commands, vd_ffmpeg: fix switch_ratio slave command

The implementation of the switch_ratio command was hacky and called
mpcodecs_config_vo() to reconfigure the filter/VO chain from under an
existing decoder. This call no longer worked properly with vd_ffmpeg
after that started using mpcodec_config_vo2(). Add new video decoder
control command VDCTRL_RESET_ASPECT and use this to tell vd_ffmpeg to
reinitialize the output chain properly.

command.c

@@ -2948,7 +2948,7 @@ void run_command(MPContext *mpctx, mp_cmd_t *cmd)
             opts->movie_aspect = (float) sh_video->disp_w / sh_video->disp_h;
         else
             opts->movie_aspect = cmd->args[0].v.f;
-        mpcodecs_config_vo(sh_video, sh_video->disp_w, sh_video->disp_h, 0);
+        video_reset_aspect(sh_video);
         break;
 
     case MP_CMD_SPEED_INCR: {

libmpcodecs/dec_video.c

@@ -212,6 +212,13 @@ void resync_video_stream(sh_video_t *sh_video)
     sh_video->prev_sorted_pts = MP_NOPTS_VALUE;
 }
 
+void video_reset_aspect(struct sh_video *sh_video)
+{
+    int r = sh_video->vd_driver->control(sh_video, VDCTRL_RESET_ASPECT, NULL);
+    if (r != true)
+        mpcodecs_config_vo(sh_video, sh_video->disp_w, sh_video->disp_h, 0);
+}
+
 int get_current_video_decoder_lag(sh_video_t *sh_video)
 {
     const struct vd_functions *vd = sh_video->vd_driver;

libmpcodecs/dec_video.h

@@ -46,6 +46,7 @@ void set_video_colorspace(struct sh_video *sh);
 int set_rectangle(sh_video_t *sh_video, int param, int value);
 int redraw_osd(struct sh_video *sh_video, struct osd_state *osd);
 void resync_video_stream(sh_video_t *sh_video);
+void video_reset_aspect(struct sh_video *sh_video);
 int get_current_video_decoder_lag(sh_video_t *sh_video);
 
 extern int divx_quality;

libmpcodecs/vd.h

@@ -50,6 +50,7 @@ extern const vd_functions_t *const mpcodecs_vd_drivers[];
 #define VDCTRL_GET_EQUALIZER 7 // get color options (brightness,contrast etc)
 #define VDCTRL_RESYNC_STREAM 8 // reset decode state after seeking
 #define VDCTRL_QUERY_UNSEEN_FRAMES 9 // current decoder lag
+#define VDCTRL_RESET_ASPECT 10 // reinit filter/VO chain for new aspect ratio
 
 // callbacks:
 int mpcodecs_config_vo2(sh_video_t *sh, int w, int h,

libmpcodecs/vd_ffmpeg.c

@@ -119,40 +119,6 @@ static enum AVDiscard str2AVDiscard(char *str)
     return AVDISCARD_DEFAULT;
 }
 
-static int control(sh_video_t *sh, int cmd, void *arg, ...)
-{
-    vd_ffmpeg_ctx *ctx = sh->context;
-    AVCodecContext *avctx = ctx->avctx;
-    switch (cmd) {
-    case VDCTRL_QUERY_FORMAT:
-    {
-        int format = (*((int *)arg));
-        if (format == ctx->best_csp)
-            return CONTROL_TRUE;
-        // possible conversions:
-        switch (format) {
-        case IMGFMT_YV12:
-        case IMGFMT_IYUV:
-        case IMGFMT_I420:
-            // "converted" using pointer/stride modification
-            if (ctx->best_csp == IMGFMT_YV12)
-                return CONTROL_TRUE;   // u/v swap
-            if (ctx->best_csp == IMGFMT_422P && !ctx->do_dr1)
-                return CONTROL_TRUE;   // half stride
-            break;
-        }
-        return CONTROL_FALSE;
-    }
-    case VDCTRL_RESYNC_STREAM:
-        avcodec_flush_buffers(avctx);
-        return CONTROL_TRUE;
-    case VDCTRL_QUERY_UNSEEN_FRAMES:;
-        int delay = avctx->has_b_frames;
-        return delay + 10;
-    }
-    return CONTROL_UNKNOWN;
-}
-
 static int init(sh_video_t *sh)
 {
     struct lavc_param *lavc_param = &sh->opts->lavc_param;
@@ -864,6 +830,44 @@ static enum PixelFormat get_format(struct AVCodecContext *avctx,
     return fmt[i];
 }
 
+static int control(sh_video_t *sh, int cmd, void *arg, ...)
+{
+    vd_ffmpeg_ctx *ctx = sh->context;
+    AVCodecContext *avctx = ctx->avctx;
+    switch (cmd) {
+    case VDCTRL_QUERY_FORMAT: {
+        int format = (*((int *)arg));
+        if (format == ctx->best_csp)
+            return CONTROL_TRUE;
+        // possible conversions:
+        switch (format) {
+        case IMGFMT_YV12:
+        case IMGFMT_IYUV:
+        case IMGFMT_I420:
+            // "converted" using pointer/stride modification
+            if (ctx->best_csp == IMGFMT_YV12)
+                return CONTROL_TRUE;   // u/v swap
+            if (ctx->best_csp == IMGFMT_422P && !ctx->do_dr1)
+                return CONTROL_TRUE;   // half stride
+            break;
+        }
+        return CONTROL_FALSE;
+    }
+    case VDCTRL_RESYNC_STREAM:
+        avcodec_flush_buffers(avctx);
+        return CONTROL_TRUE;
+    case VDCTRL_QUERY_UNSEEN_FRAMES:;
+        int delay = avctx->has_b_frames;
+        return delay + 10;
+    case VDCTRL_RESET_ASPECT:
+        if (ctx->vo_initialized)
+            ctx->vo_initialized = false;
+        init_vo(sh, avctx->pix_fmt);
+        return true;
+    }
+    return CONTROL_UNKNOWN;
+}
+
 const struct vd_functions mpcodecs_vd_ffmpeg = {
     .info = &info,
     .init = init,