utils.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

/*
 * Various utilities for ffmpeg system
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 *
 * 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 Lesser 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
 */
#include "avformat.h"

#undef NDEBUG
#include <assert.h>

AVInputFormat *first_iformat;
AVOutputFormat *first_oformat;
AVImageFormat *first_image_format;

void av_register_input_format(AVInputFormat *format)
{
    AVInputFormat **p;
    p = &first_iformat;
    while (*p != NULL) p = &(*p)->next;
    *p = format;
    format->next = NULL;
}

void av_register_output_format(AVOutputFormat *format)
{
    AVOutputFormat **p;
    p = &first_oformat;
    while (*p != NULL) p = &(*p)->next;
    *p = format;
    format->next = NULL;
}

int match_ext(const char *filename, const char *extensions)
{
    const char *ext, *p;
    char ext1[32], *q;

    if(!filename)
        return 0;
    
    ext = strrchr(filename, '.');
    if (ext) {
        ext++;
        p = extensions;
        for(;;) {
            q = ext1;
            while (*p != '\0' && *p != ',') 
                *q++ = *p++;
            *q = '\0';
            if (!strcasecmp(ext1, ext)) 
                return 1;
            if (*p == '\0') 
                break;
            p++;
        }
    }
    return 0;
}

AVOutputFormat *guess_format(const char *short_name, const char *filename, 
                             const char *mime_type)
{
    AVOutputFormat *fmt, *fmt_found;
    int score_max, score;

    /* specific test for image sequences */
    if (!short_name && filename && 
        filename_number_test(filename) >= 0 &&
        guess_image_format(filename)) {
        return guess_format("image", NULL, NULL);
    }

    /* find the proper file type */
    fmt_found = NULL;
    score_max = 0;
    fmt = first_oformat;
    while (fmt != NULL) {
        score = 0;
        if (fmt->name && short_name && !strcmp(fmt->name, short_name))
            score += 100;
        if (fmt->mime_type && mime_type && !strcmp(fmt->mime_type, mime_type))
            score += 10;
        if (filename && fmt->extensions && 
            match_ext(filename, fmt->extensions)) {
            score += 5;
        }
        if (score > score_max) {
            score_max = score;
            fmt_found = fmt;
        }
        fmt = fmt->next;
    }
    return fmt_found;
}   

AVOutputFormat *guess_stream_format(const char *short_name, const char *filename, 
                             const char *mime_type)
{
    AVOutputFormat *fmt = guess_format(short_name, filename, mime_type);

    if (fmt) {
        AVOutputFormat *stream_fmt;
        char stream_format_name[64];

        snprintf(stream_format_name, sizeof(stream_format_name), "%s_stream", fmt->name);
        stream_fmt = guess_format(stream_format_name, NULL, NULL);

        if (stream_fmt)
            fmt = stream_fmt;
    }

    return fmt;
}

AVInputFormat *av_find_input_format(const char *short_name)
{
    AVInputFormat *fmt;
    for(fmt = first_iformat; fmt != NULL; fmt = fmt->next) {
        if (!strcmp(fmt->name, short_name))
            return fmt;
    }
    return NULL;
}

/* memory handling */

/**
 * Default packet destructor 
 */
static void av_destruct_packet(AVPacket *pkt)
{
    av_free(pkt->data);
    pkt->data = NULL; pkt->size = 0;
}

/**
 * Allocate the payload of a packet and intialized its fields to default values.
 *
 * @param pkt packet
 * @param size wanted payload size
 * @return 0 if OK. AVERROR_xxx otherwise.
 */
int av_new_packet(AVPacket *pkt, int size)
{
    void *data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!data)
        return AVERROR_NOMEM;
    memset(data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

    av_init_packet(pkt);
    pkt->data = data; 
    pkt->size = size;
    pkt->destruct = av_destruct_packet;
    return 0;
}

/* This is a hack - the packet memory allocation stuff is broken. The
   packet is allocated if it was not really allocated */
int av_dup_packet(AVPacket *pkt)
{
    if (pkt->destruct != av_destruct_packet) {
        uint8_t *data;
        /* we duplicate the packet and don't forget to put the padding
           again */
        data = av_malloc(pkt->size + FF_INPUT_BUFFER_PADDING_SIZE);
        if (!data) {
            return AVERROR_NOMEM;
        }
        memcpy(data, pkt->data, pkt->size);
        memset(data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
        pkt->data = data;
        pkt->destruct = av_destruct_packet;
    }
    return 0;
}

/* fifo handling */

int fifo_init(FifoBuffer *f, int size)
{
    f->buffer = av_malloc(size);
    if (!f->buffer)
        return -1;
    f->end = f->buffer + size;
    f->wptr = f->rptr = f->buffer;
    return 0;
}

void fifo_free(FifoBuffer *f)
{
    av_free(f->buffer);
}

int fifo_size(FifoBuffer *f, uint8_t *rptr)
{
    int size;

    if (f->wptr >= rptr) {
        size = f->wptr - rptr;
    } else {
        size = (f->end - rptr) + (f->wptr - f->buffer);
    }
    return size;
}

