nut.c

arm平台下的H264编码和解码源代码

    if (class == 32) /* AUDIO */
    {
        st->codec.sample_rate = (get_v(bc) * nom) / denom;
        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;
    }
    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, 8, 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;
    
    av_set_pts_info(s, 60, 1, AV_TIME_BASE);

    /* 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(NUTContext *nut, AVPacket *pkt, int frame_code, int frame_type){
    AVFormatContext *s= nut->avf;
    StreamContext *stream;
    ByteIOContext *bc = &s->pb;
    int size, flags, size_mul, size_lsb, stream_id;
    int key_frame = 0;
    int64_t pts = 0;
    const int prefix_len= frame_type == 2 ? 8+1 : 1;
    const int64_t frame_start= url_ftell(bc) - prefix_len;

    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;

    if(flags & FLAG_FRAME_TYPE){
        reset(s);
        if(get_packetheader(nut, bc, prefix_len, 0) < 0)
            return -1;
        if(frame_type!=2)
            frame_type= 1;
    }

    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= !!(flags & FLAG_KEY_FRAME);

    if(flags & FLAG_PTS){
        if(flags & FLAG_FULL_PTS){
            pts= get_v(bc);
            if(frame_type && key_frame){
                int64_t av_pts= pts * AV_TIME_BASE * stream->rate_den / stream->rate_num;
                av_add_index_entry(
                    s->streams[stream_id], 
                    frame_start, 
                    av_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);
            }
        }else{
            int64_t mask = (1<<stream->msb_timestamp_shift)-1;
            int64_t delta= stream->last_pts - mask/2;
            pts= ((get_v(bc) - delta)&mask) + delta;
        }
    }else{
        pts= stream->last_pts + stream->lru_pts_delta[(flags&12)>>2];
    }
  
    if(size_mul <= size_lsb){
        size= stream->lru_size[size_lsb - size_mul];
    }else{
        if(flags & FLAG_DATA_SIZE)
            size= size_mul*get_v(bc) + size_lsb;
        else
            size= size_lsb;
    }
      
//av_log(s, AV_LOG_DEBUG, "fs:%lld fc:%d ft:%d kf:%d pts:%lld size:%d\n", frame_start, frame_code, frame_type, key_frame, pts, size);

    if(url_ftell(bc) - nut->packet_start + size > nut->written_packet_size){
        av_log(s, AV_LOG_ERROR, "frame size too large\n");
        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 * AV_TIME_BASE * stream->rate_den / stream->rate_num;

    update(nut, stream_id, frame_start, frame_type, frame_code, key_frame, size, pts);
    
    return 0;
}

static int nut_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    NUTContext *nut = s->priv_data;
    ByteIOContext *bc = &s->pb;
    int size, i, frame_code=0;
    int64_t pos;

    for(;;){
        int frame_type= 0;
        uint64_t tmp= nut->next_startcode;
        nut->next_startcode=0;

        if (url_feof(bc))
            return -1;

        if(!tmp){
            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, 8, 0);
            url_fseek(bc, nut->written_packet_size + nut->packet_start, SEEK_SET);
            break;
        case INFO_STARTCODE:
            if(decode_info_header(nut)<0)
                goto resync;
            break;
        case KEYFRAME_STARTCODE:
            frame_type = 2;
            frame_code = get_byte(bc);
        case 0:
            if(decode_frame(nut, pkt, frame_code, frame_type)>=0)
                return 0;
        default:
resync:
av_log(s, AV_LOG_DEBUG, "syncing from %lld\n", nut->packet_start+1);
            tmp= find_any_startcode(bc, nut->packet_start+1);
            if(tmp==0)
                return -1;
av_log(s, AV_LOG_DEBUG, "sync\n");
            if(url_is_streamed(bc)){
                nut->next_startcode= tmp;
                break;
            }

            pos= url_ftell(bc) - 8;
av_log(s, AV_LOG_DEBUG, "at %lld code=%llX\n", pos, tmp);
            if(tmp==KEYFRAME_STARTCODE){
                get_byte(bc);
            }
            get_v(bc);
            size= get_v(bc);
            
            while(size > 2 && size < 100000 && nut->packet_start < pos - size){
                url_fseek(bc, pos - size, SEEK_SET);
                frame_code= get_byte(bc);
                if(!(nut->frame_code[ frame_code ].flags & FLAG_FRAME_TYPE))
                    break;
                if(get_v(bc) != size)
                    break;
                pos -= size;
                size= get_v(bc);
av_log(s, AV_LOG_DEBUG, "steping back to %lld next %d\n", pos, size);
            }
            url_fseek(bc, pos, SEEK_SET);
            
            nut->written_packet_size= -1;
        }
    }
}

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, flags, stream_id, i;
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;

    // find a previous startcode, FIXME use forward search and follow backward pointers if undamaged stream
    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(;;){
        int64_t pos= url_ftell(bc);
        uint64_t tmp=0;
        int prefix_len=1;
        
        if(pos > pos_limit)
            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:
            nut->written_packet_size= -1;
            get_packetheader(nut, bc, 8, 0);
            url_fseek(bc, nut->written_packet_size + nut->packet_start, SEEK_SET);
            break;
        case KEYFRAME_STARTCODE:
            nut->written_packet_size= -1;
            prefix_len+=8;
            frame_code = get_byte(bc);
        case 0:
            flags= nut->frame_code[frame_code].flags;
            stream_id= nut->frame_code[frame_code].stream_id_plus1 - 1;

            if(get_packetheader(nut, bc, prefix_len, 0) < 0)
                goto resync;

            if(!(flags & FLAG_FRAME_TYPE) || !(flags & FLAG_PTS) || !(flags & FLAG_FULL_PTS))
                goto resync;

            if(stream_id==-1)
                stream_id= get_v(bc);
            if(stream_id >= s->nb_streams)
                goto resync;
                
            stream= &nut->stream[stream_id];
            pts= get_v(bc) * AV_TIME_BASE * stream->rate_den / stream->rate_num;
    
            if(flags & FLAG_KEY_FRAME){
                av_add_index_entry(
                    s->streams[stream_id], 
                    pos, 
                    pts, 
                    pos - nut->stream[stream_id].last_sync_pos,
                    AVINDEX_KEYFRAME);
                nut->stream[stream_id].last_sync_pos= pos;
            }
            if(stream_id != stream_index || !(flags & FLAG_KEY_FRAME) || nut->packet_start < *pos_arg){
                url_fseek(bc, nut->written_packet_size + nut->packet_start, SEEK_SET);
                break;
            }
 
            *pos_arg= nut->packet_start;
            assert(nut->packet_start == pos);
            return pts;
        default:
resync:
av_log(s, AV_LOG_DEBUG, "syncing from %lld\n", nut->packet_start+1);
            if(!find_any_startcode(bc, nut->packet_start+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;
    int i;

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

    nut->written_packet_size= -1;
    pos= url_ftell(&s->pb);
    for(i=0; i<s->nb_streams; i++)
        nut->stream[i].last_sync_pos= pos;

    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;
}