+
+ /*
+ * We want CFR output if and only if one of those is true:
+ * 1) user specified output framerate with -r
+ * 2) user specified -vsync cfr
+ * 3) output format is CFR and the user didn't force vsync to
+ * something else than CFR
+ *
+ * in such a case, set ost->frame_rate
+ */
+ if (ost->encoding_needed && ost->enc_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
+ int format_cfr = !(oc->oformat->flags & (AVFMT_NOTIMESTAMPS | AVFMT_VARIABLE_FPS));
+ int need_cfr = !!ost->frame_rate.num;
+
+ if (video_sync_method == VSYNC_CFR ||
+ (video_sync_method == VSYNC_AUTO && format_cfr))
+ need_cfr = 1;
+
+ if (need_cfr && !ost->frame_rate.num) {
+ InputStream *ist = ost->source_index >= 0 ? input_streams[ost->source_index] : NULL;
+
+ if (ist && ist->framerate.num)
+ ost->frame_rate = ist->framerate;
+ else if (ist && ist->st->avg_frame_rate.num)
+ ost->frame_rate = ist->st->avg_frame_rate;
+ else {
+ av_log(NULL, AV_LOG_WARNING, "Constant framerate requested "
+ "for the output stream #%d:%d, but no information "
+ "about the input framerate is available. Falling "
+ "back to a default value of 25fps. Use the -r option "
+ "if you want a different framerate.\n",
+ ost->file_index, ost->index);
+ ost->frame_rate = (AVRational){ 25, 1 };
+ }
+ }
+
+ if (need_cfr && ost->enc->supported_framerates && !ost->force_fps) {
+ int idx = av_find_nearest_q_idx(ost->frame_rate, ost->enc->supported_framerates);
+ ost->frame_rate = ost->enc->supported_framerates[idx];
+ }
+ }
+