utils.c

ffmpeg源码分析

        p = p->next;
    }
    return NULL;
}

AVCodec *avcodec_find_decoder_by_name(const char *name)
{
    AVCodec *p;
    p = first_avcodec;
    while (p) {
        if (p->decode != NULL && strcmp(name,p->name) == 0)
            return p;
        p = p->next;
    }
    return NULL;
}

void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode)
{
    const char *codec_name;
    AVCodec *p;
    char buf1[32];
    char channels_str[100];
    int bitrate;

    if (encode)
        p = avcodec_find_encoder(enc->codec_id);
    else
        p = avcodec_find_decoder(enc->codec_id);

    if (p) {
        codec_name = p->name;
        if (!encode && enc->codec_id == CODEC_ID_MP3) {
            if (enc->sub_id == 2)
                codec_name = "mp2";
            else if (enc->sub_id == 1)
                codec_name = "mp1";
        }
    } else if (enc->codec_id == CODEC_ID_MPEG2TS) {
        /* fake mpeg2 transport stream codec (currently not
           registered) */
        codec_name = "mpeg2ts";
    } else if (enc->codec_name[0] != '\0') {
        codec_name = enc->codec_name;
    } else {
        /* output avi tags */
        if(   isprint(enc->codec_tag&0xFF) && isprint((enc->codec_tag>>8)&0xFF)
           && isprint((enc->codec_tag>>16)&0xFF) && isprint((enc->codec_tag>>24)&0xFF)){
            snprintf(buf1, sizeof(buf1), "%c%c%c%c / 0x%04X",
                     enc->codec_tag & 0xff,
                     (enc->codec_tag >> 8) & 0xff,
                     (enc->codec_tag >> 16) & 0xff,
                     (enc->codec_tag >> 24) & 0xff,
                      enc->codec_tag);
        } else {
            snprintf(buf1, sizeof(buf1), "0x%04x", enc->codec_tag);
        }
        codec_name = buf1;
    }

    switch(enc->codec_type) {
    case CODEC_TYPE_VIDEO:
        snprintf(buf, buf_size,
                 "Video: %s%s",
                 codec_name, enc->mb_decision ? " (hq)" : "");
        if (enc->pix_fmt != PIX_FMT_NONE) {
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", %s",
                     avcodec_get_pix_fmt_name(enc->pix_fmt));
        }
        if (enc->width) {
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", %dx%d",
                     enc->width, enc->height);
            if(av_log_get_level() >= AV_LOG_DEBUG){
                int g= ff_gcd(enc->time_base.num, enc->time_base.den);
                snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", %d/%d",
                     enc->time_base.num/g, enc->time_base.den/g);
            }
        }
        if (encode) {
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", q=%d-%d", enc->qmin, enc->qmax);
        }
        bitrate = enc->bit_rate;
        break;
    case CODEC_TYPE_AUDIO:
        snprintf(buf, buf_size,
                 "Audio: %s",
                 codec_name);
        switch (enc->channels) {
            case 1:
                strcpy(channels_str, "mono");
                break;
            case 2:
                strcpy(channels_str, "stereo");
                break;
            case 6:
                strcpy(channels_str, "5:1");
                break;
            default:
                snprintf(channels_str, sizeof(channels_str), "%d channels", enc->channels);
                break;
        }
        if (enc->sample_rate) {
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", %d Hz, %s",
                     enc->sample_rate,
                     channels_str);
        }

        /* for PCM codecs, compute bitrate directly */
        switch(enc->codec_id) {
        case CODEC_ID_PCM_S32LE:
        case CODEC_ID_PCM_S32BE:
        case CODEC_ID_PCM_U32LE:
        case CODEC_ID_PCM_U32BE:
            bitrate = enc->sample_rate * enc->channels * 32;
            break;
        case CODEC_ID_PCM_S24LE:
        case CODEC_ID_PCM_S24BE:
        case CODEC_ID_PCM_U24LE:
        case CODEC_ID_PCM_U24BE:
        case CODEC_ID_PCM_S24DAUD:
            bitrate = enc->sample_rate * enc->channels * 24;
            break;
        case CODEC_ID_PCM_S16LE:
        case CODEC_ID_PCM_S16BE:
        case CODEC_ID_PCM_U16LE:
        case CODEC_ID_PCM_U16BE:
            bitrate = enc->sample_rate * enc->channels * 16;
            break;
        case CODEC_ID_PCM_S8:
        case CODEC_ID_PCM_U8:
        case CODEC_ID_PCM_ALAW:
        case CODEC_ID_PCM_MULAW:
            bitrate = enc->sample_rate * enc->channels * 8;
            break;
        default:
            bitrate = enc->bit_rate;
            break;
        }
        break;
    case CODEC_TYPE_DATA:
        snprintf(buf, buf_size, "Data: %s", codec_name);
        bitrate = enc->bit_rate;
        break;
    case CODEC_TYPE_SUBTITLE:
        snprintf(buf, buf_size, "Subtitle: %s", codec_name);
        bitrate = enc->bit_rate;
        break;
    default:
        snprintf(buf, buf_size, "Invalid Codec type %d", enc->codec_type);
        return;
    }
    if (encode) {
        if (enc->flags & CODEC_FLAG_PASS1)
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", pass 1");
        if (enc->flags & CODEC_FLAG_PASS2)
            snprintf(buf + strlen(buf), buf_size - strlen(buf),
                     ", pass 2");
    }
    if (bitrate != 0) {
        snprintf(buf + strlen(buf), buf_size - strlen(buf),
                 ", %d kb/s", bitrate / 1000);
    }
}

