Crash in onQueueAccessUnit about how-to-miracast-on-aosp HOT 1 OPEN

if (!(mFormatKnownMask & (1ul << trackIndex))) {
    sp<MetaData> meta = source->getFormat();
    CHECK(meta != NULL);

    CHECK_EQ((status_t)OK, convertMetaDataToMessage(meta, &format));

    // mFormatKnownMask |= 1ul << trackIndex;     //delete by andy
}

status_t finalResult;
while (source->hasBufferAvailable(&finalResult)) {
    sp<ABuffer> accessUnit;
    status_t err = source->dequeueAccessUnit(&accessUnit);
    if (err == OK) {
        mFormatKnownMask |= 1ul << trackIndex;    //modify by andy
        postAccessUnit(trackIndex, accessUnit, format);
        format.clear();
    } else if (err != INFO_DISCONTINUITY) {
        notifyError(err);
    }
}