizeof(StreamContext)*nut->stream_count);

    /* stream headers */
    pos=0;
    for(inited_stream_count=0; inited_stream_count < nut->stream_count;){
        pos= find_startcode(bc, STREAM_STARTCODE, pos)+1;
        if (pos<0){
            av_log(s, AV_LOG_ERROR, "not all stream headers found\n");
            return -1;
        }
        if(decode_stream_header(nut) >= 0)
            inited_stream_count++;
    }

    /* info headers */
    pos=0;
    for(;;){
        uint64_t startcode= find_any_startcode(bc, pos);
        pos= url_ftell(bc);

        if(startcode==0){
            av_log(s, AV_LOG_ERROR, "EOF before video frames\n");
            return -1;
        }else if(startcode == KEYFRAME_STARTCODE){
            nut->next_startcode= startcode;
            break;
        }else if(startcode != INFO_STARTCODE){
            continue;
        }

        decode_info_header(nut);
    }

    return 0;
}

static int decode_frame_header(NUTContext *nut, int *key_frame_ret, int64_t *pts_ret, int *stream_id_ret, int frame_code, int frame_type, int64_t frame_start){
    AVFormatContext *s= nut->avf;
    StreamContext *stream;
    ByteIOContext *bc = &s->pb;
    int size, flags, size_mul, size_lsb, stream_id, time_delta;
    int64_t pts = 0;

    if(frame_type < 2 && frame_start - nut->packet_start[2] > nut->max_distance){
        av_log(s, AV_LOG_ERROR, "last frame must have been damaged\n");
        return -1;
    }

    if(frame_type)
        nut->packet_start[ frame_type ]= frame_start; //otherwise 1 goto 1 may happen
    
    flags= nut->frame_code[frame_code].flags;
    size_mul= nut->frame_code[frame_code].size_mul;
    size_lsb= nut->frame_code[frame_code].size_lsb;
    stream_id= nut->frame_code[frame_code].stream_id_plus1 - 1;
    time_delta= nut->frame_code[frame_code].timestamp_delta;
    
    if(stream_id==-1)
        stream_id= get_v(bc);
    if(stream_id >= s->nb_streams){
        av_log(s, AV_LOG_ERROR, "illegal stream_id\n");
        return -1;
    }
    stream= &nut->stream[stream_id];

//    av_log(s, AV_LOG_DEBUG, "ft:%d ppts:%d %d %d\n", frame_type, stream->lru_pts_delta[0], stream->lru_pts_delta[1], stream->lru_pts_delta[2]);

    *key_frame_ret= !!(flags & FLAG_KEY_FRAME);

    if(!time_delta){
        int64_t mask = (1<<stream->msb_timestamp_shift)-1;
        pts= get_v(bc);
        if(pts > mask){
            pts -= mask+1;
        }else{
            if(stream->last_pts == AV_NOPTS_VALUE){
                av_log(s, AV_LOG_ERROR, "no reference pts available\n");
                return -1;
            }
            pts= lsb2full(stream, pts);
        }
    }else{
        if(stream->last_pts == AV_NOPTS_VALUE){
            av_log(s, AV_LOG_ERROR, "no reference pts available\n");
            return -1;
        }
        pts= stream->last_pts + time_delta;
    }

    if(*key_frame_ret){
//        av_log(s, AV_LOG_DEBUG, "stream:%d start:%lld pts:%lld length:%lld\n",stream_id, frame_start, av_pts, frame_start - nut->stream[stream_id].last_sync_pos);
        av_add_index_entry(
            s->streams[stream_id], 
            frame_start, 
            pts, 
            frame_start - nut->stream[stream_id].last_sync_pos,
            AVINDEX_KEYFRAME);
        nut->stream[stream_id].last_sync_pos= frame_start;
//                assert(nut->packet_start == frame_start);
    }

    assert(size_mul > size_lsb);
    size= size_lsb;
    if(flags & FLAG_DATA_SIZE)
        size+= size_mul*get_v(bc);
      
