utils.c

    st = av_mallocz(sizeof(AVStream));
    if (!st)
        return NULL;
    avcodec_get_context_defaults(&st->codec);
    if (s->iformat) {
        /* no default bitrate if decoding */
        st->codec.bit_rate = 0;
    }
    st->index = s->nb_streams;
    st->id = id;
    st->start_time = AV_NOPTS_VALUE;
    st->duration = AV_NOPTS_VALUE;
    s->streams[s->nb_streams++] = st;
    return st;
}

/************************************************************/
/* output media file */

int av_set_parameters(AVFormatContext *s, AVFormatParameters *ap)
{
    int ret;
    
    if (s->oformat->priv_data_size > 0) {
        s->priv_data = av_mallocz(s->oformat->priv_data_size);
        if (!s->priv_data)
            return AVERROR_NOMEM;
    } else
        s->priv_data = NULL;
	
    if (s->oformat->set_parameters) {
        ret = s->oformat->set_parameters(s, ap);
        if (ret < 0)
            return ret;
    }
    return 0;
}

/**
 * allocate the stream private data and write the stream header to an
 * output media file
 *
 * @param s media file handle
 * @return 0 if OK. AVERROR_xxx if error.  
 */
int av_write_header(AVFormatContext *s)
{
    int ret, i;
    AVStream *st;

    /* default pts settings is MPEG like */
    av_set_pts_info(s, 33, 1, 90000);
    ret = s->oformat->write_header(s);
    if (ret < 0)
        return ret;

    /* init PTS generation */
    for(i=0;i<s->nb_streams;i++) {
        st = s->streams[i];

        switch (st->codec.codec_type) {
        case CODEC_TYPE_AUDIO:
            av_frac_init(&st->pts, 0, 0, 
                         (int64_t)s->pts_num * st->codec.sample_rate);
            break;
        case CODEC_TYPE_VIDEO:
            av_frac_init(&st->pts, 0, 0, 
                         (int64_t)s->pts_num * st->codec.frame_rate);
            break;
        default:
            break;
        }
    }
    return 0;
}

/**
 * Write a packet to an output media file. The packet shall contain
 * one audio or video frame.
 *
 * @param s media file handle
 * @param stream_index stream index
 * @param buf buffer containing the frame data
 * @param size size of buffer
 * @return < 0 if error, = 0 if OK, 1 if end of stream wanted.
 */
int av_write_frame(AVFormatContext *s, int stream_index, const uint8_t *buf, 
                   int size)
{
    AVStream *st;
    int64_t pts_mask;
    int ret, frame_size;

    st = s->streams[stream_index];
    pts_mask = (1LL << s->pts_wrap_bits) - 1;
    ret = s->oformat->write_packet(s, stream_index, (uint8_t *)buf, size, 
                                   st->pts.val & pts_mask);
    if (ret < 0)
        return ret;

    /* update pts */
    switch (st->codec.codec_type) {
    case CODEC_TYPE_AUDIO:
        if (st->codec.frame_size <= 1) {
            frame_size = size / st->codec.channels;
            /* specific hack for pcm codecs because no frame size is provided */
            switch(st->codec.codec_id) {
            case CODEC_ID_PCM_S16LE:
            case CODEC_ID_PCM_S16BE:
            case CODEC_ID_PCM_U16LE:
            case CODEC_ID_PCM_U16BE:
                frame_size >>= 1;
                break;
            default:
                break;
            }
        } else {
            frame_size = st->codec.frame_size;
        }
        av_frac_add(&st->pts, 
                    (int64_t)s->pts_den * frame_size);
        break;
    case CODEC_TYPE_VIDEO:
        av_frac_add(&st->pts, 
                    (int64_t)s->pts_den * st->codec.frame_rate_base);
        break;
    default:
        break;
    }
    return ret;
}

/**
 * write the stream trailer to an output media file and and free the
 * file private data.
 *
 * @param s media file handle
 * @return 0 if OK. AVERROR_xxx if error.  */
int av_write_trailer(AVFormatContext *s)
{
    int ret;
    ret = s->oformat->write_trailer(s);
    av_freep(&s->priv_data);
    return ret;
}

