Re: [alsa-devel] Capture not working in MMAP mode with '-v'

9 Nov 2009


      On Mon, 2009-11-09 at 09:05 +0100, ext Aggarwal, Anuj wrote:
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-----Original Message-----
From: Eero Nurkkala [mailto:ext-eero.nurkkala@nokia.com]
Sent: Monday, November 09, 2009 1:28 PM
To: Aggarwal, Anuj
Cc: alsa-devel@alsa-project.org
Subject: Re: [alsa-devel] Capture not working in MMAP mode with '-v'
On Mon, 2009-11-09 at 08:56 +0100, ext Aggarwal, Anuj wrote:
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-----Original Message-----
From: Aggarwal, Anuj
Sent: Thursday, September 24, 2009 2:28 PM
To: alsa-devel@alsa-project.org
Subject: Capture not working in MMAP mode with '-v'
Hi,
When I try to capture audio in MMAP mode using the following
command, it works properly:
arecord -f cd -d 10 -M rec01.wav
However, if I specify '-v' along with the above command, it fails to
capture anything and prints log and returns immediately:
Recording WAVE 'rec03.wav' : Signed 16 bit Little Endian,
Rate 44100 Hz, Stereo
Plug PCM: Hardware PCM card 0 'omap3evm' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 44100
  exact rate   : 44100 (44100/1)
  msbits       : 16
  buffer_size  : 22052
  period_size  : 5513
  period_time  : 125011
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 5513
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 22052
  silence_threshold: 0
  silence_size : 0
  boundary     : 1445199872
  appl_ptr     : 0
  hw_ptr       : 0
mmap_area[0] = 0x4030e000,0,32 (16)
mmap_area[1] = 0x4030e000,16,32 (16)
I have not observed this problem while playing audio, only
while capture this issue crops up.
Any pointers?
Any updates on this? We have observed similar problem on other
platforms as well.
Yeah, it's an aplay bug, I've seen it & tracked down to aplay. It
actually makes the recording file very huge instantly on some systems.
Patch out the aplay when -M and -v are used =)
Is there a new version of alsa-utils available which fixes this
problem? Also, I have seen this problem only while using arecord,
not aplay, though they both point to the same source file? Whats
the reason for this?
As far as I know, nobody fixed it. Yeah, aplay = arecord, and it occurs
only with arecord to be more specific, and is present on all platforms
out there:
My workaround:
"
arecord is only buggy, if -M and -v flags are used, and
chunk_size goes to zero (which is perfectly OK).
This is the functional version of aplay:
<----------------------------->
        /* show mmap buffer arragment */
        if (mmap_flag && verbose) {
const snd_pcm_channel_area_t *areas;
                snd_pcm_uframes_t offset;
                int i, chunk_prev = chunk_size;
snd_pcm_avail_update(handle);
                err = snd_pcm_mmap_begin(handle, &areas, &offset, &chunk_size);
                if (err < 0) {
                        error("snd_pcm_mmap_begin problem: %s",
snd_strerror(err));
                        exit(EXIT_FAILURE);
                }
                for (i = 0; i < hwparams.channels; i++)
                        fprintf(stderr, "mmap_area[%i] = %p,%u,%u (%u)\n", i,
areas[i].addr, areas[i].first, areas[i].step,
snd_pcm_format_physical_width(hwparams.format));
                if (!chunk_size)
                        chunk_size = chunk_prev;
                /* not required, but for sure */
                snd_pcm_mmap_commit(handle, offset, 0);
        }
<----------------------------------_>
"
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Thanks & Regards,
Anuj Aggarwal

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