zffmpeg/MediaAVFilter.cpp

#include "MediaAVFilter.h"

MediaAVFilter::MediaAVFilter()
{
}
MediaAVFilter::~MediaAVFilter()
{
    if(m_src_filter_ctx != nullptr){
        avfilter_free(m_src_filter_ctx);
        m_src_filter_ctx = nullptr;
    }
    if(m_sink_filter_ctx != nullptr){
        avfilter_free(m_sink_filter_ctx);
        m_sink_filter_ctx = nullptr;
    }
    if(m_fraph != nullptr){
        avfilter_graph_free(&m_fraph);
        m_fraph = nullptr;
    }
}
int MediaAVFilter::initAVFilter(AVCodecContext **m_avcodec_context,char *value)
{
    m_fraph = avfilter_graph_alloc();
    // 源过滤器和格式转换过滤器参数
    std::string s1 = "sample_rate=" + std::to_string((*m_avcodec_context)->sample_rate) + ":sample_fmt=" + av_get_sample_fmt_name((*m_avcodec_context)->sample_fmt) + ":channel_layout=" + std::to_string((*m_avcodec_context)->channel_layout);
    std::string s2 = "sample_rates=" + std::to_string((*m_avcodec_context)->sample_rate) + ":sample_fmts=" + av_get_sample_fmt_name((*m_avcodec_context)->sample_fmt) + ":channel_layouts=" + std::to_string((*m_avcodec_context)->channel_layout);
    //创建源过滤器
    const AVFilter *src_filter=avfilter_get_by_name("buffer");
    m_src_filter_ctx=avfilter_graph_alloc_filter(m_fraph,src_filter,"src");
    if (avfilter_init_str(m_src_filter_ctx, s1.c_str()) < 0) {
        printf("init src filter fail!\n");
        return -1;
    }
    //创建变速过滤器
    const AVFilter *tempo_filter = avfilter_get_by_name("tempo");
    AVFilterContext *tempo_filter_ctx = avfilter_graph_alloc_filter(m_fraph, tempo_filter, "tempo");
    AVDictionary *args = NULL;
    av_dict_set(&args, "tempo", value, 0);//根据value的值调节速度
    if (avfilter_init_dict(tempo_filter_ctx, &args) < 0) {
        printf("init speed filter fail!\n");
        return -1;
    }
    //创建格式转化过滤器
    const AVFilter *fmt_filter = avfilter_get_by_name("format");
    AVFilterContext *fmt_filter_ctx = avfilter_graph_alloc_filter(m_fraph, fmt_filter, "format");
    if (avfilter_init_str(fmt_filter_ctx, s2.c_str()) < 0) {
        printf("init fmt filter fail!\n");
        return -1;
    }
    //创建接收过滤器
    const AVFilter *sink_filter=avfilter_get_by_name("buffersink");
    m_sink_filter_ctx=avfilter_graph_alloc_filter(m_fraph,sink_filter,"sink");
    if (avfilter_init_dict(m_sink_filter_ctx, NULL) < 0) {
        printf("link filter fail!\n");
        return -1;
    }
    //链接过滤器
    if(avfilter_link(m_src_filter_ctx,0,tempo_filter_ctx,0) != 0){
        printf("link filter fail!\n");
        return -1;
    }
    if(avfilter_link(tempo_filter_ctx,0,fmt_filter_ctx,0) != 0){
        printf("link filter fail!\n");
        return -1;
    }
    if(avfilter_link(fmt_filter_ctx,0,m_sink_filter_ctx,0) != 0){
        printf("link filter fail!\n");
        return -1;
    }

    //配置图
    if (avfilter_graph_config(m_fraph, NULL) < 0) {
        printf("config graph fail!\n");
        return -1;
    }
    return 0;
}