[pulseaudio-discuss] [PATCH v4 09/41] bluetooth: Implement org.bluez.MediaEndpoint1.SelectConfiguration()

[Tanu Kaskinen]

On Sat, 2013-09-21 at 13:30 -0500, João Paulo Rechi Vita wrote:
> On Sat, Sep 21, 2013 at 5:16 AM, Tanu Kaskinen
> <tanu.kaskinen at linux.intel.com> wrote:
> > On Wed, 2013-09-18 at 16:17 -0500, jprvita at gmail.com wrote:
> >>  static DBusMessage *endpoint_select_configuration(DBusConnection *conn, DBusMessage *m, void *userdata) {
> >> +    pa_bluetooth_discovery *y = userdata;
> >> +    a2dp_sbc_t *cap, config;
> >> +    uint8_t *pconf = (uint8_t *) &config;
> >> +    int i, size;
> >>      DBusMessage *r;
> >> +    DBusError err;
> >>
> >> -    pa_assert_se(r = dbus_message_new_error(m, BLUEZ_MEDIA_ENDPOINT_INTERFACE ".Error.NotImplemented",
> >> -                                            "Method not implemented"));
> >> +    static const struct {
> >> +        uint32_t rate;
> >> +        uint8_t cap;
> >> +    } freq_table[] = {
> >> +        { 16000U, SBC_SAMPLING_FREQ_16000 },
> >> +        { 32000U, SBC_SAMPLING_FREQ_32000 },
> >> +        { 44100U, SBC_SAMPLING_FREQ_44100 },
> >> +        { 48000U, SBC_SAMPLING_FREQ_48000 }
> >> +    };
> >> +
> >> +    dbus_error_init(&err);
> >> +
> >> +    if (!dbus_message_get_args(m, &err, DBUS_TYPE_ARRAY, DBUS_TYPE_BYTE, &cap, &size, DBUS_TYPE_INVALID)) {
> >> +        pa_log_error("Endpoint SelectConfiguration(): %s", err.message);
> >> +        dbus_error_free(&err);
> >> +        goto fail;
> >> +    }
> >> +
> >> +    if (size != sizeof(config)) {
> >> +        pa_log_error("Capabilities array has invalid size");
> >> +        goto fail;
> >> +    }
> >> +
> >> +    pa_zero(config);
> >> +
> >> +    /* Find the lowest freq that is at least as high as the requested sampling rate */
> >> +    for (i = 0; (unsigned) i < PA_ELEMENTSOF(freq_table); i++)
> >> +        if (freq_table[i].rate >= y->core->default_sample_spec.rate && (cap->frequency & freq_table[i].cap)) {
> >> +            config.frequency = freq_table[i].cap;
> >> +            break;
> >> +        }
> >>
> >> +    if ((unsigned) i == PA_ELEMENTSOF(freq_table)) {
> >> +        for (--i; i >= 0; i--) {
> >> +            if (cap->frequency & freq_table[i].cap) {
> >> +                config.frequency = freq_table[i].cap;
> >> +                break;
> >> +            }
> >> +        }
> >> +
> >> +        if (i < 0) {
> >> +            pa_log_error("Not suitable sample rate");
> >> +            goto fail;
> >> +        }
> >> +    }
> >> +
> >> +    pa_assert((unsigned) i < PA_ELEMENTSOF(freq_table));
> >> +
> >> +    if (y->core->default_sample_spec.channels <= 1)
> >> +        if (cap->channel_mode & SBC_CHANNEL_MODE_MONO)
> >> +            config.channel_mode = SBC_CHANNEL_MODE_MONO;
> >
> > You forgot to fix this code. The problem still exists that if
> > default_sample_spec.channels is 1 and the cap->channel_mode doesn't
> > contain SBC_CHANNEL_MODE_MONO, then config.channel_mode is left
> > uninitialized.
> >
> 
> No, I didn't, but I may have misunderstood you. Re-reading it new
> trying to give another interpretation, it seems you suggest that we
> don't differentiate between (y->core->default_sample_spec.channels <=
> 1) and (y->core->default_sample_spec.channels >= 2), but I don't think
> that's what you meant. Can you please explain how we should
> differentiate those two cases?

There are four modes we support: mono, and three stereo modes. We should
always allow any any of those modes. Depending on
default_sample_spec.channels, we should either prefer the mono mode or
the stereo modes, but if the device doesn't support our preferred mode,
we should fall back to a mode that the device supports. In your code
that fallback is implemented when default_sample_spec.channels >= 2, but
not if default_sample_spec.channels == 1.

-- 
Tanu