[FFmpeg-devel] [PATCH 08/10] fftools/ffplay: stop using avfilter_graph_alloc_filter() incorrectly

[Anton Khirnov]

This function creates AND initializes a filter, so setting any filter
options after it is wrong. It happens to work when the filter's init
function does not touch the options in question, but is forbidden by the
API and is not guaranteed to remain functional.

Instead, use avfilter_graph_alloc_filter(), followed by setting the
options, and avfilter_init_dict().
---
 fftools/ffplay.c | 56 +++++++++++++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 22 deletions(-)

diff --git a/fftools/ffplay.c b/fftools/ffplay.c
index 60d8874eab..349c6075da 100644
--- a/fftools/ffplay.c
+++ b/fftools/ffplay.c
@@ -1861,7 +1861,6 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
 {
     enum AVPixelFormat pix_fmts[FF_ARRAY_ELEMS(sdl_texture_format_map)];
     char sws_flags_str[512] = "";
-    char buffersrc_args[256];
     int ret;
     AVFilterContext *filt_src = NULL, *filt_out = NULL, *last_filter = NULL;
     AVCodecParameters *codecpar = is->video_st->codecpar;
@@ -1895,38 +1894,48 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
 
     graph->scale_sws_opts = av_strdup(sws_flags_str);
 
-    snprintf(buffersrc_args, sizeof(buffersrc_args),
-             "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d:"
-             "colorspace=%d:range=%d",
-             frame->width, frame->height, frame->format,
-             is->video_st->time_base.num, is->video_st->time_base.den,
-             codecpar->sample_aspect_ratio.num, FFMAX(codecpar->sample_aspect_ratio.den, 1),
-             frame->colorspace, frame->color_range);
-    if (fr.num && fr.den)
-        av_strlcatf(buffersrc_args, sizeof(buffersrc_args), ":frame_rate=%d/%d", fr.num, fr.den);
 
-    if ((ret = avfilter_graph_create_filter(&filt_src,
-                                            avfilter_get_by_name("buffer"),
-                                            "ffplay_buffer", buffersrc_args, NULL,
-                                            graph)) < 0)
+    filt_src = avfilter_graph_alloc_filter(graph, avfilter_get_by_name("buffer"),
+                                           "ffplay_buffer");
+    if (!filt_src) {
+        ret = AVERROR(ENOMEM);
         goto fail;
+    }
+
+    par->format              = frame->format;
+    par->time_base           = is->video_st->time_base;
+    par->width               = frame->width;
+    par->height              = frame->height;
+    par->sample_aspect_ratio = codecpar->sample_aspect_ratio;
+    par->color_space         = frame->colorspace;
+    par->color_range         = frame->color_range;
+    par->frame_rate          = fr;
     par->hw_frames_ctx = frame->hw_frames_ctx;
     ret = av_buffersrc_parameters_set(filt_src, par);
     if (ret < 0)
         goto fail;
 
-    ret = avfilter_graph_create_filter(&filt_out,
-                                       avfilter_get_by_name("buffersink"),
-                                       "ffplay_buffersink", NULL, NULL, graph);
+    ret = avfilter_init_dict(filt_src, NULL);
     if (ret < 0)
         goto fail;
 
+    filt_out = avfilter_graph_alloc_filter(graph, avfilter_get_by_name("buffersink"),
+                                           "ffplay_buffersink");
+    if (!filt_out) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
     if ((ret = av_opt_set_int_list(filt_out, "pix_fmts", pix_fmts,  AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN)) < 0)
         goto fail;
     if (!vk_renderer &&
         (ret = av_opt_set_int_list(filt_out, "color_spaces", sdl_supported_color_spaces,  AVCOL_SPC_UNSPECIFIED, AV_OPT_SEARCH_CHILDREN)) < 0)
         goto fail;
 
+    ret = avfilter_init_dict(filt_out, NULL);
+    if (ret < 0)
+        goto fail;
+
     last_filter = filt_out;
 
 /* Note: this macro adds a filter before the lastly added filter, so the
@@ -2029,12 +2038,12 @@ static int configure_audio_filters(VideoState *is, const char *afilters, int for
     if (ret < 0)
         goto end;
 
-
-    ret = avfilter_graph_create_filter(&filt_asink,
-                                       avfilter_get_by_name("abuffersink"), "ffplay_abuffersink",
-                                       NULL, NULL, is->agraph);
-    if (ret < 0)
+    filt_asink = avfilter_graph_alloc_filter(is->agraph, avfilter_get_by_name("abuffersink"),
+                                             "ffplay_abuffersink");
+    if (!filt_asink) {
+        ret = AVERROR(ENOMEM);
         goto end;
+    }
 
     if ((ret = av_opt_set_int_list(filt_asink, "sample_fmts", sample_fmts,  AV_SAMPLE_FMT_NONE, AV_OPT_SEARCH_CHILDREN)) < 0)
         goto end;
@@ -2053,6 +2062,9 @@ static int configure_audio_filters(VideoState *is, const char *afilters, int for
             goto end;
     }
 
+    ret = avfilter_init_dict(filt_asink, NULL);
+    if (ret < 0)
+        goto end;
 
     if ((ret = configure_filtergraph(is->agraph, afilters, filt_asrc, filt_asink)) < 0)
         goto end;
-- 
2.43.0