swr_convert()
Audio processing for each frame. An audio frame for the corresponding resampling
int swr_convert(struct SwrContext *s, uint8_t **out, int out_count, const uint8_t **in, int in_count);
Parameter 1: context of audio resampling
Parameter 2: output pointer. Transmission output array
Number of samples of the output, not the number of bytes: 3 parameters. The number of samples of a single channel.
Parameter 4: the input array, AVFrame the decoded DATA
Parameter 5: the number of samples of a single channel input.