/* "user interface" functions */

void dump_format(AVFormatContext *ic,
                 int index, 
                 const char *url,
                 int is_output)
{
    int i, flags;
    char buf[256];

    fprintf(stderr, "%s #%d, %s, %s '%s':\n", 
            is_output ? "Output" : "Input",
            index, 
            is_output ? ic->oformat->name : ic->iformat->name, 
            is_output ? "to" : "from", url);
    if (!is_output) {
        fprintf(stderr, "  Duration: ");
        if (ic->duration != AV_NOPTS_VALUE) {
            int hours, mins, secs, us;
            secs = ic->duration / AV_TIME_BASE;
            us = ic->duration % AV_TIME_BASE;
            mins = secs / 60;
            secs %= 60;
            hours = mins / 60;
            mins %= 60;
            fprintf(stderr, "%02d:%02d:%02d.%01d", hours, mins, secs, 
                   (10 * us) / AV_TIME_BASE);
        } else {
            fprintf(stderr, "N/A");
        }
        fprintf(stderr, ", bitrate: ");
        if (ic->bit_rate) {
            fprintf(stderr,"%d kb/s", ic->bit_rate / 1000);
        } else {
            fprintf(stderr, "N/A");
        }
        fprintf(stderr, "\n");
    }
    for(i=0;i<ic->nb_streams;i++) {
        AVStream *st = ic->streams[i];
        avcodec_string(buf, sizeof(buf), &st->codec, is_output);
        fprintf(stderr, "  Stream #%d.%d", index, i);
        /* the pid is an important information, so we display it */
        /* XXX: add a generic system */
        if (is_output)
            flags = ic->oformat->flags;
        else
            flags = ic->iformat->flags;
        if (flags & AVFMT_SHOW_IDS) {
            fprintf(stderr, "[0x%x]", st->id);
        }
        fprintf(stderr, ": %s\n", buf);
    }
}

typedef struct {
    const char *abv;
    int width, height;
    int frame_rate, frame_rate_base;
} AbvEntry;

static AbvEntry frame_abvs[] = {
    { "ntsc",      720, 480, 30000, 1001 },
    { "pal",       720, 576,    25,    1 },
    { "qntsc",     352, 240, 30000, 1001 }, /* VCD compliant ntsc */
    { "qpal",      352, 288,    25,    1 }, /* VCD compliant pal */
    { "sntsc",     640, 480, 30000, 1001 }, /* square pixel ntsc */
    { "spal",      768, 576,    25,    1 }, /* square pixel pal */
    { "film",      352, 240,    24,    1 },
    { "ntsc-film", 352, 240, 24000, 1001 },
    { "sqcif",     128,  96,     0,    0 },
    { "qcif",      176, 144,     0,    0 },
    { "cif",       352, 288,     0,    0 },
    { "4cif",      704, 576,     0,    0 },
};

int parse_image_size(int *width_ptr, int *height_ptr, const char *str)
{
    int i;
    int n = sizeof(frame_abvs) / sizeof(AbvEntry);
    const char *p;
    int frame_width = 0, frame_height = 0;

    for(i=0;i<n;i++) {
        if (!strcmp(frame_abvs[i].abv, str)) {
            frame_width = frame_abvs[i].width;
            frame_height = frame_abvs[i].height;
            break;
        }
    }
    if (i == n) {
        p = str;
        frame_width = strtol(p, (char **)&p, 10);
        if (*p)
            p++;
        frame_height = strtol(p, (char **)&p, 10);
    }
    if (frame_width <= 0 || frame_height <= 0)
        return -1;
    *width_ptr = frame_width;
    *height_ptr = frame_height;
    return 0;
}

int parse_frame_rate(int *frame_rate, int *frame_rate_base, const char *arg)
{
    int i;
    char* cp;
   