unsigned avcodec_version( void )
{
  return LIBAVCODEC_VERSION_INT;
}

unsigned avcodec_build( void )
{
  return LIBAVCODEC_BUILD;
}

static void init_crcs(void){
    av_crc04C11DB7= av_mallocz_static(sizeof(AVCRC) * 257);
    av_crc8005    = av_mallocz_static(sizeof(AVCRC) * 257);
    av_crc07      = av_mallocz_static(sizeof(AVCRC) * 257);
    av_crc_init(av_crc04C11DB7, 0, 32, 0x04c11db7, sizeof(AVCRC)*257);
    av_crc_init(av_crc8005    , 0, 16, 0x8005    , sizeof(AVCRC)*257);
    av_crc_init(av_crc07      , 0,  8, 0x07      , sizeof(AVCRC)*257);
}

/* must be called before any other functions */
void avcodec_init(void)
{
    static int inited = 0;

    if (inited != 0)
        return;
    inited = 1;

    dsputil_static_init();
    init_crcs();
}

/**
 * Flush buffers, should be called when seeking or when swicthing to a different stream.
 */
void avcodec_flush_buffers(AVCodecContext *avctx)
{
    if(avctx->codec->flush)
        avctx->codec->flush(avctx);
}

void avcodec_default_free_buffers(AVCodecContext *s){
    int i, j;

    if(s->internal_buffer==NULL) return;

    for(i=0; i<INTERNAL_BUFFER_SIZE; i++){
        InternalBuffer *buf= &((InternalBuffer*)s->internal_buffer)[i];
        for(j=0; j<4; j++){
            av_freep(&buf->base[j]);
            buf->data[j]= NULL;
        }
    }
    av_freep(&s->internal_buffer);

    s->internal_buffer_count=0;
}

char av_get_pict_type_char(int pict_type){
    switch(pict_type){
    case I_TYPE: return 'I';
    case P_TYPE: return 'P';
    case B_TYPE: return 'B';
    case S_TYPE: return 'S';
    case SI_TYPE:return 'i';
    case SP_TYPE:return 'p';
    default:     return '?';
    }
}

/* av_log API */

static int av_log_level = AV_LOG_INFO;

static void av_log_default_callback(void* ptr, int level, const char* fmt, va_list vl)
{
    static int print_prefix=1;
    AVClass* avc= ptr ? *(AVClass**)ptr : NULL;
    if(level>av_log_level)
        return;
#undef fprintf
    if(print_prefix && avc) {
            fprintf(stderr, "[%s @ %p]", avc->item_name(ptr), avc);
    }
#define fprintf please_use_av_log

    print_prefix= strstr(fmt, "\n") != NULL;

    vfprintf(stderr, fmt, vl);
}

static void (*av_log_callback)(void*, int, const char*, va_list) = av_log_default_callback;

void av_log(void* avcl, int level, const char *fmt, ...)
{
    va_list vl;
    va_start(vl, fmt);
    av_vlog(avcl, level, fmt, vl);
    va_end(vl);
}

void av_vlog(void* avcl, int level, const char *fmt, va_list vl)
{
    av_log_callback(avcl, level, fmt, vl);
}

int av_log_get_level(void)
{
    return av_log_level;
}

void av_log_set_level(int level)
{
    av_log_level = level;
}

void av_log_set_callback(void (*callback)(void*, int, const char*, va_list))
{
    av_log_callback = callback;
}

#if !defined(HAVE_THREADS)
int avcodec_thread_init(AVCodecContext *s, int thread_count){
    return -1;
}
#endif

unsigned int av_xiphlacing(unsigned char *s, unsigned int v)
{
    unsigned int n = 0;

    while(v >= 0xff) {
        *s++ = 0xff;
        v -= 0xff;
        n++;
    }
    *s = v;
    n++;
    return n;
}

/* Wrapper to work around the lack of mkstemp() on mingw/cygin.
 * Also, tries to create file in /tmp first, if possible.
 * *prefix can be a character constant; *filename will be allocated internally.
 * Returns file descriptor of opened file (or -1 on error)
 * and opened file name in **filename. */
int av_tempfile(char *prefix, char **filename) {
    int fd=-1;
#ifdef CONFIG_WIN32
    *filename = tempnam(".", prefix);
#else
    size_t len = strlen(prefix) + 12; /* room for "/tmp/" and "XXXXXX\0" */
    *filename = av_malloc(len * sizeof(char));
#endif
    /* -----common section-----*/
    if (*filename == NULL) {
        av_log(NULL, AV_LOG_ERROR, "ff_tempfile: Cannot allocate file name\n");
        return -1;
    }
#ifdef CONFIG_WIN32
    fd = open(*filename, _O_RDWR | _O_BINARY | _O_CREAT, 0444);
#else
    snprintf(*filename, len, "/tmp/%sXXXXXX", prefix);
    fd = mkstemp(*filename);
    if (fd < 0) {
        snprintf(*filename, len, "./%sXXXXXX", prefix);
        fd = mkstemp(*filename);
    }
#endif
    /* -----common section-----*/
    if (fd < 0) {
        av_log(NULL, AV_LOG_ERROR, "ff_tempfile: Cannot open temporary file %s\n", *filename);
        return -1;
    }
    return fd; /* success */
}