video: move handling of container vs. stream AR out of vd_lavc.c

Now the actual decoder doesn't need to care about this anymore, and it's
handled in generic code instead. This simplifies vd_lavc.c, and in
particular we don't need to detect format changes in the old way
anymore.

video/decode/dec_video.c

@@ -339,13 +339,26 @@ int mpcodecs_reconfig_vo(struct dec_video *d_video,
         d_video->vfilter = vf;
         flip = false;
     }
-    // time to do aspect ratio corrections...
+
+    float decoder_aspect = p.d_w / (float)p.d_h;
+    if (d_video->initial_decoder_aspect == 0)
+        d_video->initial_decoder_aspect = decoder_aspect;
+
+    // We normally prefer the container aspect, unless the decoder aspect
+    // changes at least once.
+    if (d_video->initial_decoder_aspect == decoder_aspect) {
+        if (sh->aspect > 0)
+            vf_set_dar(&p.d_w, &p.d_h, p.w, p.h, sh->aspect);
+    } else {
+        // Even if the aspect switches back, don't use container aspect again.
+        d_video->initial_decoder_aspect = -1;
+    }
 
     float force_aspect = opts->movie_aspect;
     if (force_aspect > -1.0 && d_video->stream_aspect != 0.0)
         force_aspect = d_video->stream_aspect;
 
-    if (force_aspect >= 0)
+    if (force_aspect > 0)
         vf_set_dar(&p.d_w, &p.d_h, p.w, p.h, force_aspect);
 
     if (abs(p.d_w - p.w) >= 4 || abs(p.d_h - p.h) >= 4) {

video/decode/dec_video.h

@@ -57,6 +57,8 @@ struct dec_video {
 
     float stream_aspect;  // aspect ratio in media headers (DVD IFO files)
     int i_bps;            // == bitrate  (compressed bytes/sec)
+
+    float initial_decoder_aspect;
 };
 
 struct mp_decoder_list *video_decoder_list(void);

video/decode/lavc.h

@@ -32,7 +32,6 @@ typedef struct lavc_ctx {
     int best_csp;
     struct mp_image_params image_params;
     struct mp_image_params vo_image_params;
-    AVRational last_sample_aspect_ratio;
     enum AVDiscard skip_frame;
     const char *software_fallback_decoder;
 

video/decode/vd_lavc.c

@@ -502,7 +502,6 @@ static void uninit_avctx(struct dec_video *vd)
     avcodec_free_frame(&ctx->pic);
     mp_buffer_pool_free(&ctx->dr1_buffer_pool);
 #endif
-    ctx->last_sample_aspect_ratio = (AVRational){0, 0};
 }
 
 static void uninit(struct dec_video *vd)
@@ -517,49 +516,30 @@ static void update_image_params(struct dec_video *vd, AVFrame *frame)
     int height = frame->height;
     float aspect = av_q2d(frame->sample_aspect_ratio) * width / height;
     int pix_fmt = frame->format;
-    struct sh_video *sh = vd->header->video;
 
 #if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(54, 40, 0)
     pix_fmt = ctx->avctx->pix_fmt;
 #endif
 
-    if (av_cmp_q(frame->sample_aspect_ratio, ctx->last_sample_aspect_ratio) ||
-            width != sh->disp_w || height != sh->disp_h ||
-            pix_fmt != ctx->pix_fmt || !ctx->image_params.imgfmt)
-    {
-        mp_image_pool_clear(ctx->non_dr1_pool);
-        mp_msg(MSGT_DECVIDEO, MSGL_V, "[ffmpeg] aspect_ratio: %f\n", aspect);
-
-        // Do not overwrite s->aspect on the first call, so that a container
-        // aspect if available is preferred.
-        // But set it even if the sample aspect did not change, since a
-        // resolution change can cause an aspect change even if the
-        // _sample_ aspect is unchanged.
-        float use_aspect = sh->aspect;
-        if (use_aspect == 0 || ctx->last_sample_aspect_ratio.den)
-            use_aspect = aspect;
-        ctx->last_sample_aspect_ratio = frame->sample_aspect_ratio;
-        sh->disp_w = width;
-        sh->disp_h = height;
-
+    if (pix_fmt != ctx->pix_fmt) {
         ctx->pix_fmt = pix_fmt;
         ctx->best_csp = pixfmt2imgfmt(pix_fmt);
-
-        int d_w, d_h;
-        vf_set_dar(&d_w, &d_h, width, height, use_aspect);
-
-        ctx->image_params = (struct mp_image_params) {
-            .imgfmt = ctx->best_csp,
-            .w = width,
-            .h = height,
-            .d_w = d_w,
-            .d_h = d_h,
-            .colorspace = avcol_spc_to_mp_csp(ctx->avctx->colorspace),
-            .colorlevels = avcol_range_to_mp_csp_levels(ctx->avctx->color_range),
-            .chroma_location =
-                avchroma_location_to_mp(ctx->avctx->chroma_sample_location),
-        };
     }
+
+    int d_w, d_h;
+    vf_set_dar(&d_w, &d_h, width, height, aspect);
+
+    ctx->image_params = (struct mp_image_params) {
+        .imgfmt = ctx->best_csp,
+        .w = width,
+        .h = height,
+        .d_w = d_w,
+        .d_h = d_h,
+        .colorspace = avcol_spc_to_mp_csp(ctx->avctx->colorspace),
+        .colorlevels = avcol_range_to_mp_csp_levels(ctx->avctx->color_range),
+        .chroma_location =
+            avchroma_location_to_mp(ctx->avctx->chroma_sample_location),
+    };
 }
 
 static enum PixelFormat get_format_hwdec(struct AVCodecContext *avctx,
@@ -793,6 +773,7 @@ static int decode(struct dec_video *vd, struct demux_packet *packet,
     mp_image_params_from_image(&vo_params, mpi);
 
     if (!mp_image_params_equals(&vo_params, &ctx->vo_image_params)) {
+        mp_image_pool_clear(ctx->non_dr1_pool);
         if (mpcodecs_reconfig_vo(vd, &vo_params) < 0) {
             talloc_free(mpi);
             return -1;