    /* First, we check our abbreviation table */
    for (i = 0; i < sizeof(frame_abvs)/sizeof(*frame_abvs); ++i)
         if (!strcmp(frame_abvs[i].abv, arg)) {
	     *frame_rate = frame_abvs[i].frame_rate;
	     *frame_rate_base = frame_abvs[i].frame_rate_base;
	     return 0;
	 }

    /* Then, we try to parse it as fraction */
    cp = strchr(arg, '/');
    if (cp) {
        char* cpp;
	*frame_rate = strtol(arg, &cpp, 10);
	if (cpp != arg || cpp == cp) 
	    *frame_rate_base = strtol(cp+1, &cpp, 10);
	else
	   *frame_rate = 0;
    } 
    else {
        /* Finally we give up and parse it as double */
        *frame_rate_base = DEFAULT_FRAME_RATE_BASE;
        *frame_rate = (int)(strtod(arg, 0) * (*frame_rate_base) + 0.5);
    }
    if (!*frame_rate || !*frame_rate_base)
        return -1;
    else
        return 0;
}

/* Syntax:
 * - If not a duration:
 *  [{YYYY-MM-DD|YYYYMMDD}]{T| }{HH[:MM[:SS[.m...]]][Z]|HH[MM[SS[.m...]]][Z]}
 * Time is localtime unless Z is suffixed to the end. In this case GMT
 * Return the date in micro seconds since 1970 
 * - If duration:
 *  HH[:MM[:SS[.m...]]]
 *  S+[.m...]
 */
int64_t parse_date(const char *datestr, int duration)
{
    const char *p;
    int64_t t;
    struct tm dt;
    int i;
    static const char *date_fmt[] = {
        "%Y-%m-%d",
        "%Y%m%d",
    };
    static const char *time_fmt[] = {
        "%H:%M:%S",
        "%H%M%S",
    };
    const char *q;
    int is_utc, len;
    char lastch;
    time_t now = time(0);

    len = strlen(datestr);
    if (len > 0)
        lastch = datestr[len - 1];
    else
        lastch = '\0';
    is_utc = (lastch == 'z' || lastch == 'Z');

    memset(&dt, 0, sizeof(dt));

    p = datestr;
    q = NULL;
    if (!duration) {
        for (i = 0; i < sizeof(date_fmt) / sizeof(date_fmt[0]); i++) {
            q = small_strptime(p, date_fmt[i], &dt);
            if (q) {
                break;
            }
        }

        if (!q) {
            if (is_utc) {
                dt = *gmtime(&now);
            } else {
                dt = *localtime(&now);
            }
            dt.tm_hour = dt.tm_min = dt.tm_sec = 0;
        } else {
            p = q;
        }

        if (*p == 'T' || *p == 't' || *p == ' ')
            p++;

        for (i = 0; i < sizeof(time_fmt) / sizeof(time_fmt[0]); i++) {
            q = small_strptime(p, time_fmt[i], &dt);
            if (q) {
                break;
            }
        }
    } else {
        q = small_strptime(p, time_fmt[0], &dt);
        if (!q) {
            dt.tm_sec = strtol(p, (char **)&q, 10);
            dt.tm_min = 0;
            dt.tm_hour = 0;
        }
    }

    /* Now we have all the fields that we can get */
    if (!q) {
        if (duration)
            return 0;
        else
            return now * int64_t_C(1000000);
    }

    if (duration) {
        t = dt.tm_hour * 3600 + dt.tm_min * 60 + dt.tm_sec;
    } else {
        dt.tm_isdst = -1;       /* unknown */
        if (is_utc) {
            t = mktimegm(&dt);
        } else {
            t = mktime(&dt);
        }
    }

    t *= 1000000;

    if (*q == '.') {
        int val, n;
        q++;
        for (val = 0, n = 100000; n >= 1; n /= 10, q++) {
            if (!isdigit(*q)) 
                break;
            val += n * (*q - '0');
        }
        t += val;
    }
    return t;
}

