nut.c

F:图像处理资料264264书籍ffmpeg-0.4.9-pre1VideoStream.rar 一个视频解压缩源代码

/*
 * "NUT" Container Format muxer and demuxer (DRAFT-200403??)
 * Copyright (c) 2003 Alex Beregszaszi
 * Copyright (c) 2004 Michael Niedermayer
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * NUT DRAFT can be found in MPlayer CVS at DOCS/tech/mpcf.txt
 *
 * AND http://people.fsn.hu/~alex/nut/ (TeX, pdf, ps, dvi, ..)
 *
 */

/*
 * TODO:
 * - index writing
 * - index packet reading support
*/

//#define DEBUG 1

#include <limits.h>
#include "avformat.h"
#include "mpegaudio.h"
#include "avi.h"

#undef NDEBUG
#include <assert.h>

//#define TRACE

//from /dev/random

#define     MAIN_STARTCODE (0x7A561F5F04ADULL + (((uint64_t)('N'<<8) + 'M')<<48)) 
#define   STREAM_STARTCODE (0x11405BF2F9DBULL + (((uint64_t)('N'<<8) + 'S')<<48)) 
#define KEYFRAME_STARTCODE (0xE4ADEECA4569ULL + (((uint64_t)('N'<<8) + 'K')<<48)) 
#define    INDEX_STARTCODE (0xDD672F23E64EULL + (((uint64_t)('N'<<8) + 'X')<<48)) 
#define     INFO_STARTCODE (0xAB68B596BA78ULL + (((uint64_t)('N'<<8) + 'I')<<48)) 

#define ID_STRING "nut/multimedia container\0"

#define MAX_DISTANCE (1024*16-1)
#define MAX_SHORT_DISTANCE (1024*4-1)

#define FLAG_DATA_SIZE       1
#define FLAG_KEY_FRAME       2
#define FLAG_INVALID         4

typedef struct {
    uint8_t flags;
    uint8_t stream_id_plus1;
    uint16_t size_mul;
    uint16_t size_lsb;
    int16_t timestamp_delta;
    uint8_t reserved_count;
} FrameCode;

typedef struct {
    int last_key_frame;
    int msb_timestamp_shift;
    int rate_num;
    int rate_den;
    int64_t last_pts;
    int64_t last_sync_pos;                    ///<pos of last 1/2 type frame
    int decode_delay;
} StreamContext;

typedef struct {
    AVFormatContext *avf;
    int written_packet_size;
    int64_t packet_start[3]; //0-> startcode less, 1-> short startcode 2-> long startcodes
    FrameCode frame_code[256];
    int stream_count;
    uint64_t next_startcode;     ///< stores the next startcode if it has alraedy been parsed but the stream isnt seekable
    StreamContext *stream;
    int max_distance;
    int max_short_distance;
    int rate_num;
    int rate_den;
    int short_startcode;
} NUTContext;

static char *info_table[][2]={
	{NULL			,  NULL }, // end
	{NULL			,  NULL },
	{NULL			, "UTF8"},
	{NULL			, "v"},
	{NULL			, "s"},
	{"StreamId"		, "v"},
	{"SegmentId"		, "v"},
	{"StartTimestamp"	, "v"},
	{"EndTimestamp"		, "v"},
	{"Author"		, "UTF8"},
	{"Title"		, "UTF8"},
	{"Description"		, "UTF8"},
	{"Copyright"		, "UTF8"},
	{"Encoder"		, "UTF8"},
	{"Keyword"		, "UTF8"},
	{"Cover"		, "JPEG"},
	{"Cover"		, "PNG"},
};

static void update(NUTContext *nut, int stream_index, int64_t frame_start, int frame_type, int frame_code, int key_frame, int size, int64_t pts){
    StreamContext *stream= &nut->stream[stream_index];
    
    stream->last_key_frame= key_frame;
    nut->packet_start[ frame_type ]= frame_start;
    stream->last_pts= pts;
}

static void reset(AVFormatContext *s, int64_t global_ts){
    NUTContext *nut = s->priv_data;
    int i;
    
    for(i=0; i<s->nb_streams; i++){
        StreamContext *stream= &nut->stream[i];
    
        stream->last_key_frame= 1;

