int len, i, channel_id = 0;
int64_t layout, layout0;
+ /* try to parse a channel name, e.g. "FL" */
if (sscanf(*arg, " %7[A-Z] %n", buf, &len)) {
layout0 = layout = av_get_channel_layout(buf);
+ /* channel_id <- first set bit in layout */
for (i = 32; i > 0; i >>= 1) {
if (layout >= (int64_t)1 << i) {
channel_id += i;
layout >>= i;
}
}
+ /* reject layouts that are not a single channel */
if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
return AVERROR(EINVAL);
*rchannel = channel_id;
*arg += len;
return 0;
}
+ /* try to parse a channel number, e.g. "c2" */
if (sscanf(*arg, " c%d %n", &channel_id, &len) &&
channel_id >= 0 && channel_id < MAX_CHANNELS) {
*rchannel = channel_id;