int swr_convert_frame(SwrContext *s, AVFrame *out, const AVFrame *in) { int ret, setup = 0; if (!swr_is_initialized(s)) { if ((ret = swr_config_frame(s, out, in)) < 0) return ret; if ((ret = swr_init(s)) < 0) return ret; setup = 1; } else { // return as is or reconfigure for input changes? if ((ret = config_changed(s, out, in))) return ret; } if (out) { if (!out->linesize[0]) { out->nb_samples = swr_get_delay(s, s->out_sample_rate) + in->nb_samples*(int64_t)s->out_sample_rate / s->in_sample_rate + 3; if ((ret = av_frame_get_buffer(out, 0)) < 0) { if (setup) swr_close(s); return ret; } } else { if (!out->nb_samples) out->nb_samples = available_samples(out); } } return convert_frame(s, out, in); }