Revert "Add some basic FreeDV API usage to documentation."

This reverts commit e54b50d.

Author: tmiw

README_freedv.md

@@ -93,143 +93,6 @@ See also [freedv_api.h](src/freedv_api.h) and [freedv_api.c](src/freedv_api.c),
 $ ./freedv_tx 1600 ../../raw/hts1.raw - | ./freedv_rx 1600 - - | aplay -f S16_LE
 $ cat freedv_rx_log.txt
 ```
-
-### Using the API
-
-Generally, the FreeDV API is used as follows:
-
-#### Creating FreeDV objects
-
-Call freedv\_open() or freedv\_advanced\_open() depending on the mode being used:
-
-```
-\#include "freedv\_api.h"
-
-struct freedv* dv;
-if ((mode == FREEDV\_MODE\_700D) || (mode == FREEDV\_MODE\_700E) || (mode == FREEDV\_MODE\_2020)) {
-    struct freedv_advanced adv;
-    dv = freedv\_open\_advanced(mode, &adv);
-} else {
-    dv = fredv\_open(mode);
-}
-
-if (dv == NULL) {
-    // handle error condition
-}
-```
-
-Available modes:
-
-* FREEDV\_MODE\_1600
-* FREEDV\_MODE\_2400A
-* FREEDV\_MODE\_2400B
-* FREEDV\_MODE\_800XA
-* FREEDV\_MODE\_700C
-* FREEDV\_MODE\_700D
-* FREEDV\_MODE\_2020
-* FREEDV\_MODE\_700E
-
-#### Enabling reliable receiving/sending of callsigns in the voice stream (e.g. for PSK Reporter)
-
-```
-\#include "reliable\_text.h"
-
-reliable\_text\_t rt = reliable\_text\_create();
-if (rt == NULL) { /* handle error */ }
-
-void* stateObject = NULL; /* can be a pointer to anything */
-reliable\_text\_use\_with\_freedv(rt, dv, &OnReliableTextRx, stateObject);
-
-char* callsign = "KA6ABC";
-reliable\_text\_set\_string(rt, callsign, strlen(callsign));
-
-...
-
-void OnReliableTextRx(reliable\_text\_t rt, const char* txt\_ptr, int length, void* state) 
-{
-    fprintf(stderr, "OnReliableTextRx: received %s\n", txt\_ptr);
-    ...
-    reliable\_text\_reset(rt);
-}
-```
-
-#### Enabling normal text (e.g. not callsigns)
-
-*Note: this is mutually exclusive with reliable\_text above.*
-
-```
-freedv\_set\_callback\_txt(dv, &TextRxFn, &TextTxFn, stateObject);
-
-...
-
-static char* text = "This is a test";
-static int currentIndex = 0;
-
-char TextTxFn(void *callback_state) 
-{
-    currentIndex = (currentIndex + 1) % strlen(text);
-    return text[currentIndex];
-}
-
-void TextRxFn(void *callback\_state, char c)
-{
-    fprintf(stderr, "Received character %c from stream\n", c);
-}
-```
-
-#### Decoding audio
-
-```
-int freedvRxModulatedSampleRate = freedv\_get\_modem\_sample\_rate(dv);
-int freedvRxSpeechSampleRate = freedv\_get\_speech\_sample\_rate(dv);
-
-/* Note that FreeDV expects int16 samples, not float. Input audio should be 
-   resampled to the rate expected by the current mode (e.g. inside freedvRxModulatedSampleRate
-   above). */
-short* resampledRxInput = malloc(/* size of resampled input buffer */);
-short* rxOutput = malloc(/* size of output buffer */);
-resample(rxInput, resampledRxInput, radioRate, freedvRxModulatedSampleRate);
-
-/* Loop through available samples until we run out. Each time, call freedv\_nin() to get
-   the current number of samples the mode needs followed by freedv\_rx() to actually feed
-   them in. 0 is perfectly okay for freedv\_nin() depending on the current internal state. */
-int nsamples = freedv\_nin(dv);
-short* currentBuf = resampledRxInput;
-while (currentBuf < sizeofBuffer)
-{
-    freedv\_rx(dv, rxOutput, currentBuf);
-    resample(rxOutput, radioOutput, freedvRxSpeechSampleRate, radioRate);
-    currentBuf += nsamples;
-    nsamples = freedv\_nin(dv);
-}
-```
-
-#### Transmitting audio
-
-```
-int freedvTxModulatedSampleRate = freedv\_get\_modem\_sample\_rate(dv);
-int freedvTxSpeechSampleRate = freedv\_get\_speech\_sample\_rate(dv);
-int requiredTxSpeechSamples = freedv\_get\_n\_speech\_samples(dv);
-
-short* txInput = malloc(/* size of resampled output buffer */);
-short* txOutput = malloc(/* size of output buffer */);
-
-while(speech samples available)
-{
-    memcpy(txInput, radioSamples, requiredTxSpeechSamples);
-    freedv\_tx(dv, txOutput, txInput);
-}
-
-#### Cleanup
-
-```
-/* if reliable\_text is enabled */
-reliable\_text\_unlink\_from\_freedv(rt);
-
-/* always required to free memory */
-freedv\_close(dv);
-```
-
 ## FreeDV 2400A and 2400B modes
 
 FreeDV 2400A and FreeDV 2400B are modes designed for VHF radio. FreeDV 2400A is designed for SDR radios (it has a 5 kHz RF bandwidth), however FreeDV 2400B is designed to pass through commodity FM radios.