        stream->last_pts= av_rescale(global_ts, stream->rate_num*(int64_t)nut->rate_den, stream->rate_den*(int64_t)nut->rate_num);
    }
}

static void build_frame_code(AVFormatContext *s){
    NUTContext *nut = s->priv_data;
    int key_frame, index, pred, stream_id;
    int start=0;
    int end= 255;
    int keyframe_0_esc= s->nb_streams > 2;
    int pred_table[10];

    if(keyframe_0_esc){
        /* keyframe = 0 escape */
        FrameCode *ft= &nut->frame_code[start];
        ft->flags= FLAG_DATA_SIZE;
        ft->stream_id_plus1= 0;
        ft->size_mul=1;
        ft->timestamp_delta=0;
        start++;
    }

    for(stream_id= 0; stream_id<s->nb_streams; stream_id++){
        int start2= start + (end-start)*stream_id / s->nb_streams;
        int end2  = start + (end-start)*(stream_id+1) / s->nb_streams;
        AVCodecContext *codec = &s->streams[stream_id]->codec;
        int is_audio= codec->codec_type == CODEC_TYPE_AUDIO;
        int intra_only= /*codec->intra_only || */is_audio;
        int pred_count;

        for(key_frame=0; key_frame<2; key_frame++){
            if(intra_only && keyframe_0_esc && key_frame==0)
                continue;
            
            {
                FrameCode *ft= &nut->frame_code[start2];
                ft->flags= FLAG_KEY_FRAME*key_frame;
                ft->flags|= FLAG_DATA_SIZE;
                ft->stream_id_plus1= stream_id + 1;
                ft->size_mul=1;
                ft->timestamp_delta=0;
                start2++;
            }
        }

        key_frame= intra_only;
#if 1
        if(is_audio){
            int frame_bytes= codec->frame_size*(int64_t)codec->bit_rate / (8*codec->sample_rate);
            int pts;
            for(pts=0; pts<2; pts++){
                for(pred=0; pred<2; pred++){
                    FrameCode *ft= &nut->frame_code[start2];
                    ft->flags= FLAG_KEY_FRAME*key_frame;
                    ft->stream_id_plus1= stream_id + 1;
                    ft->size_mul=frame_bytes + 2;
                    ft->size_lsb=frame_bytes + pred;
                    ft->timestamp_delta=pts;
                    start2++;
                }
            }
        }else{
            FrameCode *ft= &nut->frame_code[start2];
            ft->flags= FLAG_KEY_FRAME | FLAG_DATA_SIZE;
            ft->stream_id_plus1= stream_id + 1;
            ft->size_mul=1;
            ft->timestamp_delta=1;
            start2++;
        }
#endif

        if(codec->has_b_frames){
            pred_count=5;
            pred_table[0]=-2;
            pred_table[1]=-1;
            pred_table[2]=1;
            pred_table[3]=3;
            pred_table[4]=4;
        }else if(codec->codec_id == CODEC_ID_VORBIS){
            pred_count=3;
            pred_table[0]=2;
            pred_table[1]=9;
            pred_table[2]=16;
        }else{
            pred_count=1;
            pred_table[0]=1;
        }

        for(pred=0; pred<pred_count; pred++){
            int start3= start2 + (end2-start2)*pred / pred_count;
            int end3  = start2 + (end2-start2)*(pred+1) / pred_count;

            for(index=start3; index<end3; index++){
                FrameCode *ft= &nut->frame_code[index];
                ft->flags= FLAG_KEY_FRAME*key_frame;
                ft->flags|= FLAG_DATA_SIZE;
                ft->stream_id_plus1= stream_id + 1;
//FIXME use single byte size and pred from last
                ft->size_mul= end3-start3;
                ft->size_lsb= index - start3;
                ft->timestamp_delta= pred_table[pred];
            }
        }
    }
    memmove(&nut->frame_code['N'+1], &nut->frame_code['N'], sizeof(FrameCode)*(255-'N'));
    nut->frame_code['N'].flags= FLAG_INVALID;
}