#ifdef TRACE
av_log(s, AV_LOG_DEBUG, "fs:%lld fc:%d ft:%d kf:%d pts:%lld size:%d mul:%d lsb:%d flags:%d delta:%d\n", frame_start, frame_code, frame_type, *key_frame_ret, pts, size, size_mul, size_lsb, flags, time_delta);
#endif

    if(frame_type==0 && url_ftell(bc) - nut->packet_start[2] + size > nut->max_distance){
        av_log(s, AV_LOG_ERROR, "frame size too large\n");
        return -1;
    }
    
    *stream_id_ret = stream_id;
    *pts_ret = pts;

    update(nut, stream_id, frame_start, frame_type, frame_code, *key_frame_ret, size, pts);

    return size;
}

static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code, int frame_type, int64_t frame_start){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;
    int size, stream_id, key_frame;
    int64_t pts;
    
    size= decode_frame_header(nut, &key_frame, &pts, &stream_id, frame_code, frame_type, frame_start);
    if(size < 0)
        return -1;

    av_new_packet(pkt, size);
    get_buffer(bc, pkt->data, size);
    pkt->stream_index = stream_id;
    if (key_frame)
	pkt->flags |= PKT_FLAG_KEY;
    pkt->pts = pts;

    return 0;
}

static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    NUTContext *nut = s->priv_data;
    ByteIOContext *bc = &s->pb;
    int i, frame_code=0;

    for(;;){
        int64_t pos= url_ftell(bc);
        int frame_type= 0;
        uint64_t tmp= nut->next_startcode;
        nut->next_startcode=0;

        if (url_feof(bc))
            return -1;

        if(tmp){
            pos-=8;
        }else{
            frame_code = get_byte(bc);
            if(frame_code == 'N'){
                tmp= frame_code;
                for(i=1; i<8; i++)
                    tmp = (tmp<<8) + get_byte(bc);
            }
        }
        switch(tmp){
        case MAIN_STARTCODE:
        case STREAM_STARTCODE:
        case INDEX_STARTCODE:
            get_packetheader(nut, bc, 0);
            assert(nut->packet_start[2] == pos);
            url_fseek(bc, nut->written_packet_size + nut->packet_start[2], SEEK_SET);
            break;
        case INFO_STARTCODE:
            if(decode_info_header(nut)<0)
                goto resync;
            break;
        case KEYFRAME_STARTCODE:
            frame_type = 2;
            reset(s, get_v(bc));
            frame_code = get_byte(bc);
        case 0:
            if(decode_frame(nut, pkt, frame_code, frame_type, pos)>=0)
                return 0;
        default:
resync:
av_log(s, AV_LOG_DEBUG, "syncing from %lld\n", nut->packet_start[2]+1);
            tmp= find_any_startcode(bc, nut->packet_start[2]+1);
            if(tmp==0)
                return -1;
av_log(s, AV_LOG_DEBUG, "sync\n");
            nut->next_startcode= tmp;
        }
    }
}

static int64_t nut_read_timestamp(AVFormatContext *s, int stream_index, int64_t *pos_arg, int64_t pos_limit){
    NUTContext *nut = s->priv_data;
    StreamContext *stream;
    ByteIOContext *bc = &s->pb;
    int64_t pos, pts;
    uint64_t code;
    int frame_code,step, stream_id, i,size, key_frame;
av_log(s, AV_LOG_DEBUG, "read_timestamp(X,%d,%lld,%lld)\n", stream_index, *pos_arg, pos_limit);

    if(*pos_arg < 0)
        return AV_NOPTS_VALUE;

    pos= *pos_arg;
    step= FFMIN(16*1024, pos);
    do{
        pos-= step;
        code= find_any_startcode(bc, pos);

        if(code && url_ftell(bc) - 8 <= *pos_arg)
            break;
        step= FFMIN(2*step, pos);
    }while(step);

