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authorRoman Khassraf <roman@khassraf.at>2015-07-11 15:08:01 +0200
committerRoman Khassraf <roman@khassraf.at>2015-07-11 15:08:01 +0200
commitb86836781e8531dadf6612552c31085729a69351 (patch)
tree8127123050a26e4c2198d611ba29d156dd32165d /lib/decoding
parent42411c6ef0e0d3cae3dcdf20b45cbe5fabd0fa64 (diff)
Added handling of channel mode modify messages for AMR
Diffstat (limited to 'lib/decoding')
-rw-r--r--lib/decoding/tch_f_decoder_impl.cc55
1 files changed, 53 insertions, 2 deletions
diff --git a/lib/decoding/tch_f_decoder_impl.cc b/lib/decoding/tch_f_decoder_impl.cc
index 3ec7205..a3b09fb 100644
--- a/lib/decoding/tch_f_decoder_impl.cc
+++ b/lib/decoding/tch_f_decoder_impl.cc
@@ -68,7 +68,7 @@ namespace gr {
{
throw std::runtime_error("TCH/F Decoder: can't open file\n");
}
-
+
const unsigned char amr_nb_magic[6] = { 0x23, 0x21, 0x41, 0x4d, 0x52, 0x0a };
if (d_tch_mode != TCH_FS)
@@ -163,6 +163,56 @@ namespace gr {
pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob);
message_port_pub(pmt::mp("msgs"), msg_out);
+
+ // if we are in an AMR-mode and we receive a channel mode modify message,
+ // we set the mode according to the multirate configuration from the message
+ // see GSM 04.18, section 9.1.5 and 10.5.2.21aa
+ if (d_tch_mode != TCH_FS && d_tch_mode != TCH_EFR)
+ {
+ if (outmsg[3] == 0x06 && outmsg[4] == 0x10)
+ {
+ // Verify that multirate version 1 is set
+ if ((outmsg[11] >> 5) == 1)
+ {
+ // the set of active codecs, max 4 modes
+ // active_codec_set[0] corresponds to CODEC_MODE_1 with lowest bit rate
+ // active_codec_set[3] corresponds to CODEC_MODE_4 with highest bit rate
+ tch_mode active_codec_set[4];
+ uint8_t mode_count = 0;
+ for (i = 0; i<8; i++)
+ {
+ if (((outmsg[12] >> i) & 0x1) == 1 && mode_count < 4)
+ {
+ active_codec_set[mode_count++] = static_cast<tch_mode>(7-i);
+ }
+ }
+
+ // check Initial Codec Mode Indicator ICMI
+ // if ICMI == 1, then use the one defined in start mode field
+ // else use implicit rule defined in GSM 05.09, section 3.4.3
+ if (((outmsg[11] >> 3) & 0x1) == 1)
+ {
+ // from start field
+ setCodingMode(active_codec_set[ (outmsg[11] & 0x3) ]);
+ }
+ else
+ {
+ // implicit mode
+ // if the set contains only 1 codec, we use that one
+ // else if there are 2 or 3 codecs in the set, we use the one with lowest bitrate
+ if (mode_count >= 1 && mode_count <= 3)
+ {
+ setCodingMode(active_codec_set[0]);
+ }
+ // if there are 4 codecs in the set, we use the second lowest bitrate
+ else if (mode_count == 4)
+ {
+ setCodingMode(active_codec_set[1]);
+ }
+ }
+ }
+ }
+ }
}
}
@@ -302,8 +352,9 @@ namespace gr {
void tch_f_decoder_impl::setCodingMode(tch_mode mode)
{
- if (d_tch_mode != TCH_FS && d_tch_mode != TCH_EFR)
+ if (mode != TCH_FS && d_tch_mode != TCH_EFR)
{
+ d_tch_mode = mode;
mKd = GSM::gAMRKd[d_tch_mode];
mTCHD.resize(mKd);
mTCHU.resize(mKd+6);