nutdec.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * "NUT" Container Format demuxer
 * Copyright (c) 2004-2006 Michael Niedermayer
 * Copyright (c) 2003 Alex Beregszaszi
 *
 * 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 "tree.h"
#include "nut.h"
#include "avstring.h"

#undef NDEBUG
#include <assert.h>

static uint64_t get_v(ByteIOContext *bc){
    uint64_t val = 0;
    int tmp;

    do{
        tmp = get_byte(bc);
        val= (val<<7) + (tmp&127);
    }while(tmp&128);
    return val;
}

static int get_str(ByteIOContext *bc, char *string, unsigned int maxlen){
    unsigned int len= get_v(bc);

    if(len && maxlen)
        get_buffer(bc, string, FFMIN(len, maxlen));
    while(len > maxlen){
        get_byte(bc);
        len--;
    }

    if(maxlen)
        string[FFMIN(len, maxlen-1)]= 0;

    if(maxlen == len)
        return -1;
    else
        return 0;
}

static int64_t get_s(ByteIOContext *bc){
    int64_t v = get_v(bc) + 1;

    if (v&1) return -(v>>1);
    else     return  (v>>1);
}

static uint64_t get_fourcc(ByteIOContext *bc){
    unsigned int len= get_v(bc);

    if     (len==2) return get_le16(bc);
    else if(len==4) return get_le32(bc);
    else            return -1;
}

#ifdef TRACE
static inline uint64_t get_v_trace(ByteIOContext *bc, char *file, char *func, int line){
    uint64_t v= get_v(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
    return v;
}

static inline int64_t get_s_trace(ByteIOContext *bc, char *file, char *func, int line){
    int64_t v= get_s(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
    return v;
}

static inline uint64_t get_vb_trace(ByteIOContext *bc, char *file, char *func, int line){
    uint64_t v= get_vb(bc);

    av_log(NULL, AV_LOG_DEBUG, "get_vb %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);
    return v;
}
#define get_v(bc)  get_v_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define get_s(bc)  get_s_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define get_vb(bc)  get_vb_trace(bc, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#endif

static int get_packetheader(NUTContext *nut, ByteIOContext *bc, int calculate_checksum, uint64_t startcode)
{
    int64_t size;
//    start= url_ftell(bc) - 8;

    startcode= be2me_64(startcode);
    startcode= av_crc04C11DB7_update(0, &startcode, 8);

    init_checksum(bc, av_crc04C11DB7_update, startcode);
    size= get_v(bc);
    if(size > 4096)
        get_be32(bc);
    if(get_checksum(bc) && size > 4096)
        return -1;

    init_checksum(bc, calculate_checksum ? av_crc04C11DB7_update : NULL, 0);

    return size;
}

static uint64_t find_any_startcode(ByteIOContext *bc, int64_t pos){
    uint64_t state=0;

    if(pos >= 0)
        url_fseek(bc, pos, SEEK_SET); //note, this may fail if the stream is not seekable, but that should not matter, as in this case we simply start where we are currently

    while(!url_feof(bc)){
        state= (state<<8) | get_byte(bc);
        if((state>>56) != 'N')
            continue;
        switch(state){
        case MAIN_STARTCODE:
        case STREAM_STARTCODE:
        case SYNCPOINT_STARTCODE:
        case INFO_STARTCODE:
        case INDEX_STARTCODE:
            return state;
        }
    }

    return 0;
}

/**
 * Find the given startcode.
 * @param code the startcode
 * @param pos the start position of the search, or -1 if the current position
 * @returns the position of the startcode or -1 if not found
 */
static int64_t find_startcode(ByteIOContext *bc, uint64_t code, int64_t pos){
    for(;;){
        uint64_t startcode= find_any_startcode(bc, pos);
        if(startcode == code)
            return url_ftell(bc) - 8;
        else if(startcode == 0)
            return -1;
        pos=-1;
    }
}

static int nut_probe(AVProbeData *p){
    int i;
    uint64_t code= 0;

    for (i = 0; i < p->buf_size; i++) {
        code = (code << 8) | p->buf[i];
        if (code == MAIN_STARTCODE)
            return AVPROBE_SCORE_MAX;
    }
    return 0;
}