    if(!code) //nothing found, not even after pos_arg
        return AV_NOPTS_VALUE;

    url_fseek(bc, -8, SEEK_CUR);
    for(i=0; i<s->nb_streams; i++)
        nut->stream[i].last_sync_pos= url_ftell(bc);
        
    for(;;){
        int frame_type=0;
        int64_t pos= url_ftell(bc);
        uint64_t tmp=0;
        
        if(pos > pos_limit || url_feof(bc))
            return AV_NOPTS_VALUE;

        frame_code = get_byte(bc);
        if(frame_code == 'N'){
            tmp= frame_code;
            for(i=1; i<8; i++)
                tmp = (tmp<<8) + get_byte(bc);
        }
//av_log(s, AV_LOG_DEBUG, "before switch %llX at=%lld\n", tmp, pos);

        switch(tmp){
        case MAIN_STARTCODE:
        case STREAM_STARTCODE:
        case INDEX_STARTCODE:
        case INFO_STARTCODE:
            get_packetheader(nut, bc, 0);
            assert(nut->packet_start[2]==pos);
            url_fseek(bc, nut->written_packet_size + pos, SEEK_SET);
            break;
        case KEYFRAME_STARTCODE:
            frame_type=2;
            reset(s, get_v(bc));
            frame_code = get_byte(bc);
        case 0:
            size= decode_frame_header(nut, &key_frame, &pts, &stream_id, frame_code, frame_type, pos);
            if(size < 0)
                goto resync;
                
            stream= &nut->stream[stream_id];
            if(stream_id != stream_index || !key_frame || pos < *pos_arg){
                url_fseek(bc, size, SEEK_CUR);
                break;
            }
 
            *pos_arg= pos;
            return pts;
        default:
resync:
av_log(s, AV_LOG_DEBUG, "syncing from %lld\n", nut->packet_start[2]+1);
            if(!find_any_startcode(bc, nut->packet_start[2]+1))
                return AV_NOPTS_VALUE;

            url_fseek(bc, -8, SEEK_CUR);
        }
    }
    return AV_NOPTS_VALUE;
}

static int nut_read_seek(AVFormatContext *s, int stream_index, int64_t target_ts){
//    NUTContext *nut = s->priv_data;
    int64_t pos;

    if(av_seek_frame_binary(s, stream_index, target_ts) < 0)
        return -1;

    pos= url_ftell(&s->pb);
    nut_read_timestamp(s, stream_index, &pos, pos-1);

    return 0;
}

static int nut_read_close(AVFormatContext *s)
{
    NUTContext *nut = s->priv_data;
    int i;

    for(i=0;i<s->nb_streams;i++) {
        av_freep(&s->streams[i]->codec.extradata);
    }
    av_freep(&nut->stream);

    return 0;
}

static AVInputFormat nut_iformat = {
    "nut",
    "nut format",
    sizeof(NUTContext),
    nut_probe,
    nut_read_header,
    nut_read_packet,
    nut_read_close,
    nut_read_seek,
    nut_read_timestamp,
    .extensions = "nut",
};

#ifdef CONFIG_ENCODERS
static AVOutputFormat nut_oformat = {
    "nut",
    "nut format",
    "video/x-nut",
    "nut",
    sizeof(NUTContext),
#ifdef CONFIG_VORBIS
    CODEC_ID_VORBIS,
#elif defined(CONFIG_MP3LAME)
    CODEC_ID_MP3,
#else
    CODEC_ID_MP2, /* AC3 needs liba52 decoder */
#endif
    CODEC_ID_MPEG4,
    nut_write_header,
    nut_write_packet,
    nut_write_trailer,
};
#endif //CONFIG_ENCODERS

int nut_init(void)
{
    av_register_input_format(&nut_iformat);
#ifdef CONFIG_ENCODERS
    av_register_output_format(&nut_oformat);
#endif //CONFIG_ENCODERS
    return 0;
}