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M17 - Tweak Dead Air; Disable Non-Zero Fill;

This commit is contained in:
lwvmobile 2024-03-08 16:34:22 -05:00
parent ac6284819a
commit 75bc2b7b35
1 changed files with 40 additions and 45 deletions
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85
src/m17.c
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@ -1154,14 +1154,7 @@ void encodeM17RF (dsd_opts * opts, dsd_state * state, uint8_t * input, int type)
// fprintf (stderr, " %d", output_symbols[i]);
// }
//save symbols (dibits, actually) to symbol capture bin file format
if (opts->symbol_out_f)
{
for (i = 0; i < 192; i++)
fputc (output_dibits[i], opts->symbol_out_f);
}
//WIP: symbols to audio
//symbols to audio
//upsample 10x
int output_up[192*10]; memset (output_up, 0, 192*10*sizeof(int));
@ -1195,6 +1188,21 @@ void encodeM17RF (dsd_opts * opts, dsd_state * state, uint8_t * input, int type)
// fprintf (stderr, " %d", baseband[i]);
// }
//dead air type, output to all enabled formats zero sample to simulate dead air
//NOTE: 25 rounds is approximately 1 second even, seems optimal
if (type == 9)
{
memset (output_dibits, 0xFF, sizeof(output_dibits)); //NOTE: 0xFF works better on bin files
memset (baseband, 0, 1920*sizeof(short));
}
//save symbols (dibits, actually) to symbol capture bin file format
if (opts->symbol_out_f)
{
for (i = 0; i < 192; i++)
fputc (output_dibits[i], opts->symbol_out_f);
}
//playing back signal audio into device/udp
//NOTE: Open the analog output device, use -8
if (opts->monitor_input_audio == 1)
@ -1230,8 +1238,8 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
{
//WIP: Finish creating audio of the encoded signal
short empty[1920]; //empty audio sample for dead air on wav file output
uint8_t nil[368]; //empty array to send to RF during Preamble and EOT Marker
uint8_t nil[368]; //empty array to send to RF during Preamble, EOT Marker, or Dead Air
memset (nil, 0, sizeof(nil));
//Enable frame, TX and Ncurses Printer
opts->frame_m17 = 1;
@ -1257,16 +1265,9 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
short sample = 0; //individual audio sample from source
size_t nsam = 160; //number of samples to be read in (default is for codec2 3200 bps)
//if saving a wav file of baseband audio, insert initial dead air time
if (opts->wav_out_raw != NULL)
{
memset (empty, 0, 1920*sizeof(short)); //bugfix
for (i = 0; i < 20; i++)
{
sf_write_short(opts->wav_out_raw, empty, 1920);
sf_write_sync (opts->wav_out_raw);
}
}
//send dead air with type 9
for (i = 0; i < 25; i++)
encodeM17RF (opts, state, nil, 9);
//WIP: Open UDP port to 17000 and see if any other config info is necessary for running standard IP frames, etc,
//or perhaps just also configure an input format for that ip streaming method, may need to handle UDP control packets (conn, ackn, nack, ping, pong, disc)
@ -1355,12 +1356,13 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
//Viterbi decoder seems to respond better to non-zero fill, so, when no enc is used
//let's set the lsf_es to 2 for RES, and fill the nonce value with repeating 0x69
if (lsf_et == 0)
{
lsf_es = 3; //RES
for (i = 0; i < 14; i++)
nonce[i] = 0x69;
}
//NOTE: This has seemingly been fixed with the dead air tweaks
// if (lsf_et == 0)
// {
// lsf_es = 3; //RES
// for (i = 0; i < 14; i++)
// nonce[i] = 0x69;
// }
//compose the 16-bit frame information from the above sub elements
uint16_t lsf_fi = 0;
@ -1415,7 +1417,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
}
//if AES enc employed, insert the iv into LSF
// if (lsf_et == 2) //disable to allow the 0x69 repeating non-zero fill on RES
if (lsf_et == 2)
{
for (i = 0; i < 112; i++)
m17_lsf[i+112] = iv[i];
@ -1950,12 +1952,13 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
//Viterbi decoder seems to respond better to non-zero fill, so, when no enc is used
//let's set the lsf_es to 2 for RES, and fill the nonce value with repeating 0x69
if (lsf_et == 0)
{
lsf_es = 3; //RES
for (i = 0; i < 14; i++)
nonce[i] = 0x69;
}
//NOTE: This has seemingly been fixed with the dead air tweaks
// if (lsf_et == 0)
// {
// lsf_es = 3; //RES
// for (i = 0; i < 14; i++)
// nonce[i] = 0x69;
// }
//load the nonce from packed bytes to a bitwise iv array
memset(iv, 0, sizeof(iv));
@ -1967,7 +1970,7 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
}
//if AES enc employed, insert the iv into LSF
// if (lsf_et == 2) //disable to allow the 0x69 repeating non-zero fill on RES
if (lsf_et == 2) //disable to allow the 0x69 repeating non-zero fill on RES
{
for (i = 0; i < 112; i++) m17_lsf[i+112] = iv[i];
}
@ -2028,17 +2031,9 @@ void encodeM17STR(dsd_opts * opts, dsd_state * state)
memset (nil, 0, sizeof(nil));
encodeM17RF (opts, state, nil, 5); //EOT Marker
//if saving a wav file of baseband audio, insert dead air time
//so subsequent encodes have a little bit of breathing room
if (opts->wav_out_raw != NULL)
{
memset (empty, 0, 1920*sizeof(short)); //bugfix
for (i = 0; i < 4; i++)
{
sf_write_short(opts->wav_out_raw, empty, 1920);
sf_write_sync (opts->wav_out_raw);
}
}
//send dead air with type 9
for (i = 0; i < 25; i++)
encodeM17RF (opts, state, nil, 9);
//reset indicators
eot = 0;