asf.c

ffmpeg源码分析

                rsize += asf->packet_replic_size; // FIXME - check validity
            } else if (asf->packet_replic_size==1){
                // multipacket - frag_offset is begining timestamp
                asf->packet_time_start = asf->packet_frag_offset;
                asf->packet_frag_offset = 0;
                asf->packet_frag_timestamp = asf->packet_timestamp;

                asf->packet_time_delta = get_byte(pb);
                rsize++;
            }else{
                assert(asf->packet_replic_size==0);
            }
            if (asf->packet_flags & 0x01) {
                DO_2BITS(asf->packet_segsizetype >> 6, asf->packet_frag_size, 0); // 0 is illegal
#undef DO_2BITS
                //printf("Fragsize %d\n", asf->packet_frag_size);
            } else {
                asf->packet_frag_size = asf->packet_size_left - rsize;
                //printf("Using rest  %d %d %d\n", asf->packet_frag_size, asf->packet_size_left, rsize);
            }
            if (asf->packet_replic_size == 1) {
                asf->packet_multi_size = asf->packet_frag_size;
                if (asf->packet_multi_size > asf->packet_size_left) {
                    asf->packet_segments = 0;
                    continue;
                }
            }
            asf->packet_size_left -= rsize;
            //printf("___objsize____  %d   %d    rs:%d\n", asf->packet_obj_size, asf->packet_frag_offset, rsize);

            if (asf->stream_index < 0
                || s->streams[asf->stream_index]->discard >= AVDISCARD_ALL
                || (!asf->packet_key_frame && s->streams[asf->stream_index]->discard >= AVDISCARD_NONKEY)
                ) {
                asf->packet_time_start = 0;
                /* unhandled packet (should not happen) */
                url_fskip(pb, asf->packet_frag_size);
                asf->packet_size_left -= asf->packet_frag_size;
                if(asf->stream_index < 0)
                    av_log(s, AV_LOG_ERROR, "ff asf skip %d  %d\n", asf->packet_frag_size, num & 0x7f);
                continue;
            }
            asf->asf_st = s->streams[asf->stream_index]->priv_data;
        }
        asf_st = asf->asf_st;

        if ((asf->packet_frag_offset != asf_st->frag_offset
             || (asf->packet_frag_offset
                 && asf->packet_seq != asf_st->seq)) // seq should be ignored
           ) {
            /* cannot continue current packet: free it */
            // FIXME better check if packet was already allocated
            av_log(s, AV_LOG_INFO, "ff asf parser skips: %d - %d     o:%d - %d    %d %d   fl:%d\n",
                   asf_st->pkt.size,
                   asf->packet_obj_size,
                   asf->packet_frag_offset, asf_st->frag_offset,
                   asf->packet_seq, asf_st->seq, asf->packet_frag_size);
            if (asf_st->pkt.size)
                av_free_packet(&asf_st->pkt);
            asf_st->frag_offset = 0;
            if (asf->packet_frag_offset != 0) {
                url_fskip(pb, asf->packet_frag_size);
                av_log(s, AV_LOG_INFO, "ff asf parser skipping %db\n", asf->packet_frag_size);
                asf->packet_size_left -= asf->packet_frag_size;
                continue;
            }
        }
        if (asf->packet_replic_size == 1) {
            // frag_offset is here used as the begining timestamp
            asf->packet_frag_timestamp = asf->packet_time_start;
            asf->packet_time_start += asf->packet_time_delta;
            asf->packet_obj_size = asf->packet_frag_size = get_byte(pb);
            asf->packet_size_left--;
            asf->packet_multi_size--;
            if (asf->packet_multi_size < asf->packet_obj_size)
            {
                asf->packet_time_start = 0;
                url_fskip(pb, asf->packet_multi_size);
                asf->packet_size_left -= asf->packet_multi_size;
                continue;
            }
            asf->packet_multi_size -= asf->packet_obj_size;
            //printf("COMPRESS size  %d  %d  %d   ms:%d\n", asf->packet_obj_size, asf->packet_frag_timestamp, asf->packet_size_left, asf->packet_multi_size);
        }
        if (asf_st->frag_offset == 0) {
            /* new packet */
            av_new_packet(&asf_st->pkt, asf->packet_obj_size);
            asf_st->seq = asf->packet_seq;
            asf_st->pkt.pts = asf->packet_frag_timestamp;
            asf_st->pkt.stream_index = asf->stream_index;
            asf_st->pkt.pos =
            asf_st->packet_pos= asf->packet_pos;
//printf("new packet: stream:%d key:%d packet_key:%d audio:%d size:%d\n",
//asf->stream_index, asf->packet_key_frame, asf_st->pkt.flags & PKT_FLAG_KEY,
//s->streams[asf->stream_index]->codec->codec_type == CODEC_TYPE_AUDIO, asf->packet_obj_size);
            if (s->streams[asf->stream_index]->codec->codec_type == CODEC_TYPE_AUDIO)
                asf->packet_key_frame = 1;
            if (asf->packet_key_frame)
                asf_st->pkt.flags |= PKT_FLAG_KEY;
        }

