lavd video: check vid subs from sw_pix_fmt

Check if video subsampling is 4:2:0 from sw_pix_fmt than iterating over
received pix_fmts. This is simplier and more effective since the SW
format is set the get_format() callback to the nominal SW format (if any).

src/libavcodec/lavc_common.c

@@ -288,24 +288,6 @@ void print_decoder_error(const char *mod_name, int rc) {
         }
 }
 
-bool pixfmt_has_420_subsampling(enum AVPixelFormat fmt){
-        const AVPixFmtDescriptor *fmt_desc = av_pix_fmt_desc_get(fmt);
-
-        return fmt_desc && (fmt_desc->log2_chroma_w == 1 && fmt_desc->log2_chroma_h == 1);
-}
-
-/// @retval true if all pixel formats have either 420 subsampling or are HW accelerated
-bool pixfmt_list_has_420_subsampling(const enum AVPixelFormat *fmt){
-        for(const enum AVPixelFormat *it = fmt; *it != AV_PIX_FMT_NONE; it++){
-                const AVPixFmtDescriptor *fmt_desc = av_pix_fmt_desc_get(*it);
-                if (!pixfmt_has_420_subsampling(*it) && !(fmt_desc->flags & AV_PIX_FMT_FLAG_HWACCEL)) {
-                        return false;
-                }
-        }
-
-        return true;
-}
-
 const char *lavc_thread_type_to_str(int thread_type) {
         static _Thread_local char buf[128];
         memset(buf, 0, sizeof buf);

src/libavcodec/lavc_common.h

@@ -105,9 +105,6 @@ extern "C" {
 #endif
 
 void print_decoder_error(const char *mod_name, int rc);
-bool pixfmt_has_420_subsampling(enum AVPixelFormat fmt);
-/// @retval true if all pixel formats have either 420 subsampling or are HW accelerated
-bool pixfmt_list_has_420_subsampling(const enum AVPixelFormat *fmt);
 
 void print_libav_error(int verbosity, const char *msg, int rc);
 void printf_libav_error(int verbosity, int rc, const char *msg, ...) __attribute__((format (printf, 3, 4)));

src/video_decompress/libavcodec.c

@@ -597,7 +597,7 @@ static enum AVPixelFormat get_format_callback(struct AVCodecContext *s, const en
 
         if (hwaccel != NULL) {
                 struct state_libavcodec_decompress *state = (struct state_libavcodec_decompress *) s->opaque; 
-                if (!pixfmt_list_has_420_subsampling(fmt)){
+                if (av_pixfmt_get_subsampling(s->sw_pix_fmt) != SUBS_420) {
                         log_msg(LOG_LEVEL_WARNING, "[lavd] Hw. acceleration requested "
                                         "but incoming video has not 4:2:0 subsampling, "
                                         "which is usually not supported by hw. accelerators\n");