static int init_filters(const char *filters_descr) { char args[512]; int ret; AVFilter *abuffersrc = avfilter_get_by_name("abuffer"); AVFilter *abuffersink = avfilter_get_by_name("abuffersink"); AVFilterInOut *outputs = avfilter_inout_alloc(); AVFilterInOut *inputs = avfilter_inout_alloc(); const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16, -1 }; const int packing_fmts[] = { AVFILTER_PACKED, -1 }; const int64_t *chlayouts = avfilter_all_channel_layouts; AVABufferSinkParams *abuffersink_params; const AVFilterLink *outlink; filter_graph = avfilter_graph_alloc(); /* buffer audio source: the decoded frames from the decoder will be inserted here. */ if (!dec_ctx->channel_layout) dec_ctx->channel_layout = av_get_default_channel_layout(dec_ctx->channels); snprintf(args, sizeof(args), "%d:%d:0x%"PRIx64":packed", dec_ctx->sample_rate, dec_ctx->sample_fmt, dec_ctx->channel_layout); ret = avfilter_graph_create_filter(&buffersrc_ctx, abuffersrc, "in", args, NULL, filter_graph); if (ret < 0) { av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n"); return ret; } /* buffer audio sink: to terminate the filter chain. */ abuffersink_params = av_abuffersink_params_alloc(); abuffersink_params->sample_fmts = sample_fmts; abuffersink_params->channel_layouts = chlayouts; abuffersink_params->packing_fmts = packing_fmts; ret = avfilter_graph_create_filter(&buffersink_ctx, abuffersink, "out", NULL, abuffersink_params, filter_graph); if (ret < 0) { av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n"); return ret; } /* Endpoints for the filter graph. */ outputs->name = av_strdup("in"); outputs->filter_ctx = buffersrc_ctx; outputs->pad_idx = 0; outputs->next = NULL; inputs->name = av_strdup("out"); inputs->filter_ctx = buffersink_ctx; inputs->pad_idx = 0; inputs->next = NULL; if ((ret = avfilter_graph_parse(filter_graph, filter_descr, &inputs, &outputs, NULL)) < 0) return ret; if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0) return ret; /* Print summary of the sink buffer * Note: args buffer is reused to store channel layout string */ outlink = buffersink_ctx->inputs[0]; av_get_channel_layout_string(args, sizeof(args), -1, outlink->channel_layout); av_log(NULL, AV_LOG_INFO, "Output: srate:%dHz fmt:%s chlayout:%s\n", (int)outlink->sample_rate, (char *)av_x_if_null(av_get_sample_fmt_name(outlink->format), "?"), args); return 0; }