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

            av_parser_close(st->parser);
        }
        av_free(st->index_entries);
        av_free(st);
    }
    flush_packet_queue(s);
    must_open_file = 1;
    if (s->iformat->flags & AVFMT_NOFILE) {
        must_open_file = 0;
    }
    if (must_open_file) {
        url_fclose(&s->pb);
    }
    av_freep(&s->priv_data);
    av_free(s);
}

/**
 * Add a new stream to a media file. Can only be called in the
 * read_header function. If the flag AVFMTCTX_NOHEADER is in the
 * format context, then new streams can be added in read_packet too.
 *
 *
 * @param s media file handle
 * @param id file format dependent stream id 
 */
AVStream *av_new_stream(AVFormatContext *s, int id)
{
    AVStream *st;

    if (s->nb_streams >= MAX_STREAMS)
        return NULL;

    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;
    st->cur_dts = AV_NOPTS_VALUE;

    /* default pts settings is MPEG like */
    av_set_pts_info(st, 33, 1, 90000);
    st->last_IP_pts = 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;

    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)st->time_base.num * st->codec.sample_rate);
            break;
        case CODEC_TYPE_VIDEO:
            av_frac_init(&st->pts, 0, 0, 
                         (int64_t)st->time_base.num * st->codec.frame_rate);
            break;
        default:
            break;
        }
    }
    return 0;
}

//FIXME merge with compute_pkt_fields
static void compute_pkt_fields2(AVStream *st, AVPacket *pkt){
    int b_frames = FFMAX(st->codec.has_b_frames, st->codec.max_b_frames);
    int num, den, frame_size;

//    av_log(NULL, AV_LOG_DEBUG, "av_write_frame: pts:%lld dts:%lld cur_dts:%lld b:%d size:%d st:%d\n", pkt->pts, pkt->dts, st->cur_dts, b_frames, pkt->size, pkt->stream_index);
    
/*    if(pkt->pts == AV_NOPTS_VALUE && pkt->dts == AV_NOPTS_VALUE)
        return -1;*/
            
    if(pkt->pts != AV_NOPTS_VALUE)
        pkt->pts = av_rescale(pkt->pts, st->time_base.den, AV_TIME_BASE * (int64_t)st->time_base.num);
    if(pkt->dts != AV_NOPTS_VALUE)
        pkt->dts = av_rescale(pkt->dts, st->time_base.den, AV_TIME_BASE * (int64_t)st->time_base.num);

    /* duration field */
    pkt->duration = av_rescale(pkt->duration, st->time_base.den, AV_TIME_BASE * (int64_t)st->time_base.num);
    if (pkt->duration == 0) {
        compute_frame_duration(&num, &den, st, NULL, pkt);
        if (den && num) {
            pkt->duration = av_rescale(1, num * (int64_t)st->time_base.den, den * (int64_t)st->time_base.num);
        }
    }

    //XXX/FIXME this is a temporary hack until all encoders output pts
    if((pkt->pts == 0 || pkt->pts == AV_NOPTS_VALUE) && pkt->dts == AV_NOPTS_VALUE && !b_frames){
        pkt->dts=
//        pkt->pts= st->cur_dts;
        pkt->pts= st->pts.val;
    }

    //calculate dts from pts    
    if(pkt->pts != AV_NOPTS_VALUE && pkt->dts == AV_NOPTS_VALUE){
        if(b_frames){
            if(st->last_IP_pts == AV_NOPTS_VALUE){
                st->last_IP_pts= -pkt->duration;
            }
            if(st->last_IP_pts < pkt->pts){
                pkt->dts= st->last_IP_pts;
                st->last_IP_pts= pkt->pts;
            }else
                pkt->dts= pkt->pts;
        }else
            pkt->dts= pkt->pts;
    }
    
//    av_log(NULL, AV_LOG_DEBUG, "av_write_frame: pts2:%lld dts2:%lld\n", pkt->pts, pkt->dts);
    st->cur_dts= pkt->dts;
    st->pts.val= pkt->dts;

    /* update pts */
    switch (st->codec.codec_type) {
    case CODEC_TYPE_AUDIO:
        frame_size = get_audio_frame_size(&st->codec, pkt->size);

        /* HACK/FIXME, we skip the initial 0-size packets as they are most likely equal to the encoder delay,
           but it would be better if we had the real timestamps from the encoder */
        if (frame_size >= 0 && (pkt->size || st->pts.num!=st->pts.den>>1 || st->pts.val)) {
            av_frac_add(&st->pts, (int64_t)st->time_base.den * frame_size);
        }
        break;
    case CODEC_TYPE_VIDEO:
        av_frac_add(&st->pts, (int64_t)st->time_base.den * st->codec.frame_rate_base);
        break;
    default:
        break;
    }
}

static void truncate_ts(AVStream *st, AVPacket *pkt){
    int64_t pts_mask = (2LL << (st->pts_wrap_bits-1)) - 1;
    
    if(pkt->dts < 0)
        pkt->dts= 0;  //this happens for low_delay=0 and b frames, FIXME, needs further invstigation about what we should do here
    
