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Commit b4b3daa8 authored by Pavlin Radoslavov's avatar Pavlin Radoslavov
Browse files

Always restrict the AVDTP MTU for SBC codec to MAX_2MBPS_AVDTP_MTU(663) 

Some devices claim they can handle large MTU and large SBC bitpool.
However, they are struggling and eventually over time they
start delaying the "Rcvd Number of Completed Packets" reports.
Now we always limit the payload MTU to MAX_2MBPS_AVDTP_MTU(663) -
with the overhead of (4 bytes L2CAP Header + 12 bytes AVDTP Header)
such packet can fit within 2-DH5 payload size of 679 bytes.

Bug: 34127145
Test: A2DP SBC streaming to headsets and carkit
Change-Id: I2f32becba703d77d36be46158f68b8a9ef3f299a
parent 907759fc

system/stack/a2dp/a2dp_sbc_encoder.cc

+7 −14
Original line number Diff line number Diff line
@@ -746,22 +746,15 @@ static uint8_t calculate_max_frames_per_packet(void) { 


  LOG_VERBOSE(LOG_TAG, "%s: original AVDTP MTU size: %d", __func__,

              a2dp_sbc_encoder_cb.TxAaMtuSize);

  if (a2dp_sbc_encoder_cb.is_peer_edr &&

      !a2dp_sbc_encoder_cb.peer_supports_3mbps) {

    // This condition would be satisfied only if the remote device is

    // EDR and supports only 2 Mbps, but the effective AVDTP MTU size

    // exceeds the 2DH5 packet size.

    LOG_VERBOSE(LOG_TAG,

                "%s: The remote device is EDR but does not support 3 Mbps",

                __func__);



  // Restrict the MTU - even though some Sink devices are advertising large

  // MTU, they are not able to handle the packets and are stuttering.

  if (effective_mtu_size > MAX_2MBPS_AVDTP_MTU) {

    LOG_WARN(LOG_TAG, "%s: Restricting AVDTP MTU size to %d", __func__,

             MAX_2MBPS_AVDTP_MTU);

    effective_mtu_size = MAX_2MBPS_AVDTP_MTU;

    a2dp_sbc_encoder_cb.TxAaMtuSize = effective_mtu_size;

  }

  }



  if (!p_encoder_params->s16NumOfSubBands) {

    LOG_ERROR(LOG_TAG, "%s: SubBands are set to 0, resetting to %d", __func__,