/* syntax: '?tag1=val1&tag2=val2...'. Little URL decoding is done. Return
   1 if found */
int find_info_tag(char *arg, int arg_size, const char *tag1, const char *info)
{
    const char *p;
    char tag[128], *q;

    p = info;
    if (*p == '?')
        p++;
    for(;;) {
        q = tag;
        while (*p != '\0' && *p != '=' && *p != '&') {
            if ((q - tag) < sizeof(tag) - 1)
                *q++ = *p;
            p++;
        }
        *q = '\0';
        q = arg;
        if (*p == '=') {
            p++;
            while (*p != '&' && *p != '\0') {
                if ((q - arg) < arg_size - 1) {
                    if (*p == '+')
                        *q++ = ' ';
                    else
                        *q++ = *p;
                }
                p++;
            }
            *q = '\0';
        }
        if (!strcmp(tag, tag1)) 
            return 1;
        if (*p != '&')
            break;
        p++;
    }
    return 0;
}

/* Return in 'buf' the path with '%d' replaced by number. Also handles
   the '%0nd' format where 'n' is the total number of digits and
   '%%'. Return 0 if OK, and -1 if format error */
int get_frame_filename(char *buf, int buf_size,
                       const char *path, int number)
{
    const char *p;
    char *q, buf1[20], c;
    int nd, len, percentd_found;

    q = buf;
    p = path;
    percentd_found = 0;
    for(;;) {
        c = *p++;
        if (c == '\0')
            break;
        if (c == '%') {
            do {
                nd = 0;
                while (isdigit(*p)) {
                    nd = nd * 10 + *p++ - '0';
                }
                c = *p++;
            } while (isdigit(c));

            switch(c) {
            case '%':
                goto addchar;
            case 'd':
                if (percentd_found)
                    goto fail;
                percentd_found = 1;
                snprintf(buf1, sizeof(buf1), "%0*d", nd, number);
                len = strlen(buf1);
                if ((q - buf + len) > buf_size - 1)
                    goto fail;
                memcpy(q, buf1, len);
                q += len;
                break;
            default:
                goto fail;
            }
        } else {
        addchar:
            if ((q - buf) < buf_size - 1)
                *q++ = c;
        }
    }
    if (!percentd_found)
        goto fail;
    *q = '\0';
    return 0;
 fail:
    *q = '\0';
    return -1;
}

/**
 *
 * Print on stdout a nice hexa dump of a buffer
 * @param buf buffer
 * @param size buffer size
 */
void av_hex_dump(uint8_t *buf, int size)
{
    int len, i, j, c;

    for(i=0;i<size;i+=16) {
        len = size - i;
        if (len > 16)
            len = 16;
        printf("%08x ", i);
        for(j=0;j<16;j++) {
            if (j < len)
                printf(" %02x", buf[i+j]);
            else
                printf("   ");
        }
        printf(" ");
        for(j=0;j<len;j++) {
            c = buf[i+j];
            if (c < ' ' || c > '~')
                c = '.';
            printf("%c", c);
        }
        printf("\n");
    }
}

void url_split(char *proto, int proto_size,
               char *hostname, int hostname_size,
               int *port_ptr,
               char *path, int path_size,
               const char *url)
{
    const char *p;
    char *q;
    int port;

    port = -1;

    p = url;
    q = proto;
    while (*p != ':' && *p != '\0') {
        if ((q - proto) < proto_size - 1)
            *q++ = *p;
        p++;
    }
    if (proto_size > 0)
        *q = '\0';
    if (*p == '\0') {
        if (proto_size > 0)
            proto[0] = '\0';
        if (hostname_size > 0)
            hostname[0] = '\0';
        p = url;
    } else {
        p++;
        if (*p == '/')
            p++;
        if (*p == '/')
            p++;
        q = hostname;
        while (*p != ':' && *p != '/' && *p != '?' && *p != '\0') {
            if ((q - hostname) < hostname_size - 1)
                *q++ = *p;
            p++;
        }
        if (hostname_size > 0)
            *q = '\0';
        if (*p == ':') {
            p++;
            port = strtoul(p, (char **)&p, 10);
        }
    }
    if (port_ptr)
        *port_ptr = port;
    pstrcpy(path, path_size, p);
}

