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Commit 28c35e5c authored by Phil Burk's avatar Phil Burk
Browse files

qcom/audio/hal: add offset to MMAP output time 

Try to fix glitches on AAudio MMAP output on some devices.
The DSP is returning a position/time pair that is too soon.

Bug: 122680738
Test: Should see glitch.count = 0 when you run this test.
Test: adb shell aaudio_loopback -tm -b999 -s20 -x -X

Change-Id: I7bc9924a7aaa34d2e721365aa8ee0b69de5936f8
Merged-In: I7bc9924a7aaa34d2e721365aa8ee0b69de5936f8
parent 1bc15de5

hal/audio_hw.c

+16 −1
Original line number Diff line number Diff line
@@ -3360,6 +3360,17 @@ static void adjust_mmap_period_count(struct pcm_config *config, int32_t min_size 
    ALOGV("%s requested config.period_count = %d", __func__, config->period_count);

}



// Read offset for the positional timestamp from a persistent vendor property.

// This is to workaround apparent inaccuracies in the timing information that

// is used by the AAudio timing model. The inaccuracies can cause glitches.

static int64_t get_mmap_out_time_offset() {

    const int32_t kDefaultOffsetMicros = 0;

    int32_t mmap_time_offset_micros = property_get_int32(

        "persist.audio.out_mmap_delay_micros", kDefaultOffsetMicros);

    ALOGI("mmap_time_offset_micros = %d for output", mmap_time_offset_micros);

    return mmap_time_offset_micros * (int64_t)1000;

}



static int out_create_mmap_buffer(const struct audio_stream_out *stream,

                                  int32_t min_size_frames,

                                  struct audio_mmap_buffer_info *info)
@@ -3437,6 +3448,8 @@ static int out_create_mmap_buffer(const struct audio_stream_out *stream, 
        goto exit;

    }



    out->mmap_time_offset_nanos = get_mmap_out_time_offset();



    out->standby = false;

    ret = 0;
@@ -3480,7 +3493,9 @@ static int out_get_mmap_position(const struct audio_stream_out *stream, 
        ALOGE("%s: %s", __func__, pcm_get_error(out->pcm));

        goto exit;

    }

    position->time_nanoseconds = audio_utils_ns_from_timespec(&ts);

    position->time_nanoseconds = audio_utils_ns_from_timespec(&ts)

            + out->mmap_time_offset_nanos;



exit:

    pthread_mutex_unlock(&out->lock);

    return ret;

hal/audio_hw.h

+1 −0
Original line number Diff line number Diff line
@@ -230,6 +230,7 @@ struct stream_out { 
    uint32_t supported_sample_rates[MAX_SUPPORTED_SAMPLE_RATES + 1];

    bool muted;

    uint64_t written; /* total frames written, not cleared when entering standby */

    int64_t mmap_time_offset_nanos; /* fudge factor to correct inaccuracies in DSP */

    audio_io_handle_t handle;



    int non_blocking;