Hi Andrei,
On Fri, May 9, 2014 at 11:14 AM, Andrei Emeltchenko
<Andrei.Emeltchenko.news@xxxxxxxxx> wrote:
> Hi Luiz,
>
> On Thu, May 08, 2014 at 04:51:48PM +0300, Luiz Augusto von Dentz wrote:
>> Hi Andrei,
>>
>> On Thu, May 8, 2014 at 3:25 PM, Andrei Emeltchenko
>> <Andrei.Emeltchenko.news@xxxxxxxxx> wrote:
>> > From: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx>
>> >
>> > For synchronization interleave read() and write().
>> > ---
>> > android/hal-sco.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> > 1 file changed, 73 insertions(+)
>> >
>> > diff --git a/android/hal-sco.c b/android/hal-sco.c
>> > index 7b6608b..5ec56ce 100644
>> > --- a/android/hal-sco.c
>> > +++ b/android/hal-sco.c
>> > @@ -41,6 +41,8 @@
>> > #define OUT_BUFFER_SIZE 2560
>> > #define OUT_STREAM_FRAMES 2560
>> >
>> > +#define SOCKET_POLL_TIMEOUT_MS 500
>> > +
>> > static int listen_sk = -1;
>> > static int audio_sk = -1;
>> >
>> > @@ -275,6 +277,74 @@ static void downmix_to_mono(struct sco_stream_out *out, const uint8_t *buffer,
>> > }
>> > }
>> >
>> > +static bool write_data(struct sco_stream_out *out, const uint8_t *buffer,
>> > + size_t bytes)
>> > +{
>> > + struct pollfd pfd;
>> > + size_t len, written = 0;
>> > + int ret;
>> > + uint16_t mtu = /* out->cfg.mtu */ 48;
>> > + uint8_t read_buf[mtu];
>> > + bool do_write = false;
>> > +
>> > + pfd.fd = out->fd;
>> > + pfd.events = POLLOUT | POLLIN | POLLHUP | POLLNVAL;
>> > +
>> > + while (bytes > written) {
>> > +
>> > + /* poll for sending */
>> > + if (poll(&pfd, 1, SOCKET_POLL_TIMEOUT_MS) == 0) {
>> > + DBG("timeout fd %d", out->fd);
>> > + return false;
>> > + }
>> > +
>> > + if (pfd.revents & (POLLHUP | POLLNVAL)) {
>> > + error("error fd %d, events 0x%x", out->fd, pfd.revents);
>> > + return false;
>> > + }
>> > +
>> > + if (pfd.revents & POLLIN) {
>> > + ret = read(out->fd, read_buf, mtu);
>> > + if (ret < 0) {
>> > + error("Error reading fd %d (%s)", out->fd,
>> > + strerror(errno));
>> > + return false;
>> > + }
>> > +
>> > + do_write = true;
>>
>> You probably gonna have store the read data in a buffer to be read by
>> upper layer after remixed to 44.1 KHz, to safe space you can probably
>> leave the remixing to be done on the read callback. Im fine to do this
>> in a separate patch but we should at least add a comment about it.
>
> I think we need to have special thread which does read-write since Android
> might call read() without write().
PulseAudio synchronize by time if audio in not open in both direction,
this means we would have to sleep as we do in A2DP.
--
Luiz Augusto von Dentz
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