diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c
index c29435b1a857806d47d8a09b6019519c934bb684..7c9e8d5b3e04f65e625e14d6cae8aa6cdce42340 100644
--- a/libavcodec/pngenc.c
+++ b/libavcodec/pngenc.c
@@ -242,10 +242,12 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         color_type = PNG_COLOR_TYPE_RGB;
         break;
     case PIX_FMT_RGBA:
+        avctx->bits_per_coded_sample = 32;
         bit_depth = 8;
         color_type = PNG_COLOR_TYPE_RGB_ALPHA;
         break;
     case PIX_FMT_RGB24:
+        avctx->bits_per_coded_sample = 24;
         bit_depth = 8;
         color_type = PNG_COLOR_TYPE_RGB;
         break;
@@ -254,6 +256,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         color_type = PNG_COLOR_TYPE_GRAY;
         break;
     case PIX_FMT_GRAY8:
+        avctx->bits_per_coded_sample = 0x28;
         bit_depth = 8;
         color_type = PNG_COLOR_TYPE_GRAY;
         break;
@@ -262,10 +265,12 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
         break;
     case PIX_FMT_MONOBLACK:
+        avctx->bits_per_coded_sample =
         bit_depth = 1;
         color_type = PNG_COLOR_TYPE_GRAY;
         break;
     case PIX_FMT_PAL8:
+        avctx->bits_per_coded_sample =
         bit_depth = 8;
         color_type = PNG_COLOR_TYPE_PALETTE;
         break;