fix

Author: Cuda-Chen

README.md

@@ -12,13 +12,13 @@ A minimalist RISC-V system emulator capable of running Linux the kernel and corr
 - Three types of I/O support using VirtIO standard:
     - virtio-blk acquires disk image from the host.
     - virtio-net is mapped as TAP interface.
-    - virtio-snd uses [PortAudio](https://github.com/PortAudio/portaudio) for sound playback and capture on the host with one limitations:
+    - virtio-snd uses [PortAudio](https://github.com/PortAudio/portaudio) for sound playback and capture on the host with one limitation:
         - As a confirmed issue that `semu` cannot send/receive PCM frames in time, causing
           the ALSA stack stuck in XRUN state until `semu` being rebooted.
         - For playback, you can try to adjust the buffer size to more than four times of period size.
             - For instance, the following buffer/period size settings on `aplay` has been tested
               with broken and stutter effects yet complete with no any errors: `aplay --buffer-size=32768 --period-size=4096 /usr/share/sounds/alsa/Front_Center.wav`.
-        - For capture, ALSA usually stucks in XRUN state, so you may try more times and pray for your own luck. 
+        - For capture, ALSA usually get stuck in XRUN state, so you may need to try multiple times. 
 
 ## Prerequisites
 

virtio-snd.c

@@ -831,7 +831,7 @@ static void virtio_snd_read_pcm_prepare(const virtio_snd_pcm_hdr_t *query,
             goto pa_err;
     } else if (dir == VIRTIO_SND_D_INPUT) {
         PaStreamParameters params = {
-            .device = Pa_GetDefaultOutputDevice(),
+            .device = Pa_GetDefaultInputDevice(),
             .channelCount = props->pp.channels,
             .sampleFormat = paInt16, /* FIXME: set mapping of format */
             .hostApiSpecificStreamInfo = NULL,