        /* read data */
        //printf("READ PACKET s:%d  os:%d  o:%d,%d  l:%d   DATA:%p\n",
        //       asf->packet_size, asf_st->pkt.size, asf->packet_frag_offset,
        //       asf_st->frag_offset, asf->packet_frag_size, asf_st->pkt.data);
        asf->packet_size_left -= asf->packet_frag_size;
        if (asf->packet_size_left < 0)
            continue;
        get_buffer(pb, asf_st->pkt.data + asf->packet_frag_offset,
                   asf->packet_frag_size);
        asf_st->frag_offset += asf->packet_frag_size;
        /* test if whole packet is read */
        if (asf_st->frag_offset == asf_st->pkt.size) {
            /* return packet */
            if (asf_st->ds_span > 1) {
                /* packet descrambling */
                char* newdata = av_malloc(asf_st->pkt.size);
                if (newdata) {
                    int offset = 0;
                    while (offset < asf_st->pkt.size) {
                        int off = offset / asf_st->ds_chunk_size;
                        int row = off / asf_st->ds_span;
                        int col = off % asf_st->ds_span;
                        int idx = row + col * asf_st->ds_packet_size / asf_st->ds_chunk_size;
                        //printf("off:%d  row:%d  col:%d  idx:%d\n", off, row, col, idx);
                        memcpy(newdata + offset,
                               asf_st->pkt.data + idx * asf_st->ds_chunk_size,
                               asf_st->ds_chunk_size);
                        offset += asf_st->ds_chunk_size;
                    }
                    av_free(asf_st->pkt.data);
                    asf_st->pkt.data = newdata;
                }
            }
            asf_st->frag_offset = 0;
            memcpy(pkt, &asf_st->pkt, sizeof(AVPacket));
            //printf("packet %d %d\n", asf_st->pkt.size, asf->packet_frag_size);
            asf_st->pkt.size = 0;
            asf_st->pkt.data = 0;
            break; // packet completed
        }
    }
    return 0;
}

static int asf_read_close(AVFormatContext *s)
{
    int i;

    for(i=0;i<s->nb_streams;i++) {
        AVStream *st = s->streams[i];
        av_free(st->priv_data);
        av_free(st->codec->extradata);
    av_free(st->codec->palctrl);
    }
    return 0;
}

// Added to support seeking after packets have been read
// If information is not reset, read_packet fails due to
// leftover information from previous reads
static void asf_reset_header(AVFormatContext *s)
{
    ASFContext *asf = s->priv_data;
    ASFStream *asf_st;
    int i;

    asf->packet_nb_frames = 0;
    asf->packet_timestamp_start = -1;
    asf->packet_timestamp_end = -1;
    asf->packet_size_left = 0;
    asf->packet_segments = 0;
    asf->packet_flags = 0;
    asf->packet_property = 0;
    asf->packet_timestamp = 0;
    asf->packet_segsizetype = 0;
    asf->packet_segments = 0;
    asf->packet_seq = 0;
    asf->packet_replic_size = 0;
    asf->packet_key_frame = 0;
    asf->packet_padsize = 0;
    asf->packet_frag_offset = 0;
    asf->packet_frag_size = 0;
    asf->packet_frag_timestamp = 0;
    asf->packet_multi_size = 0;
    asf->packet_obj_size = 0;
    asf->packet_time_delta = 0;
    asf->packet_time_start = 0;

    for(i=0; i<s->nb_streams; i++){
        asf_st= s->streams[i]->priv_data;
        av_free_packet(&asf_st->pkt);
        asf_st->frag_offset=0;
        asf_st->seq=0;
    }
    asf->asf_st= NULL;
}

static int64_t asf_read_pts(AVFormatContext *s, int stream_index, int64_t *ppos, int64_t pos_limit)
{
    ASFContext *asf = s->priv_data;
    AVPacket pkt1, *pkt = &pkt1;
    ASFStream *asf_st;
    int64_t pts;
    int64_t pos= *ppos;
    int i;
    int64_t start_pos[s->nb_streams];

    for(i=0; i<s->nb_streams; i++){
        start_pos[i]= pos;
    }

    pos= (pos+asf->packet_size-1-s->data_offset)/asf->packet_size*asf->packet_size+ s->data_offset;
    *ppos= pos;
    url_fseek(&s->pb, pos, SEEK_SET);

//printf("asf_read_pts\n");
    asf_reset_header(s);
    for(;;){
        if (av_read_frame(s, pkt) < 0){
            av_log(s, AV_LOG_INFO, "seek failed\n");
            return AV_NOPTS_VALUE;
        }

        pts= pkt->pts;

        av_free_packet(pkt);
        if(pkt->flags&PKT_FLAG_KEY){
            i= pkt->stream_index;

            asf_st= s->streams[i]->priv_data;

            assert((asf_st->packet_pos - s->data_offset) % asf->packet_size == 0);
            pos= asf_st->packet_pos;

            av_add_index_entry(s->streams[i], pos, pkt->size, pts, pos - start_pos[i] + 1, AVINDEX_KEYFRAME);
            start_pos[i]= asf_st->packet_pos + 1;

            if(pkt->stream_index == stream_index)
               break;
        }
    }

    *ppos= pos;
//printf("found keyframe at %Ld stream %d stamp:%Ld\n", *ppos, stream_index, pts);

    return pts;
}

static int asf_read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flags)
{
    ASFContext *asf = s->priv_data;

    if (asf->packet_size <= 0)
        return -1;

    if(av_seek_frame_binary(s, stream_index, pts, flags)<0)
        return -1;

    asf_reset_header(s);
    return 0;
}

static AVInputFormat asf_iformat = {
    "asf",
    "asf format",
    sizeof(ASFContext),
    asf_probe,
    asf_read_header,
    asf_read_packet,
    asf_read_close,
    asf_read_seek,
    asf_read_pts,
};

#ifdef CONFIG_MUXERS
    extern AVOutputFormat asf_oformat;
    extern AVOutputFormat asf_stream_oformat;
#endif //CONFIG_MUXERS

int asf_init(void)
{
    av_register_input_format(&asf_iformat);
#ifdef CONFIG_MUXERS
    av_register_output_format(&asf_oformat);
    av_register_output_format(&asf_stream_oformat);
#endif //CONFIG_MUXERS
    return 0;
}