Hi Leo!
On 2024-12-01 09:20 -0500, Leo Izen wrote:
> The PNGv3 Specification Draft [1] has changed the capitalization
> of mDCV and cLLI chunks (formerly mDCv and cLLi). This patch updates
> FFmpeg to work with the new chunk names while retaining decode-side
> compatibility with files created using the old names.
>
> [1]: https://w3c.github.io/png/
>
> Signed-off-by: Leo Izen <leo.i...@gmail.com>
> ---
> libavcodec/pngdec.c | 12 +++++++-----
> libavcodec/pngenc.c | 4 ++--
> tests/ref/fate/png-mdcv | 2 +-
> 3 files changed, 10 insertions(+), 8 deletions(-)
LGTM.
Your changes are sensible and complete as far as I could check.
Only problem I could think of is being to fast, as it isn't
in the latest published version of the W3C yet.
If I understood chunk naming conventions correctly they marked
those 2 chunks unsafe to copy, which will probably stay that
way. So I think the patch can be pushed.
Best regards,
Alexander
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index c5b32c166d..f8cb61775e 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -757,7 +757,7 @@ static int populate_avctx_color_fields(AVCodecContext
> *avctx, AVFrame *frame)
> if (clli) {
> /*
> * 0.0001 divisor value
> - * see: https://www.w3.org/TR/png-3/#cLLi-chunk
> + * see: https://www.w3.org/TR/png-3/#cLLI-chunk
> */
> clli->MaxCLL = s->clli_max / 10000;
> clli->MaxFALL = s->clli_avg / 10000;
> @@ -1566,18 +1566,20 @@ static int decode_frame_common(AVCodecContext *avctx,
> PNGDecContext *s,
>
> break;
> }
> - case MKTAG('c', 'L', 'L', 'i'):
> + case MKTAG('c', 'L', 'L', 'i'): /* legacy spelling, for backwards
> compat */
> + case MKTAG('c', 'L', 'L', 'I'):
> if (bytestream2_get_bytes_left(&gb_chunk) != 8) {
> - av_log(avctx, AV_LOG_WARNING, "Invalid cLLi chunk size:
> %d\n", bytestream2_get_bytes_left(&gb_chunk));
> + av_log(avctx, AV_LOG_WARNING, "Invalid cLLI chunk size:
> %d\n", bytestream2_get_bytes_left(&gb_chunk));
> break;
> }
> s->have_clli = 1;
> s->clli_max = bytestream2_get_be32u(&gb_chunk);
> s->clli_avg = bytestream2_get_be32u(&gb_chunk);
> break;
> - case MKTAG('m', 'D', 'C', 'v'):
> + case MKTAG('m', 'D', 'C', 'v'): /* legacy spelling, for backward
> compat */
> + case MKTAG('m', 'D', 'C', 'V'):
> if (bytestream2_get_bytes_left(&gb_chunk) != 24) {
> - av_log(avctx, AV_LOG_WARNING, "Invalid mDCv chunk size:
> %d\n", bytestream2_get_bytes_left(&gb_chunk));
> + av_log(avctx, AV_LOG_WARNING, "Invalid mDCV chunk size:
> %d\n", bytestream2_get_bytes_left(&gb_chunk));
> break;
> }
> s->have_mdcv = 1;
> diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c
> index cb79c04e11..37e8d5bfcf 100644
> --- a/libavcodec/pngenc.c
> +++ b/libavcodec/pngenc.c
> @@ -445,7 +445,7 @@ static int encode_headers(AVCodecContext *avctx, const
> AVFrame *pict)
> AVContentLightMetadata *clli = (AVContentLightMetadata *)
> side_data->data;
> AV_WB32(s->buf, clli->MaxCLL * 10000);
> AV_WB32(s->buf + 4, clli->MaxFALL * 10000);
> - png_write_chunk(&s->bytestream, MKTAG('c', 'L', 'L', 'i'), s->buf,
> 8);
> + png_write_chunk(&s->bytestream, MKTAG('c', 'L', 'L', 'I'), s->buf,
> 8);
> }
>
> side_data = av_frame_get_side_data(pict,
> AV_FRAME_DATA_MASTERING_DISPLAY_METADATA);
> @@ -460,7 +460,7 @@ static int encode_headers(AVCodecContext *avctx, const
> AVFrame *pict)
> AV_WB16(s->buf + 14, PNG_Q2D(mdcv->white_point[1], 50000));
> AV_WB32(s->buf + 16, PNG_Q2D(mdcv->max_luminance, 10000));
> AV_WB32(s->buf + 20, PNG_Q2D(mdcv->min_luminance, 10000));
> - png_write_chunk(&s->bytestream, MKTAG('m', 'D', 'C', 'v'),
> s->buf, 24);
> + png_write_chunk(&s->bytestream, MKTAG('m', 'D', 'C', 'V'),
> s->buf, 24);
> }
> }
>
> diff --git a/tests/ref/fate/png-mdcv b/tests/ref/fate/png-mdcv
> index c524a94ded..4328c56349 100644
> --- a/tests/ref/fate/png-mdcv
> +++ b/tests/ref/fate/png-mdcv
> @@ -1,4 +1,4 @@
> -fc68fe6c8c72343b96d2695f6913995b *tests/data/fate/png-mdcv.image2pipe
> +b1837f5557ad969a3f9763840480d5c0 *tests/data/fate/png-mdcv.image2pipe
> 439248 tests/data/fate/png-mdcv.image2pipe
> #tb 0: 1/25
> #media_type 0: video
> --
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
