if (!req->feed) return 0;
static int modify_current_stream(HTTPContext *c, char *rates){    int i;    FFStream *req = c->stream;    int action_required = 0;    for (i = 0; i < req->nb_streams; i++) {        AVCodecContext *codec = &req->streams[i]->codec;        switch(rates[i]) {            case 0:                c->switch_feed_streams[i] = req->feed_streams[i];                break;            case 1:                c->switch_feed_streams[i] = find_stream_in_feed(req->feed, codec, codec->bit_rate / 2);                break;            case 2:                /* Wants off or slow */                c->switch_feed_streams[i] = find_stream_in_feed(req->feed, codec, codec->bit_rate / 4);#ifdef WANTS_OFF                /* This doesn't work well when it turns off the only stream! */                c->switch_feed_streams[i] = -2;                c->feed_streams[i] = -2;#endif                break;        }        if (c->switch_feed_streams[i] >= 0 && c->switch_feed_streams[i] != c->feed_streams[i])            action_required = 1;    }    return action_required;}