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Avoid FEC regeneration and DTMF blanking for null AMBE data 

FEC recalculation always reports errors for null AMBE frames, and
there is no DTMF present by definition.

In practice, null AMBE data is often (always?) sent by the Kenwood
TH-D74 in the first 21 voice frames, and I've also seen it at the end
of a fast data transmission.
This commit is contained in:
Tim Stewart 2020-12-13 16:28:47 -05:00
parent efe9b3d459
commit b2844bc0a6
2 changed files with 23 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
DStarControl.cpp
View File

@ -165,12 +165,25 @@ unsigned int CDStarControl::maybeFixupVoiceFrame(
*skip_dtmf_blanking_frames = FAST_DATA_BEEP_GRACE_FRAMES;
LogMessage("%s frame %u: found fast data (cont.)", log_prefix, n);
} else {
if (n == 1U) {
bool voice_sync_data_is_null_ambe_data = false;
bool data_is_null_ambe_data = false;
if ((n == 1U) && (::memcmp(voice_sync_data + offset, DSTAR_NULL_AMBE_DATA_BYTES_SCRAMBLED, DSTAR_VOICE_FRAME_LENGTH_BYTES) == 0)) {
LogMessage("%s frame 0: *** Null AMBE data detected in voice frame ***", log_prefix);
voice_sync_data_is_null_ambe_data = true;
}
if (::memcmp(data + offset, DSTAR_NULL_AMBE_DATA_BYTES_SCRAMBLED, DSTAR_VOICE_FRAME_LENGTH_BYTES) == 0) {
LogMessage("%s frame %u: *** Null AMBE data detected in voice frame ***", log_prefix, n);
data_is_null_ambe_data = true;
}
if ((n == 1U) && !voice_sync_data_is_null_ambe_data) {
LogMessage("%s frame 0: *** REGENERATING FEC ***", log_prefix);
errors += m_fec.regenerateDStar(voice_sync_data + offset);
}
LogMessage("%s frame %u: *** REGENERATING FEC ***", log_prefix, n);
errors += m_fec.regenerateDStar(data + offset);
if (!data_is_null_ambe_data) {
LogMessage("%s frame %u: *** REGENERATING FEC ***", log_prefix, n);
errors += m_fec.regenerateDStar(data + offset);
}
if (blank_dtmf && (*skip_dtmf_blanking_frames > 0U)) {
(*skip_dtmf_blanking_frames)--;
@ -180,12 +193,14 @@ unsigned int CDStarControl::maybeFixupVoiceFrame(
LogMessage("%s frame %u: *** Not BLANKING DTMF (left to skip: %u) ***",
log_prefix, n, *skip_dtmf_blanking_frames);
} else if (blank_dtmf && (*skip_dtmf_blanking_frames == 0U)) {
if (n == 1U) {
if ((n == 1U) && !voice_sync_data_is_null_ambe_data) {
LogMessage("%s frame 0: *** BLANKING DTMF ***", log_prefix);
blankDTMF(voice_sync_data + offset);
}
LogMessage("%s frame %u: *** BLANKING DTMF ***", log_prefix, n);
blankDTMF(data + offset);
if (!data_is_null_ambe_data) {
LogMessage("%s frame %u: *** BLANKING DTMF ***", log_prefix, n);
blankDTMF(data + offset);
}
}
}

2
DStarDefines.h
View File

@ -28,6 +28,8 @@ const unsigned char DSTAR_END_PATTERN_BYTES[] = { TAG_EOT, 0x55, 0x55, 0x55, 0x5
const unsigned int DSTAR_END_PATTERN_LENGTH_BYTES = 6U;
const unsigned char DSTAR_NULL_AMBE_DATA_BYTES[] = { 0x9E, 0x8D, 0x32, 0x88, 0x26, 0x1A, 0x3F, 0x61, 0xE8 };
// DSTAR_NULL_AMBE_DATA_BYTES_SCRAMBLED is DSTAR_NULL_AMBE_DATA_BYTES XORed with DSTAR_SCRAMBLER_BYTES.
const unsigned char DSTAR_NULL_AMBE_DATA_BYTES_SCRAMBLED[] = { 0xEEU, 0xC2U, 0xA1U, 0xC8U, 0x42U, 0x6EU, 0x52U, 0x51U, 0xC3U };
const unsigned char DSTAR_NULL_SLOW_SYNC_BYTES[] = { 0x55, 0x2D, 0x16 };
// Note that these are already scrambled, 0x66 0x66 0x66 otherwise