static int push_single_pic(AVFilterLink *outlink) { AVFilterContext *ctx = outlink->src; AVFilterLink *inlink = ctx->inputs[0]; ShowWavesContext *showwaves = ctx->priv; int64_t n = 0, max_samples = showwaves->total_samples / outlink->w; AVFrame *out = showwaves->outpicref; struct frame_node *node; const int nb_channels = inlink->channels; const int x = 255 / (showwaves->split_channels ? 1 : nb_channels); const int ch_height = showwaves->split_channels ? outlink->h / nb_channels : outlink->h; const int linesize = out->linesize[0]; int col = 0; int64_t *sum = showwaves->sum; av_log(ctx, AV_LOG_DEBUG, "Create frame averaging %"PRId64" samples per column\n", max_samples); memset(sum, 0, nb_channels); for (node = showwaves->audio_frames; node; node = node->next) { int i; const AVFrame *frame = node->frame; const int16_t *p = (const int16_t *)frame->data[0]; for (i = 0; i < frame->nb_samples; i++) { int ch; for (ch = 0; ch < nb_channels; ch++) sum[ch] += abs(p[ch + i*nb_channels]) << 1; if (n++ == max_samples) { for (ch = 0; ch < nb_channels; ch++) { int16_t sample = sum[ch] / max_samples; uint8_t *buf = out->data[0] + col; if (showwaves->split_channels) buf += ch*ch_height*linesize; av_assert0(col < outlink->w); showwaves->draw_sample(buf, ch_height, linesize, sample, &showwaves->buf_idy[ch], x); sum[ch] = 0; col++; n = 0; return push_frame(outlink);