/* get data from the fifo (return -1 if not enough data) */
int fifo_read(FifoBuffer *f, uint8_t *buf, int buf_size, uint8_t **rptr_ptr)
{
    uint8_t *rptr = *rptr_ptr;
    int size, len;

    if (f->wptr >= rptr) {
        size = f->wptr - rptr;
    } else {
        size = (f->end - rptr) + (f->wptr - f->buffer);
    }
    
    if (size < buf_size)
        return -1;
    while (buf_size > 0) {
        len = f->end - rptr;
        if (len > buf_size)
            len = buf_size;
        memcpy(buf, rptr, len);
        buf += len;
        rptr += len;
        if (rptr >= f->end)
            rptr = f->buffer;
        buf_size -= len;
    }
    *rptr_ptr = rptr;
    return 0;
}

void fifo_write(FifoBuffer *f, uint8_t *buf, int size, uint8_t **wptr_ptr)
{
    int len;
    uint8_t *wptr;
    wptr = *wptr_ptr;
    while (size > 0) {
        len = f->end - wptr;
        if (len > size)
            len = size;
        memcpy(wptr, buf, len);
        wptr += len;
        if (wptr >= f->end)
            wptr = f->buffer;
        buf += len;
        size -= len;
    }
    *wptr_ptr = wptr;
}

int filename_number_test(const char *filename)
{
    char buf[1024];
    if(!filename)
        return -1;
    return get_frame_filename(buf, sizeof(buf), filename, 1);
}

/* guess file format */
AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened)
{
    AVInputFormat *fmt1, *fmt;
    int score, score_max;

    fmt = NULL;
    score_max = 0;
    for(fmt1 = first_iformat; fmt1 != NULL; fmt1 = fmt1->next) {
        if (!is_opened && !(fmt1->flags & AVFMT_NOFILE))
            continue;
        score = 0;
        if (fmt1->read_probe) {
            score = fmt1->read_probe(pd);
        } else if (fmt1->extensions) {
            if (match_ext(pd->filename, fmt1->extensions)) {
                score = 50;
            }
        } 
        if (score > score_max) {
            score_max = score;
            fmt = fmt1;
        }
    }
    return fmt;
}

/************************************************************/
/* input media file */

/**
 * open a media file from an IO stream. 'fmt' must be specified.
 */

static const char* format_to_name(void* ptr)
{
    AVFormatContext* fc = (AVFormatContext*) ptr;
    if(fc->iformat) return fc->iformat->name;
    else if(fc->oformat) return fc->oformat->name;
    else return "NULL";
}

static const AVClass av_format_context_class = { "AVFormatContext", format_to_name };

AVFormatContext *av_alloc_format_context(void)
{
    AVFormatContext *ic;
    ic = av_mallocz(sizeof(AVFormatContext));
    if (!ic) return ic;
    ic->av_class = &av_format_context_class;
    return ic;
}

int av_open_input_stream(AVFormatContext **ic_ptr, 
                         ByteIOContext *pb, const char *filename, 
                         AVInputFormat *fmt, AVFormatParameters *ap)
{
    int err;
    AVFormatContext *ic;

    ic = av_alloc_format_context();
    if (!ic) {
        err = AVERROR_NOMEM;
        goto fail;
    }
    ic->iformat = fmt;
    if (pb)
        ic->pb = *pb;
    ic->duration = AV_NOPTS_VALUE;
    ic->start_time = AV_NOPTS_VALUE;
    pstrcpy(ic->filename, sizeof(ic->filename), filename);

    /* allocate private data */
    if (fmt->priv_data_size > 0) {
        ic->priv_data = av_mallocz(fmt->priv_data_size);
        if (!ic->priv_data) {
            err = AVERROR_NOMEM;
            goto fail;
        }
    } else {
        ic->priv_data = NULL;
    }

    err = ic->iformat->read_header(ic, ap);
    if (err < 0)
        goto fail;

    if (pb)
        ic->data_offset = url_ftell(&ic->pb);

    *ic_ptr = ic;
    return 0;
 fail:
    if (ic) {
        av_freep(&ic->priv_data);
    }
    av_free(ic);
    *ic_ptr = NULL;
    return err;
}

#define PROBE_BUF_SIZE 2048

/**
 * Open a media file as input. The codec are not opened. Only the file
 * header (if present) is read.
 *
 * @param ic_ptr the opened media file handle is put here
 * @param filename filename to open.
 * @param fmt if non NULL, force the file format to use
 * @param buf_size optional buffer size (zero if default is OK)
 * @param ap additionnal parameters needed when opening the file (NULL if default)
 * @return 0 if OK. AVERROR_xxx otherwise.
 */
int av_open_input_file(AVFormatContext **ic_ptr, const char *filename, 
                       AVInputFormat *fmt,
                       int buf_size,
                       AVFormatParameters *ap)
{
    int err, must_open_file, file_opened;
    uint8_t buf[PROBE_BUF_SIZE];
    AVProbeData probe_data, *pd = &probe_data;
    ByteIOContext pb1, *pb = &pb1;
    
    file_opened = 0;
    pd->filename = "";
    if (filename)
        pd->filename = filename;
    pd->buf = buf;
    pd->buf_size = 0;

    if (!fmt) {
        /* guess format if no file can be opened  */
        fmt = av_probe_input_format(pd, 0);
    }

    /* do not open file if the format does not need it. XXX: specific
       hack needed to handle RTSP/TCP */
    must_open_file = 1;
    if (fmt && (fmt->flags & AVFMT_NOFILE)) {
        must_open_file = 0;
    }

    if (!fmt || must_open_file) {
        /* if no file needed do not try to open one */
        if (url_fopen(pb, filename, URL_RDONLY) < 0) {
            err = AVERROR_IO;
            goto fail;
        }
        file_opened = 1;
        if (buf_size > 0) {
            url_setbufsize(pb, buf_size);
        }
        if (!fmt) {
            /* read probe data */
            pd->buf_size = get_buffer(pb, buf, PROBE_BUF_SIZE);
            url_fseek(pb, 0, SEEK_SET);
        }
    }
    
    /* guess file format */
    if (!fmt) {
        fmt = av_probe_input_format(pd, 1);
    }

    /* if still no format found, error */