ALSA - samplerate conversion - c++

Question

I have a text-to-speech application, that generate an audio-stream (raw-data) with a samplerate of 22kHz.
I have a USB-SoundCard that support only 44kHz.
With my asound.conf I can play wav-files that contains 22kHz and 44kHz audio-stream without problems in aplay.
My Application use the alsa-libs and set the samplerate of the device.
In this case only 44kHz will succeed, because the hardware supports only this samplerate. But now, when i write the generated audio-stream to alsa, it sounds wrong, because the samplerates dosn't match. The audio-stream (raw-data) dosn't contain any header information, so I think alsa don't use any plugin zu convert the samplerate. Alsa don't know that the stream has a different samplerate
My question is now, what is the right way to tell alsa, that the generated audio-stream have a different samplerate, so the alsa-plugin convert it.
The following code works on the USB SoundCard only with sampleRate = 44100, otherwise an error occured (-22, invalid parameters).
void initAlsa()
{
const char* name = "default";
alsaAudio = true;
writeRiffAtClose = false;
int err = snd_pcm_open (&alsaPlaybackHandle, name, SND_PCM_STREAM_PLAYBACK, 0);
if (err < 0)
throw TtsException({"Alsa: cannot open playback audio device ", name, " (" , snd_strerror (err), ")"}, 0);
sampleRate = 44100;
err = snd_pcm_set_params(alsaPlaybackHandle, // pcm PCM handle
SND_PCM_FORMAT_S16_LE, // format required PCM format
SND_PCM_ACCESS_RW_INTERLEAVED, // access required PCM access
2, // channels required PCM channels (Stereo)
sampleRate, // rate required sample rate in Hz
1, // soft_resample 0 = disallow alsa-lib resample stream, 1 = allow resampling
250000); /* 0.25sec */ // latency required overall latency in us
if (err < 0)
throw TtsException({"Alsa: cannot set parameters (" , err, " = " , snd_strerror(err), ") on ", name}, 0);
LOG_DEBUG("Alsa audio initialized");
}
Other way are, I manuelly convert the sample rate, before i put it to alsa, but i think: why not use the alsa-plugin.
I don't have the option to get 44kHz audio-stream from the tts-engine (it's another software).
Or exist another way, that I don't see?
Best regards.