libtwamr encoder: always emit frame->mode = mode; In the original implementation of amr_encode_frame(), the 'mode' member of the output struct was set to 0xFF if the output frame type is TX_NO_DATA. This design was made to mimic the mode field (16-bit word) being set to 0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends on this struct member being set in any way, and amr_frame_to_tseq() generates the needed 0xFFFF on its own, based on frame->type being equal to TX_NO_DATA. It is simpler and more efficient to always set frame->mode to the actual encoding mode in amr_encode_frame(), and this new behavior has already been documented in doc/AMR-library-API description in anticipation of the present change.

/*
 * This program generates a binary file of 256 bytes, containing every
 * possible octet value in linearly increasing order.  The purpose of this
 * datum is testing of A-linear-A and mu-linear-mu PCM conversions: we need
 * to ensure that each of those sequences is an identity transform for all
 * possible PCM octet values.
 */

#include <stdio.h>
#include <stdlib.h>

main(argc, argv)
	char **argv;
{
	FILE *outf;
	unsigned val;

	if (argc != 2) {
		fprintf(stderr, "usage: %s output-bin-file\n", argv[0]);
		exit(1);
	}
	outf = fopen(argv[1], "w");
	if (!outf) {
		perror(argv[1]);
		exit(1);
	}
	for (val = 0; val < 256; val++)
		putc(val, outf);
	fclose(outf);
	exit(0);
}