[PATCH v3 20/24] echo-cancel: Add beamforming support in the webrtc canceller

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On Mon, 2016-01-18 at 13:06 +0530, arun at accosted.net wrote:
> From: Arun Raghavan <git at arunraghavan.net>
> 
> ---
>  src/modules/echo-cancel/webrtc.cc | 138 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 137 insertions(+), 1 deletion(-)
> 
> diff --git a/src/modules/echo-cancel/webrtc.cc b/src/modules/echo-cancel/webrtc.cc
> index 5f00286..9ae5d77 100644
> --- a/src/modules/echo-cancel/webrtc.cc
> +++ b/src/modules/echo-cancel/webrtc.cc
> @@ -52,6 +52,7 @@ PA_C_DECL_END
>  #define DEFAULT_INTELLIGIBILITY_ENHANCER false
>  #define DEFAULT_EXPERIMENTAL_AGC false
>  #define DEFAULT_AGC_START_VOLUME 85
> +#define DEFAULT_BEAMFORMING false
>  #define DEFAULT_TRACE false
>  
>  #define WEBRTC_AGC_MAX_VOLUME 255
> @@ -70,6 +71,9 @@ static const char* const valid_modargs[] = {
>      "intelligibility_enhancer",
>      "experimental_agc",
>      "agc_start_volume",
> +    "beamforming",
> +    "mic_geometry", /* documented in parse_mic_geometry() */
> +    "target_direction", /* documented in parse_mic_geometry() */
>      "trace",
>      NULL
>  };
> @@ -138,6 +142,76 @@ static void pa_webrtc_ec_fixate_spec(pa_sample_spec *rec_ss, pa_channel_map *rec
>      play_ss->rate = rec_ss->rate;
>  }
>  
> +static bool parse_point(const char **point, float (&f)[3]) {
> +    int ret, length;
> +
> +    ret = sscanf(*point, "%g,%g,%g%n", &f[0], &f[1], &f[2], &length);
> +    if (ret != 3)
> +        return false;
> +
> +    /* Consume the bytes we've read so far */
> +    *point += length;
> +
> +    /* Consume trailing comma if there is one */
> +    if (**point == ',')
> +        (*point)++;

I don't think this should be done in this function. When expecting only
one point, we should fail on "1,2,3," but this code accepts that
string.

> +
> +    return true;
> +}
> +
> +static bool parse_mic_geometry(const char **mic_geometry, std::vector& geometry) {
> +    /* The microphone geometry is expressed as cartesian point form:
> +     *   x1,y1,z1,x2,y2,z2,...
> +     *
> +     * Where x1,y1,z1 is the position of the first microphone with regards to
> +     * the array's "center", x2,y2,z2 the position of the second, and so on.
> +     *
> +     * 'x' is the horizontal coordinate, with positive values being to the
> +     * right from the mic array's perspective.
> +     *
> +     * 'y' is the depth coordinate, with positive values being in front of the
> +     * array.
> +     *
> +     * 'z' is the vertical coordinate, with positive values being above the
> +     * array.
> +     *
> +     * All distances are in meters.
> +     */

It's a bit unclear what "the mic array's perspective" means. Should I
imagine the array as a person standing upright, looking straight ahead?
Then positive x is to the right from the "person's" point of view,
positive y is in front of the array guy and positive z is above the
array.

