do string compare with mime immediately after we get the value

    }

    for (size_t i = 0; i < extractor->countTracks(); ++i) {

        sp<MediaSource> track = extractor->getTrack(i);

        sp<MetaData> meta = extractor->getTrackMetaData(i);

        const char *mime;

        CHECK(meta->findCString(kKeyMIMEType, &mime));

        sp<MediaSource> track = extractor->getTrack(i);

        // Do the string compare immediately with "mime",

        // we can't assume "mime" would stay valid after another

        // extractor operation, some extractors might modify meta

        // during getTrack() and make it invalid.

        if (!strncasecmp(mime, "audio/", 6)) {

            if (mAudioTrack.mSource == NULL) {

                mAudioTrack.mIndex = i;