#define GET_V(dst, check) \
    tmp= get_v(bc);\
    if(!(check)){\
        av_log(s, AV_LOG_ERROR, "Error " #dst " is (%"PRId64")\n", tmp);\
        return -1;\
    }\
    dst= tmp;

static int skip_reserved(ByteIOContext *bc, int64_t pos){
    pos -= url_ftell(bc);
    if(pos<0){
        url_fseek(bc, pos, SEEK_CUR);
        return -1;
    }else{
        while(pos--)
            get_byte(bc);
        return 0;
    }
}

static int decode_main_header(NUTContext *nut){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;
    uint64_t tmp, end;
    unsigned int stream_count;
    int i, j, tmp_stream, tmp_mul, tmp_pts, tmp_size, count, tmp_res;

    end= get_packetheader(nut, bc, 1, MAIN_STARTCODE);
    end += url_ftell(bc);

    GET_V(tmp              , tmp >=2 && tmp <= 3)
    GET_V(stream_count     , tmp > 0 && tmp <=MAX_STREAMS)

    nut->max_distance = get_v(bc);
    if(nut->max_distance > 65536){
        av_log(s, AV_LOG_DEBUG, "max_distance %d\n", nut->max_distance);
        nut->max_distance= 65536;
    }

    GET_V(nut->time_base_count, tmp>0 && tmp<INT_MAX / sizeof(AVRational))
    nut->time_base= av_malloc(nut->time_base_count * sizeof(AVRational));

    for(i=0; i<nut->time_base_count; i++){
        GET_V(nut->time_base[i].num, tmp>0 && tmp<(1ULL<<31))
        GET_V(nut->time_base[i].den, tmp>0 && tmp<(1ULL<<31))
        if(ff_gcd(nut->time_base[i].num, nut->time_base[i].den) != 1){
            av_log(s, AV_LOG_ERROR, "time base invalid\n");
            return -1;
        }
    }
    tmp_pts=0;
    tmp_mul=1;
    tmp_stream=0;
    for(i=0; i<256;){
        int tmp_flags = get_v(bc);
        int tmp_fields= get_v(bc);
        if(tmp_fields>0) tmp_pts   = get_s(bc);
        if(tmp_fields>1) tmp_mul   = get_v(bc);
        if(tmp_fields>2) tmp_stream= get_v(bc);
        if(tmp_fields>3) tmp_size  = get_v(bc);
        else             tmp_size  = 0;
        if(tmp_fields>4) tmp_res   = get_v(bc);
        else             tmp_res   = 0;
        if(tmp_fields>5) count     = get_v(bc);
        else             count     = tmp_mul - tmp_size;

        while(tmp_fields-- > 6)
           get_v(bc);

        if(count == 0 || i+count > 256){
            av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
            return -1;
        }
        if(tmp_stream >= stream_count){
            av_log(s, AV_LOG_ERROR, "illegal stream number\n");
            return -1;
        }

        for(j=0; j<count; j++,i++){
            if (i == 'N') {
                nut->frame_code[i].flags= FLAG_INVALID;
                j--;
                continue;
            }
            nut->frame_code[i].flags           = tmp_flags ;
            nut->frame_code[i].pts_delta       = tmp_pts   ;
            nut->frame_code[i].stream_id       = tmp_stream;
            nut->frame_code[i].size_mul        = tmp_mul   ;
            nut->frame_code[i].size_lsb        = tmp_size+j;
            nut->frame_code[i].reserved_count  = tmp_res   ;
        }
    }
    assert(nut->frame_code['N'].flags == FLAG_INVALID);

    if(skip_reserved(bc, end) || get_checksum(bc)){
        av_log(s, AV_LOG_ERROR, "main header checksum mismatch\n");
        return -1;
    }

    nut->stream = av_mallocz(sizeof(StreamContext)*stream_count);
    for(i=0; i<stream_count; i++){
        av_new_stream(s, i);
    }

    return 0;
}

static int decode_stream_header(NUTContext *nut){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;
    StreamContext *stc;
    int class, stream_id;
    uint64_t tmp, end;
    AVStream *st;

    end= get_packetheader(nut, bc, 1, STREAM_STARTCODE);
    end += url_ftell(bc);

    GET_V(stream_id, tmp < s->nb_streams && !nut->stream[tmp].time_base);
    stc= &nut->stream[stream_id];

    st = s->streams[stream_id];
    if (!st)
        return AVERROR(ENOMEM);