> +
> +    /* The target direction is expected to be in spherical point form:
> +     *   a,e,r
> +     *
> +     * Where 'a is the azimuth of the first mic channel, 'e' its elevation,
> +     * and 'r' the radius.
> +     *
> +     * 0 radians azimuth is to the right of the array, and positive angles
> +     * move in a counter-clockwise direction.
> +     *
> +     * 0 radians elevation is horizontal w.r.t. the array, and positive
> +     * angles go upwards.
> +     *
> +     * radius is distance from the array center in meters.
> +     */
> +
> +    int i;
> +    float f[3];
> +
> +    for (i = 0; i < geometry.size(); i++) {
> +        if (!parse_point(mic_geometry, f)) {
> +            pa_log("Failed to parse channel %d in mic_geometry", i);
> +            return false;
> +        }
> +
> +        pa_log_debug("Got mic #%d position: (%g, %g, %g)", i, f[0], f[1], f[2]);
> +
> +        geometry[i].c[0] = f[0];
> +        geometry[i].c[1] = f[1];
> +        geometry[i].c[2] = f[2];
> +    }
> +
> +    return true;
> +}
> +
>  bool pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
>                         pa_sample_spec *rec_ss, pa_channel_map *rec_map,
>                         pa_sample_spec *play_ss, pa_channel_map *play_map,
> @@ -146,7 +220,7 @@ bool pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
>      webrtc::AudioProcessing *apm = NULL;
>      webrtc::ProcessingConfig pconfig;
>      webrtc::Config config;
> -    bool hpf, ns, agc, dgc, mobile, cn, vad, ext_filter, intelligibility, experimental_agc;
> +    bool hpf, ns, agc, dgc, mobile, cn, vad, ext_filter, intelligibility, experimental_agc, beamforming;
>      int rm = -1;
>      uint32_t agc_start_volume;
>      pa_modargs *ma;
> @@ -255,6 +329,12 @@ bool pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
>      }
>      ec->params.webrtc.agc_start_volume = agc_start_volume;
>  
> +    beamforming = DEFAULT_BEAMFORMING;
> +    if (pa_modargs_get_value_boolean(ma, "beamforming", &beamforming) < 0) {
> +        pa_log("Failed to parse beamforming value");
> +        goto fail;
> +    }
> +
>      if (ext_filter)
>          config.Set(new webrtc::ExtendedFilter(true));
>      if (intelligibility)
> @@ -276,6 +356,62 @@ bool pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
>  
>      pa_webrtc_ec_fixate_spec(rec_ss, rec_map, play_ss, play_map, out_ss, out_map);
>  
> +    /* We do this after fixate because we need the capture channel count */
> +    if (beamforming) {
> +        std::vector geometry(rec_ss->channels);
> +        webrtc::SphericalPointf direction(0.0f, 0.0f, 0.0f);
> +        const char *mic_geometry, *target_direction;
> +
> +        if (!(mic_geometry = pa_modargs_get_value(ma, "mic_geometry", NULL))) {
> +            pa_log("mic_geometry must be set if beamforming is enabled");
> +            goto fail;
> +        }
> +
> +        if (!parse_mic_geometry(&mic_geometry, geometry)) {
> +            pa_log("Failed to parse mic_geometry value");
> +            goto fail;
> +        }
> +
> +        if (*mic_geometry != '\0') {
> +            pa_log("Failed to parse mic_geometry value: more parameters than expected");
> +            goto fail;
> +        }

This check could be moved to parse_mic_geometry().

> +
> +        if ((target_direction = pa_modargs_get_value(ma, "target_direction", NULL))) {
> +            float f[3];
> +
> +            if (!parse_point(&target_direction, f)) {
> +                pa_log("Failed to parse target_direction value");
> +                goto fail;
> +            }
> +
> +            if (*target_direction != '\0') {
> +                pa_log("Failed to parse target_direction value: more parameters than expected");
> +                goto fail;
> +            }
> +
> +#define IS_ZERO(f) ((f) < 0.000001 && (f) > -0.000001)

This kind of macro would be nice to have in some shared location.
speex.c and a couple of tests have similar code, and I remember needing
it in the volume control patches.

> +
> +	    if (!IS_ZERO(f[1]) || !IS_ZERO(f[2])) {

This line contains a tab character.

> +                pa_log("The beamformer currently only supports targeting along the azimuth");
> +                goto fail;
> +            }
> +
> +            direction.s[0] = f[0];
> +            direction.s[1] = f[1];
> +            direction.s[2] = f[2];
> +        }
> +
> +        /* The beamformer gives us a single channel */
> +        out_ss->channels = 1;
> +        pa_channel_map_init_mono(out_map);

Could this be moved to fixate_spec()? I don't like the audio format
parameters being calculated all over the place.

-- 
Tanu
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