T.31 now gets somewhere in T.38 mode, although it still needs more work so

it functions properly in T.38 + ECM mode.

libs/spandsp/src/spandsp/private/t31.h

@@ -63,8 +63,8 @@ typedef struct
 {
     /*! \brief Internet Aware FAX mode bit mask. */
     int iaf;
-    /*! \brief Required time between T.38 transmissions, in ms. */
-    int ms_per_tx_chunk;
+    /*! \brief Required time between T.38 transmissions, in us. */
+    int us_per_tx_chunk;
     /*! \brief Bit fields controlling the way data is packed into chunked for transmission. */
     int chunking_modes;
 
@@ -125,6 +125,8 @@ typedef struct
     int32_t samples;
     /*! \brief The value for samples at the next transmission point. */
     int32_t next_tx_samples;
+    /*! \brief The current transmit timeout. */
+    int32_t timeout_tx_samples;
     /*! \brief The current receive timeout. */
     int32_t timeout_rx_samples;
 } t31_t38_front_end_state_t;