capture-test: Add buffer size control & verbose logging

Recent SOF drivers have started populating the buffer size of ALSA
hw_params structs with values that produce an -EINVAL if you try to
set them (unclear to me if this is a bug or not).

Regardless, the capture test wants control over that, so add it.  Also
hook the ALSA hw_params dump code (for debugging issues like this) and
hide it under a "--verbose" flag.

Signed-off-by: Andy Ross <andyross@google.com>

Author: andyross

tools/capture-test.py

@@ -46,15 +46,17 @@
 """
 
 def parse_opts():
-    global opts
+    global opts # pylint: disable=global-statement
     ap = argparse.ArgumentParser(description=HELP_TEXT,
                                  formatter_class=argparse.RawDescriptionHelpFormatter)
+    ap.add_argument("-v", "--verbose", action="store_true", help="Verbose output")
     ap.add_argument("--disable-rtnr", action="store_true", help="Disable RTNR noise reduction")
     ap.add_argument("-c", "--card", type=int, default=0, help="ALSA card index")
     ap.add_argument("--pcm", type=int, default=16, help="Output ALSA PCM index")
     ap.add_argument("--cap", type=int, default=18, help="Capture ALSA PCM index")
     ap.add_argument("--rate", type=int, default=48000, help="Sample rate")
     ap.add_argument("--chan", type=int, default=2, help="Output channel count")
+    ap.add_argument("--bufsz", type=int, default=2048, help="Buffer size in frames")
     ap.add_argument("--capchan", type=int,
                       help="Capture channel count (if different from output)")
     ap.add_argument("--capbits", type=int, default=16, help="Capture sample bits (16 or 32)")
@@ -103,6 +105,7 @@ def err_wrap(ret):
         return ret
     def alloc(self, typ):
         return (C.c_byte * getattr(self.lib, f"snd_{typ}_sizeof")())()
+    # pylint: disable=too-few-public-methods
     class pcm_channel_area_t(C.Structure):
         _fields_ = [("addr", C.c_ulong), ("first", C.c_int), ("step", C.c_int)]
 
@@ -111,8 +114,18 @@ def pcm_init_stream(pcm, rate, chans, fmt, access):
     alsa.snd_pcm_hw_params_any(pcm, hwp)
     alsa.snd_pcm_hw_params_set_format(pcm, hwp, fmt)
     alsa.snd_pcm_hw_params_set_channels(pcm, hwp, chans)
-    alsa.snd_pcm_hw_params_set_rate(pcm, hwp, rate, alsa.PCM_STREAM_PLAYBACK)
+    alsa.snd_pcm_hw_params_set_rate(pcm, hwp, rate, 0)
     alsa.snd_pcm_hw_params_set_access(pcm, hwp, access)
+    alsa.snd_pcm_hw_params_set_buffer_size(pcm, hwp, opts.bufsz)
+    if opts.verbose:
+        print(f"Set hw_params:")
+        out = C.c_ulong(0)
+        alsa.snd_output_buffer_open(C.byref(out))
+        alsa.snd_pcm_hw_params_dump(hwp, out)
+        buf = C.c_ulong(0)
+        alsa.snd_output_buffer_string(out, C.byref(buf))
+        print(C.string_at(buf.value).decode("ascii"))
+
     alsa.snd_pcm_hw_params(pcm, hwp)
 
 def ctl_disable_rtnr():
@@ -352,7 +365,7 @@ def echo_test():
     # Just slurps in the wav file and chops off the header, assuming
     # the user got the format and sampling rate correct.
     WAV_HDR_LEN = 44
-    buf = open(opts.noise, "rb").read()[WAV_HDR_LEN:]
+    buf = open(opts.noise, "rb").read()[WAV_HDR_LEN:] # pylint: disable=consider-using-with
 
     (rfd, wfd) = os.pipe()
     pid = os.fork()