ffmpeg——av_write_trailer写文件尾

ffmpeg 的 Mux 主要分为 三步操作：

    avformat_write_header ： 写文件头

    av_write_frame/av_interleaved_write_frame： 写packet

    av_write_trailer ： 写文件尾

本文主要分析 av_write_trailer 。

<span style="font-size:14px;">int av_write_trailer(AVFormatContext *s)
{
    int ret, i;

    for (;; ) {
        AVPacket pkt;
        ret = interleave_packet(s, &pkt, NULL, 1);
        if (ret < 0)
            goto fail;
        if (!ret)
            break;

        ret = write_packet(s, &pkt);
        if (ret >= 0)
            s->streams[pkt.stream_index]->nb_frames++;

        av_packet_unref(&pkt);

        if (ret < 0)
            goto fail;
        if(s->pb && s->pb->error)
            goto fail;
    }

    if (!s->internal->header_written) {
        ret = s->internal->write_header_ret ? s->internal->write_header_ret : write_header_internal(s);
        if (ret < 0)
            goto fail;
    }

fail:
    if (s->internal->header_written && s->oformat->write_trailer) {
        if (!(s->oformat->flags & AVFMT_NOFILE) && s->pb)
            avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_TRAILER);
        if (ret >= 0) {
        ret = s->oformat->write_trailer(s);
        } else {
            s->oformat->write_trailer(s);
        }
    }

    if (s->oformat->deinit)
        s->oformat->deinit(s);

    if (s->pb)
       avio_flush(s->pb);
    if (ret == 0)
       ret = s->pb ? s->pb->error : 0;
    for (i = 0; i < s->nb_streams; i++) {
        av_freep(&s->streams[i]->priv_data);
        av_freep(&s->streams[i]->index_entries);
    }
    if (s->oformat->priv_class)
        av_opt_free(s->priv_data);
    av_freep(&s->priv_data);
    return ret;
}</span>

额外参考 ： http://blog.youkuaiyun.com/leixiaohua1020/article/details/44201645