/**
 * Set the pts for a given stream
 * @param s stream 
 * @param pts_wrap_bits number of bits effectively used by the pts
 *        (used for wrap control, 33 is the value for MPEG) 
 * @param pts_num numerator to convert to seconds (MPEG: 1) 
 * @param pts_den denominator to convert to seconds (MPEG: 90000)
 */
void av_set_pts_info(AVFormatContext *s, int pts_wrap_bits,
                     int pts_num, int pts_den)
{
    s->pts_wrap_bits = pts_wrap_bits;
    s->pts_num = pts_num;
    s->pts_den = pts_den;
}

/* fraction handling */

/**
 * f = val + (num / den) + 0.5. 'num' is normalized so that it is such
 * as 0 <= num < den.
 *
 * @param f fractional number
 * @param val integer value
 * @param num must be >= 0
 * @param den must be >= 1 
 */
void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den)
{
    num += (den >> 1);
    if (num >= den) {
        val += num / den;
        num = num % den;
    }
    f->val = val;
    f->num = num;
    f->den = den;
}

/* set f to (val + 0.5) */
void av_frac_set(AVFrac *f, int64_t val)
{
    f->val = val;
    f->num = f->den >> 1;
}

/**
 * Fractionnal addition to f: f = f + (incr / f->den)
 *
 * @param f fractional number
 * @param incr increment, can be positive or negative
 */
void av_frac_add(AVFrac *f, int64_t incr)
{
    int64_t num, den;

    num = f->num + incr;
    den = f->den;
    if (num < 0) {
        f->val += num / den;
        num = num % den;
        if (num < 0) {
            num += den;
            f->val--;
        }
    } else if (num >= den) {
        f->val += num / den;
        num = num % den;
    }
    f->num = num;
}

/**
 * register a new image format
 * @param img_fmt Image format descriptor
 */
void av_register_image_format(AVImageFormat *img_fmt)
{
    AVImageFormat **p;

    p = &first_image_format;
    while (*p != NULL) p = &(*p)->next;
    *p = img_fmt;
    img_fmt->next = NULL;
}

/* guess image format */
AVImageFormat *av_probe_image_format(AVProbeData *pd)
{
    AVImageFormat *fmt1, *fmt;
    int score, score_max;

    fmt = NULL;
    score_max = 0;
    for(fmt1 = first_image_format; fmt1 != NULL; fmt1 = fmt1->next) {
        if (fmt1->img_probe) {
            score = fmt1->img_probe(pd);
            if (score > score_max) {
                score_max = score;
                fmt = fmt1;
            }
        }
    }
    return fmt;
}

AVImageFormat *guess_image_format(const char *filename)
{
    AVImageFormat *fmt1;

    for(fmt1 = first_image_format; fmt1 != NULL; fmt1 = fmt1->next) {
        if (fmt1->extensions && match_ext(filename, fmt1->extensions))
            return fmt1;
    }
    return NULL;
}

/**
 * Read an image from a stream. 
 * @param gb byte stream containing the image
 * @param fmt image format, NULL if probing is required
 */
int av_read_image(ByteIOContext *pb, const char *filename,
                  AVImageFormat *fmt,
                  int (*alloc_cb)(void *, AVImageInfo *info), void *opaque)
{
    char buf[PROBE_BUF_SIZE];
    AVProbeData probe_data, *pd = &probe_data;
    offset_t pos;
    int ret;

    if (!fmt) {
        pd->filename = filename;
        pd->buf = buf;
        pos = url_ftell(pb);
        pd->buf_size = get_buffer(pb, buf, PROBE_BUF_SIZE);
        url_fseek(pb, pos, SEEK_SET);
        fmt = av_probe_image_format(pd);
    }
    if (!fmt)
        return AVERROR_NOFMT;
    ret = fmt->img_read(pb, alloc_cb, opaque);
    return ret;
}

/**
 * Write an image to a stream.
 * @param pb byte stream for the image output
 * @param fmt image format
 * @param img image data and informations
 */
int av_write_image(ByteIOContext *pb, AVImageFormat *fmt, AVImageInfo *img)
{
    return fmt->img_write(pb, img);
}