fftools/ffmpeg: deprecate -fps_mode/vsync drop

It depends on the ability of muxers to generate timestamps, which is
itself deprecated.

doc/ffmpeg.texi

@@ -1742,9 +1742,6 @@ constant frame rate.
 @item vfr (2)
 Frames are passed through with their timestamp or dropped so as to
 prevent 2 frames from having the same timestamp.
-@item drop
-As passthrough but destroys all timestamps, making the muxer generate
-fresh timestamps based on frame-rate.
 @item auto (-1)
 Chooses between cfr and vfr depending on muxer capabilities. This is the
 default method.

fftools/ffmpeg.h

@@ -60,6 +60,7 @@
 #define FFMPEG_OPT_ENC_TIME_BASE_NUM 1
 #define FFMPEG_OPT_TOP 1
 #define FFMPEG_OPT_FORCE_KF_SOURCE_NO_DROP 1
+#define FFMPEG_OPT_VSYNC_DROP 1
 
 #define FFMPEG_ERROR_RATE_EXCEEDED FFERRTAG('E', 'R', 'E', 'D')
 
@@ -69,7 +70,9 @@ enum VideoSyncMethod {
     VSYNC_CFR,
     VSYNC_VFR,
     VSYNC_VSCFR,
+#if FFMPEG_OPT_VSYNC_DROP
     VSYNC_DROP,
+#endif
 };
 
 enum EncTimeBase {

fftools/ffmpeg_filter.c

@@ -2104,8 +2104,11 @@ static void video_sync_process(OutputFilterPriv *ofp, AVFrame *frame,
 
     if (delta0 < 0 &&
         delta > 0 &&
-        ost->vsync_method != VSYNC_PASSTHROUGH &&
-        ost->vsync_method != VSYNC_DROP) {
+        ost->vsync_method != VSYNC_PASSTHROUGH
+#if FFMPEG_OPT_VSYNC_DROP
+        && ost->vsync_method != VSYNC_DROP
+#endif
+        ) {
         if (delta0 < -0.6) {
             av_log(ost, AV_LOG_VERBOSE, "Past duration %f too large\n", -delta0);
         } else
@@ -2143,7 +2146,9 @@ static void video_sync_process(OutputFilterPriv *ofp, AVFrame *frame,
             ofp->next_pts = llrint(sync_ipts);
         frame->duration = llrint(duration);
         break;
+#if FFMPEG_OPT_VSYNC_DROP
     case VSYNC_DROP:
+#endif
     case VSYNC_PASSTHROUGH:
         ofp->next_pts = llrint(sync_ipts);
         frame->duration = llrint(duration);

fftools/ffmpeg_mux.c

@@ -150,8 +150,10 @@ static int write_packet(Muxer *mux, OutputStream *ost, AVPacket *pkt)
         goto fail;
     }
 
+#if FFMPEG_OPT_VSYNC_DROP
     if (ost->type == AVMEDIA_TYPE_VIDEO && ost->vsync_method == VSYNC_DROP)
         pkt->pts = pkt->dts = AV_NOPTS_VALUE;
+#endif
 
     // rescale timestamps to the stream timebase
     if (ost->type == AVMEDIA_TYPE_AUDIO && !ost->enc) {

fftools/ffmpeg_opt.c

@@ -188,7 +188,12 @@ int parse_and_set_vsync(const char *arg, int *vsync_var, int file_idx, int st_id
     if      (!av_strcasecmp(arg, "cfr"))         *vsync_var = VSYNC_CFR;
     else if (!av_strcasecmp(arg, "vfr"))         *vsync_var = VSYNC_VFR;
     else if (!av_strcasecmp(arg, "passthrough")) *vsync_var = VSYNC_PASSTHROUGH;
-    else if (!av_strcasecmp(arg, "drop"))        *vsync_var = VSYNC_DROP;
+#if FFMPEG_OPT_VSYNC_DROP
+    else if (!av_strcasecmp(arg, "drop")) {
+        av_log(NULL, AV_LOG_WARNING, "-vsync/fps_mode drop is deprecated\n");
+        *vsync_var = VSYNC_DROP;
+    }
+#endif
     else if (!is_global && !av_strcasecmp(arg, "auto"))  *vsync_var = VSYNC_AUTO;
     else if (!is_global) {
         av_log(NULL, AV_LOG_FATAL, "Invalid value %s specified for fps_mode of #%d:%d.\n", arg, file_idx, st_idx);