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

    for(;;)
    {
	int tmp = get_byte(bc);

	if (tmp&0x80)
	    val= (val<<7) + tmp - 0x80;
	else{
//av_log(NULL, AV_LOG_DEBUG, "get_v()= %lld\n", (val<<7) + tmp);
	    return (val<<7) + tmp;
        }
    }
    return -1;
}

static int get_str(ByteIOContext *bc, char *string, int maxlen){
    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_vb(ByteIOContext *bc){
    uint64_t val=0;
    int i= get_v(bc);
    
    if(i>8)
        return UINT64_MAX;
    
    while(i--)
        val = (val<<8) + get_byte(bc);
    
//av_log(NULL, AV_LOG_DEBUG, "get_vb()= %lld\n", val);
    return val;
}

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

    printf("get_v %5lld / %llX 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);

    printf("get_s %5lld / %llX 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);

    printf("get_vb %5lld / %llX 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)
{
    int64_t start, size;
    start= url_ftell(bc) - 8;

    init_checksum(bc, calculate_checksum ? update_adler32 : NULL, 0);

    size= get_v(bc);

    nut->packet_start[2] = start;
    nut->written_packet_size= size;

    return size;
}

static int check_checksum(ByteIOContext *bc){
    unsigned long checksum= get_checksum(bc);
    return checksum != get_be32(bc);
}

/**
 * 
 */
static int get_length(uint64_t val){
    int i;

    for (i=7; val>>i; i+=7);

    return i;
}

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 isnt seekable, but that shouldnt 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 KEYFRAME_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;
    }
}

#ifdef CONFIG_ENCODERS

static void put_v(ByteIOContext *bc, uint64_t val)
{
    int i;

//av_log(NULL, AV_LOG_DEBUG, "put_v()= %lld\n", val);
    val &= 0x7FFFFFFFFFFFFFFFULL; // FIXME can only encode upto 63 bits currently
    i= get_length(val);

    for (i-=7; i>0; i-=7){
	put_byte(bc, 0x80 | (val>>i));
    }

    put_byte(bc, val&0x7f);
}

/**
 * stores a string as vb.
 */
static void put_str(ByteIOContext *bc, const char *string){
    int len= strlen(string);
    
    put_v(bc, len);
    put_buffer(bc, string, len);
}

static void put_s(ByteIOContext *bc, uint64_t val){
    if (val<=0) put_v(bc, -2*val  );
    else        put_v(bc,  2*val-1);
}

static void put_vb(ByteIOContext *bc, uint64_t val){
    int i;
    
    for (i=8; val>>i; i+=8);

    put_v(bc, i>>3);
    for(i-=8; i>=0; i-=8)
        put_byte(bc, (val>>i)&0xFF);
}

#ifdef TRACE
static inline void put_v_trace(ByteIOContext *bc, uint64_t v, char *file, char *func, int line){
    printf("get_v %5lld / %llX in %s %s:%d\n", v, v, file, func, line);
    
    put_v(bc, v);
}

static inline void put_s_trace(ByteIOContext *bc, int64_t v, char *file, char *func, int line){
    printf("get_s %5lld / %llX in %s %s:%d\n", v, v, file, func, line);
    
    put_s(bc, v);
}

static inline void put_vb_trace(ByteIOContext *bc, uint64_t v, char *file, char *func, int line){
    printf("get_vb %5lld / %llX in %s %s:%d\n", v, v, file, func, line);
    
    put_vb(bc, v);
}
#define put_v(bc, v)  put_v_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define put_s(bc, v)  put_s_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define put_vb(bc, v)  put_vb_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#endif

static int put_packetheader(NUTContext *nut, ByteIOContext *bc, int max_size, int calculate_checksum)
{
    put_flush_packet(bc);
    nut->packet_start[2]+= nut->written_packet_size;
    assert(url_ftell(bc) - 8 == nut->packet_start[2]);
    nut->written_packet_size = max_size;
    
    if(calculate_checksum)
        init_checksum(bc, update_adler32, 0);

    /* packet header */
    put_v(bc, nut->written_packet_size); /* forward ptr */

    return 0;
}

static int update_packetheader(NUTContext *nut, ByteIOContext *bc, int additional_size, int calculate_checksum){
    int64_t start= nut->packet_start[2];
    int64_t cur= url_ftell(bc);
    int size= cur - start + additional_size;
    
    if(calculate_checksum)