+/**
+ * Peek data from an AVAudioFifo.
+ *
+ * @see enum AVSampleFormat
+ * The documentation for AVSampleFormat describes the data layout.
+ *
+ * @param af AVAudioFifo to read from
+ * @param data audio data plane pointers
+ * @param nb_samples number of samples to peek
+ * @param offset offset from current read position
+ * @return number of samples actually peek, or negative AVERROR code
+ * on failure. The number of samples actually peek will not
+ * be greater than nb_samples, and will only be less than
+ * nb_samples if av_audio_fifo_size is less than nb_samples.
+ */
+int av_audio_fifo_peek_at(AVAudioFifo *af, void **data, int nb_samples, int offset);
+