From c125860892e931d9b10f88ace73c91484815c3a8 Mon Sep 17 00:00:00 2001 From: Leo Izen Date: Tue, 21 Mar 2023 23:26:26 -0400 Subject: [PATCH] avcodec/pngenc: write sBIT chunks Add support for writing sBIT chunks, which mark the significant bit depth of the PNG file. This obtains the metadata using the field bits_per_raw_sample of AVCodecContext. Signed-off-by: Leo Izen --- libavcodec/pngenc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c index 1489256d00..21b033ea16 100644 --- a/libavcodec/pngenc.c +++ b/libavcodec/pngenc.c @@ -442,6 +442,12 @@ static int encode_headers(AVCodecContext *avctx, const AVFrame *pict) if (png_get_gama(pict->color_trc, s->buf)) png_write_chunk(&s->bytestream, MKTAG('g', 'A', 'M', 'A'), s->buf, 4); + if (avctx->bits_per_raw_sample > 0 && avctx->bits_per_raw_sample < s->bit_depth) { + int len = ff_png_get_nb_channels(s->color_type); + memset(s->buf, avctx->bits_per_raw_sample, len); + png_write_chunk(&s->bytestream, MKTAG('s', 'B', 'I', 'T'), s->buf, len); + } + /* put the palette if needed, must be after colorspace information */ if (s->color_type == PNG_COLOR_TYPE_PALETTE) { int has_alpha, alpha, i;