From c0de7ac52067efe27d8515de7a078afe441ec0ec Mon Sep 17 00:00:00 2001 From: Leo Izen Date: Mon, 29 Jan 2024 19:34:03 -0500 Subject: [PATCH] avcodec/libjxlenc: support negative linesizes libjxl doesn't support negative strides, but JPEG XL has an orientation flag inside the codestream. We can use this to work around the library limitation, by taking the absolute value of the negative row stride, sending the image up-side-down, and telling the library that the image has a vertical-flip orientation. Signed-off-by: Leo Izen --- libavcodec/libjxlenc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/libavcodec/libjxlenc.c b/libavcodec/libjxlenc.c index 67be8a01ca..5f5f9751dc 100644 --- a/libavcodec/libjxlenc.c +++ b/libavcodec/libjxlenc.c @@ -259,6 +259,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra size_t available = ctx->buffer_size; size_t bytes_written = 0; uint8_t *next_out = ctx->buffer; + const uint8_t *data; ret = libjxl_init_jxl_encoder(avctx); if (ret) { @@ -303,6 +304,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra /* bitexact lossless requires there to be no XYB transform */ info.uses_original_profile = ctx->distance == 0.0; + info.orientation = frame->linesize[0] >= 0 ? JXL_ORIENT_IDENTITY : JXL_ORIENT_FLIP_VERTICAL; if (JxlEncoderSetBasicInfo(ctx->encoder, &info) != JXL_ENC_SUCCESS) { av_log(avctx, AV_LOG_ERROR, "Failed to set JxlBasicInfo\n"); @@ -383,9 +385,15 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra } jxl_fmt.endianness = JXL_NATIVE_ENDIAN; - jxl_fmt.align = frame->linesize[0]; + if (frame->linesize[0] >= 0) { + jxl_fmt.align = frame->linesize[0]; + data = frame->data[0]; + } else { + jxl_fmt.align = -frame->linesize[0]; + data = frame->data[0] + frame->linesize[0] * (info.ysize - 1); + } - if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, frame->data[0], jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { + if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, data, jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { av_log(avctx, AV_LOG_ERROR, "Failed to add Image Frame\n"); return AVERROR_EXTERNAL; }