diff mbox series

[FFmpeg-devel,v3] avcodec/libjxlenc: support negative linesizes

Message ID 20240130152424.56123-1-leo.izen@gmail.com
State Accepted
Commit c0de7ac52067efe27d8515de7a078afe441ec0ec
Headers show
Series [FFmpeg-devel,v3] avcodec/libjxlenc: support negative linesizes | expand

Checks

Context Check Description
yinshiyou/make_loongarch64 success Make finished
yinshiyou/make_fate_loongarch64 success Make fate finished
andriy/make_x86 success Make finished
andriy/make_fate_x86 success Make fate finished

Commit Message

Leo Izen Jan. 30, 2024, 3:24 p.m. UTC 
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 <leo.izen@gmail.com>
---
 libavcodec/libjxlenc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Comments

Leo Izen Jan. 30, 2024, 3:25 p.m. UTC | #1 
On 1/30/24 10:24, Leo Izen wrote:
> +        jxl_fmt.align = -frame->linesize[0];
> +        data = frame->data[0] + frame->linesize[0] * (info.ysize - 1);
> +    }
>   

Something like this ^ is what you're requesting, right?

- Leo Izen (Traneptora)
diff mbox series

Patch

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;
     }