does sending silence to audiomixer work

[Jaime Nualart]

OK, so I missed this part in gstaudiotestsrc.c ...

  if (G_UNLIKELY ((src->wave == GST_AUDIO_TEST_SRC_WAVE_SILENCE)
          || (src->volume == 0.0))) {
    GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_GAP);
  }


So that explains the GAP buffers.

But I'm still confused why I encounter problems.

I created a small test tone using audacity (DTMF 1, 48000Hz, 50milliseconds).

This pipeline works fine every time:
gst-launch-1.0 audiotestsrc do-timestamp=true is-live=true  volume=0.01 freq=1000 ! audiomixer name=mix ! audioconvert ! audio/x-raw,channels=1,sample-rate=48000,format=S16LE ! queue ! alsasink filesrc location=/root/audacity_dtmf_1.wav blocksize=960 do-timestamp=true ! rawaudioparse pcm-format=s16le sample-rate=48000 num-channels=1 ! mix.

Start the above, and ctrl-c once you've heard the dtmf tone play. Repeat several times.

This pipeline occassionally has audio glitches in the dtmf tone, or sometimes doesn't even play the dtmf tone:
gst-launch-1.0 audiotestsrc do-timestamp=true is-live=true  volume=0 freq=1000 ! audiomixer name=mix ! audioconvert ! audio/x-raw,channels=1,sample-rate=48000,format=S16LE ! queue ! alsasink filesrc location=/root/audacity_dtmf_1.wav blocksize=960 do-timestamp=true ! rawaudioparse pcm-format=s16le sample-rate=48000 num-channels=1 ! mix.

I feel like I must be missing something, or I'm just misunderstanding some basic concept.

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