    class = get_v(bc);
    tmp = get_fourcc(bc);
    st->codec->codec_tag= tmp;
    switch(class)
    {
        case 0:
            st->codec->codec_type = CODEC_TYPE_VIDEO;
            st->codec->codec_id = codec_get_id(codec_bmp_tags, tmp);
            if (st->codec->codec_id == CODEC_ID_NONE)
                av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
            break;
        case 1:
            st->codec->codec_type = CODEC_TYPE_AUDIO;
            st->codec->codec_id = codec_get_id(codec_wav_tags, tmp);
            if (st->codec->codec_id == CODEC_ID_NONE)
                av_log(s, AV_LOG_ERROR, "Unknown codec?!\n");
            break;
        case 2:
//            st->codec->codec_type = CODEC_TYPE_TEXT;
//            break;
        case 3:
            st->codec->codec_type = CODEC_TYPE_DATA;
            break;
        default:
            av_log(s, AV_LOG_ERROR, "unknown stream class (%d)\n", class);
            return -1;
    }
    GET_V(stc->time_base_id    , tmp < nut->time_base_count);
    GET_V(stc->msb_pts_shift   , tmp < 16);
    stc->max_pts_distance= get_v(bc);
    GET_V(stc->decode_delay    , tmp < 1000); //sanity limit, raise this if Moore's law is true
    st->codec->has_b_frames= stc->decode_delay;
    get_v(bc); //stream flags

    GET_V(st->codec->extradata_size, tmp < (1<<30));
    if(st->codec->extradata_size){
        st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
        get_buffer(bc, st->codec->extradata, st->codec->extradata_size);
    }

    if (st->codec->codec_type == CODEC_TYPE_VIDEO){
        GET_V(st->codec->width , tmp > 0)
        GET_V(st->codec->height, tmp > 0)
        st->codec->sample_aspect_ratio.num= get_v(bc);
        st->codec->sample_aspect_ratio.den= get_v(bc);
        if((!st->codec->sample_aspect_ratio.num) != (!st->codec->sample_aspect_ratio.den)){
            av_log(s, AV_LOG_ERROR, "invalid aspect ratio\n");
            return -1;
        }
        get_v(bc); /* csp type */
    }else if (st->codec->codec_type == CODEC_TYPE_AUDIO){
        GET_V(st->codec->sample_rate , tmp > 0)
        tmp= get_v(bc); // samplerate_den
        if(tmp > st->codec->sample_rate){
            av_log(s, AV_LOG_ERROR, "Bleh, libnut muxed this ;)\n");
            st->codec->sample_rate= tmp;
        }
        GET_V(st->codec->channels, tmp > 0)
    }
    if(skip_reserved(bc, end) || get_checksum(bc)){
        av_log(s, AV_LOG_ERROR, "stream header %d checksum mismatch\n", stream_id);
        return -1;
    }
    stc->time_base= &nut->time_base[stc->time_base_id];
    av_set_pts_info(s->streams[stream_id], 63, stc->time_base->num, stc->time_base->den);
    return 0;
}

static int decode_info_header(NUTContext *nut){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;
    uint64_t tmp;
    unsigned int stream_id_plus1, chapter_start, chapter_len, count;
    int chapter_id, i;
    int64_t value, end;
    char name[256], str_value[1024], type_str[256], *type= type_str;

    end= get_packetheader(nut, bc, 1, INFO_STARTCODE);
    end += url_ftell(bc);

    GET_V(stream_id_plus1, tmp <= s->nb_streams)
    chapter_id   = get_s(bc);
    chapter_start= get_v(bc);
    chapter_len  = get_v(bc);
    count        = get_v(bc);
    for(i=0; i<count; i++){
        get_str(bc, name, sizeof(name));
        value= get_s(bc);
        if(value == -1){
            type= "UTF-8";
            get_str(bc, str_value, sizeof(str_value));
        }else if(value == -2){
            get_str(bc, type, sizeof(type));
            get_str(bc, str_value, sizeof(str_value));
        }else if(value == -3){
            type= "s";
            value= get_s(bc);
        }else if(value == -4){
            type= "t";
            value= get_v(bc);
        }else if(value < -4){
            type= "r";
            get_s(bc);
        }else{
            type= "v";
        }

        if(chapter_id==0 && !strcmp(type, "UTF-8")){
            if     (!strcmp(name, "Author"))
                av_strlcpy(s->author   , str_value, sizeof(s->author));
            else if(!strcmp(name, "Title"))
                av_strlcpy(s->title    , str_value, sizeof(s->title));
            else if(!strcmp(name, "Copyright"))
                av_strlcpy(s->copyright, str_value, sizeof(s->copyright));
            else if(!strcmp(name, "Description"))
                av_strlcpy(s->comment  , str_value, sizeof(s->comment));
        }
    }

    if(skip_reserved(bc, end) || get_checksum(bc)){
        av_log(s, AV_LOG_ERROR, "info header checksum mismatch\n");
        return -1;
    }
    return 0;
}

static int decode_syncpoint(NUTContext *nut, int64_t *ts, int64_t *back_ptr){
    AVFormatContext *s= nut->avf;
    ByteIOContext *bc = &s->pb;