    pkt->pts &= pts_mask;
    pkt->dts &= pts_mask;
}

/**
 * Write a packet to an output media file. The packet shall contain
 * one audio or video frame.
 *
 * @param s media file handle
 * @param pkt the packet, which contains the stream_index, buf/buf_size, dts/pts, ...
 * @return < 0 if error, = 0 if OK, 1 if end of stream wanted.
 */
int av_write_frame(AVFormatContext *s, AVPacket *pkt)
{
    compute_pkt_fields2(s->streams[pkt->stream_index], pkt);
    
    truncate_ts(s->streams[pkt->stream_index], pkt);

    return s->oformat->write_packet(s, pkt);
}

/**
 * Writes a packet to an output media file ensuring correct interleaving. 
 * The packet shall contain one audio or video frame.
 * If the packets are already correctly interleaved the application should
 * call av_write_frame() instead as its slightly faster, its also important
 * to keep in mind that non interlaved input will need huge amounts
 * of memory to interleave with this, so its prefereable to interleave at the
 * demuxer level
 *
 * @param s media file handle
 * @param pkt the packet, which contains the stream_index, buf/buf_size, dts/pts, ...
 * @return < 0 if error, = 0 if OK, 1 if end of stream wanted.
 */
int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt){
    AVPacketList *pktl, **next_point, *this_pktl;
    int stream_count=0;
    int streams[MAX_STREAMS];
    AVStream *st= s->streams[ pkt->stream_index];

    compute_pkt_fields2(st, pkt);
    
    //FIXME/XXX/HACK drop zero sized packets
    if(st->codec.codec_type == CODEC_TYPE_AUDIO && pkt->size==0)
        return 0;

    if(pkt->dts == AV_NOPTS_VALUE)
        return -1;
        
    assert(pkt->destruct != av_destruct_packet); //FIXME

    this_pktl = av_mallocz(sizeof(AVPacketList));
    this_pktl->pkt= *pkt;
    av_dup_packet(&this_pktl->pkt);

    next_point = &s->packet_buffer;
    while(*next_point){
        AVStream *st2= s->streams[ (*next_point)->pkt.stream_index];
        int64_t left=  st2->time_base.num * (int64_t)st ->time_base.den;
        int64_t right= st ->time_base.num * (int64_t)st2->time_base.den;
        if((*next_point)->pkt.dts * left > pkt->dts * right) //FIXME this can overflow
            break;
        next_point= &(*next_point)->next;
    }
    this_pktl->next= *next_point;
    *next_point= this_pktl;
    
    memset(streams, 0, sizeof(streams));
    pktl= s->packet_buffer;
    while(pktl){
//av_log(s, AV_LOG_DEBUG, "show st:%d dts:%lld\n", pktl->pkt.stream_index, pktl->pkt.dts);
        if(streams[ pktl->pkt.stream_index ] == 0)
            stream_count++;
        streams[ pktl->pkt.stream_index ]++;
        pktl= pktl->next;
    }

    while(s->nb_streams == stream_count){
        int ret;

        pktl= s->packet_buffer;
//av_log(s, AV_LOG_DEBUG, "write st:%d dts:%lld\n", pktl->pkt.stream_index, pktl->pkt.dts);
        truncate_ts(s->streams[pktl->pkt.stream_index], &pktl->pkt);
        ret= s->oformat->write_packet(s, &pktl->pkt);
        
        s->packet_buffer= pktl->next;        
        if((--streams[ pktl->pkt.stream_index ]) == 0)
            stream_count--;

        av_free_packet(&pktl->pkt);
        av_freep(&pktl);
        
        if(ret<0)
            return ret;
    }
    return 0;
}

/**
 * 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;
    
    while(s->packet_buffer){
        int ret;
        AVPacketList *pktl= s->packet_buffer;

//av_log(s, AV_LOG_DEBUG, "write_trailer st:%d dts:%lld\n", pktl->pkt.stream_index, pktl->pkt.dts);
        truncate_ts(s->streams[pktl->pkt.stream_index], &pktl->pkt);
        ret= s->oformat->write_packet(s, &pktl->pkt);
        
        s->packet_buffer= pktl->next;        

        av_free_packet(&pktl->pkt);
        av_freep(&pktl);
        
        if(ret<0)
            return 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];

    av_log(NULL, AV_LOG_DEBUG, "%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) {
        av_log(NULL, AV_LOG_DEBUG, "  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;
            av_log(NULL, AV_LOG_DEBUG, "%02d:%02d:%02d.%01d", hours, mins, secs, 
                   (10 * us) / AV_TIME_BASE);
        } else {
            av_log(NULL, AV_LOG_DEBUG, "N/A");
        }
        av_log(NULL, AV_LOG_DEBUG, ", bitrate: ");
        if (ic->bit_rate) {
            av_log(NULL, AV_LOG_DEBUG,"%d kb/s", ic->bit_rate / 1000);
        } else {
            av_log(NULL, AV_LOG_DEBUG, "N/A");
        }
        av_log(NULL, AV_LOG_DEBUG, "\n");
    }
    for(i=0;i<ic->nb_streams;i++) {
        AVStream *st = ic->streams[i];
        avcodec_string(buf, sizeof(buf), &st->codec, is_output);
        av_log(NULL, AV_LOG_DEBUG, "  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) {
            av_log(NULL, AV_LOG_DEBUG, "[0x%x]", st->id);
        }
        av_log(NULL, AV_LOG_DEBUG, ": %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 */